Merge pull request #3239 from opatomic/win2kdns

add support for win2k
diff --git a/.gitignore b/.gitignore
index 0f95b4c..ee2cd46 100644
--- a/.gitignore
+++ b/.gitignore
@@ -34,6 +34,9 @@
 # CMake generates *.dir/ folders for in-tree builds (used by MSVC projects), ignore all of those:
 *.dir/
 
+# Microsoft CMake extension for Visual Studio Code generates a build directory by default
+/build/
+
 # Visual Studio artifacts
 /visualc/VS2010/.localhistory/
 /visualc/VS2010/.vs/
diff --git a/.travis.yml b/.travis.yml
index 0685bdb..c67c0cd 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,28 +1,60 @@
 language: c
-compiler:
-- clang
-- gcc
+compiler: gcc
 sudo: false
 cache: ccache
 
-script:
-- tests/scripts/recursion.pl library/*.c
-- tests/scripts/check-generated-files.sh
-- tests/scripts/check-doxy-blocks.pl
-- tests/scripts/check-names.sh
-- tests/scripts/check-files.py
-- tests/scripts/doxygen.sh
-- cmake -D CMAKE_BUILD_TYPE:String="Check" .
-- make
-- make test
-- programs/test/selftest
-- OSSL_NO_DTLS=1 tests/compat.sh
-- tests/ssl-opt.sh -e '\(DTLS\|SCSV\).*openssl'
-- tests/scripts/test-ref-configs.pl
-- tests/scripts/curves.pl
-- tests/scripts/key-exchanges.pl
+jobs:
+  include:
+    - name: basic checks and reference configurations
+      addons:
+        apt:
+          packages:
+          - gnutls-bin
+          - doxygen
+          - graphviz
+          - gcc-arm-none-eabi
+          - libnewlib-arm-none-eabi
+      language: python # Needed to get pip for Python 3
+      python: 3.5 # version from Ubuntu 16.04
+      install:
+        - pip install pylint==2.4.4
+      script:
+        - tests/scripts/all.sh -k 'check_*'
+        - tests/scripts/all.sh -k test_default_out_of_box
+        - tests/scripts/test-ref-configs.pl
+        - tests/scripts/all.sh -k build_arm_none_eabi_gcc_arm5vte build_arm_none_eabi_gcc_m0plus
+
+    - name: full configuration
+      script:
+        - tests/scripts/all.sh -k test_full_cmake_gcc_asan
+
+    - name: check compilation guards
+      script:
+        - tests/scripts/all.sh -k 'test_depends_*' 'build_key_exchanges'
+
+    - name: macOS
+      os: osx
+      compiler: clang
+      script:
+        - tests/scripts/all.sh -k test_default_out_of_box
+
+    - name: Windows
+      os: windows
+      before_install:
+        - choco install python --version=3.5.4
+      env:
+        # Add the directory where the Choco package goes
+        - PATH=/c/Python35:/c/Python35/Scripts:$PATH
+      script:
+        - type python; python --version
+        - python scripts/generate_psa_constants.py
+        # Logs appear out of sequence on Windows. Give time to catch up.
+        - sleep 5
+        - scripts/windows_msbuild.bat v141 # Visual Studio 2017
+
 after_failure:
 - tests/scripts/travis-log-failure.sh
+
 env:
   global:
     - SEED=1
@@ -31,8 +63,7 @@
 addons:
   apt:
     packages:
-    - doxygen
-    - graphviz
+    - gnutls-bin
   coverity_scan:
     project:
       name: "ARMmbed/mbedtls"
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4d17af8..c84194c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -14,6 +14,7 @@
 option(ENABLE_PROGRAMS "Build mbed TLS programs." ON)
 
 option(UNSAFE_BUILD "Allow unsafe builds. These builds ARE NOT SECURE." OFF)
+option(MBEDTLS_FATAL_WARNINGS "Compiler warnings treated as errors" ON)
 
 string(REGEX MATCH "Clang" CMAKE_COMPILER_IS_CLANG "${CMAKE_C_COMPILER_ID}")
 string(REGEX MATCH "GNU" CMAKE_COMPILER_IS_GNU "${CMAKE_C_COMPILER_ID}")
@@ -140,9 +141,9 @@
     set(CMAKE_C_FLAGS_RELEASE     "-O2")
     set(CMAKE_C_FLAGS_DEBUG       "-O0 -g3")
     set(CMAKE_C_FLAGS_COVERAGE    "-O0 -g3 --coverage")
-    set(CMAKE_C_FLAGS_ASAN        "-Werror -fsanitize=address -fno-common -fsanitize=undefined -fno-sanitize-recover=all -O3")
-    set(CMAKE_C_FLAGS_ASANDBG     "-Werror -fsanitize=address -fno-common -fsanitize=undefined -fno-sanitize-recover=all -O1 -g3 -fno-omit-frame-pointer -fno-optimize-sibling-calls")
-    set(CMAKE_C_FLAGS_CHECK       "-Werror -Os")
+    set(CMAKE_C_FLAGS_ASAN        "-fsanitize=address -fno-common -fsanitize=undefined -fno-sanitize-recover=all -O3")
+    set(CMAKE_C_FLAGS_ASANDBG     "-fsanitize=address -fno-common -fsanitize=undefined -fno-sanitize-recover=all -O1 -g3 -fno-omit-frame-pointer -fno-optimize-sibling-calls")
+    set(CMAKE_C_FLAGS_CHECK       "-Os")
     set(CMAKE_C_FLAGS_CHECKFULL   "${CMAKE_C_FLAGS_CHECK} -Wcast-qual")
 endif(CMAKE_COMPILER_IS_GNU)
 
@@ -151,11 +152,11 @@
     set(CMAKE_C_FLAGS_RELEASE     "-O2")
     set(CMAKE_C_FLAGS_DEBUG       "-O0 -g3")
     set(CMAKE_C_FLAGS_COVERAGE    "-O0 -g3 --coverage")
-    set(CMAKE_C_FLAGS_ASAN        "-Werror -fsanitize=address -fno-common -fsanitize=undefined -fno-sanitize-recover=all -O3")
-    set(CMAKE_C_FLAGS_ASANDBG     "-Werror -fsanitize=address -fno-common -fsanitize=undefined -fno-sanitize-recover=all -O1 -g3 -fno-omit-frame-pointer -fno-optimize-sibling-calls")
-    set(CMAKE_C_FLAGS_MEMSAN      "-Werror -fsanitize=memory -O3")
-    set(CMAKE_C_FLAGS_MEMSANDBG   "-Werror -fsanitize=memory -O1 -g3 -fno-omit-frame-pointer -fno-optimize-sibling-calls -fsanitize-memory-track-origins=2")
-    set(CMAKE_C_FLAGS_CHECK       "-Werror -Os")
+    set(CMAKE_C_FLAGS_ASAN        "-fsanitize=address -fno-common -fsanitize=undefined -fno-sanitize-recover=all -O3")
+    set(CMAKE_C_FLAGS_ASANDBG     "-fsanitize=address -fno-common -fsanitize=undefined -fno-sanitize-recover=all -O1 -g3 -fno-omit-frame-pointer -fno-optimize-sibling-calls")
+    set(CMAKE_C_FLAGS_MEMSAN      "-fsanitize=memory -O3")
+    set(CMAKE_C_FLAGS_MEMSANDBG   "-fsanitize=memory -O1 -g3 -fno-omit-frame-pointer -fno-optimize-sibling-calls -fsanitize-memory-track-origins=2")
+    set(CMAKE_C_FLAGS_CHECK       "-Os")
 endif(CMAKE_COMPILER_IS_CLANG)
 
 if(CMAKE_COMPILER_IS_IAR)
@@ -163,11 +164,25 @@
 endif(CMAKE_COMPILER_IS_IAR)
 
 if(CMAKE_COMPILER_IS_MSVC)
-    # Strictest warnings, and treat as errors
+    # Strictest warnings
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /W3")
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /WX")
 endif(CMAKE_COMPILER_IS_MSVC)
 
+if(MBEDTLS_FATAL_WARNINGS)
+    if(CMAKE_COMPILER_IS_MSVC)
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /WX")
+    endif(CMAKE_COMPILER_IS_MSVC)
+
+    if(CMAKE_COMPILER_IS_CLANG OR CMAKE_COMPILER_IS_GNU)
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Werror")
+        if(UNSAFE_BUILD)
+            set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-error=cpp")
+            set(CMAKE_C_FLAGS_ASAN "${CMAKE_C_FLAGS_ASAN} -Wno-error=cpp")
+            set(CMAKE_C_FLAGS_ASANDBG "${CMAKE_C_FLAGS_ASANDBG} -Wno-error=cpp")
+        endif(UNSAFE_BUILD)
+    endif(CMAKE_COMPILER_IS_CLANG OR CMAKE_COMPILER_IS_GNU)
+endif(MBEDTLS_FATAL_WARNINGS)
+
 if(CMAKE_BUILD_TYPE STREQUAL "Coverage")
     if(CMAKE_COMPILER_IS_GNU OR CMAKE_COMPILER_IS_CLANG)
         set(CMAKE_SHARED_LINKER_FLAGS "--coverage")
diff --git a/ChangeLog.d/bugfix.txt b/ChangeLog.d/bugfix.txt
new file mode 100644
index 0000000..499fd40
--- /dev/null
+++ b/ChangeLog.d/bugfix.txt
@@ -0,0 +1,4 @@
+Bugfix
+   * Fix the Visual Studio Release x64 build configuration for mbedtls itself.
+     Completes a previous fix in Mbed TLS 2.19 that only fixed the build for
+     the example programs. Reported in #1430 and fix contributed by irwir.
\ No newline at end of file
diff --git a/ChangeLog.d/error_const.txt b/ChangeLog.d/error_const.txt
new file mode 100644
index 0000000..e0086b7
--- /dev/null
+++ b/ChangeLog.d/error_const.txt
@@ -0,0 +1,6 @@
+Features
+   * New functions in the error module return constant strings for
+     high- and low-level error codes, complementing mbedtls_strerror()
+     which constructs a string for any error code, including compound
+     ones, but requires a writable buffer. Contributed by Gaurav Aggarwal
+     in #3176.
diff --git a/ChangeLog.d/fix-ecp_double_add_mxz.txt b/ChangeLog.d/fix-ecp_double_add_mxz.txt
new file mode 100644
index 0000000..91531b2
--- /dev/null
+++ b/ChangeLog.d/fix-ecp_double_add_mxz.txt
@@ -0,0 +1,4 @@
+Changes
+   * Fix minor performance issue in operations on Curve25519 caused by using a
+     suboptimal modular reduction in one place. Found and fix contributed by
+     Aurelien Jarno in #3209.
diff --git a/ChangeLog.d/max_pathlen.txt b/ChangeLog.d/max_pathlen.txt
new file mode 100644
index 0000000..08f9c65
--- /dev/null
+++ b/ChangeLog.d/max_pathlen.txt
@@ -0,0 +1,5 @@
+Bugfix
+   * Fix undefined behavior in X.509 certificate parsing if the
+     pathLenConstraint basic constraint value is equal to INT_MAX.
+     The actual effect with almost every compiler is the intended
+     behavior, so this is unlikely to be exploitable anywhere. #3192
diff --git a/ChangeLog.d/md_switch.txt b/ChangeLog.d/md_switch.txt
new file mode 100644
index 0000000..a4d369b
--- /dev/null
+++ b/ChangeLog.d/md_switch.txt
@@ -0,0 +1,3 @@
+Changes
+   * Combine identical cases in switch statements in md.c. Contributed
+     by irwir in #3208.
diff --git a/ChangeLog.d/ssl_context_info.txt b/ChangeLog.d/ssl_context_info.txt
new file mode 100644
index 0000000..6a15061
--- /dev/null
+++ b/ChangeLog.d/ssl_context_info.txt
@@ -0,0 +1,3 @@
+Features
+   * The new utility programs/ssl/ssl_context_info prints a human-readable
+     dump of an SSL context saved with mbedtls_ssl_context_save().
diff --git a/ChangeLog.d/ssl_write_certificate_request.txt b/ChangeLog.d/ssl_write_certificate_request.txt
new file mode 100644
index 0000000..2d3067a
--- /dev/null
+++ b/ChangeLog.d/ssl_write_certificate_request.txt
@@ -0,0 +1,3 @@
+Changes
+   * Simplify a bounds check in ssl_write_certificate_request(). Contributed
+     by irwir in #3150.
diff --git a/README.md b/README.md
index f868a0a..2058d24 100644
--- a/README.md
+++ b/README.md
@@ -85,11 +85,11 @@
 
     mkdir /path/to/build_dir && cd /path/to/build_dir
     cmake /path/to/mbedtls_source
-    make
+    cmake --build .
 
