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tls_server.c
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tls_server.c
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/**
* @file tls_server.c
* @brief Handshake message processing (TLS server)
*
* @section License
*
* SPDX-License-Identifier: GPL-2.0-or-later
*
* Copyright (C) 2010-2022 Oryx Embedded SARL. All rights reserved.
*
* This file is part of CycloneSSL Open.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* @section Description
*
* The TLS protocol provides communications security over the Internet. The
* protocol allows client/server applications to communicate in a way that
* is designed to prevent eavesdropping, tampering, or message forgery
*
* @author Oryx Embedded SARL (www.oryx-embedded.com)
* @version 2.1.4
**/
//Switch to the appropriate trace level
#define TRACE_LEVEL TLS_TRACE_LEVEL
//Dependencies
#include <string.h>
#include "tls.h"
#include "tls_cipher_suites.h"
#include "tls_handshake.h"
#include "tls_server.h"
#include "tls_server_extensions.h"
#include "tls_server_misc.h"
#include "tls_common.h"
#include "tls_extensions.h"
#include "tls_signature.h"
#include "tls_key_material.h"
#include "tls_transcript_hash.h"
#include "tls_cache.h"
#include "tls_ffdhe.h"
#include "tls_record.h"
#include "tls_misc.h"
#include "tls13_server.h"
#include "tls13_server_extensions.h"
#include "tls13_server_misc.h"
#include "dtls_record.h"
#include "dtls_misc.h"
#include "pkix/pem_import.h"
#include "pkix/x509_cert_parse.h"
#include "date_time.h"
#include "debug.h"
//Check TLS library configuration
#if (TLS_SUPPORT == ENABLED && TLS_SERVER_SUPPORT == ENABLED)
/**
* @brief Send ServerHello message
*
* The server will send this message in response to a ClientHello
* message when it was able to find an acceptable set of algorithms.
* If it cannot find such a match, it will respond with a handshake
* failure alert
*
* @param[in] context Pointer to the TLS context
* @return Error code
**/
error_t tlsSendServerHello(TlsContext *context)
{
error_t error;
size_t length;
TlsServerHello *message;
//Point to the buffer where to format the message
message = (TlsServerHello *) (context->txBuffer + context->txBufferLen);
//Generate the server random value using a cryptographically-safe
//pseudorandom number generator
error = tlsGenerateRandomValue(context, context->serverRandom);
//Check status code
if(!error)
{
//Format ServerHello message
error = tlsFormatServerHello(context, message, &length);
}
//Check status code
if(!error)
{
//Debug message
TRACE_INFO("Sending ServerHello message (%" PRIuSIZE " bytes)...\r\n", length);
TRACE_DEBUG_ARRAY(" ", message, length);
//Send handshake message
error = tlsSendHandshakeMessage(context, message, length,
TLS_TYPE_SERVER_HELLO);
}
//Check status code
if(error == NO_ERROR || error == ERROR_WOULD_BLOCK || error == ERROR_TIMEOUT)
{
//Version of TLS prior to TLS 1.3?
if(context->version <= TLS_VERSION_1_2)
{
#if (TLS_SESSION_RESUME_SUPPORT == ENABLED)
//Use abbreviated handshake?
if(context->resume)
{
//Derive session keys from the master secret
error = tlsGenerateSessionKeys(context);
//Key material successfully generated?
if(!error)
{
#if (TLS_TICKET_SUPPORT == ENABLED)
//The server uses a zero-length SessionTicket extension to
//indicate to the client that it will send a new session ticket
//using the NewSessionTicket handshake message
if(context->sessionTicketExtSent)
{
//Send a NewSessionTicket message to the client
context->state = TLS_STATE_NEW_SESSION_TICKET;
}
else
#endif
{
//At this point, both client and server must send ChangeCipherSpec
//messages and proceed directly to Finished messages
context->state = TLS_STATE_SERVER_CHANGE_CIPHER_SPEC;
}
}
}
else
#endif
{
//Perform a full handshake
context->state = TLS_STATE_SERVER_CERTIFICATE;
}
}
else
{
#if (TLS13_MIDDLEBOX_COMPAT_SUPPORT == ENABLED)
//First handshake message sent by the server?
