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MFL API Fix #243

Merged
merged 5 commits into from
Aug 9, 2021
Merged

MFL API Fix #243

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29092e6
Changed function signature for writing MFL extension
hannestschofenig Apr 27, 2021
ab8d4b7
Removed code in mbedtls_ssl_get_input_max_frag_len
hannestschofenig Apr 27, 2021
0e8d7e8
Changes to client and server MFL extension API
hannestschofenig Apr 28, 2021
24c0538
Update ssl_tls13_server.c
hannestschofenig Jun 21, 2021
5e3aa85
Update library/ssl_tls13_client.c
hannestschofenig Jun 21, 2021
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4 changes: 3 additions & 1 deletion library/ssl_tls.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5703,12 +5703,14 @@ size_t mbedtls_ssl_get_input_max_frag_len( const mbedtls_ssl_context *ssl )
size_t max_len = MBEDTLS_SSL_MAX_CONTENT_LEN;
size_t read_mfl;

#if defined(MBEDTLS_SSL_PROTO_TLS1_2_OR_EARLIER)
/* Use the configured MFL for the client if we're past SERVER_HELLO_DONE */
if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT &&
ssl->state >= MBEDTLS_SSL_SERVER_HELLO_DONE )
{
return ssl_mfl_code_to_length( ssl->conf->mfl_code );
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_2_OR_EARLIER */

/* Check if a smaller max length was negotiated */
if( ssl->session_out != NULL )
Expand All @@ -5720,7 +5722,7 @@ size_t mbedtls_ssl_get_input_max_frag_len( const mbedtls_ssl_context *ssl )
}
}

// During a handshake, use the value being negotiated
/* During a handshake, use the value being negotiated */
if( ssl->session_negotiate != NULL )
{
read_mfl = ssl_mfl_code_to_length( ssl->session_negotiate->mfl_code );
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10 changes: 8 additions & 2 deletions library/ssl_tls13_client.c
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Original file line number Diff line number Diff line change
Expand Up @@ -569,7 +569,7 @@ static int ssl_write_max_fragment_length_ext( mbedtls_ssl_context *ssl,
return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
}

MBEDTLS_SSL_DEBUG_MSG( 3, ( "client hello, adding max_fragment_length extension" ) );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "adding max_fragment_length extension" ) );

*p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH >> 8 ) & 0xFF );
*p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH ) & 0xFF );
Expand Down Expand Up @@ -1754,7 +1754,13 @@ static int ssl_client_hello_write_partial( mbedtls_ssl_context* ssl,
#endif /* MBEDTLS_SSL_ALPN */

#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
ssl_write_max_fragment_length_ext( ssl, buf, end, &cur_ext_len );
if( ( ret = ssl_write_max_fragment_length_ext( ssl, buf,
end - buf, &cur_ext_len ) ) != 0 )
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{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_max_fragment_length_ext", ret );
return( ret );
}

total_ext_len += cur_ext_len;
buf += cur_ext_len;
#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */
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28 changes: 15 additions & 13 deletions library/ssl_tls13_server.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3067,35 +3067,37 @@ static int ssl_client_hello_postprocess( mbedtls_ssl_context* ssl,


#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
static void ssl_write_max_fragment_length_ext( mbedtls_ssl_context *ssl,
unsigned char *buf,
size_t *olen )
static int ssl_write_max_fragment_length_ext( mbedtls_ssl_context *ssl,
unsigned char *buf,
size_t buflen,
size_t *olen )
{
unsigned char *p = buf;

*olen = 0;
if( ( ssl->handshake->extensions_present & MAX_FRAGMENT_LENGTH_EXTENSION )
== 0 )
{
return( 0 );
}

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if( ssl->session_negotiate->mfl_code == MBEDTLS_SSL_MAX_FRAG_LEN_NONE )
{
*olen = 0;
return( 0 );
}

MBEDTLS_SSL_DEBUG_MSG( 3, ( "server hello, max_fragment_length extension" ) );
MBEDTLS_SSL_DEBUG_MSG( 3,
( "adding max_fragment_length extension" ) );

MBEDTLS_SSL_CHK_BUF_PTR( p, buf + buflen, 5 );

*p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH >> 8 ) & 0xFF );
*p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH ) & 0xFF );
*p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH >> 8 )
& 0xFF );
*p++ = (unsigned char)( ( MBEDTLS_TLS_EXT_MAX_FRAGMENT_LENGTH )
& 0xFF );

*p++ = 0x00;
*p++ = 1;

*p++ = ssl->session_negotiate->mfl_code;

*olen = 5;

return( 0 );
}
#endif /* MBEDTLS_SSL_MAX_FRAGMENT_LENGTH */

Expand Down