void chapProcessPacket(PppContext *context,
const PppPacket *packet, size_t length)
{
//Ensure the length of the incoming CHAP packet is valid
if(length < sizeof(PppPacket))
return;
//Check the length field
if(ntohs(packet->length) > length)
return;
if(ntohs(packet->length) < sizeof(PppPacket))
return;
//Save the length of the CHAP packet
length = ntohs(packet->length);
//Debug message
TRACE_INFO("CHAP packet received (%" PRIuSIZE " bytes)...\r\n", length);
//Dump CHAP packet contents for debugging purpose
pppDumpPacket(packet, length, PPP_PROTOCOL_CHAP);
//CHAP is done at initial link establishment, and could also be
//requested after link establishment
if(context->pppPhase != PPP_PHASE_AUTHENTICATE &&
context->pppPhase != PPP_PHASE_NETWORK)
{
//Any packets received during any other phase must be silently discarded
return;
}
//Check CHAP code field
switch(packet->code)
{
//Challenge packet?
case CHAP_CODE_CHALLENGE:
//Process Challenge packet
chapProcessChallenge(context, (ChapChallengePacket *) packet, length);
break;
//Response packet?
case CHAP_CODE_RESPONSE:
//Process Response packet
chapProcessResponse(context, (ChapResponsePacket *) packet, length);
break;
//Success packet?
case CHAP_CODE_SUCCESS:
//Process Success packet
chapProcessSuccess(context, (ChapSuccessPacket *) packet, length);
break;
//Failure packet?
case CHAP_CODE_FAILURE:
//Process Failure packet
chapProcessFailure(context, (ChapFailurePacket *) packet, length);
break;
//Unknown code field
default:
//Silently drop the incoming packet
break;
}
}
error_t chapSendResponse(PppContext *context, const uint8_t *value)
{
error_t error;
size_t n;
size_t length;
size_t offset;
NetBuffer *buffer;
ChapResponsePacket *responsePacket;
//Retrieve the length of the username
n = strlen(context->username);
//Calculate the length of the Response packet
length = sizeof(ChapResponsePacket) + MD5_DIGEST_SIZE + n;
//Allocate a buffer memory to hold the Response packet
buffer = pppAllocBuffer(length, &offset);
//Failed to allocate memory?
if(!buffer) return ERROR_OUT_OF_MEMORY;
//Point to the Response packet
responsePacket = netBufferAt(buffer, offset);
//Format packet header
responsePacket->code = CHAP_CODE_RESPONSE;
responsePacket->identifier = context->chapFsm.peerIdentifier;
responsePacket->length = htons(length);
responsePacket->valueSize = MD5_DIGEST_SIZE;
//Copy the Response value
memcpy(responsePacket->value, value, MD5_DIGEST_SIZE);
//The Name field is one or more octets representing the
//identification of the system transmitting the packet
memcpy(responsePacket->value + MD5_DIGEST_SIZE, context->username, n);
//Debug message
TRACE_INFO("Sending CHAP Response packet (%" PRIuSIZE " bytes)...\r\n", length);
//Dump packet contents for debugging purpose
pppDumpPacket((PppPacket *) responsePacket, length, PPP_PROTOCOL_CHAP);
//Send PPP frame
error = pppSendFrame(context->interface, buffer, offset, PPP_PROTOCOL_CHAP);
//Free previously allocated memory block
netBufferFree(buffer);
//Return status code
return error;
}
error_t pppSendTerminateAck(PppContext *context,
uint8_t identifier, PppProtocol protocol)
{
error_t error;
size_t length;
size_t offset;
NetBuffer *buffer;
PppTerminatePacket *terminateAckPacket;
//Length of the Terminate-Ack packet
length = sizeof(PppTerminatePacket);
//Allocate a buffer memory to hold the Terminate-Ack packet
buffer = pppAllocBuffer(length, &offset);
//Failed to allocate memory?