if(context->state == TLS_STATE_SERVER_HELLO)
{
//In middlebox compatibility mode, the server must send a dummy
//ChangeCipherSpec record immediately after its first handshake
//message
context->state = TLS_STATE_SERVER_CHANGE_CIPHER_SPEC;
}
else
#endif
{
//All handshake messages after the ServerHello are now encrypted
context->state = TLS_STATE_HANDSHAKE_TRAFFIC_KEYS;
}
}
}
//Return status code
return error;
}
/**
* @brief Send ServerKeyExchange message
*
* The ServerKeyExchange message is sent by the server only when the
* server Certificate message does not contain enough data to allow
* the client to exchange a premaster secret
*
* @param[in] context Pointer to the TLS context
* @return Error code
**/
error_t tlsSendServerKeyExchange(TlsContext *context)
{
error_t error;
size_t length;
TlsServerKeyExchange *message;
//Initialize status code
error = NO_ERROR;
//Point to the buffer where to format the message
message = (TlsServerKeyExchange *) (context->txBuffer + context->txBufferLen);
//Initialize length
length = 0;
//The ServerKeyExchange message is sent by the server only when the server
//Certificate message (if sent) does not contain enough data to allow the
//client to exchange a premaster secret
if(context->keyExchMethod == TLS_KEY_EXCH_DH_ANON ||
context->keyExchMethod == TLS_KEY_EXCH_DHE_RSA ||
context->keyExchMethod == TLS_KEY_EXCH_DHE_DSS ||
context->keyExchMethod == TLS_KEY_EXCH_DHE_PSK ||
context->keyExchMethod == TLS_KEY_EXCH_ECDH_ANON ||
context->keyExchMethod == TLS_KEY_EXCH_ECDHE_RSA ||
context->keyExchMethod == TLS_KEY_EXCH_ECDHE_ECDSA ||
context->keyExchMethod == TLS_KEY_EXCH_ECDHE_PSK)
{
//Format ServerKeyExchange message
error = tlsFormatServerKeyExchange(context, message, &length);
}
else if(context->keyExchMethod == TLS_KEY_EXCH_PSK ||
context->keyExchMethod == TLS_KEY_EXCH_RSA_PSK)
{
#if (TLS_PSK_KE_SUPPORT == ENABLED || TLS_RSA_PSK_KE_SUPPORT == ENABLED || \
TLS_DHE_PSK_KE_SUPPORT == ENABLED || TLS_ECDHE_PSK_KE_SUPPORT == ENABLED)
//If no PSK identity hint is provided by the server, the
//ServerKeyExchange message is omitted...
if(context->pskIdentityHint != NULL)
{
//Format ServerKeyExchange message
error = tlsFormatServerKeyExchange(context, message, &length);
}
#endif
}
//Check status code
if(!error)
{
//Any message to send?
if(length > 0)
{
//Debug message
TRACE_INFO("Sending ServerKeyExchange message (%" PRIuSIZE " bytes)...\r\n", length);
TRACE_DEBUG_ARRAY(" ", message, length);
//Send handshake message
error = tlsSendHandshakeMessage(context, message, length,
TLS_TYPE_SERVER_KEY_EXCHANGE);
}
}
//Check status code
if(error == NO_ERROR || error == ERROR_WOULD_BLOCK || error == ERROR_TIMEOUT)
{
//A server can optionally request a certificate from the client
context->state = TLS_STATE_CERTIFICATE_REQUEST;
}
//Return status code
return error;
}
/**
* @brief Send CertificateRequest message
*
* A server can optionally request a certificate from the client, if
* appropriate for the selected cipher suite. This message will
* immediately follow the ServerKeyExchange message
*
* @param[in] context Pointer to the TLS context
* @return Error code
**/
error_t tlsSendCertificateRequest(TlsContext *context)
{
error_t error;
size_t length;
TlsCertificateRequest *message;
//Initialize status code
error = NO_ERROR;
#if (TLS_RSA_SIGN_SUPPORT == ENABLED || TLS_RSA_PSS_SIGN_SUPPORT == ENABLED || \
TLS_DSA_SIGN_SUPPORT == ENABLED || TLS_ECDSA_SIGN_SUPPORT == ENABLED)
//A server can optionally request a certificate from the client
if(context->clientAuthMode != TLS_CLIENT_AUTH_NONE)
{
//Non-anonymous key exchange?
