Add mbedtls_ssl_get_max_frag_len()
This is not very useful for TLS as mbedtls_ssl_write() will automatically
fragment and return the length used, and the application should check for that
anyway, but this is useful for DTLS where mbedtls_ssl_write() returns an
error, and the application needs to be able to query the maximum length
instead of just guessing.
diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index 9007562..283e80a 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -5862,6 +5862,29 @@
return( (int)( mbedtls_ssl_hdr_len( ssl ) + transform_expansion ) );
}
+#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
+size_t mbedtls_ssl_get_max_frag_len( const mbedtls_ssl_context *ssl )
+{
+ size_t max_len;
+
+ /*
+ * Assume mfl_code is correct since it was checked when set
+ */
+ max_len = mfl_code_to_length[ssl->conf->mfl_code];
+
+ /*
+ * Check if a smaller max length was negotiated
+ */
+ if( ssl->session_out != NULL &&
+ mfl_code_to_length[ssl->session_out->mfl_code] < max_len )
+ {
+ max_len = mfl_code_to_length[ssl->session_out->mfl_code];
+ }
+
+ return max_len;
+}
+#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
+
#if defined(MBEDTLS_X509_CRT_PARSE_C)
const mbedtls_x509_crt *mbedtls_ssl_get_peer_cert( const mbedtls_ssl_context *ssl )
{
@@ -6339,23 +6362,7 @@
{
int ret;
#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
- unsigned int max_len;
-#endif
-
-#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
- /*
- * Assume mfl_code is correct since it was checked when set
- */
- max_len = mfl_code_to_length[ssl->conf->mfl_code];
-
- /*
- * Check if a smaller max length was negotiated
- */
- if( ssl->session_out != NULL &&
- mfl_code_to_length[ssl->session_out->mfl_code] < max_len )
- {
- max_len = mfl_code_to_length[ssl->session_out->mfl_code];
- }
+ size_t max_len = mbedtls_ssl_get_max_frag_len( ssl );
if( len > max_len )
{