 In order to run the tests, enter:
 
-    make test
+    ctest
 
 The test suites need Python to be built and Perl to be executed. If you don't have one of these installed, you'll want to disable the test suites with:
 
diff --git a/library/CMakeLists.txt b/library/CMakeLists.txt
index fd98fa5..f6a186f 100644
--- a/library/CMakeLists.txt
+++ b/library/CMakeLists.txt
@@ -113,12 +113,6 @@
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wmissing-declarations -Wmissing-prototypes -Wdocumentation -Wno-documentation-deprecated-sync -Wunreachable-code")
 endif(CMAKE_COMPILER_IS_CLANG)
 
-if(UNSAFE_BUILD)
-    set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wno-error")
-    set(CMAKE_C_FLAGS_ASAN "${CMAKE_C_FLAGS_ASAN} -Wno-error")
-    set(CMAKE_C_FLAGS_ASANDBG "${CMAKE_C_FLAGS_ASANDBG} -Wno-error")
-endif(UNSAFE_BUILD)
-
 if(WIN32)
     set(libs ${libs} ws2_32)
 endif(WIN32)
diff --git a/library/ecp.c b/library/ecp.c
index fa91b3e..104e1f1 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -2332,7 +2332,7 @@
     MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mod( grp, &D,    &Q->X,   &Q->Z ) );
     MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mod( grp, &DA,   &D,      &A    ) );
     MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mod( grp, &CB,   &C,      &B    ) );
-    MBEDTLS_MPI_CHK( mbedtls_mpi_add_mpi( &S->X, &DA,     &CB   ) ); MOD_MUL( S->X );
+    MBEDTLS_MPI_CHK( mbedtls_mpi_add_mod( grp, &S->X, &DA,     &CB   ) );
     MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mod( grp, &S->X, &S->X,   &S->X ) );
     MBEDTLS_MPI_CHK( mbedtls_mpi_sub_mod( grp, &S->Z, &DA,     &CB   ) );
     MBEDTLS_MPI_CHK( mbedtls_mpi_mul_mod( grp, &S->Z, &S->Z,   &S->Z ) );
diff --git a/library/error.c b/library/error.c
index d2f1b18..22c7b16 100644
--- a/library/error.c
+++ b/library/error.c
@@ -216,7 +216,6 @@
 const char * mbedtls_high_level_strerr( int error_code )
 {
     int high_level_error_code;
-    const char *error_description = NULL;
 
     if( error_code < 0 )
         error_code = -error_code;
@@ -229,497 +228,343 @@
         /* Begin Auto-Generated Code. */
 #if defined(MBEDTLS_CIPHER_C)
         case -(MBEDTLS_ERR_CIPHER_FEATURE_UNAVAILABLE):
-            error_description = "CIPHER - The selected feature is not available";
-            break;
+            return( "CIPHER - The selected feature is not available" );
         case -(MBEDTLS_ERR_CIPHER_BAD_INPUT_DATA):
-            error_description = "CIPHER - Bad input parameters";
-            break;
+            return( "CIPHER - Bad input parameters" );
         case -(MBEDTLS_ERR_CIPHER_ALLOC_FAILED):
-            error_description = "CIPHER - Failed to allocate memory";
-            break;
+            return( "CIPHER - Failed to allocate memory" );
         case -(MBEDTLS_ERR_CIPHER_INVALID_PADDING):
-            error_description = "CIPHER - Input data contains invalid padding and is rejected";
-            break;
+            return( "CIPHER - Input data contains invalid padding and is rejected" );
         case -(MBEDTLS_ERR_CIPHER_FULL_BLOCK_EXPECTED):
-            error_description = "CIPHER - Decryption of block requires a full block";
-            break;
+            return( "CIPHER - Decryption of block requires a full block" );
         case -(MBEDTLS_ERR_CIPHER_AUTH_FAILED):
-            error_description = "CIPHER - Authentication failed (for AEAD modes)";
-            break;
+            return( "CIPHER - Authentication failed (for AEAD modes)" );
         case -(MBEDTLS_ERR_CIPHER_INVALID_CONTEXT):
-            error_description = "CIPHER - The context is invalid. For example, because it was freed";
-            break;
+            return( "CIPHER - The context is invalid. For example, because it was freed" );
         case -(MBEDTLS_ERR_CIPHER_HW_ACCEL_FAILED):
-            error_description = "CIPHER - Cipher hardware accelerator failed";
-            break;
+            return( "CIPHER - Cipher hardware accelerator failed" );
 #endif /* MBEDTLS_CIPHER_C */
 
 #if defined(MBEDTLS_DHM_C)
         case -(MBEDTLS_ERR_DHM_BAD_INPUT_DATA):
-            error_description = "DHM - Bad input parameters";
-            break;
+            return( "DHM - Bad input parameters" );
         case -(MBEDTLS_ERR_DHM_READ_PARAMS_FAILED):
-            error_description = "DHM - Reading of the DHM parameters failed";
-            break;
+            return( "DHM - Reading of the DHM parameters failed" );
         case -(MBEDTLS_ERR_DHM_MAKE_PARAMS_FAILED):
-            error_description = "DHM - Making of the DHM parameters failed";
-            break;
+            return( "DHM - Making of the DHM parameters failed" );
         case -(MBEDTLS_ERR_DHM_READ_PUBLIC_FAILED):
-            error_description = "DHM - Reading of the public values failed";
-            break;
+            return( "DHM - Reading of the public values failed" );
         case -(MBEDTLS_ERR_DHM_MAKE_PUBLIC_FAILED):
-            error_description = "DHM - Making of the public value failed";
-            break;
+            return( "DHM - Making of the public value failed" );
         case -(MBEDTLS_ERR_DHM_CALC_SECRET_FAILED):
-            error_description = "DHM - Calculation of the DHM secret failed";
-            break;
+            return( "DHM - Calculation of the DHM secret failed" );
         case -(MBEDTLS_ERR_DHM_INVALID_FORMAT):
-            error_description = "DHM - The ASN.1 data is not formatted correctly";
-            break;
+            return( "DHM - The ASN.1 data is not formatted correctly" );
         case -(MBEDTLS_ERR_DHM_ALLOC_FAILED):
-            error_description = "DHM - Allocation of memory failed";
-            break;
+            return( "DHM - Allocation of memory failed" );
         case -(MBEDTLS_ERR_DHM_FILE_IO_ERROR):
-            error_description = "DHM - Read or write of file failed";
-            break;
+            return( "DHM - Read or write of file failed" );
         case -(MBEDTLS_ERR_DHM_HW_ACCEL_FAILED):
-            error_description = "DHM - DHM hardware accelerator failed";
-            break;
+            return( "DHM - DHM hardware accelerator failed" );
         case -(MBEDTLS_ERR_DHM_SET_GROUP_FAILED):
-            error_description = "DHM - Setting the modulus and generator failed";
-            break;
+            return( "DHM - Setting the modulus and generator failed" );
 #endif /* MBEDTLS_DHM_C */
 
 #if defined(MBEDTLS_ECP_C)
         case -(MBEDTLS_ERR_ECP_BAD_INPUT_DATA):
-            error_description = "ECP - Bad input parameters to function";
-            break;
+            return( "ECP - Bad input parameters to function" );
         case -(MBEDTLS_ERR_ECP_BUFFER_TOO_SMALL):
-            error_description = "ECP - The buffer is too small to write to";
-            break;
+            return( "ECP - The buffer is too small to write to" );
         case -(MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE):
-            error_description = "ECP - The requested feature is not available, for example, the requested curve is not supported";
-            break;
+            return( "ECP - The requested feature is not available, for example, the requested curve is not supported" );
         case -(MBEDTLS_ERR_ECP_VERIFY_FAILED):
-            error_description = "ECP - The signature is not valid";
-            break;
+            return( "ECP - The signature is not valid" );
         case -(MBEDTLS_ERR_ECP_ALLOC_FAILED):
-            error_description = "ECP - Memory allocation failed";
-            break;
+            return( "ECP - Memory allocation failed" );
         case -(MBEDTLS_ERR_ECP_RANDOM_FAILED):
-            error_description = "ECP - Generation of random value, such as ephemeral key, failed";
-            break;
+            return( "ECP - Generation of random value, such as ephemeral key, failed" );
         case -(MBEDTLS_ERR_ECP_INVALID_KEY):
-            error_description = "ECP - Invalid private or public key";
-            break;
+            return( "ECP - Invalid private or public key" );
         case -(MBEDTLS_ERR_ECP_SIG_LEN_MISMATCH):
-            error_description = "ECP - The buffer contains a valid signature followed by more data";
-            break;
+            return( "ECP - The buffer contains a valid signature followed by more data" );
         case -(MBEDTLS_ERR_ECP_HW_ACCEL_FAILED):
-            error_description = "ECP - The ECP hardware accelerator failed";
-            break;
+            return( "ECP - The ECP hardware accelerator failed" );
         case -(MBEDTLS_ERR_ECP_IN_PROGRESS):
-            error_description = "ECP - Operation in progress, call again with the same parameters to continue";
-            break;
+            return( "ECP - Operation in progress, call again with the same parameters to continue" );
 #endif /* MBEDTLS_ECP_C */
 
 #if defined(MBEDTLS_MD_C)
         case -(MBEDTLS_ERR_MD_FEATURE_UNAVAILABLE):
-            error_description = "MD - The selected feature is not available";
-            break;
+            return( "MD - The selected feature is not available" );
         case -(MBEDTLS_ERR_MD_BAD_INPUT_DATA):
-            error_description = "MD - Bad input parameters to function";
-            break;
+            return( "MD - Bad input parameters to function" );
         case -(MBEDTLS_ERR_MD_ALLOC_FAILED):
-            error_description = "MD - Failed to allocate memory";
-            break;
+            return( "MD - Failed to allocate memory" );
         case -(MBEDTLS_ERR_MD_FILE_IO_ERROR):
-            error_description = "MD - Opening or reading of file failed";
-            break;
+            return( "MD - Opening or reading of file failed" );
         case -(MBEDTLS_ERR_MD_HW_ACCEL_FAILED):
-            error_description = "MD - MD hardware accelerator failed";
-            break;
+            return( "MD - MD hardware accelerator failed" );
 #endif /* MBEDTLS_MD_C */
 