if(context->keyExchMethod == TLS_KEY_EXCH_RSA ||
context->keyExchMethod == TLS_KEY_EXCH_DHE_RSA ||
context->keyExchMethod == TLS_KEY_EXCH_DHE_DSS ||
context->keyExchMethod == TLS_KEY_EXCH_ECDHE_RSA ||
context->keyExchMethod == TLS_KEY_EXCH_ECDHE_ECDSA ||
context->keyExchMethod == TLS_KEY_EXCH_RSA_PSK ||
context->keyExchMethod == TLS13_KEY_EXCH_DHE ||
context->keyExchMethod == TLS13_KEY_EXCH_ECDHE)
{
//Point to the buffer where to format the message
message = (TlsCertificateRequest *) (context->txBuffer + context->txBufferLen);
//Format CertificateRequest message
error = tlsFormatCertificateRequest(context, message, &length);
//Check status code
if(!error)
{
//Debug message
TRACE_INFO("Sending CertificateRequest message (%" PRIuSIZE " bytes)...\r\n", length);
TRACE_DEBUG_ARRAY(" ", message, length);
//Send handshake message
error = tlsSendHandshakeMessage(context, message, length,
TLS_TYPE_CERTIFICATE_REQUEST);
}
}
}
#endif
//Check status code
if(error == NO_ERROR || error == ERROR_WOULD_BLOCK || error == ERROR_TIMEOUT)
{
//Version of TLS prior to TLS 1.3?
if(context->version <= TLS_VERSION_1_2)
{
//Send a ServerHelloDone message to the client
context->state = TLS_STATE_SERVER_HELLO_DONE;
}
else
{
//Send a Certificate message to the client
context->state = TLS_STATE_SERVER_CERTIFICATE;
}
}
//Return status code
return error;
}
/**
* @brief Send ServerHelloDone message
*
* The ServerHelloDone message is sent by the server to indicate the
* end of the ServerHello and associated messages. After sending this
* message, the server will wait for a client response
*
* @param[in] context Pointer to the TLS context
* @return Error code
**/
error_t tlsSendServerHelloDone(TlsContext *context)
{
error_t error;
size_t length;
TlsServerHelloDone *message;
//Point to the buffer where to format the message
message = (TlsServerHelloDone *) (context->txBuffer + context->txBufferLen);
//Format ServerHelloDone message
error = tlsFormatServerHelloDone(context, message, &length);
//Check status code
if(!error)
{
//Debug message
TRACE_INFO("Sending ServerHelloDone message (%" PRIuSIZE " bytes)...\r\n", length);
TRACE_DEBUG_ARRAY(" ", message, length);
//Send handshake message
error = tlsSendHandshakeMessage(context, message, length,
TLS_TYPE_SERVER_HELLO_DONE);
}
//Check status code
if(error == NO_ERROR || error == ERROR_WOULD_BLOCK || error == ERROR_TIMEOUT)
{
//The client must send a Certificate message if the server requests it
if(context->clientAuthMode != TLS_CLIENT_AUTH_NONE)
{
context->state = TLS_STATE_CLIENT_CERTIFICATE;
}
else
{
context->state = TLS_STATE_CLIENT_KEY_EXCHANGE;
}
}
//Return status code
return error;
}
/**
* @brief Send NewSessionTicket message
*
* This NewSessionTicket message is sent by the server during the TLS handshake
* before the ChangeCipherSpec message
*
* @param[in] context Pointer to the TLS context
* @return Error code
**/
error_t tlsSendNewSessionTicket(TlsContext *context)
{
error_t error;
size_t length;
TlsNewSessionTicket *message;
//Point to the buffer where to format the message
message = (TlsNewSessionTicket *) (context->txBuffer + context->txBufferLen);
//Format NewSessionTicket message
error = tlsFormatNewSessionTicket(context, message, &length);
//Check status code
if(!error)
{
//Debug message
TRACE_INFO("Sending NewSessionTicket message (%" PRIuSIZE " bytes)...\r\n", length);
TRACE_DEBUG_ARRAY(" ", message, length);
//Send handshake message
error = tlsSendHandshakeMessage(context, message, length,