if(!buffer) return ERROR_OUT_OF_MEMORY;
//Point to the Terminate-Ack packet
terminateAckPacket = netBufferAt(buffer, offset);
//Format packet header
terminateAckPacket->code = PPP_CODE_TERMINATE_ACK;
terminateAckPacket->identifier = identifier;
terminateAckPacket->length = htons(length);
//Debug message
TRACE_INFO("Sending Terminate-Ack packet (%" PRIuSIZE " bytes)...\r\n", length);
//Dump packet contents for debugging purpose
pppDumpPacket((PppPacket *) terminateAckPacket, length, protocol);
//Send PPP frame
error = pppSendFrame(context->interface, buffer, offset, protocol);
//Free previously allocated memory block
netBufferFree(buffer);
//Return status code
return error;
}
error_t chapSendFailure(PppContext *context)
{
error_t error;
size_t length;
size_t offset;
NetBuffer *buffer;
PppPacket *failurePacket;
//Retrieve the length of the Failure packet
length = sizeof(PppPacket);
//Allocate a buffer memory to hold the Failure packet
buffer = pppAllocBuffer(length, &offset);
//Failed to allocate memory?
if(!buffer) return ERROR_OUT_OF_MEMORY;
//Point to the Failure packet
failurePacket = netBufferAt(buffer, offset);
//Format packet header
failurePacket->code = CHAP_CODE_FAILURE;
failurePacket->identifier = context->chapFsm.localIdentifier;
failurePacket->length = htons(length);
//Debug message
TRACE_INFO("Sending CHAP Failure packet (%" PRIuSIZE " bytes)...\r\n", length);
//Dump packet contents for debugging purpose
pppDumpPacket((PppPacket *) failurePacket, length, PPP_PROTOCOL_CHAP);
//Send PPP frame
error = pppSendFrame(context->interface, buffer, offset, PPP_PROTOCOL_CHAP);
//Free previously allocated memory block
netBufferFree(buffer);
//Return status code
return error;
}
error_t lcpSendConfigureReq(PppContext *context)
{
error_t error;
size_t length;
size_t offset;
NetBuffer *buffer;
PppConfigurePacket *configureReqPacket;
//Debug message
TRACE_INFO("LCP Send-Configure-Request callback\r\n");
//Calculate the maximum size of the Configure-Request packet
length = sizeof(PppConfigurePacket) +
sizeof(LcpMruOption) + sizeof(LcpAccmOption);
//Allocate a buffer memory to hold the packet
buffer = pppAllocBuffer(length, &offset);
//Failed to allocate memory?
if(!buffer) return ERROR_OUT_OF_MEMORY;
//Point to the Configure-Request packet
configureReqPacket = netBufferAt(buffer, offset);
//Format packet header
configureReqPacket->code = PPP_CODE_CONFIGURE_REQ;
configureReqPacket->identifier = ++context->lcpFsm.identifier;
configureReqPacket->length = sizeof(PppConfigurePacket);
//Make sure the Maximum-Receive-Unit option has not been previously rejected
if(!context->localConfig.mruRejected)
{
//Convert MRU to network byte order
uint16_t value = htons(context->localConfig.mru);
//Add option
pppAddOption(configureReqPacket, LCP_OPTION_MRU, &value, sizeof(uint16_t));
}
//Make sure the Async-Control-Character-Map option has not been previously rejected
if(!context->localConfig.accmRejected)
{
//Convert ACCM to network byte order
uint32_t value = htonl(context->localConfig.accm);
//Add option
pppAddOption(configureReqPacket, LCP_OPTION_ACCM, &value, sizeof(uint32_t));
}
//Save packet length
length = configureReqPacket->length;
//Convert length field to network byte order
configureReqPacket->length = htons(length);
//Adjust the length of the multi-part buffer
netBufferSetLength(buffer, offset + length);
//Debug message
TRACE_INFO("Sending Configure-Request packet (%" PRIuSIZE " bytes)...\r\n", length);
//Dump packet contents for debugging purpose
pppDumpPacket((PppPacket *) configureReqPacket, length, PPP_PROTOCOL_LCP);
//Send PPP frame
error = pppSendFrame(context->interface, buffer, offset, PPP_PROTOCOL_LCP);
//The restart counter is decremented each time a Configure-Request is sent
if(context->lcpFsm.restartCounter > 0)
context->lcpFsm.restartCounter--;
//Save the time at which the packet was sent
context->lcpFsm.timestamp = osGetSystemTime();
//Free previously allocated memory block
netBufferFree(buffer);
//Return status code
return error;
}
void lcpProcessPacket(PppContext *context, const PppPacket *packet, size_t length)
{
//Ensure the length of the incoming LCP packet is valid
if(length < sizeof(PppPacket))
return;
//Check the length field
if(ntohs(packet->length) > length)
return;
if(ntohs(packet->length) < sizeof(PppPacket))
return;
//Save the length of the LCP packet
length = ntohs(packet->length);
//Debug message
TRACE_INFO("LCP packet received (%" PRIuSIZE " bytes)...\r\n", length);
//Dump LCP packet contents for debugging purpose
pppDumpPacket(packet, length, PPP_PROTOCOL_LCP);
//Check LCP code field
switch(packet->code)
{
//Configure-Request packet?
