Add RFC5764 - SRTP key generation during DTLS handshake
Signed-off-by: Johan Pascal <johan.pascal@belledonne-communications.com>
This commit is contained in:
Johan Pascal
parent
935b4f96f9
commit
b62bb51aff
5 changed files with 449 additions and 0 deletions
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@ -756,6 +756,79 @@ static int ssl_write_alpn_ext( mbedtls_ssl_context *ssl,
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}
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#endif /* MBEDTLS_SSL_ALPN */
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#if defined (MBEDTLS_SSL_DTLS_SRTP)
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static void ssl_write_use_srtp_ext( mbedtls_ssl_context *ssl,
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unsigned char *buf, size_t *olen )
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{
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unsigned char *p = buf;
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size_t protection_profiles_index = 0;
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*olen = 0;
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if( (ssl->dtls_srtp_profiles_list == NULL) || (ssl->dtls_srtp_profiles_list_len == 0) )
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{
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return;
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}
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MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, adding use_srtp extension" ) );
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*p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP >> 8 ) & 0xFF );
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*p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_USE_SRTP ) & 0xFF );
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/* RFC5764 section 4.1.1
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* uint8 SRTPProtectionProfile[2];
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*
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* struct {
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* SRTPProtectionProfiles SRTPProtectionProfiles;
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* opaque srtp_mki<0..255>;
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* } UseSRTPData;
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* SRTPProtectionProfile SRTPProtectionProfiles<2..2^16-1>;
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*
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* Note: srtp_mki is not supported
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*/
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/* Extension length = 2bytes for profiles lenght, ssl->dtls_srtp_profiles_list_len*2 (each profile is 2 bytes length ) + 1 byte for the non implemented srtp_mki vector length (always 0) */
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*p++ = (unsigned char)( ( ( 2 + 2*(ssl->dtls_srtp_profiles_list_len) + 1 ) >> 8 ) & 0xFF );
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*p++ = (unsigned char)( ( ( 2 + 2*(ssl->dtls_srtp_profiles_list_len) + 1 ) ) & 0xFF );
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/* protection profile length: 2*(ssl->dtls_srtp_profiles_list_len) */
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*p++ = (unsigned char)( ( ( 2*(ssl->dtls_srtp_profiles_list_len) ) >> 8 ) & 0xFF );
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*p++ = (unsigned char)( ( 2*(ssl->dtls_srtp_profiles_list_len) ) & 0xFF );
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for( protection_profiles_index=0; protection_profiles_index < ssl->dtls_srtp_profiles_list_len; protection_profiles_index++ )
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{
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switch (ssl->dtls_srtp_profiles_list[protection_profiles_index]) {
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case MBEDTLS_SRTP_AES128_CM_HMAC_SHA1_80:
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*p++ = ( ( ( MBEDTLS_SRTP_AES128_CM_HMAC_SHA1_80_IANA_VALUE ) >> 8 ) & 0xFF);
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*p++ = ( ( MBEDTLS_SRTP_AES128_CM_HMAC_SHA1_80_IANA_VALUE ) & 0xFF);
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break;
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case MBEDTLS_SRTP_AES128_CM_HMAC_SHA1_32:
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*p++ = ( ( ( MBEDTLS_SRTP_AES128_CM_HMAC_SHA1_32_IANA_VALUE ) >> 8 ) & 0xFF);
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*p++ = ( ( MBEDTLS_SRTP_AES128_CM_HMAC_SHA1_32_IANA_VALUE ) & 0xFF);
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break;
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case MBEDTLS_SRTP_NULL_HMAC_SHA1_80:
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*p++ = ( ( ( MBEDTLS_SRTP_NULL_HMAC_SHA1_80_IANA_VALUE ) >> 8 ) & 0xFF);
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*p++ = ( ( MBEDTLS_SRTP_NULL_HMAC_SHA1_80_IANA_VALUE ) & 0xFF);
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break;
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case MBEDTLS_SRTP_NULL_HMAC_SHA1_32:
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*p++ = ( ( ( MBEDTLS_SRTP_NULL_HMAC_SHA1_32_IANA_VALUE ) >> 8 ) & 0xFF);
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*p++ = ( ( MBEDTLS_SRTP_NULL_HMAC_SHA1_32_IANA_VALUE ) & 0xFF);
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break;
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default:
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/* Note: we shall never arrive here as protection profiles is checked by ssl_set_dtls_srtp_protection_profiles function */
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MBEDTLS_SSL_DEBUG_MSG( 1, ( "client hello, ignore illegal DTLS-SRTP protection profile %d", ssl->dtls_srtp_profiles_list[protection_profiles_index]) );
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break;
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}
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}
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*p++ = 0x00; /* non implemented srtp_mki vector length is always 0 */
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/* total extension length: extension type (2 bytes) + extension length (2 bytes) + protection profile length (2 bytes) + 2*nb protection profiles + srtp_mki vector length(1 byte)*/
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*olen = 2 + 2 + 2 + 2*(ssl->dtls_srtp_profiles_list_len) + 1;
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}
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#endif /* MBEDTLS_SSL_DTLS_SRTP */
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/*
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* Generate random bytes for ClientHello
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*/
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@ -1277,6 +1350,11 @@ static int ssl_write_client_hello( mbedtls_ssl_context *ssl )
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ext_len += olen;
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#endif
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#if defined(MBEDTLS_SSL_DTLS_SRTP)
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ssl_write_use_srtp_ext( ssl, p + 2 + ext_len, &olen );
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ext_len += olen;
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#endif
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#if defined(MBEDTLS_SSL_SESSION_TICKETS)
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if( ( ret = ssl_write_session_ticket_ext( ssl, p + 2 + ext_len,