TLS_TYPE_NEW_SESSION_TICKET);
}
//Check status code
if(error == NO_ERROR || error == ERROR_WOULD_BLOCK || error == ERROR_TIMEOUT)
{
//The NewSessionTicket message is sent by the server during the TLS
//handshake before the ChangeCipherSpec message
context->state = TLS_STATE_SERVER_CHANGE_CIPHER_SPEC;
}
//Return status code
return error;
}
/**
* @brief Format ServerHello message
* @param[in] context Pointer to the TLS context
* @param[out] message Buffer where to format the ServerHello message
* @param[out] length Length of the resulting ServerHello message
* @return Error code
**/
error_t tlsFormatServerHello(TlsContext *context,
TlsServerHello *message, size_t *length)
{
error_t error;
uint16_t version;
size_t n;
uint8_t *p;
TlsExtensionList *extensionList;
//In TLS 1.3, the client indicates its version preferences in the
//SupportedVersions extension and the legacy_version field must be
//set to 0x0303, which is the version number for TLS 1.2
version = MIN(context->version, TLS_VERSION_1_2);
#if (DTLS_SUPPORT == ENABLED)
//DTLS protocol?
if(context->transportProtocol == TLS_TRANSPORT_PROTOCOL_DATAGRAM)
{
//Get the corresponding DTLS version
version = dtlsTranslateVersion(version);
}
#endif
//In previous versions of TLS, the version field contains the lower of
//the version suggested by the client in the ClientHello and the highest
//supported by the server
message->serverVersion = htons(version);
//Server random value
osMemcpy(message->random, context->serverRandom, 32);
//Point to the session ID
p = message->sessionId;
//Length of the handshake message
*length = sizeof(TlsServerHello);
//Version of TLS prior to TLS 1.3?
if(context->version <= TLS_VERSION_1_2)
{
#if (TLS_SESSION_RESUME_SUPPORT == ENABLED)
//The session ID uniquely identifies the current session
osMemcpy(message->sessionId, context->sessionId, context->sessionIdLen);
message->sessionIdLen = (uint8_t) context->sessionIdLen;
#else
//The server may return an empty session ID to indicate that the session
//will not be cached and therefore cannot be resumed
message->sessionIdLen = 0;
#endif
}
else
{
//The legacy_session_id_echo echoes the contents of the client's
//legacy_session_id field
osMemcpy(message->sessionId, context->sessionId, context->sessionIdLen);
message->sessionIdLen = (uint8_t) context->sessionIdLen;
}
//Debug message
TRACE_DEBUG("Session ID (%" PRIu8 " bytes):\r\n", message->sessionIdLen);
TRACE_DEBUG_ARRAY(" ", message->sessionId, message->sessionIdLen);
//Advance data pointer
p += message->sessionIdLen;
//Adjust the length of the message
*length += message->sessionIdLen;
//The cipher_suite field contains the single cipher suite selected by
//the server
STORE16BE(context->cipherSuite.identifier, p);
//Advance data pointer
p += sizeof(uint16_t);
//Adjust the length of the message
*length += sizeof(uint16_t);
//The CRIME exploit takes advantage of TLS compression, so conservative
//implementations do not enable compression at the TLS level
*p = TLS_COMPRESSION_METHOD_NULL;
//Advance data pointer
p += sizeof(uint8_t);
//Adjust the length of the message
*length += sizeof(uint8_t);
//Only extensions offered by the client can appear in the server's list
extensionList = (TlsExtensionList *) p;
//Total length of the extension list
extensionList->length = 0;
//Point to the first extension of the list
p += sizeof(TlsExtensionList);
#if (TLS_MAX_VERSION >= TLS_VERSION_1_0 && TLS_MIN_VERSION <= TLS_VERSION_1_2)
//TLS 1.0, TLS 1.1 or TLS 1.2 selected by the server?