case PPP_CODE_CONFIGURE_REQ:
//Process Configure-Request packet
lcpProcessConfigureReq(context, (PppConfigurePacket *) packet);
break;
//Configure-Ack packet?
case PPP_CODE_CONFIGURE_ACK:
//Process Configure-Ack packet
lcpProcessConfigureAck(context, (PppConfigurePacket *) packet);
break;
//Configure-Nak packet?
case PPP_CODE_CONFIGURE_NAK:
//Process Configure-Nak packet
lcpProcessConfigureNak(context, (PppConfigurePacket *) packet);
break;
//Configure-Reject packet?
case PPP_CODE_CONFIGURE_REJ:
//Process Configure-Reject packet
lcpProcessConfigureReject(context, (PppConfigurePacket *) packet);
break;
//Terminate-Request packet?
case PPP_CODE_TERMINATE_REQ:
//Process Terminate-Request packet
lcpProcessTerminateReq(context, (PppTerminatePacket *) packet);
break;
//Terminate-Ack packet?
case PPP_CODE_TERMINATE_ACK:
//Process Terminate-Ack packet
lcpProcessTerminateAck(context, (PppTerminatePacket *) packet);
break;
//Code-Reject packet?
case PPP_CODE_CODE_REJ:
//Process Code-Reject packet
lcpProcessCodeRej(context, (PppCodeRejPacket *) packet);
break;
//Protocol-Reject packet?
case PPP_CODE_PROTOCOL_REJ:
//Process Protocol-Reject packet
lcpProcessProtocolRej(context, (PppProtocolRejPacket *) packet);
break;
//Echo-Request packet?
case PPP_CODE_ECHO_REQ:
//Process Echo-Request packet
lcpProcessEchoReq(context, (PppEchoPacket *) packet);
break;
//Echo-Reply packet?
case PPP_CODE_ECHO_REP:
//Process Echo-Reply packet
lcpProcessEchoRep(context, (PppEchoPacket *) packet);
break;
//Discard-Request packet?
case PPP_CODE_DISCARD_REQ:
//Process Discard-Request packet
lcpProcessDiscardReq(context, (PppDiscardReqPacket *) packet);
break;
//Unknown code field
default:
//The packet is un-interpretable
lcpProcessUnknownCode(context, packet);
break;
}
}
error_t pppSendConfigureAckNak(PppContext *context,
const PppConfigurePacket *configureReqPacket, PppProtocol protocol, PppCode code)
{
error_t error;
size_t length;
size_t offset;
NetBuffer *buffer;
PppConfigurePacket *configureAckNakPacket;
PppOption *option;
//Initialize status code
error = NO_ERROR;
//Retrieve the length of the Configure-Request packet
length = ntohs(configureReqPacket->length);
//Allocate a buffer memory to hold the Configure-Ack, Nak or Reject packet
buffer = pppAllocBuffer(length, &offset);
//Failed to allocate memory?
if(!buffer) return ERROR_OUT_OF_MEMORY;
//Point to the beginning of the packet
configureAckNakPacket = netBufferAt(buffer, offset);
//Format packet header
configureAckNakPacket->code = code;
configureAckNakPacket->identifier = configureReqPacket->identifier;
configureAckNakPacket->length = sizeof(PppConfigurePacket);
//Retrieve the length of the option list
length -= sizeof(PppConfigurePacket);
//Point to the first option
option = (PppOption *) configureReqPacket->options;
//Parse configuration options
while(length > 0)
{
//LCP protocol?
