Handle errors from functions that now return int

A few functions were changed from returning void to returning int three
commits ago. Make sure their callers check the return values.

This commits was basically a matter of declaring newly-int-returning
functions MBEDTLS_CHECK_RETURN_CRITICAL and then fixing the resulting
warnings. A few functions had to be made int in the process; they were
applied the same process as well.

Signed-off-by: Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com>
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 81c289a..047b97a 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -486,6 +486,7 @@
                                               const unsigned char *ciphersuites,
                                               const unsigned char *ciphersuites_end)
 {
+    int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
     const unsigned char *identities = pre_shared_key_ext;
     const unsigned char *p_identity_len;
     size_t identities_len;
@@ -521,8 +522,12 @@
     MBEDTLS_SSL_CHK_BUF_READ_PTR(p_binder_len, pre_shared_key_ext_end, binders_len);
     binders_end = p_binder_len + binders_len;
 
-    ssl->handshake->update_checksum(ssl, pre_shared_key_ext,
-                                    identities_end - pre_shared_key_ext);
+    ret = ssl->handshake->update_checksum(ssl, pre_shared_key_ext,
+                                          identities_end - pre_shared_key_ext);
+    if (0 != ret) {
+        MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret);
+        return ret;
+    }
 
     while (p_identity_len < identities_end && p_binder_len < binders_end) {
         const unsigned char *identity;
@@ -530,7 +535,6 @@
         uint32_t obfuscated_ticket_age;
         const unsigned char *binder;
         size_t binder_len;
-        int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
         int psk_type;
         uint16_t cipher_suite;
         const mbedtls_ssl_ciphersuite_t *ciphersuite_info;
@@ -642,9 +646,13 @@
     }
 
     /* Update the handshake transcript with the binder list. */
-    ssl->handshake->update_checksum(ssl,
-                                    identities_end,
-                                    (size_t) (binders_end - identities_end));
+    ret = ssl->handshake->update_checksum(ssl,
+                                          identities_end,
+                                          (size_t) (binders_end - identities_end));
+    if (0 != ret) {
+        MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret);
+        return ret;
+    }
     if (matched_identity == -1) {
         MBEDTLS_SSL_DEBUG_MSG(3, ("No matched PSK or ticket."));
         return MBEDTLS_ERR_SSL_UNKNOWN_IDENTITY;
@@ -1590,9 +1598,13 @@
     MBEDTLS_SSL_PRINT_EXTS(3, MBEDTLS_SSL_HS_CLIENT_HELLO,
                            handshake->received_extensions);
 
-    mbedtls_ssl_add_hs_hdr_to_checksum(ssl,
-                                       MBEDTLS_SSL_HS_CLIENT_HELLO,
-                                       p - buf);
+    ret = mbedtls_ssl_add_hs_hdr_to_checksum(ssl,
+                                             MBEDTLS_SSL_HS_CLIENT_HELLO,
+                                             p - buf);
+    if (0 != ret) {
+        MBEDTLS_SSL_DEBUG_RET(1, ("mbedtls_ssl_add_hs_hdr_to_checksum"), ret);
+        return ret;
+    }
 
 #if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED)
     /* Update checksum with either
@@ -1603,8 +1615,12 @@
     if (mbedtls_ssl_tls13_some_psk_enabled(ssl) &&
         mbedtls_ssl_conf_tls13_some_psk_enabled(ssl) &&
         (handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(PRE_SHARED_KEY))) {
-        handshake->update_checksum(ssl, buf,
-                                   pre_shared_key_ext - buf);
+        ret = handshake->update_checksum(ssl, buf,
+                                         pre_shared_key_ext - buf);
+        if (0 != ret) {
+            MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret);
+            return ret;
+        }
         ret = ssl_tls13_parse_pre_shared_key_ext(ssl,
                                                  pre_shared_key_ext,
                                                  pre_shared_key_ext_end,
@@ -1620,7 +1636,11 @@
     } else
 #endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_PSK_ENABLED */
     {
-        handshake->update_checksum(ssl, buf, p - buf);
+        ret = handshake->update_checksum(ssl, buf, p - buf);
+        if (0 != ret) {
+            MBEDTLS_SSL_DEBUG_RET(1, ("update_checksum"), ret);
+            return ret;
+        }
     }
 
     ret = ssl_tls13_determine_key_exchange_mode(ssl);
@@ -2134,8 +2154,8 @@
                                                            &msg_len,
                                                            0));
 
-    mbedtls_ssl_add_hs_msg_to_checksum(
-        ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, msg_len);
+    MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum(
+                         ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, msg_len));
 
     MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg(
                              ssl, buf_len, msg_len));
@@ -2207,8 +2227,8 @@
                                                            buf + buf_len,
                                                            &msg_len,
                                                            1));
-    mbedtls_ssl_add_hs_msg_to_checksum(
-        ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, msg_len);
+    MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum(
+        ssl, MBEDTLS_SSL_HS_SERVER_HELLO, buf, msg_len));
 
 
     MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg(ssl, buf_len,
@@ -2306,8 +2326,8 @@
     MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_encrypted_extensions_body(
                              ssl, buf, buf + buf_len, &msg_len));
 
-    mbedtls_ssl_add_hs_msg_to_checksum(
-        ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, buf, msg_len);
+    MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum(
+        ssl, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS, buf, msg_len));
 
     MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg(
                              ssl, buf_len, msg_len));
@@ -2439,8 +2459,8 @@
         MBEDTLS_SSL_PROC_CHK(ssl_tls13_write_certificate_request_body(
                                  ssl, buf, buf + buf_len, &msg_len));
 
-        mbedtls_ssl_add_hs_msg_to_checksum(
-            ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, buf, msg_len);
+        MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_add_hs_msg_to_checksum(
+            ssl, MBEDTLS_SSL_HS_CERTIFICATE_REQUEST, buf, msg_len));
 
         MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_finish_handshake_msg(
                                  ssl, buf_len, msg_len));