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end, &olen ) ) != 0 )
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@ -1710,6 +1788,81 @@ static int ssl_parse_alpn_ext( mbedtls_ssl_context *ssl,
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}
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#endif /* MBEDTLS_SSL_ALPN */
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#if defined(MBEDTLS_SSL_DTLS_SRTP)
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static int ssl_parse_use_srtp_ext( mbedtls_ssl_context *ssl,
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const unsigned char *buf, size_t len )
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{
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enum mbedtls_DTLS_SRTP_protection_profiles server_protection = MBEDTLS_SRTP_UNSET_PROFILE;
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size_t i;
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uint16_t server_protection_profile_value = 0;
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/* If use_srtp is not configured, just ignore the extension */
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if( ( ssl->dtls_srtp_profiles_list == NULL ) || ( ssl->dtls_srtp_profiles_list_len == 0 ) )
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return( 0 );
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/* RFC5764 section 4.1.1
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* uint8 SRTPProtectionProfile[2];
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*
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* struct {
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* SRTPProtectionProfiles SRTPProtectionProfiles;
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* opaque srtp_mki<0..255>;
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* } UseSRTPData;
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* SRTPProtectionProfile SRTPProtectionProfiles<2..2^16-1>;
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*
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* Note: srtp_mki is not supported
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*/
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/* Length is 5 : one protection profile(2 bytes) + length(2 bytes) and potential srtp_mki which won't be parsed */
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if( len < 5 )
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return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
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/*
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* get the server protection profile
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*/
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if (((uint16_t)(buf[0]<<8 | buf[1])) != 0x0002) { /* protection profile length must be 0x0002 as we must have only one protection profile in server Hello */
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return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
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} else {
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server_protection_profile_value = buf[2]<<8 | buf[3];
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}
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/*
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* Check we have the server profile in our list
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*/
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for( i=0; i < ssl->dtls_srtp_profiles_list_len; i++)
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{
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switch ( server_protection_profile_value ) {
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case MBEDTLS_SRTP_AES128_CM_HMAC_SHA1_80_IANA_VALUE:
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server_protection = MBEDTLS_SRTP_AES128_CM_HMAC_SHA1_80;
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break;
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case MBEDTLS_SRTP_AES128_CM_HMAC_SHA1_32_IANA_VALUE:
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server_protection = MBEDTLS_SRTP_AES128_CM_HMAC_SHA1_32;
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break;
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case MBEDTLS_SRTP_NULL_HMAC_SHA1_80_IANA_VALUE:
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server_protection = MBEDTLS_SRTP_NULL_HMAC_SHA1_80;
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break;
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case MBEDTLS_SRTP_NULL_HMAC_SHA1_32_IANA_VALUE:
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server_protection = MBEDTLS_SRTP_NULL_HMAC_SHA1_32;
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break;
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default:
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server_protection = MBEDTLS_SRTP_UNSET_PROFILE;
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break;
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}
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if (server_protection == ssl->dtls_srtp_profiles_list[i]) {
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ssl->chosen_dtls_srtp_profile = ssl->dtls_srtp_profiles_list[i];
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return 0;
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}
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}
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/* If we get there, no match was found : server problem, it shall never answer with incompatible profile */
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ssl->chosen_dtls_srtp_profile = MBEDTLS_SRTP_UNSET_PROFILE;
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mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
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MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE );
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return( MBEDTLS_ERR_SSL_BAD_HS_SERVER_HELLO );
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}
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#endif /* MBEDTLS_SSL_DTLS_SRTP */
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/*
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* Parse HelloVerifyRequest. Only called after verifying the HS type.
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*/
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@ -2278,6 +2431,16 @@ static int ssl_parse_server_hello( mbedtls_ssl_context *ssl )
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break;
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#endif /* MBEDTLS_SSL_ALPN */
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#if defined(MBEDTLS_SSL_DTLS_SRTP)
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case MBEDTLS_TLS_EXT_USE_SRTP:
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MBEDTLS_SSL_DEBUG_MSG( 3, ( "found use_srtp extension" ) );
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if( ( ret = ssl_parse_use_srtp_ext( ssl, ext + 4, ext_size ) ) != 0 )
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return( ret );
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break;
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#endif /* MBEDTLS_SSL_DTLS_SRTP */
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default:
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MBEDTLS_SSL_DEBUG_MSG( 3,
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( "unknown extension found: %d (ignoring)", ext_id ) );
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