if(protocol == PPP_PROTOCOL_LCP)
{
//Parse LCP option
lcpParseOption(context, option, length, configureAckNakPacket);
}
#if (IPV4_SUPPORT)
//IPCP protocol?
else if(protocol == PPP_PROTOCOL_IPCP)
{
//Parse IPCP option
ipcpParseOption(context, option, length, configureAckNakPacket);
}
#endif
//Remaining bytes to process
length -= option->length;
//Jump to the next option
option = (PppOption *) ((uint8_t *) option + option->length);
}
//Adjust the length of the multi-part buffer
netBufferSetLength(buffer, offset + configureAckNakPacket->length);
//Convert length field to network byte order
configureAckNakPacket->length = htons(configureAckNakPacket->length);
//Debug message
if(code == PPP_CODE_CONFIGURE_ACK)
{
TRACE_INFO("Sending Configure-Ack packet (%" PRIuSIZE " bytes)...\r\n",
ntohs(configureAckNakPacket->length));
}
else if(code == PPP_CODE_CONFIGURE_NAK)
{
TRACE_INFO("Sending Configure-Nak packet (%" PRIuSIZE " bytes)...\r\n",
ntohs(configureAckNakPacket->length));
}
else if(code == PPP_CODE_CONFIGURE_REJ)
{
TRACE_INFO("Sending Configure-Reject packet (%" PRIuSIZE " bytes)...\r\n",
ntohs(configureAckNakPacket->length));
}
//Dump packet contents for debugging purpose
pppDumpPacket((PppPacket *) configureAckNakPacket,
ntohs(configureAckNakPacket->length), protocol);
//Send PPP frame
error = pppSendFrame(context->interface, buffer, offset, protocol);
//Free previously allocated memory block
netBufferFree(buffer);
//Return status code
return error;
}
error_t chapSendChallenge(PppContext *context)
{
error_t error;
size_t n;
size_t length;
size_t offset;
NetBuffer *buffer;
ChapChallengePacket *challengePacket;
//Retrieve the length of the username
n = strlen(context->username);
//Calculate the length of the Challenge packet
length = sizeof(ChapChallengePacket) + MD5_DIGEST_SIZE + n;
//Allocate a buffer memory to hold the Challenge packet
buffer = pppAllocBuffer(length, &offset);
//Failed to allocate memory?
if(!buffer) return ERROR_OUT_OF_MEMORY;
//Point to the Challenge packet
challengePacket = netBufferAt(buffer, offset);
//Format packet header
challengePacket->code = CHAP_CODE_CHALLENGE;
challengePacket->identifier = ++context->chapFsm.localIdentifier;
challengePacket->length = htons(length);
challengePacket->valueSize = MD5_DIGEST_SIZE;
//Make sure that the callback function has been registered
if(context->settings.randCallback != NULL)
{
//Generate a random challenge value
error = context->settings.randCallback(
context->chapFsm.challenge, MD5_DIGEST_SIZE);
}
else
{
//Report an error
error = ERROR_FAILURE;
}
//Check status code
if(!error)
{
//Copy the challenge value
memcpy(challengePacket->value, context->chapFsm.challenge, MD5_DIGEST_SIZE);
//The Name field is one or more octets representing the
//identification of the system transmitting the packet
memcpy(challengePacket->value + MD5_DIGEST_SIZE, context->username, n);
//Debug message
TRACE_INFO("Sending CHAP Challenge packet (%" PRIuSIZE " bytes)...\r\n", length);
//Dump packet contents for debugging purpose
pppDumpPacket((PppPacket *) challengePacket, length, PPP_PROTOCOL_CHAP);
//Send PPP frame
error = pppSendFrame(context->interface, buffer, offset, PPP_PROTOCOL_CHAP);
//The restart counter is decremented each time a Challenge packet is sent
if(context->chapFsm.restartCounter > 0)
context->chapFsm.restartCounter--;
//Save the time at which the packet was sent
context->chapFsm.timestamp = osGetSystemTime();
}
//Free previously allocated memory block
netBufferFree(buffer);
//Return status code
return error;
}