if(context->version <= TLS_VERSION_1_2)
{
#if (TLS_SNI_SUPPORT == ENABLED)
//The server may include a SNI extension in the ServerHello
error = tlsFormatServerSniExtension(context, p, &n);
//Any error to report?
if(error)
return error;
//Fix the length of the extension list
extensionList->length += (uint16_t) n;
//Point to the next field
p += n;
#endif
#if (TLS_MAX_FRAG_LEN_SUPPORT == ENABLED)
//Servers that receive an ClientHello containing a MaxFragmentLength
//extension may accept the requested maximum fragment length by including
//an extension of type MaxFragmentLength in the ServerHello
error = tlsFormatServerMaxFragLenExtension(context, p, &n);
//Any error to report?
if(error)
return error;
//Fix the length of the extension list
extensionList->length += (uint16_t) n;
//Point to the next field
p += n;
#endif
#if (TLS_RECORD_SIZE_LIMIT_SUPPORT == ENABLED)
//The value of RecordSizeLimit is the maximum size of record in octets
//that the endpoint is willing to receive
error = tlsFormatServerRecordSizeLimitExtension(context, p, &n);
//Any error to report?
if(error)
return error;
//Fix the length of the extension list
extensionList->length += (uint16_t) n;
//Point to the next field
p += n;
#endif
#if (TLS_ECDH_ANON_KE_SUPPORT == ENABLED || TLS_ECDHE_RSA_KE_SUPPORT == ENABLED || \
TLS_ECDHE_ECDSA_KE_SUPPORT == ENABLED || TLS_ECDHE_PSK_KE_SUPPORT == ENABLED)
//A server that selects an ECC cipher suite in response to a ClientHello
//message including an EcPointFormats extension appends this extension
//to its ServerHello message
error = tlsFormatServerEcPointFormatsExtension(context, p, &n);
//Any error to report?
if(error)
return error;
//Fix the length of the extension list
extensionList->length += (uint16_t) n;
//Point to the next field
p += n;
#endif
#if (TLS_ALPN_SUPPORT == ENABLED)
//The ALPN extension contains the name of the selected protocol
error = tlsFormatServerAlpnExtension(context, p, &n);
//Any error to report?
if(error)
return error;
//Fix the length of the extension list
extensionList->length += (uint16_t) n;
//Point to the next field
p += n;
#endif
#if (TLS_RAW_PUBLIC_KEY_SUPPORT == ENABLED)
//The ClientCertType extension in the ServerHello indicates the type
//of certificates the client is requested to provide in a subsequent
//certificate payload
error = tlsFormatClientCertTypeExtension(context, p, &n);
//Any error to report?
if(error)
return error;
//Fix the length of the extension list
extensionList->length += (uint16_t) n;
//Point to the next field
p += n;
//With the ServerCertType extension in the ServerHello, the TLS server
//indicates the certificate type carried in the certificate payload
error = tlsFormatServerCertTypeExtension(context, p, &n);
//Any error to report?
if(error)
return error;
//Fix the length of the extension list
extensionList->length += (uint16_t) n;
//Point to the next field
p += n;
#endif
#if (TLS_EXT_MASTER_SECRET_SUPPORT == ENABLED)
//If a server implementing RFC 7627 receives the ExtendedMasterSecret
//extension, it must include the extension in its ServerHello message
error = tlsFormatServerEmsExtension(context, p, &n);
//Any error to report?
if(error)
return error;
//Fix the length of the extension list
extensionList->length += (uint16_t) n;
//Point to the next field
p += n;
#endif
#if (TLS_TICKET_SUPPORT == ENABLED)
//The server uses the SessionTicket extension to indicate to the client
//that it will send a new session ticket using the NewSessionTicket
//handshake message
error = tlsFormatServerSessionTicketExtension(context, p, &n);
//Any error to report?
if(error)
return error;
//Fix the length of the extension list
extensionList->length += (uint16_t) n;
//Point to the next field
p += n;
#endif
#if (TLS_SECURE_RENEGOTIATION_SUPPORT == ENABLED)
//During secure renegotiation, the server must include a renegotiation_info
//extension containing the saved client_verify_data and server_verify_data
error = tlsFormatServerRenegoInfoExtension(context, p, &n);
//Any error to report?