 #if defined(MBEDTLS_PEM_PARSE_C) || defined(MBEDTLS_PEM_WRITE_C)
         case -(MBEDTLS_ERR_PEM_NO_HEADER_FOOTER_PRESENT):
-            error_description = "PEM - No PEM header or footer found";
-            break;
+            return( "PEM - No PEM header or footer found" );
         case -(MBEDTLS_ERR_PEM_INVALID_DATA):
-            error_description = "PEM - PEM string is not as expected";
-            break;
+            return( "PEM - PEM string is not as expected" );
         case -(MBEDTLS_ERR_PEM_ALLOC_FAILED):
-            error_description = "PEM - Failed to allocate memory";
-            break;
+            return( "PEM - Failed to allocate memory" );
         case -(MBEDTLS_ERR_PEM_INVALID_ENC_IV):
-            error_description = "PEM - RSA IV is not in hex-format";
-            break;
+            return( "PEM - RSA IV is not in hex-format" );
         case -(MBEDTLS_ERR_PEM_UNKNOWN_ENC_ALG):
-            error_description = "PEM - Unsupported key encryption algorithm";
-            break;
+            return( "PEM - Unsupported key encryption algorithm" );
         case -(MBEDTLS_ERR_PEM_PASSWORD_REQUIRED):
-            error_description = "PEM - Private key password can't be empty";
-            break;
+            return( "PEM - Private key password can't be empty" );
         case -(MBEDTLS_ERR_PEM_PASSWORD_MISMATCH):
-            error_description = "PEM - Given private key password does not allow for correct decryption";
-            break;
+            return( "PEM - Given private key password does not allow for correct decryption" );
         case -(MBEDTLS_ERR_PEM_FEATURE_UNAVAILABLE):
-            error_description = "PEM - Unavailable feature, e.g. hashing/encryption combination";
-            break;
+            return( "PEM - Unavailable feature, e.g. hashing/encryption combination" );
         case -(MBEDTLS_ERR_PEM_BAD_INPUT_DATA):
-            error_description = "PEM - Bad input parameters to function";
-            break;
+            return( "PEM - Bad input parameters to function" );
 #endif /* MBEDTLS_PEM_PARSE_C || MBEDTLS_PEM_WRITE_C */
 
 #if defined(MBEDTLS_PK_C)
         case -(MBEDTLS_ERR_PK_ALLOC_FAILED):
-            error_description = "PK - Memory allocation failed";
-            break;
+            return( "PK - Memory allocation failed" );
         case -(MBEDTLS_ERR_PK_TYPE_MISMATCH):
-            error_description = "PK - Type mismatch, eg attempt to encrypt with an ECDSA key";
-            break;
+            return( "PK - Type mismatch, eg attempt to encrypt with an ECDSA key" );
         case -(MBEDTLS_ERR_PK_BAD_INPUT_DATA):
-            error_description = "PK - Bad input parameters to function";
-            break;
+            return( "PK - Bad input parameters to function" );
         case -(MBEDTLS_ERR_PK_FILE_IO_ERROR):
-            error_description = "PK - Read/write of file failed";
-            break;
+            return( "PK - Read/write of file failed" );
         case -(MBEDTLS_ERR_PK_KEY_INVALID_VERSION):
-            error_description = "PK - Unsupported key version";
-            break;
+            return( "PK - Unsupported key version" );
         case -(MBEDTLS_ERR_PK_KEY_INVALID_FORMAT):
-            error_description = "PK - Invalid key tag or value";
-            break;
+            return( "PK - Invalid key tag or value" );
         case -(MBEDTLS_ERR_PK_UNKNOWN_PK_ALG):
-            error_description = "PK - Key algorithm is unsupported (only RSA and EC are supported)";
-            break;
+            return( "PK - Key algorithm is unsupported (only RSA and EC are supported)" );
         case -(MBEDTLS_ERR_PK_PASSWORD_REQUIRED):
-            error_description = "PK - Private key password can't be empty";
-            break;
+            return( "PK - Private key password can't be empty" );
         case -(MBEDTLS_ERR_PK_PASSWORD_MISMATCH):
-            error_description = "PK - Given private key password does not allow for correct decryption";
-            break;
+            return( "PK - Given private key password does not allow for correct decryption" );
         case -(MBEDTLS_ERR_PK_INVALID_PUBKEY):
-            error_description = "PK - The pubkey tag or value is invalid (only RSA and EC are supported)";
-            break;
+            return( "PK - The pubkey tag or value is invalid (only RSA and EC are supported)" );
         case -(MBEDTLS_ERR_PK_INVALID_ALG):
-            error_description = "PK - The algorithm tag or value is invalid";
-            break;
+            return( "PK - The algorithm tag or value is invalid" );
         case -(MBEDTLS_ERR_PK_UNKNOWN_NAMED_CURVE):
-            error_description = "PK - Elliptic curve is unsupported (only NIST curves are supported)";
-            break;
+            return( "PK - Elliptic curve is unsupported (only NIST curves are supported)" );
         case -(MBEDTLS_ERR_PK_FEATURE_UNAVAILABLE):
-            error_description = "PK - Unavailable feature, e.g. RSA disabled for RSA key";
-            break;
+            return( "PK - Unavailable feature, e.g. RSA disabled for RSA key" );
         case -(MBEDTLS_ERR_PK_SIG_LEN_MISMATCH):
-            error_description = "PK - The buffer contains a valid signature followed by more data";
-            break;
+            return( "PK - The buffer contains a valid signature followed by more data" );
         case -(MBEDTLS_ERR_PK_HW_ACCEL_FAILED):
-            error_description = "PK - PK hardware accelerator failed";
-            break;
+            return( "PK - PK hardware accelerator failed" );
 #endif /* MBEDTLS_PK_C */
 
 #if defined(MBEDTLS_PKCS12_C)
         case -(MBEDTLS_ERR_PKCS12_BAD_INPUT_DATA):
-            error_description = "PKCS12 - Bad input parameters to function";
-            break;
+            return( "PKCS12 - Bad input parameters to function" );
         case -(MBEDTLS_ERR_PKCS12_FEATURE_UNAVAILABLE):
-            error_description = "PKCS12 - Feature not available, e.g. unsupported encryption scheme";
-            break;
+            return( "PKCS12 - Feature not available, e.g. unsupported encryption scheme" );
         case -(MBEDTLS_ERR_PKCS12_PBE_INVALID_FORMAT):
-            error_description = "PKCS12 - PBE ASN.1 data not as expected";
-            break;
+            return( "PKCS12 - PBE ASN.1 data not as expected" );
         case -(MBEDTLS_ERR_PKCS12_PASSWORD_MISMATCH):
-            error_description = "PKCS12 - Given private key password does not allow for correct decryption";
-            break;
+            return( "PKCS12 - Given private key password does not allow for correct decryption" );
 #endif /* MBEDTLS_PKCS12_C */
 
 #if defined(MBEDTLS_PKCS5_C)
         case -(MBEDTLS_ERR_PKCS5_BAD_INPUT_DATA):
-            error_description = "PKCS5 - Bad input parameters to function";
-            break;
+            return( "PKCS5 - Bad input parameters to function" );
         case -(MBEDTLS_ERR_PKCS5_INVALID_FORMAT):
-            error_description = "PKCS5 - Unexpected ASN.1 data";
-            break;
+            return( "PKCS5 - Unexpected ASN.1 data" );
         case -(MBEDTLS_ERR_PKCS5_FEATURE_UNAVAILABLE):
-            error_description = "PKCS5 - Requested encryption or digest alg not available";
-            break;
+            return( "PKCS5 - Requested encryption or digest alg not available" );
         case -(MBEDTLS_ERR_PKCS5_PASSWORD_MISMATCH):
-            error_description = "PKCS5 - Given private key password does not allow for correct decryption";
-            break;
+            return( "PKCS5 - Given private key password does not allow for correct decryption" );
 #endif /* MBEDTLS_PKCS5_C */
 
 #if defined(MBEDTLS_RSA_C)
         case -(MBEDTLS_ERR_RSA_BAD_INPUT_DATA):
-            error_description = "RSA - Bad input parameters to function";
-            break;
+            return( "RSA - Bad input parameters to function" );
         case -(MBEDTLS_ERR_RSA_INVALID_PADDING):
-            error_description = "RSA - Input data contains invalid padding and is rejected";
-            break;
+            return( "RSA - Input data contains invalid padding and is rejected" );
         case -(MBEDTLS_ERR_RSA_KEY_GEN_FAILED):
-            error_description = "RSA - Something failed during generation of a key";
-            break;
+            return( "RSA - Something failed during generation of a key" );
         case -(MBEDTLS_ERR_RSA_KEY_CHECK_FAILED):
-            error_description = "RSA - Key failed to pass the validity check of the library";
-            break;
+            return( "RSA - Key failed to pass the validity check of the library" );
         case -(MBEDTLS_ERR_RSA_PUBLIC_FAILED):
-            error_description = "RSA - The public key operation failed";
-            break;
+            return( "RSA - The public key operation failed" );
         case -(MBEDTLS_ERR_RSA_PRIVATE_FAILED):
-            error_description = "RSA - The private key operation failed";
-            break;
+            return( "RSA - The private key operation failed" );
         case -(MBEDTLS_ERR_RSA_VERIFY_FAILED):
-            error_description = "RSA - The PKCS#1 verification failed";
-            break;
+            return( "RSA - The PKCS#1 verification failed" );
         case -(MBEDTLS_ERR_RSA_OUTPUT_TOO_LARGE):
-            error_description = "RSA - The output buffer for decryption is not large enough";
-            break;
+            return( "RSA - The output buffer for decryption is not large enough" );
         case -(MBEDTLS_ERR_RSA_RNG_FAILED):
-            error_description = "RSA - The random generator failed to generate non-zeros";
-            break;
+            return( "RSA - The random generator failed to generate non-zeros" );
         case -(MBEDTLS_ERR_RSA_UNSUPPORTED_OPERATION):
-            error_description = "RSA - The implementation does not offer the requested operation, for example, because of security violations or lack of functionality";
-            break;
+            return( "RSA - The implementation does not offer the requested operation, for example, because of security violations or lack of functionality" );
         case -(MBEDTLS_ERR_RSA_HW_ACCEL_FAILED):
-            error_description = "RSA - RSA hardware accelerator failed";
-            break;
+            return( "RSA - RSA hardware accelerator failed" );
 #endif /* MBEDTLS_RSA_C */
 
