Make mbedtls_ssl_read/write_version static inline
Reasons:
- If the transport type is fixed at compile-time,
mbedtls_ssl_read_version() and mbedtls_ssl_write_version()
are called with a compile-time determined `transport`
parameter, so the transport-type branch in their body
can be eliminated at compile-time.
- mbedtls_ssl_read_version() is called with addresses of
local variables, which so far need to be put on the stack
to be addressable. Inlining the call allows to read directly
into the registers holding these local variables.
This saves 60 bytes w.r.t. the measurement performed by
> ./scripts/baremetal.sh --rom --gcc
diff --git a/include/mbedtls/ssl_internal.h b/include/mbedtls/ssl_internal.h
index 43443bf..5ba2f30 100644
--- a/include/mbedtls/ssl_internal.h
+++ b/include/mbedtls/ssl_internal.h
@@ -1020,11 +1020,6 @@
uint32_t *flags );
#endif /* MBEDTLS_X509_CRT_PARSE_C */
-void mbedtls_ssl_write_version( int major, int minor, int transport,
- unsigned char ver[2] );
-void mbedtls_ssl_read_version( int *major, int *minor, int transport,
- const unsigned char ver[2] );
-
static inline size_t mbedtls_ssl_in_hdr_len( const mbedtls_ssl_context *ssl )
{
return( (size_t) ( ssl->in_iv - ssl->in_hdr ) );
@@ -1104,6 +1099,69 @@
#endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 || \
MBEDTLS_SSL_PROTO_TLS1_2 */
+/*
+ * Convert version numbers to/from wire format
+ * and, for DTLS, to/from TLS equivalent.
+ *
+ * For TLS this is the identity.
+ * For DTLS, use 1's complement (v -> 255 - v, and then map as follows:
+ * 1.0 <-> 3.2 (DTLS 1.0 is based on TLS 1.1)
+ * 1.x <-> 3.x+1 for x != 0 (DTLS 1.2 based on TLS 1.2)
+ */
+static inline void mbedtls_ssl_write_version( int major, int minor,
+ int transport,
+ unsigned char ver[2] )
+{
+#if !defined(MBEDTLS_SSL_TRANSPORT__BOTH)
+ ((void) transport);
+#endif
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+ if( MBEDTLS_SSL_TRANSPORT_IS_DTLS( transport ) )
+ {
+ if( minor == MBEDTLS_SSL_MINOR_VERSION_2 )
+ --minor; /* DTLS 1.0 stored as TLS 1.1 internally */
+
+ ver[0] = (unsigned char)( 255 - ( major - 2 ) );
+ ver[1] = (unsigned char)( 255 - ( minor - 1 ) );
+ }
+ MBEDTLS_SSL_TRANSPORT_ELSE
+#endif
+#if defined(MBEDTLS_SSL_PROTO_TLS)
+ {
+ ver[0] = (unsigned char) major;
+ ver[1] = (unsigned char) minor;
+ }
+#endif
+}
+
+static inline void mbedtls_ssl_read_version( int *major, int *minor,
+ int transport,
+ const unsigned char ver[2] )
+{
+#if !defined(MBEDTLS_SSL_TRANSPORT__BOTH)
+ ((void) transport);
+#endif
+
+#if defined(MBEDTLS_SSL_PROTO_DTLS)
+ if( MBEDTLS_SSL_TRANSPORT_IS_DTLS( transport ) )
+ {
+ *major = 255 - ver[0] + 2;
+ *minor = 255 - ver[1] + 1;
+
+ if( *minor == MBEDTLS_SSL_MINOR_VERSION_1 )
+ ++*minor; /* DTLS 1.0 stored as TLS 1.1 internally */
+ }
+ MBEDTLS_SSL_TRANSPORT_ELSE
+#endif /* MBEDTLS_SSL_PROTO_DTLS */
+#if defined(MBEDTLS_SSL_PROTO_TLS)
+ {
+ *major = ver[0];
+ *minor = ver[1];
+ }
+#endif /* MBEDTLS_SSL_PROTO_TLS */
+}
+
#ifdef __cplusplus
}
#endif