if(error)
return error;
//Fix the length of the extension list
extensionList->length += (uint16_t) n;
//Point to the next field
p += n;
#endif
}
else
#endif
#if (TLS_MAX_VERSION >= TLS_VERSION_1_3 && TLS_MIN_VERSION <= TLS_VERSION_1_3)
//TLS 1.3 selected by the server?
if(context->version == TLS_VERSION_1_3)
{
//A server which negotiates TLS 1.3 must respond by sending a
//SupportedVersions extension containing the selected version value
error = tls13FormatServerSupportedVersionsExtension(context, p, &n);
//Any error to report?
if(error)
return error;
//Fix the length of the extension list
extensionList->length += (uint16_t) n;
//Point to the next field
p += n;
//If using (EC)DHE key establishment, servers offer exactly one
//KeyShareEntry in the ServerHello
error = tls13FormatServerKeyShareExtension(context, p, &n);
//Any error to report?
if(error)
return error;
//Fix the length of the extension list
extensionList->length += (uint16_t) n;
//Point to the next field
p += n;
//In order to accept PSK key establishment, the server sends a
//PreSharedKey extension indicating the selected identity
error = tls13FormatServerPreSharedKeyExtension(context, p, &n);
//Any error to report?
if(error)
return error;
//Fix the length of the extension list
extensionList->length += (uint16_t) n;
//Point to the next field
p += n;
}
else
#endif
//Invalid TLS version?
{
//Report an error
return ERROR_INVALID_VERSION;
}
//Any extensions included in the ServerHello message?
if(extensionList->length > 0)
{
//Convert the length of the extension list to network byte order
extensionList->length = htons(extensionList->length);
//Total length of the message
*length += sizeof(TlsExtensionList) + htons(extensionList->length);
}
//Successful processing
return NO_ERROR;
}
/**
* @brief Format ServerKeyExchange message
* @param[in] context Pointer to the TLS context
* @param[out] message Buffer where to format the ServerKeyExchange message
* @param[out] length Length of the resulting ServerKeyExchange message
* @return Error code
**/
error_t tlsFormatServerKeyExchange(TlsContext *context,
TlsServerKeyExchange *message, size_t *length)
{
error_t error;
size_t n;
size_t paramsLen;
uint8_t *p;
uint8_t *params;
//Point to the beginning of the handshake message
p = message;
//Length of the handshake message
*length = 0;
#if (TLS_PSK_KE_SUPPORT == ENABLED || TLS_RSA_PSK_KE_SUPPORT == ENABLED || \
TLS_DHE_PSK_KE_SUPPORT == ENABLED || TLS_ECDHE_PSK_KE_SUPPORT == ENABLED)
//PSK key exchange method?
if(context->keyExchMethod == TLS_KEY_EXCH_PSK ||
context->keyExchMethod == TLS_KEY_EXCH_RSA_PSK ||
context->keyExchMethod == TLS_KEY_EXCH_DHE_PSK ||
context->keyExchMethod == TLS_KEY_EXCH_ECDHE_PSK)
{
//To help the client in selecting which identity to use, the server
//can provide a PSK identity hint in the ServerKeyExchange message
error = tlsFormatPskIdentityHint(context, p, &n);
//Any error to report?
if(error)
return error;
//Advance data pointer
p += n;
//Adjust the length of the message
*length += n;
}
#endif
//Diffie-Hellman or ECDH key exchange method?
if(context->keyExchMethod == TLS_KEY_EXCH_DH_ANON ||
context->keyExchMethod == TLS_KEY_EXCH_DHE_RSA ||
context->keyExchMethod == TLS_KEY_EXCH_DHE_DSS ||
context->keyExchMethod == TLS_KEY_EXCH_DHE_PSK ||
context->keyExchMethod == TLS_KEY_EXCH_ECDH_ANON ||
context->keyExchMethod == TLS_KEY_EXCH_ECDHE_RSA ||
context->keyExchMethod == TLS_KEY_EXCH_ECDHE_ECDSA ||
context->keyExchMethod == TLS_KEY_EXCH_ECDHE_PSK)
{
//Point to the server's key exchange parameters
params = p;
//Format server's key exchange parameters
error = tlsFormatServerKeyParams(context, p, ¶msLen);
//Any error to report?