 #if defined(MBEDTLS_SSL_TLS_C)
         case -(MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE):
-            error_description = "SSL - The requested feature is not available";
-            break;
+            return( "SSL - The requested feature is not available" );
         case -(MBEDTLS_ERR_SSL_BAD_INPUT_DATA):
-            error_description = "SSL - Bad input parameters to function";
-            break;
+            return( "SSL - Bad input parameters to function" );
         case -(MBEDTLS_ERR_SSL_INVALID_MAC):
-            error_description = "SSL - Verification of the message MAC failed";
-            break;
+            return( "SSL - Verification of the message MAC failed" );
         case -(MBEDTLS_ERR_SSL_INVALID_RECORD):
-            error_description = "SSL - An invalid SSL record was received";
-            break;
+            return( "SSL - An invalid SSL record was received" );
         case -(MBEDTLS_ERR_SSL_CONN_EOF):
-            error_description = "SSL - The connection indicated an EOF";
-            break;
+            return( "SSL - The connection indicated an EOF" );
         case -(MBEDTLS_ERR_SSL_UNKNOWN_CIPHER):
-            error_description = "SSL - An unknown cipher was received";
-            break;
+            return( "SSL - An unknown cipher was received" );
         case -(MBEDTLS_ERR_SSL_NO_CIPHER_CHOSEN):
-            error_description = "SSL - The server has no ciphersuites in common with the client";
-            break;
+            return( "SSL - The server has no ciphersuites in common with the client" );
         case -(MBEDTLS_ERR_SSL_NO_RNG):
-            error_description = "SSL - No RNG was provided to the SSL module";
-            break;
+            return( "SSL - No RNG was provided to the SSL module" );
         case -(MBEDTLS_ERR_SSL_NO_CLIENT_CERTIFICATE):
-            error_description = "SSL - No client certification received from the client, but required by the authentication mode";
-            break;
+            return( "SSL - No client certification received from the client, but required by the authentication mode" );
         case -(MBEDTLS_ERR_SSL_CERTIFICATE_TOO_LARGE):
-            error_description = "SSL - Our own certificate(s) is/are too large to send in an SSL message";
-            break;
+            return( "SSL - Our own certificate(s) is/are too large to send in an SSL message" );
         case -(MBEDTLS_ERR_SSL_CERTIFICATE_REQUIRED):
-            error_description = "SSL - The own certificate is not set, but needed by the server";
-            break;
+            return( "SSL - The own certificate is not set, but needed by the server" );
         case -(MBEDTLS_ERR_SSL_PRIVATE_KEY_REQUIRED):
-            error_description = "SSL - The own private key or pre-shared key is not set, but needed";
-            break;
+            return( "SSL - The own private key or pre-shared key is not set, but needed" );
         case -(MBEDTLS_ERR_SSL_CA_CHAIN_REQUIRED):
-            error_description = "SSL - No CA Chain is set, but required to operate";
-            break;
+            return( "SSL - No CA Chain is set, but required to operate" );
         case -(MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE):
-            error_description = "SSL - An unexpected message was received from our peer";
-            break;
+            return( "SSL - An unexpected message was received from our peer" );
         case -(MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE):
-            error_description = "SSL - A fatal alert message was received from our peer";
-            break;
+            return( "SSL - A fatal alert message was received from our peer" );
         case -(MBEDTLS_ERR_SSL_PEER_VERIFY_FAILED):
-            error_description = "SSL - Verification of our peer failed";
-            break;
+            return( "SSL - Verification of our peer failed" );
         case -(MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY):
-            error_description = "SSL - The peer notified us that the connection is going to be closed";
-            break;
+            return( "SSL - The peer notified us that the connection is going to be closed" );
         case -(MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO):
-            error_description = "SSL - Processing of the ClientHello handshake message failed";
-            break;
+            return( "SSL - Processing of the ClientHello handshake message failed" );
         case -(MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO):
-            error_description = "SSL - Processing of the ServerHello handshake message failed";
-            break;
+            return( "SSL - Processing of the ServerHello handshake message failed" );
         case -(MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE):
-            error_description = "SSL - Processing of the Certificate handshake message failed";
-            break;
+            return( "SSL - Processing of the Certificate handshake message failed" );
         case -(MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE_REQUEST):
-            error_description = "SSL - Processing of the CertificateRequest handshake message failed";
-            break;
+            return( "SSL - Processing of the CertificateRequest handshake message failed" );
         case -(MBEDTLS_ERR_SSL_BAD_HS_SERVER_KEY_EXCHANGE):
-            error_description = "SSL - Processing of the ServerKeyExchange handshake message failed";
-            break;
+            return( "SSL - Processing of the ServerKeyExchange handshake message failed" );
         case -(MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO_DONE):
-            error_description = "SSL - Processing of the ServerHelloDone handshake message failed";
-            break;
+            return( "SSL - Processing of the ServerHelloDone handshake message failed" );
         case -(MBEDTLS_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE):
-            error_description = "SSL - Processing of the ClientKeyExchange handshake message failed";
-            break;
+            return( "SSL - Processing of the ClientKeyExchange handshake message failed" );
         case -(MBEDTLS_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE_RP):
-            error_description = "SSL - Processing of the ClientKeyExchange handshake message failed in DHM / ECDH Read Public";
-            break;
+            return( "SSL - Processing of the ClientKeyExchange handshake message failed in DHM / ECDH Read Public" );
         case -(MBEDTLS_ERR_SSL_BAD_HS_CLIENT_KEY_EXCHANGE_CS):
-            error_description = "SSL - Processing of the ClientKeyExchange handshake message failed in DHM / ECDH Calculate Secret";
-            break;
+            return( "SSL - Processing of the ClientKeyExchange handshake message failed in DHM / ECDH Calculate Secret" );
         case -(MBEDTLS_ERR_SSL_BAD_HS_CERTIFICATE_VERIFY):
-            error_description = "SSL - Processing of the CertificateVerify handshake message failed";
-            break;
+            return( "SSL - Processing of the CertificateVerify handshake message failed" );
         case -(MBEDTLS_ERR_SSL_BAD_HS_CHANGE_CIPHER_SPEC):
-            error_description = "SSL - Processing of the ChangeCipherSpec handshake message failed";
-            break;
+            return( "SSL - Processing of the ChangeCipherSpec handshake message failed" );
         case -(MBEDTLS_ERR_SSL_BAD_HS_FINISHED):
-            error_description = "SSL - Processing of the Finished handshake message failed";
-            break;
+            return( "SSL - Processing of the Finished handshake message failed" );
         case -(MBEDTLS_ERR_SSL_ALLOC_FAILED):
-            error_description = "SSL - Memory allocation failed";
-            break;
+            return( "SSL - Memory allocation failed" );
         case -(MBEDTLS_ERR_SSL_HW_ACCEL_FAILED):
-            error_description = "SSL - Hardware acceleration function returned with error";
-            break;
+            return( "SSL - Hardware acceleration function returned with error" );
         case -(MBEDTLS_ERR_SSL_HW_ACCEL_FALLTHROUGH):
-            error_description = "SSL - Hardware acceleration function skipped / left alone data";
-            break;
+            return( "SSL - Hardware acceleration function skipped / left alone data" );
         case -(MBEDTLS_ERR_SSL_COMPRESSION_FAILED):
-            error_description = "SSL - Processing of the compression / decompression failed";
-            break;
+            return( "SSL - Processing of the compression / decompression failed" );
         case -(MBEDTLS_ERR_SSL_BAD_HS_PROTOCOL_VERSION):
-            error_description = "SSL - Handshake protocol not within min/max boundaries";
-            break;
+            return( "SSL - Handshake protocol not within min/max boundaries" );
         case -(MBEDTLS_ERR_SSL_BAD_HS_NEW_SESSION_TICKET):
-            error_description = "SSL - Processing of the NewSessionTicket handshake message failed";
-            break;
+            return( "SSL - Processing of the NewSessionTicket handshake message failed" );
         case -(MBEDTLS_ERR_SSL_SESSION_TICKET_EXPIRED):
-            error_description = "SSL - Session ticket has expired";
-            break;
+            return( "SSL - Session ticket has expired" );
         case -(MBEDTLS_ERR_SSL_PK_TYPE_MISMATCH):
-            error_description = "SSL - Public key type mismatch (eg, asked for RSA key exchange and presented EC key)";
-            break;
+            return( "SSL - Public key type mismatch (eg, asked for RSA key exchange and presented EC key)" );
         case -(MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY):
-            error_description = "SSL - Unknown identity received (eg, PSK identity)";
-            break;
+            return( "SSL - Unknown identity received (eg, PSK identity)" );
         case -(MBEDTLS_ERR_SSL_INTERNAL_ERROR):
-            error_description = "SSL - Internal error (eg, unexpected failure in lower-level module)";
-            break;
+            return( "SSL - Internal error (eg, unexpected failure in lower-level module)" );
         case -(MBEDTLS_ERR_SSL_COUNTER_WRAPPING):
-            error_description = "SSL - A counter would wrap (eg, too many messages exchanged)";
-            break;
+            return( "SSL - A counter would wrap (eg, too many messages exchanged)" );
         case -(MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO):
-            error_description = "SSL - Unexpected message at ServerHello in renegotiation";
-            break;
+            return( "SSL - Unexpected message at ServerHello in renegotiation" );
         case -(MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED):
-            error_description = "SSL - DTLS client must retry for hello verification";
-            break;
+            return( "SSL - DTLS client must retry for hello verification" );
         case -(MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL):
-            error_description = "SSL - A buffer is too small to receive or write a message";
-            break;
+            return( "SSL - A buffer is too small to receive or write a message" );
         case -(MBEDTLS_ERR_SSL_NO_USABLE_CIPHERSUITE):
-            error_description = "SSL - None of the common ciphersuites is usable (eg, no suitable certificate, see debug messages)";
-            break;
+            return( "SSL - None of the common ciphersuites is usable (eg, no suitable certificate, see debug messages)" );
         case -(MBEDTLS_ERR_SSL_WANT_READ):
-            error_description = "SSL - No data of requested type currently available on underlying transport";
-            break;
+            return( "SSL - No data of requested type currently available on underlying transport" );
         case -(MBEDTLS_ERR_SSL_WANT_WRITE):
-            error_description = "SSL - Connection requires a write call";
-            break;
+            return( "SSL - Connection requires a write call" );
         case -(MBEDTLS_ERR_SSL_TIMEOUT):
-            error_description = "SSL - The operation timed out";
-            break;
+            return( "SSL - The operation timed out" );
         case -(MBEDTLS_ERR_SSL_CLIENT_RECONNECT):
-            error_description = "SSL - The client initiated a reconnect from the same port";
-            break;
+            return( "SSL - The client initiated a reconnect from the same port" );
         case -(MBEDTLS_ERR_SSL_UNEXPECTED_RECORD):
-            error_description = "SSL - Record header looks valid but is not expected";
-            break;
+            return( "SSL - Record header looks valid but is not expected" );
         case -(MBEDTLS_ERR_SSL_NON_FATAL):
-            error_description = "SSL - The alert message received indicates a non-fatal error";
-            break;
+            return( "SSL - The alert message received indicates a non-fatal error" );
         case -(MBEDTLS_ERR_SSL_INVALID_VERIFY_HASH):
-            error_description = "SSL - Couldn't set the hash for verifying CertificateVerify";
-            break;
+            return( "SSL - Couldn't set the hash for verifying CertificateVerify" );
         case -(MBEDTLS_ERR_SSL_CONTINUE_PROCESSING):
-            error_description = "SSL - Internal-only message signaling that further message-processing should be done";
-            break;
+            return( "SSL - Internal-only message signaling that further message-processing should be done" );
         case -(MBEDTLS_ERR_SSL_ASYNC_IN_PROGRESS):
-            error_description = "SSL - The asynchronous operation is not completed yet";
-            break;
+            return( "SSL - The asynchronous operation is not completed yet" );
         case -(MBEDTLS_ERR_SSL_EARLY_MESSAGE):
-            error_description = "SSL - Internal-only message signaling that a message arrived early";
-            break;
+            return( "SSL - Internal-only message signaling that a message arrived early" );
         case -(MBEDTLS_ERR_SSL_UNEXPECTED_CID):
-            error_description = "SSL - An encrypted DTLS-frame with an unexpected CID was received";
-            break;
+            return( "SSL - An encrypted DTLS-frame with an unexpected CID was received" );
         case -(MBEDTLS_ERR_SSL_VERSION_MISMATCH):
-            error_description = "SSL - An operation failed due to an unexpected version or configuration";
-            break;
+            return( "SSL - An operation failed due to an unexpected version or configuration" );
         case -(MBEDTLS_ERR_SSL_CRYPTO_IN_PROGRESS):
-            error_description = "SSL - A cryptographic operation is in progress. Try again later";
-            break;
+            return( "SSL - A cryptographic operation is in progress. Try again later" );
 #endif /* MBEDTLS_SSL_TLS_C */
 
