respect the max-record extension under DTLS

This resolves issue with max-record being negotiated but
ignored. Resolves #61

diff --git a/lib/dtls.c b/lib/dtls.c
index fd8163319bdcab7b6b00341ac3620d8ef7b6a108..17a91285fd626d0193887384c68d6b0b0825e950 100644 (file)
--- a/lib/dtls.c
+++ b/lib/dtls.c
@@ -62,8 +62,13 @@ transmit_message(gnutls_session_t session,
        uint8_t *data, *mtu_data;
        int ret = 0;
        unsigned int offset, frag_len, data_size;
-       const unsigned int mtu =
-           gnutls_dtls_get_data_mtu(session) - DTLS_HANDSHAKE_HEADER_SIZE;
+       unsigned int mtu =
+           gnutls_dtls_get_data_mtu(session);
+
+       if (session->security_parameters.max_record_recv_size < mtu)
+               mtu = session->security_parameters.max_record_recv_size;
+
+       mtu -= DTLS_HANDSHAKE_HEADER_SIZE;
 
        if (bufel->type == GNUTLS_CHANGE_CIPHER_SPEC) {
                _gnutls_dtls_log

diff --git a/lib/gnutls_int.h b/lib/gnutls_int.h
index 4469603dfd6ad0c80b28f9fd89521633d5a573c9..faad0d46a1fc98e6ce209406a733039e33855c6a 100644 (file)
--- a/lib/gnutls_int.h
+++ b/lib/gnutls_int.h
@@ -168,7 +168,7 @@ typedef enum record_flush_t {
  */
 #define MAX_RECORD_SEND_OVERHEAD(session) (MAX_CIPHER_BLOCK_SIZE/*iv*/+MAX_PAD_SIZE+((gnutls_compression_get(session)!=GNUTLS_COMP_NULL)?(EXTRA_COMP_SIZE):(0))+MAX_HASH_SIZE/*MAC*/)
 #define MAX_RECORD_SEND_SIZE(session) (IS_DTLS(session)? \
-       ((size_t)gnutls_dtls_get_mtu(session)): \
+       (MIN((size_t)gnutls_dtls_get_mtu(session), (size_t)session->security_parameters.max_record_send_size+MAX_RECORD_SEND_OVERHEAD(session))): \
        ((size_t)session->security_parameters.max_record_send_size+MAX_RECORD_SEND_OVERHEAD(session)))
 #define MAX_PAD_SIZE 255
 #define EXTRA_COMP_SIZE 2048
@@ -1087,9 +1087,9 @@ inline static size_t max_user_send_size(gnutls_session_t session,
 {
        size_t max;
 
-       if (IS_DTLS(session))
-               max = gnutls_dtls_get_data_mtu(session);
-       else {
+       if (IS_DTLS(session)) {
+               max = MIN(gnutls_dtls_get_data_mtu(session), session->security_parameters.max_record_send_size);
+       } else {
                max = session->security_parameters.max_record_send_size;
        }