if(error)
return error;
//Advance data pointer
p += paramsLen;
//Adjust the length of the message
*length += paramsLen;
}
else
{
//Just for sanity
params = NULL;
paramsLen = 0;
}
//For non-anonymous Diffie-Hellman and ECDH key exchanges, a signature
//over the server's key exchange parameters shall be generated
if(context->keyExchMethod == TLS_KEY_EXCH_DHE_RSA ||
context->keyExchMethod == TLS_KEY_EXCH_DHE_DSS ||
context->keyExchMethod == TLS_KEY_EXCH_ECDHE_RSA ||
context->keyExchMethod == TLS_KEY_EXCH_ECDHE_ECDSA)
{
#if (TLS_MAX_VERSION >= TLS_VERSION_1_0 && TLS_MIN_VERSION <= TLS_VERSION_1_1)
//TLS 1.0 or TLS 1.1 currently selected?
if(context->version <= TLS_VERSION_1_1)
{
//Sign server's key exchange parameters
error = tlsGenerateServerKeySignature(context,
(TlsDigitalSignature *) p, params, paramsLen, &n);
}
else
#endif
#if (TLS_MAX_VERSION >= TLS_VERSION_1_2 && TLS_MIN_VERSION <= TLS_VERSION_1_2)
//TLS 1.2 currently selected?
if(context->version == TLS_VERSION_1_2)
{
//Sign server's key exchange parameters
error = tls12GenerateServerKeySignature(context,
(Tls12DigitalSignature *) p, params, paramsLen, &n);
}
else
#endif
{
//Report an error
error = ERROR_INVALID_VERSION;
}
//Any error to report?
if(error)
return error;
//Advance data pointer
p += n;
//Adjust the length of the message
*length += n;
}
//Successful processing
return NO_ERROR;
}
/**
* @brief Format CertificateRequest message
* @param[in] context Pointer to the TLS context
* @param[out] message Buffer where to format the CertificateRequest message
* @param[out] length Length of the resulting CertificateRequest message
* @return Error code
**/
error_t tlsFormatCertificateRequest(TlsContext *context,
TlsCertificateRequest *message, size_t *length)
{
error_t error;
size_t n;
uint8_t *p;
//Initialize status code
error = NO_ERROR;
//Point to the beginning of the message
p = (uint8_t *) message;
#if (TLS_MAX_VERSION >= TLS_VERSION_1_0 && TLS_MIN_VERSION <= TLS_VERSION_1_2)
//Version of TLS prior to TLS 1.3?
if(context->version <= TLS_VERSION_1_2)
{
size_t pemCertLen;
const char_t *trustedCaList;
size_t trustedCaListLen;
uint8_t *derCert;
size_t derCertLen;
X509CertificateInfo *certInfo;
TlsCertAuthorities *certAuthorities;
//Enumerate the types of certificate types that the client may offer
n = 0;
#if (TLS_RSA_SIGN_SUPPORT == ENABLED || TLS_RSA_PSS_SIGN_SUPPORT == ENABLED)
//Accept certificates that contain an RSA public key
message->certificateTypes[n++] = TLS_CERT_RSA_SIGN;
#endif
#if (TLS_DSA_SIGN_SUPPORT == ENABLED)
//Accept certificates that contain a DSA public key
message->certificateTypes[n++] = TLS_CERT_DSS_SIGN;
#endif
#if (TLS_ECDSA_SIGN_SUPPORT == ENABLED)
//Accept certificates that contain an ECDSA public key
message->certificateTypes[n++] = TLS_CERT_ECDSA_SIGN;
#endif
//Fix the length of the list
message->certificateTypesLen = (uint8_t) n;
//Length of the handshake message
*length = sizeof(TlsCertificateRequest) + n;
//TLS 1.2 currently selected?