 #if defined(MBEDTLS_X509_USE_C) || defined(MBEDTLS_X509_CREATE_C)
         case -(MBEDTLS_ERR_X509_FEATURE_UNAVAILABLE):
-            error_description = "X509 - Unavailable feature, e.g. RSA hashing/encryption combination";
-            break;
+            return( "X509 - Unavailable feature, e.g. RSA hashing/encryption combination" );
         case -(MBEDTLS_ERR_X509_UNKNOWN_OID):
-            error_description = "X509 - Requested OID is unknown";
-            break;
+            return( "X509 - Requested OID is unknown" );
         case -(MBEDTLS_ERR_X509_INVALID_FORMAT):
-            error_description = "X509 - The CRT/CRL/CSR format is invalid, e.g. different type expected";
-            break;
+            return( "X509 - The CRT/CRL/CSR format is invalid, e.g. different type expected" );
         case -(MBEDTLS_ERR_X509_INVALID_VERSION):
-            error_description = "X509 - The CRT/CRL/CSR version element is invalid";
-            break;
+            return( "X509 - The CRT/CRL/CSR version element is invalid" );
         case -(MBEDTLS_ERR_X509_INVALID_SERIAL):
-            error_description = "X509 - The serial tag or value is invalid";
-            break;
+            return( "X509 - The serial tag or value is invalid" );
         case -(MBEDTLS_ERR_X509_INVALID_ALG):
-            error_description = "X509 - The algorithm tag or value is invalid";
-            break;
+            return( "X509 - The algorithm tag or value is invalid" );
         case -(MBEDTLS_ERR_X509_INVALID_NAME):
-            error_description = "X509 - The name tag or value is invalid";
-            break;
+            return( "X509 - The name tag or value is invalid" );
         case -(MBEDTLS_ERR_X509_INVALID_DATE):
-            error_description = "X509 - The date tag or value is invalid";
-            break;
+            return( "X509 - The date tag or value is invalid" );
         case -(MBEDTLS_ERR_X509_INVALID_SIGNATURE):
-            error_description = "X509 - The signature tag or value invalid";
-            break;
+            return( "X509 - The signature tag or value invalid" );
         case -(MBEDTLS_ERR_X509_INVALID_EXTENSIONS):
-            error_description = "X509 - The extension tag or value is invalid";
-            break;
+            return( "X509 - The extension tag or value is invalid" );
         case -(MBEDTLS_ERR_X509_UNKNOWN_VERSION):
-            error_description = "X509 - CRT/CRL/CSR has an unsupported version number";
-            break;
+            return( "X509 - CRT/CRL/CSR has an unsupported version number" );
         case -(MBEDTLS_ERR_X509_UNKNOWN_SIG_ALG):
-            error_description = "X509 - Signature algorithm (oid) is unsupported";
-            break;
+            return( "X509 - Signature algorithm (oid) is unsupported" );
         case -(MBEDTLS_ERR_X509_SIG_MISMATCH):
-            error_description = "X509 - Signature algorithms do not match. (see \\c ::mbedtls_x509_crt sig_oid)";
-            break;
+            return( "X509 - Signature algorithms do not match. (see \\c ::mbedtls_x509_crt sig_oid)" );
         case -(MBEDTLS_ERR_X509_CERT_VERIFY_FAILED):
-            error_description = "X509 - Certificate verification failed, e.g. CRL, CA or signature check failed";
-            break;
+            return( "X509 - Certificate verification failed, e.g. CRL, CA or signature check failed" );
         case -(MBEDTLS_ERR_X509_CERT_UNKNOWN_FORMAT):
-            error_description = "X509 - Format not recognized as DER or PEM";
-            break;
+            return( "X509 - Format not recognized as DER or PEM" );
         case -(MBEDTLS_ERR_X509_BAD_INPUT_DATA):
-            error_description = "X509 - Input invalid";
-            break;
+            return( "X509 - Input invalid" );
         case -(MBEDTLS_ERR_X509_ALLOC_FAILED):
-            error_description = "X509 - Allocation of memory failed";
-            break;
+            return( "X509 - Allocation of memory failed" );
         case -(MBEDTLS_ERR_X509_FILE_IO_ERROR):
-            error_description = "X509 - Read/write of file failed";
-            break;
+            return( "X509 - Read/write of file failed" );
         case -(MBEDTLS_ERR_X509_BUFFER_TOO_SMALL):
-            error_description = "X509 - Destination buffer is too small";
-            break;
+            return( "X509 - Destination buffer is too small" );
         case -(MBEDTLS_ERR_X509_FATAL_ERROR):
-            error_description = "X509 - A fatal error occurred, eg the chain is too long or the vrfy callback failed";
-            break;
+            return( "X509 - A fatal error occurred, eg the chain is too long or the vrfy callback failed" );
 #endif /* MBEDTLS_X509_USE_C || MBEDTLS_X509_CREATE_C */
         /* End Auto-Generated Code. */
 
@@ -727,13 +572,12 @@
             break;
     }
 
-    return error_description;
+    return( NULL );
 }
 
 const char * mbedtls_low_level_strerr( int error_code )
 {
     int low_level_error_code;
-    const char *error_description = NULL;
 
     if( error_code < 0 )
         error_code = -error_code;
@@ -746,398 +590,299 @@
         /* Begin Auto-Generated Code. */
 #if defined(MBEDTLS_AES_C)
         case -(MBEDTLS_ERR_AES_INVALID_KEY_LENGTH):
-            error_description = "AES - Invalid key length";
-            break;
+            return( "AES - Invalid key length" );
         case -(MBEDTLS_ERR_AES_INVALID_INPUT_LENGTH):
-            error_description = "AES - Invalid data input length";
-            break;
+            return( "AES - Invalid data input length" );
         case -(MBEDTLS_ERR_AES_BAD_INPUT_DATA):
-            error_description = "AES - Invalid input data";
-            break;
+            return( "AES - Invalid input data" );
         case -(MBEDTLS_ERR_AES_FEATURE_UNAVAILABLE):
-            error_description = "AES - Feature not available. For example, an unsupported AES key size";
-            break;
+            return( "AES - Feature not available. For example, an unsupported AES key size" );
         case -(MBEDTLS_ERR_AES_HW_ACCEL_FAILED):
-            error_description = "AES - AES hardware accelerator failed";
-            break;
+            return( "AES - AES hardware accelerator failed" );
 #endif /* MBEDTLS_AES_C */
 
 #if defined(MBEDTLS_ARC4_C)
         case -(MBEDTLS_ERR_ARC4_HW_ACCEL_FAILED):
-            error_description = "ARC4 - ARC4 hardware accelerator failed";
-            break;
+            return( "ARC4 - ARC4 hardware accelerator failed" );
 #endif /* MBEDTLS_ARC4_C */
 
 #if defined(MBEDTLS_ARIA_C)
         case -(MBEDTLS_ERR_ARIA_BAD_INPUT_DATA):
-            error_description = "ARIA - Bad input data";
-            break;
+            return( "ARIA - Bad input data" );
         case -(MBEDTLS_ERR_ARIA_INVALID_INPUT_LENGTH):
-            error_description = "ARIA - Invalid data input length";
-            break;
+            return( "ARIA - Invalid data input length" );
         case -(MBEDTLS_ERR_ARIA_FEATURE_UNAVAILABLE):
-            error_description = "ARIA - Feature not available. For example, an unsupported ARIA key size";
-            break;
+            return( "ARIA - Feature not available. For example, an unsupported ARIA key size" );
         case -(MBEDTLS_ERR_ARIA_HW_ACCEL_FAILED):
-            error_description = "ARIA - ARIA hardware accelerator failed";
-            break;
+            return( "ARIA - ARIA hardware accelerator failed" );
 #endif /* MBEDTLS_ARIA_C */
 
 #if defined(MBEDTLS_ASN1_PARSE_C)
         case -(MBEDTLS_ERR_ASN1_OUT_OF_DATA):
-            error_description = "ASN1 - Out of data when parsing an ASN1 data structure";
-            break;
+            return( "ASN1 - Out of data when parsing an ASN1 data structure" );
         case -(MBEDTLS_ERR_ASN1_UNEXPECTED_TAG):
-            error_description = "ASN1 - ASN1 tag was of an unexpected value";
-            break;
+            return( "ASN1 - ASN1 tag was of an unexpected value" );
         case -(MBEDTLS_ERR_ASN1_INVALID_LENGTH):
-            error_description = "ASN1 - Error when trying to determine the length or invalid length";
-            break;
+            return( "ASN1 - Error when trying to determine the length or invalid length" );
         case -(MBEDTLS_ERR_ASN1_LENGTH_MISMATCH):
-            error_description = "ASN1 - Actual length differs from expected length";
-            break;
+            return( "ASN1 - Actual length differs from expected length" );
         case -(MBEDTLS_ERR_ASN1_INVALID_DATA):
-            error_description = "ASN1 - Data is invalid";
-            break;
+            return( "ASN1 - Data is invalid" );
         case -(MBEDTLS_ERR_ASN1_ALLOC_FAILED):
-            error_description = "ASN1 - Memory allocation failed";
-            break;
+            return( "ASN1 - Memory allocation failed" );
         case -(MBEDTLS_ERR_ASN1_BUF_TOO_SMALL):
-            error_description = "ASN1 - Buffer too small when writing ASN.1 data structure";
-            break;
+            return( "ASN1 - Buffer too small when writing ASN.1 data structure" );
 #endif /* MBEDTLS_ASN1_PARSE_C */
 
 #if defined(MBEDTLS_BASE64_C)
         case -(MBEDTLS_ERR_BASE64_BUFFER_TOO_SMALL):
-            error_description = "BASE64 - Output buffer too small";
-            break;
+            return( "BASE64 - Output buffer too small" );
         case -(MBEDTLS_ERR_BASE64_INVALID_CHARACTER):
-            error_description = "BASE64 - Invalid character in input";
-            break;
+            return( "BASE64 - Invalid character in input" );
 #endif /* MBEDTLS_BASE64_C */
 
 #if defined(MBEDTLS_BIGNUM_C)
         case -(MBEDTLS_ERR_MPI_FILE_IO_ERROR):
-            error_description = "BIGNUM - An error occurred while reading from or writing to a file";
-            break;
+            return( "BIGNUM - An error occurred while reading from or writing to a file" );
         case -(MBEDTLS_ERR_MPI_BAD_INPUT_DATA):
-            error_description = "BIGNUM - Bad input parameters to function";
-            break;
+            return( "BIGNUM - Bad input parameters to function" );
         case -(MBEDTLS_ERR_MPI_INVALID_CHARACTER):
-            error_description = "BIGNUM - There is an invalid character in the digit string";
-            break;
+            return( "BIGNUM - There is an invalid character in the digit string" );
         case -(MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL):
-            error_description = "BIGNUM - The buffer is too small to write to";
-            break;
+            return( "BIGNUM - The buffer is too small to write to" );
         case -(MBEDTLS_ERR_MPI_NEGATIVE_VALUE):
-            error_description = "BIGNUM - The input arguments are negative or result in illegal output";
-            break;
+            return( "BIGNUM - The input arguments are negative or result in illegal output" );
         case -(MBEDTLS_ERR_MPI_DIVISION_BY_ZERO):
-            error_description = "BIGNUM - The input argument for division is zero, which is not allowed";
-            break;
+            return( "BIGNUM - The input argument for division is zero, which is not allowed" );
         case -(MBEDTLS_ERR_MPI_NOT_ACCEPTABLE):
-            error_description = "BIGNUM - The input arguments are not acceptable";
-            break;
+            return( "BIGNUM - The input arguments are not acceptable" );
         case -(MBEDTLS_ERR_MPI_ALLOC_FAILED):
-            error_description = "BIGNUM - Memory allocation failed";
-            break;
+            return( "BIGNUM - Memory allocation failed" );
 #endif /* MBEDTLS_BIGNUM_C */
 
 #if defined(MBEDTLS_BLOWFISH_C)
         case -(MBEDTLS_ERR_BLOWFISH_BAD_INPUT_DATA):
-            error_description = "BLOWFISH - Bad input data";
-            break;
+            return( "BLOWFISH - Bad input data" );
         case -(MBEDTLS_ERR_BLOWFISH_INVALID_INPUT_LENGTH):
-            error_description = "BLOWFISH - Invalid data input length";
-            break;
+            return( "BLOWFISH - Invalid data input length" );
         case -(MBEDTLS_ERR_BLOWFISH_HW_ACCEL_FAILED):
-            error_description = "BLOWFISH - Blowfish hardware accelerator failed";
-            break;
+            return( "BLOWFISH - Blowfish hardware accelerator failed" );
 #endif /* MBEDTLS_BLOWFISH_C */
 
 #if defined(MBEDTLS_CAMELLIA_C)
         case -(MBEDTLS_ERR_CAMELLIA_BAD_INPUT_DATA):
-            error_description = "CAMELLIA - Bad input data";
-            break;
+            return( "CAMELLIA - Bad input data" );
         case -(MBEDTLS_ERR_CAMELLIA_INVALID_INPUT_LENGTH):
-            error_description = "CAMELLIA - Invalid data input length";
-            break;
+            return( "CAMELLIA - Invalid data input length" );
         case -(MBEDTLS_ERR_CAMELLIA_HW_ACCEL_FAILED):
-            error_description = "CAMELLIA - Camellia hardware accelerator failed";
-            break;
+            return( "CAMELLIA - Camellia hardware accelerator failed" );
 #endif /* MBEDTLS_CAMELLIA_C */
 
 #if defined(MBEDTLS_CCM_C)
         case -(MBEDTLS_ERR_CCM_BAD_INPUT):
-            error_description = "CCM - Bad input parameters to the function";
-            break;
+            return( "CCM - Bad input parameters to the function" );
         case -(MBEDTLS_ERR_CCM_AUTH_FAILED):
-            error_description = "CCM - Authenticated decryption failed";
-            break;
+            return( "CCM - Authenticated decryption failed" );
         case -(MBEDTLS_ERR_CCM_HW_ACCEL_FAILED):
-            error_description = "CCM - CCM hardware accelerator failed";
-            break;
+            return( "CCM - CCM hardware accelerator failed" );
 #endif /* MBEDTLS_CCM_C */
 
 #if defined(MBEDTLS_CHACHA20_C)
         case -(MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA):
-            error_description = "CHACHA20 - Invalid input parameter(s)";
-            break;
+            return( "CHACHA20 - Invalid input parameter(s)" );
         case -(MBEDTLS_ERR_CHACHA20_FEATURE_UNAVAILABLE):
-            error_description = "CHACHA20 - Feature not available. For example, s part of the API is not implemented";
-            break;
+            return( "CHACHA20 - Feature not available. For example, s part of the API is not implemented" );
         case -(MBEDTLS_ERR_CHACHA20_HW_ACCEL_FAILED):
-            error_description = "CHACHA20 - Chacha20 hardware accelerator failed";
-            break;
+            return( "CHACHA20 - Chacha20 hardware accelerator failed" );
 #endif /* MBEDTLS_CHACHA20_C */
 
 #if defined(MBEDTLS_CHACHAPOLY_C)
         case -(MBEDTLS_ERR_CHACHAPOLY_BAD_STATE):
-            error_description = "CHACHAPOLY - The requested operation is not permitted in the current state";
-            break;
+            return( "CHACHAPOLY - The requested operation is not permitted in the current state" );
         case -(MBEDTLS_ERR_CHACHAPOLY_AUTH_FAILED):
-            error_description = "CHACHAPOLY - Authenticated decryption failed: data was not authentic";
-            break;
+            return( "CHACHAPOLY - Authenticated decryption failed: data was not authentic" );
 #endif /* MBEDTLS_CHACHAPOLY_C */
 
 #if defined(MBEDTLS_CMAC_C)
         case -(MBEDTLS_ERR_CMAC_HW_ACCEL_FAILED):
-            error_description = "CMAC - CMAC hardware accelerator failed";
-            break;
+            return( "CMAC - CMAC hardware accelerator failed" );
 #endif /* MBEDTLS_CMAC_C */
 
 #if defined(MBEDTLS_CTR_DRBG_C)
         case -(MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED):
-            error_description = "CTR_DRBG - The entropy source failed";
-            break;
+            return( "CTR_DRBG - The entropy source failed" );
         case -(MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG):
-            error_description = "CTR_DRBG - The requested random buffer length is too big";
-            break;
+            return( "CTR_DRBG - The requested random buffer length is too big" );
         case -(MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG):
-            error_description = "CTR_DRBG - The input (entropy + additional data) is too large";
-            break;
+            return( "CTR_DRBG - The input (entropy + additional data) is too large" );
         case -(MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR):
-            error_description = "CTR_DRBG - Read or write error in file";
-            break;
+            return( "CTR_DRBG - Read or write error in file" );
 #endif /* MBEDTLS_CTR_DRBG_C */
 
 #if defined(MBEDTLS_DES_C)
         case -(MBEDTLS_ERR_DES_INVALID_INPUT_LENGTH):
-            error_description = "DES - The data input has an invalid length";
-            break;
+            return( "DES - The data input has an invalid length" );
         case -(MBEDTLS_ERR_DES_HW_ACCEL_FAILED):
-            error_description = "DES - DES hardware accelerator failed";
-            break;
+            return( "DES - DES hardware accelerator failed" );
 #endif /* MBEDTLS_DES_C */
 
 #if defined(MBEDTLS_ENTROPY_C)
         case -(MBEDTLS_ERR_ENTROPY_SOURCE_FAILED):
-            error_description = "ENTROPY - Critical entropy source failure";
-            break;
+            return( "ENTROPY - Critical entropy source failure" );
         case -(MBEDTLS_ERR_ENTROPY_MAX_SOURCES):
-            error_description = "ENTROPY - No more sources can be added";
-            break;
+            return( "ENTROPY - No more sources can be added" );
         case -(MBEDTLS_ERR_ENTROPY_NO_SOURCES_DEFINED):
-            error_description = "ENTROPY - No sources have been added to poll";
-            break;
+            return( "ENTROPY - No sources have been added to poll" );
         case -(MBEDTLS_ERR_ENTROPY_NO_STRONG_SOURCE):
-            error_description = "ENTROPY - No strong sources have been added to poll";
-            break;
+            return( "ENTROPY - No strong sources have been added to poll" );
         case -(MBEDTLS_ERR_ENTROPY_FILE_IO_ERROR):
-            error_description = "ENTROPY - Read/write error in file";
-            break;
+            return( "ENTROPY - Read/write error in file" );
 #endif /* MBEDTLS_ENTROPY_C */
 
 #if defined(MBEDTLS_ERROR_C)
         case -(MBEDTLS_ERR_ERROR_GENERIC_ERROR):
-            error_description = "ERROR - Generic error";
-            break;
+            return( "ERROR - Generic error" );
         case -(MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED):
-            error_description = "ERROR - This is a bug in the library";
-            break;
+            return( "ERROR - This is a bug in the library" );
 #endif /* MBEDTLS_ERROR_C */
 
 #if defined(MBEDTLS_GCM_C)
         case -(MBEDTLS_ERR_GCM_AUTH_FAILED):
-            error_description = "GCM - Authenticated decryption failed";
-            break;
+            return( "GCM - Authenticated decryption failed" );
         case -(MBEDTLS_ERR_GCM_HW_ACCEL_FAILED):
-            error_description = "GCM - GCM hardware accelerator failed";
-            break;
+            return( "GCM - GCM hardware accelerator failed" );
         case -(MBEDTLS_ERR_GCM_BAD_INPUT):
-            error_description = "GCM - Bad input parameters to function";
-            break;
+            return( "GCM - Bad input parameters to function" );
 #endif /* MBEDTLS_GCM_C */
 
 #if defined(MBEDTLS_HKDF_C)
         case -(MBEDTLS_ERR_HKDF_BAD_INPUT_DATA):
-            error_description = "HKDF - Bad input parameters to function";
-            break;
+            return( "HKDF - Bad input parameters to function" );
 #endif /* MBEDTLS_HKDF_C */
 
 #if defined(MBEDTLS_HMAC_DRBG_C)
         case -(MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG):
-            error_description = "HMAC_DRBG - Too many random requested in single call";
-            break;
+            return( "HMAC_DRBG - Too many random requested in single call" );
         case -(MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG):
-            error_description = "HMAC_DRBG - Input too large (Entropy + additional)";
-            break;
+            return( "HMAC_DRBG - Input too large (Entropy + additional)" );
         case -(MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR):
-            error_description = "HMAC_DRBG - Read/write error in file";
-            break;
+            return( "HMAC_DRBG - Read/write error in file" );
         case -(MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED):
-            error_description = "HMAC_DRBG - The entropy source failed";
-            break;
+            return( "HMAC_DRBG - The entropy source failed" );
 #endif /* MBEDTLS_HMAC_DRBG_C */
 
 #if defined(MBEDTLS_MD2_C)
         case -(MBEDTLS_ERR_MD2_HW_ACCEL_FAILED):
-            error_description = "MD2 - MD2 hardware accelerator failed";
-            break;
+            return( "MD2 - MD2 hardware accelerator failed" );
 #endif /* MBEDTLS_MD2_C */
 
 #if defined(MBEDTLS_MD4_C)
         case -(MBEDTLS_ERR_MD4_HW_ACCEL_FAILED):
-            error_description = "MD4 - MD4 hardware accelerator failed";
-            break;
+            return( "MD4 - MD4 hardware accelerator failed" );
 #endif /* MBEDTLS_MD4_C */
 
 #if defined(MBEDTLS_MD5_C)
         case -(MBEDTLS_ERR_MD5_HW_ACCEL_FAILED):
-            error_description = "MD5 - MD5 hardware accelerator failed";
-            break;
+            return( "MD5 - MD5 hardware accelerator failed" );
 #endif /* MBEDTLS_MD5_C */
 
 #if defined(MBEDTLS_NET_C)
         case -(MBEDTLS_ERR_NET_SOCKET_FAILED):
-            error_description = "NET - Failed to open a socket";
-            break;
+            return( "NET - Failed to open a socket" );
         case -(MBEDTLS_ERR_NET_CONNECT_FAILED):
-            error_description = "NET - The connection to the given server / port failed";
-            break;
+            return( "NET - The connection to the given server / port failed" );
         case -(MBEDTLS_ERR_NET_BIND_FAILED):
-            error_description = "NET - Binding of the socket failed";
-            break;
+            return( "NET - Binding of the socket failed" );
         case -(MBEDTLS_ERR_NET_LISTEN_FAILED):
-            error_description = "NET - Could not listen on the socket";
-            break;
+            return( "NET - Could not listen on the socket" );
         case -(MBEDTLS_ERR_NET_ACCEPT_FAILED):
-            error_description = "NET - Could not accept the incoming connection";
-            break;
+            return( "NET - Could not accept the incoming connection" );
         case -(MBEDTLS_ERR_NET_RECV_FAILED):
-            error_description = "NET - Reading information from the socket failed";
-            break;
+            return( "NET - Reading information from the socket failed" );
         case -(MBEDTLS_ERR_NET_SEND_FAILED):
-            error_description = "NET - Sending information through the socket failed";
-            break;
+            return( "NET - Sending information through the socket failed" );
         case -(MBEDTLS_ERR_NET_CONN_RESET):
-            error_description = "NET - Connection was reset by peer";
-            break;
+            return( "NET - Connection was reset by peer" );
         case -(MBEDTLS_ERR_NET_UNKNOWN_HOST):
-            error_description = "NET - Failed to get an IP address for the given hostname";
-            break;
+            return( "NET - Failed to get an IP address for the given hostname" );
         case -(MBEDTLS_ERR_NET_BUFFER_TOO_SMALL):
-            error_description = "NET - Buffer is too small to hold the data";
-            break;
+            return( "NET - Buffer is too small to hold the data" );
         case -(MBEDTLS_ERR_NET_INVALID_CONTEXT):
-            error_description = "NET - The context is invalid, eg because it was free()ed";
-            break;
+            return( "NET - The context is invalid, eg because it was free()ed" );
         case -(MBEDTLS_ERR_NET_POLL_FAILED):
-            error_description = "NET - Polling the net context failed";
-            break;
+            return( "NET - Polling the net context failed" );
         case -(MBEDTLS_ERR_NET_BAD_INPUT_DATA):
-            error_description = "NET - Input invalid";
-            break;
+            return( "NET - Input invalid" );
 #endif /* MBEDTLS_NET_C */
 