if(context->version == TLS_VERSION_1_2)
{
TlsSignHashAlgos *supportedSignAlgos;
//Point to the list of the hash/signature algorithm pairs that the server
//is able to verify. Servers can minimize the computation cost by offering
//a restricted set of digest algorithms
supportedSignAlgos = PTR_OFFSET(message, *length);
//Enumerate the hash/signature algorithm pairs in descending
//order of preference
n = 0;
#if (TLS_SHA256_SUPPORT == ENABLED)
//The hash algorithm used for PRF operations can also be used for signing
if(context->cipherSuite.prfHashAlgo == SHA256_HASH_ALGO)
{
#if (TLS_ECDSA_SIGN_SUPPORT == ENABLED)
//ECDSA signature algorithm with SHA-256
supportedSignAlgos->value[n].signature = TLS_SIGN_ALGO_ECDSA;
supportedSignAlgos->value[n++].hash = TLS_HASH_ALGO_SHA256;
#endif
#if (TLS_RSA_PSS_SIGN_SUPPORT == ENABLED)
//Check whether the X.509 parser supports RSA-PSS signatures
if(x509IsSignAlgoSupported(X509_SIGN_ALGO_RSA_PSS))
{
//RSASSA-PSS PSS signature algorithm with SHA-256
supportedSignAlgos->value[n].signature = TLS_SIGN_ALGO_RSA_PSS_PSS_SHA256;
supportedSignAlgos->value[n++].hash = TLS_HASH_ALGO_INTRINSIC;
}
#endif
#if (TLS_RSA_PSS_SIGN_SUPPORT == ENABLED)
//RSASSA-PSS RSAE signature algorithm with SHA-256
supportedSignAlgos->value[n].signature = TLS_SIGN_ALGO_RSA_PSS_RSAE_SHA256;
supportedSignAlgos->value[n++].hash = TLS_HASH_ALGO_INTRINSIC;
#endif
#if (TLS_RSA_SIGN_SUPPORT == ENABLED)
//RSASSA-PKCS1-v1_5 signature algorithm with SHA-256
supportedSignAlgos->value[n].signature = TLS_SIGN_ALGO_RSA;
supportedSignAlgos->value[n++].hash = TLS_HASH_ALGO_SHA256;
#endif
#if (TLS_DSA_SIGN_SUPPORT == ENABLED)
//DSA signature algorithm with SHA-256
supportedSignAlgos->value[n].signature = TLS_SIGN_ALGO_DSA;
supportedSignAlgos->value[n++].hash = TLS_HASH_ALGO_SHA256;
#endif
}
#endif
#if (TLS_SHA384_SUPPORT == ENABLED)
//The hash algorithm used for PRF operations can also be used for signing
if(context->cipherSuite.prfHashAlgo == SHA384_HASH_ALGO)
{
#if (TLS_ECDSA_SIGN_SUPPORT == ENABLED)
//ECDSA signature algorithm with SHA-384
supportedSignAlgos->value[n].signature = TLS_SIGN_ALGO_ECDSA;
supportedSignAlgos->value[n++].hash = TLS_HASH_ALGO_SHA384;
#endif
#if (TLS_RSA_PSS_SIGN_SUPPORT == ENABLED)
//Check whether the X.509 parser supports RSA-PSS signatures
if(x509IsSignAlgoSupported(X509_SIGN_ALGO_RSA_PSS))
{
//RSASSA-PSS PSS signature algorithm with SHA-384
supportedSignAlgos->value[n].signature = TLS_SIGN_ALGO_RSA_PSS_PSS_SHA384;
supportedSignAlgos->value[n++].hash = TLS_HASH_ALGO_INTRINSIC;
}
#endif
#if (TLS_RSA_PSS_SIGN_SUPPORT == ENABLED)
//RSASSA-PSS RSAE signature algorithm with SHA-384
supportedSignAlgos->value[n].signature = TLS_SIGN_ALGO_RSA_PSS_RSAE_SHA384;
supportedSignAlgos->value[n++].hash = TLS_HASH_ALGO_INTRINSIC;
#endif
#if (TLS_RSA_SIGN_SUPPORT == ENABLED)