 #if defined(MBEDTLS_OID_C)
         case -(MBEDTLS_ERR_OID_NOT_FOUND):
-            error_description = "OID - OID is not found";
-            break;
+            return( "OID - OID is not found" );
         case -(MBEDTLS_ERR_OID_BUF_TOO_SMALL):
-            error_description = "OID - output buffer is too small";
-            break;
+            return( "OID - output buffer is too small" );
 #endif /* MBEDTLS_OID_C */
 
 #if defined(MBEDTLS_PADLOCK_C)
         case -(MBEDTLS_ERR_PADLOCK_DATA_MISALIGNED):
-            error_description = "PADLOCK - Input data should be aligned";
-            break;
+            return( "PADLOCK - Input data should be aligned" );
 #endif /* MBEDTLS_PADLOCK_C */
 
 #if defined(MBEDTLS_PLATFORM_C)
         case -(MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED):
-            error_description = "PLATFORM - Hardware accelerator failed";
-            break;
+            return( "PLATFORM - Hardware accelerator failed" );
         case -(MBEDTLS_ERR_PLATFORM_FEATURE_UNSUPPORTED):
-            error_description = "PLATFORM - The requested feature is not supported by the platform";
-            break;
+            return( "PLATFORM - The requested feature is not supported by the platform" );
 #endif /* MBEDTLS_PLATFORM_C */
 
 #if defined(MBEDTLS_POLY1305_C)
         case -(MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA):
-            error_description = "POLY1305 - Invalid input parameter(s)";
-            break;
+            return( "POLY1305 - Invalid input parameter(s)" );
         case -(MBEDTLS_ERR_POLY1305_FEATURE_UNAVAILABLE):
-            error_description = "POLY1305 - Feature not available. For example, s part of the API is not implemented";
-            break;
+            return( "POLY1305 - Feature not available. For example, s part of the API is not implemented" );
         case -(MBEDTLS_ERR_POLY1305_HW_ACCEL_FAILED):
-            error_description = "POLY1305 - Poly1305 hardware accelerator failed";
-            break;
+            return( "POLY1305 - Poly1305 hardware accelerator failed" );
 #endif /* MBEDTLS_POLY1305_C */
 
 #if defined(MBEDTLS_RIPEMD160_C)
         case -(MBEDTLS_ERR_RIPEMD160_HW_ACCEL_FAILED):
-            error_description = "RIPEMD160 - RIPEMD160 hardware accelerator failed";
-            break;
+            return( "RIPEMD160 - RIPEMD160 hardware accelerator failed" );
 #endif /* MBEDTLS_RIPEMD160_C */
 
 #if defined(MBEDTLS_SHA1_C)
         case -(MBEDTLS_ERR_SHA1_HW_ACCEL_FAILED):
-            error_description = "SHA1 - SHA-1 hardware accelerator failed";
-            break;
+            return( "SHA1 - SHA-1 hardware accelerator failed" );
         case -(MBEDTLS_ERR_SHA1_BAD_INPUT_DATA):
-            error_description = "SHA1 - SHA-1 input data was malformed";
-            break;
+            return( "SHA1 - SHA-1 input data was malformed" );
 #endif /* MBEDTLS_SHA1_C */
 
 #if defined(MBEDTLS_SHA256_C)
         case -(MBEDTLS_ERR_SHA256_HW_ACCEL_FAILED):
-            error_description = "SHA256 - SHA-256 hardware accelerator failed";
-            break;
+            return( "SHA256 - SHA-256 hardware accelerator failed" );
         case -(MBEDTLS_ERR_SHA256_BAD_INPUT_DATA):
-            error_description = "SHA256 - SHA-256 input data was malformed";
-            break;
+            return( "SHA256 - SHA-256 input data was malformed" );
 #endif /* MBEDTLS_SHA256_C */
 
 #if defined(MBEDTLS_SHA512_C)
         case -(MBEDTLS_ERR_SHA512_HW_ACCEL_FAILED):
-            error_description = "SHA512 - SHA-512 hardware accelerator failed";
-            break;
+            return( "SHA512 - SHA-512 hardware accelerator failed" );
         case -(MBEDTLS_ERR_SHA512_BAD_INPUT_DATA):
-            error_description = "SHA512 - SHA-512 input data was malformed";
-            break;
+            return( "SHA512 - SHA-512 input data was malformed" );
 #endif /* MBEDTLS_SHA512_C */
 
 #if defined(MBEDTLS_THREADING_C)
         case -(MBEDTLS_ERR_THREADING_FEATURE_UNAVAILABLE):
-            error_description = "THREADING - The selected feature is not available";
-            break;
+            return( "THREADING - The selected feature is not available" );
         case -(MBEDTLS_ERR_THREADING_BAD_INPUT_DATA):
-            error_description = "THREADING - Bad input parameters to function";
-            break;
+            return( "THREADING - Bad input parameters to function" );
         case -(MBEDTLS_ERR_THREADING_MUTEX_ERROR):
-            error_description = "THREADING - Locking / unlocking / free failed with error code";
-            break;
+            return( "THREADING - Locking / unlocking / free failed with error code" );
 #endif /* MBEDTLS_THREADING_C */
 
 #if defined(MBEDTLS_XTEA_C)
         case -(MBEDTLS_ERR_XTEA_INVALID_INPUT_LENGTH):
-            error_description = "XTEA - The data input has an invalid length";
-            break;
+            return( "XTEA - The data input has an invalid length" );
         case -(MBEDTLS_ERR_XTEA_HW_ACCEL_FAILED):
-            error_description = "XTEA - XTEA hardware accelerator failed";
-            break;
+            return( "XTEA - XTEA hardware accelerator failed" );
 #endif /* MBEDTLS_XTEA_C */
         /* End Auto-Generated Code. */
 
@@ -1145,7 +890,7 @@
             break;
     }
 
-    return error_description;
+    return( NULL );
 }
 
 void mbedtls_strerror( int ret, char *buf, size_t buflen )
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index dbc5a3e..ccfc4bd 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -2747,9 +2747,7 @@
     {
         ssl->session_negotiate->verify_result = MBEDTLS_X509_BADCERT_MISSING;
 
-        if( authmode == MBEDTLS_SSL_VERIFY_OPTIONAL )
-            ret = 0;
-        else
+        if( authmode != MBEDTLS_SSL_VERIFY_OPTIONAL )
             ret = MBEDTLS_ERR_SSL_NO_CLIENT_CERTIFICATE;
 
         goto exit;
diff --git a/scripts/data_files/error.fmt b/scripts/data_files/error.fmt
index 97b74bc..f65881b 100644
--- a/scripts/data_files/error.fmt
+++ b/scripts/data_files/error.fmt
@@ -45,7 +45,6 @@
 const char * mbedtls_high_level_strerr( int error_code )
 {
     int high_level_error_code;
-    const char *error_description = NULL;
 
     if( error_code < 0 )
         error_code = -error_code;
@@ -63,13 +62,12 @@
             break;
     }
 
-    return error_description;
+    return( NULL );
 }
 
 const char * mbedtls_low_level_strerr( int error_code )
 {
     int low_level_error_code;
-    const char *error_description = NULL;
 
     if( error_code < 0 )
         error_code = -error_code;
@@ -87,7 +85,7 @@
             break;
     }
 
-    return error_description;
+    return( NULL );
 }
 
 void mbedtls_strerror( int ret, char *buf, size_t buflen )
diff --git a/scripts/data_files/vs2010-main-template.vcxproj b/scripts/data_files/vs2010-main-template.vcxproj
index d3c8764..c8f13c3 100644
--- a/scripts/data_files/vs2010-main-template.vcxproj
+++ b/scripts/data_files/vs2010-main-template.vcxproj
@@ -45,7 +45,6 @@
     <UseDebugLibraries>false</UseDebugLibraries>

     <WholeProgramOptimization>true</WholeProgramOptimization>

     <CharacterSet>Unicode</CharacterSet>

-    <PlatformToolset>Windows7.1SDK</PlatformToolset>

   </PropertyGroup>

   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />

   <ImportGroup Label="ExtensionSettings">

diff --git a/scripts/generate_errors.pl b/scripts/generate_errors.pl
index cb59669..0512d59 100755
--- a/scripts/generate_errors.pl
+++ b/scripts/generate_errors.pl
@@ -161,8 +161,7 @@
     }
 
     ${$code_check} .= "${white_space}case -($error_name):\n".
-                      "${white_space}    error_description = \"$module_name - $description\";\n".
-                      "${white_space}    break;\n"
+                      "${white_space}    return( \"$module_name - $description\" );\n"
 };
 
 if ($ll_old_define ne "")
diff --git a/scripts/windows_msbuild.bat b/scripts/windows_msbuild.bat
new file mode 100644
index 0000000..e419931
--- /dev/null
+++ b/scripts/windows_msbuild.bat
@@ -0,0 +1,20 @@
+@rem Build and test Mbed TLS with Visual Studio using msbuild.

+@rem Usage: windows_msbuild [RETARGET]

+@rem   RETARGET: version of Visual Studio to emulate

+@rem             https://docs.microsoft.com/en-us/cpp/build/how-to-modify-the-target-framework-and-platform-toolset

+

+@rem These parameters are hard-coded for now.

+set "arch=x64" & @rem "x86" or "x64"

+set "cfg=Release" & @rem "Debug" or "Release"

+set "vcvarsall=C:\Program Files (x86)\Microsoft Visual Studio\2017\BuildTools\VC\Auxiliary\Build\vcvarsall.bat"

+

+if not "%~1"=="" set "retarget=,PlatformToolset=%1"

+

+@rem If the %USERPROFILE%\Source directory exists, then running

+@rem vcvarsall.bat will silently change the directory to that directory.

+@rem Setting the VSCMD_START_DIR environment variable causes it to change

+@rem to that directory instead.

+set "VSCMD_START_DIR=%~dp0\..\visualc\VS2010"

+

+"%vcvarsall%" x64 && ^

+msbuild /t:Rebuild /p:Configuration=%cfg%%retarget% /m mbedTLS.sln

diff --git a/tests/scripts/all.sh b/tests/scripts/all.sh
index 5b70caa..f5e0a87 100755
--- a/tests/scripts/all.sh
+++ b/tests/scripts/all.sh
@@ -138,6 +138,7 @@
     : ${OUT_OF_SOURCE_DIR:=./mbedtls_out_of_source_build}
     : ${ARMC5_BIN_DIR:=/usr/bin}
     : ${ARMC6_BIN_DIR:=/usr/bin}
+    : ${ARM_NONE_EABI_GCC_PREFIX:=arm-none-eabi-}
 
     # if MAKEFLAGS is not set add the -j option to speed up invocations of make
     if [ -z "${MAKEFLAGS+set}" ]; then
@@ -203,6 +204,9 @@
   -k|--keep-going       Run all tests and report errors at the end.
   -m|--memory           Additional optional memory tests.
      --append-outcome   Append to the outcome file (if used).
+     --arm-none-eabi-gcc-prefix=<string>
+                        Prefix for a cross-compiler for arm-none-eabi
+                        (default: "${ARM_NONE_EABI_GCC_PREFIX}")
      --armcc            Run ARM Compiler builds (on by default).
      --except           Exclude the COMPONENTs listed on the command line,
                         instead of running only those.
@@ -295,9 +299,13 @@
 {
     FLAGS="$1"
 
-    msg "build: ARM Compiler 6 ($FLAGS), make"
+    msg "build: ARM Compiler 6 ($FLAGS)"
     ARM_TOOL_VARIANT="ult" CC="$ARMC6_CC" AR="$ARMC6_AR" CFLAGS="$FLAGS" \
                     WARNING_CFLAGS='-xc -std=c99' make lib
+
+    msg "size: ARM Compiler 6 ($FLAGS)"
+    "$ARMC6_FROMELF" -z library/*.o
+
     make clean
 }
 
@@ -335,6 +343,7 @@
     while [ $# -gt 0 ]; do
         case "$1" in
             --append-outcome) append_outcome=1;;
+            --arm-none-eabi-gcc-prefix) shift; ARM_NONE_EABI_GCC_PREFIX="$1";;
             --armcc) no_armcc=;;
             --armc5-bin-dir) shift; ARMC5_BIN_DIR="$1";;
             --armc6-bin-dir) shift; ARMC6_BIN_DIR="$1";;
@@ -547,7 +556,7 @@
     esac
 
     case " $RUN_COMPONENTS " in
-        *_arm_none_eabi_gcc[_\ ]*) check_tools "arm-none-eabi-gcc";;
+        *_arm_none_eabi_gcc[_\ ]*) check_tools "${ARM_NONE_EABI_GCC_PREFIX}gcc";;
     esac
 
     case " $RUN_COMPONENTS " in
@@ -562,9 +571,12 @@
         *_armcc*)
             ARMC5_CC="$ARMC5_BIN_DIR/armcc"
             ARMC5_AR="$ARMC5_BIN_DIR/armar"
+            ARMC5_FROMELF="$ARMC5_BIN_DIR/fromelf"
             ARMC6_CC="$ARMC6_BIN_DIR/armclang"
             ARMC6_AR="$ARMC6_BIN_DIR/armar"
-            check_tools "$ARMC5_CC" "$ARMC5_AR" "$ARMC6_CC" "$ARMC6_AR";;
+            ARMC6_FROMELF="$ARMC6_BIN_DIR/fromelf"
+            check_tools "$ARMC5_CC" "$ARMC5_AR" "$ARMC5_FROMELF" \
+                        "$ARMC6_CC" "$ARMC6_AR" "$ARMC6_FROMELF";;
     esac
 
     msg "info: output_env.sh"
@@ -645,7 +657,7 @@
     make test
 
     msg "selftest: make, default config (out-of-box)" # ~10s
-    programs/test/selftest
+    if_build_succeeded programs/test/selftest
 
     export MBEDTLS_TEST_OUTCOME_FILE="$SAVE_MBEDTLS_TEST_OUTCOME_FILE"
     unset SAVE_MBEDTLS_TEST_OUTCOME_FILE
@@ -659,6 +671,9 @@
     msg "test: main suites (inc. selftests) (ASan build)" # ~ 50s
     make test
 
+    msg "test: selftest (ASan build)" # ~ 10s
+    if_build_succeeded programs/test/selftest
+
     msg "test: ssl-opt.sh (ASan build)" # ~ 1 min
     if_build_succeeded tests/ssl-opt.sh
 
@@ -678,6 +693,9 @@
     msg "test: main suites (inc. selftests) (full config, ASan build)"
     make test
 
+    msg "test: selftest (ASan build)" # ~ 10s
+    if_build_succeeded programs/test/selftest
+
     msg "test: ssl-opt.sh (full config, ASan build)"
     if_build_succeeded tests/ssl-opt.sh
 
@@ -1566,45 +1584,63 @@
 }
 
 component_build_arm_none_eabi_gcc () {
-    msg "build: arm-none-eabi-gcc, make" # ~ 10s
+    msg "build: ${ARM_NONE_EABI_GCC_PREFIX}gcc -O1" # ~ 10s
     scripts/config.py baremetal
-    make CC=arm-none-eabi-gcc AR=arm-none-eabi-ar LD=arm-none-eabi-ld CFLAGS='-Werror -Wall -Wextra' lib
+    make CC="${ARM_NONE_EABI_GCC_PREFIX}gcc" AR="${ARM_NONE_EABI_GCC_PREFIX}ar" LD="${ARM_NONE_EABI_GCC_PREFIX}ld" CFLAGS='-Werror -Wall -Wextra -O1' lib
+
+    msg "size: ${ARM_NONE_EABI_GCC_PREFIX}gcc -O1"
+    ${ARM_NONE_EABI_GCC_PREFIX}size library/*.o
 }
 
 component_build_arm_none_eabi_gcc_arm5vte () {
-    msg "build: arm-none-eabi-gcc -march=arm5vte, make" # ~ 10s
+    msg "build: ${ARM_NONE_EABI_GCC_PREFIX}gcc -march=arm5vte" # ~ 10s
     scripts/config.py baremetal
     # Build for a target platform that's close to what Debian uses
     # for its "armel" distribution (https://wiki.debian.org/ArmEabiPort).
     # See https://github.com/ARMmbed/mbedtls/pull/2169 and comments.
     # It would be better to build with arm-linux-gnueabi-gcc but
     # we don't have that on our CI at this time.
-    make CC=arm-none-eabi-gcc AR=arm-none-eabi-ar CFLAGS='-Werror -Wall -Wextra -march=armv5te -O1' LDFLAGS='-march=armv5te' SHELL='sh -x' lib
+    make CC="${ARM_NONE_EABI_GCC_PREFIX}gcc" AR="${ARM_NONE_EABI_GCC_PREFIX}ar" CFLAGS='-Werror -Wall -Wextra -march=armv5te -O1' LDFLAGS='-march=armv5te' SHELL='sh -x' lib
+
+    msg "size: ${ARM_NONE_EABI_GCC_PREFIX}gcc -march=armv5te -O1"
+    ${ARM_NONE_EABI_GCC_PREFIX}size library/*.o
+}
+
+component_build_arm_none_eabi_gcc_m0plus () {
+    msg "build: ${ARM_NONE_EABI_GCC_PREFIX}gcc -mthumb -mcpu=cortex-m0plus" # ~ 10s
+    scripts/config.py baremetal
+    make CC="${ARM_NONE_EABI_GCC_PREFIX}gcc" AR="${ARM_NONE_EABI_GCC_PREFIX}ar" LD="${ARM_NONE_EABI_GCC_PREFIX}ld" CFLAGS='-Werror -Wall -Wextra -mthumb -mcpu=cortex-m0plus -Os' lib
+
+    msg "size: ${ARM_NONE_EABI_GCC_PREFIX}gcc -mthumb -mcpu=cortex-m0plus -Os"
+    ${ARM_NONE_EABI_GCC_PREFIX}size library/*.o
 }
 
 component_build_arm_none_eabi_gcc_no_udbl_division () {
-    msg "build: arm-none-eabi-gcc -DMBEDTLS_NO_UDBL_DIVISION, make" # ~ 10s
+    msg "build: ${ARM_NONE_EABI_GCC_PREFIX}gcc -DMBEDTLS_NO_UDBL_DIVISION, make" # ~ 10s
     scripts/config.py baremetal
     scripts/config.py set MBEDTLS_NO_UDBL_DIVISION
-    make CC=arm-none-eabi-gcc AR=arm-none-eabi-ar LD=arm-none-eabi-ld CFLAGS='-Werror -Wall -Wextra' lib
+    make CC="${ARM_NONE_EABI_GCC_PREFIX}gcc" AR="${ARM_NONE_EABI_GCC_PREFIX}ar" LD="${ARM_NONE_EABI_GCC_PREFIX}ld" CFLAGS='-Werror -Wall -Wextra' lib
     echo "Checking that software 64-bit division is not required"
     if_build_succeeded not grep __aeabi_uldiv library/*.o
 }
 
 component_build_arm_none_eabi_gcc_no_64bit_multiplication () {
-    msg "build: arm-none-eabi-gcc MBEDTLS_NO_64BIT_MULTIPLICATION, make" # ~ 10s
+    msg "build: ${ARM_NONE_EABI_GCC_PREFIX}gcc MBEDTLS_NO_64BIT_MULTIPLICATION, make" # ~ 10s
     scripts/config.py baremetal
     scripts/config.py set MBEDTLS_NO_64BIT_MULTIPLICATION
-    make CC=arm-none-eabi-gcc AR=arm-none-eabi-ar LD=arm-none-eabi-ld CFLAGS='-Werror -O1 -march=armv6-m -mthumb' lib
+    make CC="${ARM_NONE_EABI_GCC_PREFIX}gcc" AR="${ARM_NONE_EABI_GCC_PREFIX}ar" LD="${ARM_NONE_EABI_GCC_PREFIX}ld" CFLAGS='-Werror -O1 -march=armv6-m -mthumb' lib
     echo "Checking that software 64-bit multiplication is not required"
     if_build_succeeded not grep __aeabi_lmul library/*.o
 }
 
 component_build_armcc () {
-    msg "build: ARM Compiler 5, make"
+    msg "build: ARM Compiler 5"
     scripts/config.py baremetal
-
     make CC="$ARMC5_CC" AR="$ARMC5_AR" WARNING_CFLAGS='--strict --c99' lib
+
+    msg "size: ARM Compiler 5"
+    "$ARMC5_FROMELF" -z library/*.o
+
     make clean
 
     # ARM Compiler 6 - Target ARMv7-A
diff --git a/tests/scripts/check-files.py b/tests/scripts/check-files.py
index 7474ac7..e8abd75 100755
--- a/tests/scripts/check-files.py
+++ b/tests/scripts/check-files.py
@@ -103,7 +103,7 @@
 
 def is_windows_file(filepath):
     _root, ext = os.path.splitext(filepath)
-    return ext in ('.dsp', '.sln', '.vcxproj')
+    return ext in ('.bat', '.dsp', '.sln', '.vcxproj')
 
 
 class PermissionIssueTracker(FileIssueTracker):
@@ -224,6 +224,7 @@
         self.logger = None
         self.setup_logger(log_file)
         self.extensions_to_check = (
+            ".bat",
             ".c",
             ".data",
             ".dsp",
diff --git a/tests/suites/host_test.function b/tests/suites/host_test.function
index 9dde6c2..db65c0f 100644
--- a/tests/suites/host_test.function
+++ b/tests/suites/host_test.function
@@ -551,7 +551,7 @@
         return( 1 );
     }
 
-    if( outcome_file_name != NULL )
+    if( outcome_file_name != NULL && *outcome_file_name != '\0' )
     {
         outcome_file = fopen( outcome_file_name, "a" );
         if( outcome_file == NULL )
diff --git a/visualc/VS2010/mbedTLS.vcxproj b/visualc/VS2010/mbedTLS.vcxproj
index b7678ff..07e046a 100644
--- a/visualc/VS2010/mbedTLS.vcxproj
+++ b/visualc/VS2010/mbedTLS.vcxproj
@@ -45,7 +45,6 @@
     <UseDebugLibraries>false</UseDebugLibraries>

     <WholeProgramOptimization>true</WholeProgramOptimization>

     <CharacterSet>Unicode</CharacterSet>

-    <PlatformToolset>Windows7.1SDK</PlatformToolset>

   </PropertyGroup>

   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.props" />

   <ImportGroup Label="ExtensionSettings">