stun.cxx

现在应用最广泛的一种私网穿透方式

#include <cassert>
#include <cstring>
#include <iostream>
#include <cstdlib>   
#include <errno.h>

#ifdef WIN32
#include <winsock2.h>
#include <stdlib.h>
#include <io.h>
#include <time.h>
#else

#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h> 
#include <arpa/inet.h>
#include <fcntl.h>
#include <netdb.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <net/if.h>

#endif


#if defined(__sparc__) || defined(WIN32)
#define NOSSL
#endif
#define NOSSL

#include "udp.h"
#include "stun.h"


using namespace std;


static void
computeHmac(char* hmac, const char* input, int length, const char* key, int keySize);

static bool 
stunParseAtrAddress( char* body, unsigned int hdrLen,  StunAtrAddress4& result )
{
   if ( hdrLen != 8 )
   {
      clog << "hdrLen wrong for Address" <<endl;
      return false;
   }
   result.pad = *body++;
   result.family = *body++;
   if (result.family == IPv4Family)
   {
      UInt16 nport;
      memcpy(&nport, body, 2); body+=2;
      result.ipv4.port = ntohs(nport);
		
      UInt32 naddr;
      memcpy(&naddr, body, 4); body+=4;
      result.ipv4.addr = ntohl(naddr);
      return true;
   }
   else if (result.family == IPv6Family)
   {
      clog << "ipv6 not supported" << endl;
   }
   else
   {
      clog << "bad address family: " << result.family << endl;
   }
	
   return false;
}

static bool 
stunParseAtrChangeRequest( char* body, unsigned int hdrLen,  StunAtrChangeRequest& result )
{
   if ( hdrLen != 4 )
   {
      clog << "hdr length = " << hdrLen << " expecting " << sizeof(result) << endl;
		
      clog << "Incorrect size for ChangeRequest" << endl;
      return false;
   }
   else
   {
      memcpy(&result.value, body, 4);
      result.value = ntohl(result.value);
      return true;
   }
}

static bool 
stunParseAtrError( char* body, unsigned int hdrLen,  StunAtrError& result )
{
   if ( hdrLen >= sizeof(result) )
   {
      clog << "head on Error too large" << endl;
      return false;
   }
   else
   {
      memcpy(&result.pad, body, 2); body+=2;
      result.pad = ntohs(result.pad);
      result.errorClass = *body++;
      result.number = *body++;
		
      result.sizeReason = hdrLen - 4;
      memcpy(&result.reason, body, result.sizeReason);
      result.reason[result.sizeReason] = 0;
      return true;
   }
}

static bool 
stunParseAtrUnknown( char* body, unsigned int hdrLen,  StunAtrUnknown& result )
{
   if ( hdrLen >= sizeof(result) )
   {
      return false;
   }
   else
   {
      if (hdrLen % 4 != 0) return false;
      result.numAttributes = hdrLen / 4;
      for (int i=0; i<result.numAttributes; i++)
      {
         memcpy(&result.attrType[i], body, 2); body+=2;
         result.attrType[i] = ntohs(result.attrType[i]);
      }
      return true;
   }
}


static bool 
stunParseAtrString( char* body, unsigned int hdrLen,  StunAtrString& result )
{
   if ( hdrLen >= STUN_MAX_STRING )
   {
      clog << "String is too large" << endl;
      return false;
   }
   else
   {
      if (hdrLen % 4 != 0)
      {
         clog << "Bad length string " << hdrLen << endl;
         return false;
      }
		
      result.sizeValue = hdrLen;
      memcpy(&result.value, body, hdrLen);
      result.value[hdrLen] = 0;
      return true;
   }
}


static bool 
stunParseAtrIntegrity( char* body, unsigned int hdrLen,  StunAtrIntegrity& result )
{
   if ( hdrLen != 20)
   {
      clog << "MessageIntegrity must be 20 bytes" << endl;
      return false;
   }
   else
   {
      memcpy(&result.hash, body, hdrLen);
      return true;
   }
}


bool
stunParseMessage( char* buf, unsigned int bufLen, StunMessage& msg, bool verbose)
{
   if (verbose) clog << "Received stun message: " << bufLen << " bytes" << endl;
   memset(&msg, 0, sizeof(msg));
	
   if (sizeof(StunMsgHdr) > bufLen)
   {
      clog << "Bad message" << endl;
      return false;
   }
	
   memcpy(&msg.msgHdr, buf, sizeof(StunMsgHdr));
   msg.msgHdr.msgType = ntohs(msg.msgHdr.msgType);
   msg.msgHdr.msgLength = ntohs(msg.msgHdr.msgLength);
	
   if (msg.msgHdr.msgLength + sizeof(StunMsgHdr) != bufLen)
   {
      clog << "Message header length doesn't match message size: " << msg.msgHdr.msgLength << " - " << bufLen << endl;
      return false;
   }
	
   char* body = buf + sizeof(StunMsgHdr);
   unsigned int size = msg.msgHdr.msgLength;
	
   //clog << "bytes after header = " << size << endl;
	
   while ( size > 0 )
   {
      // !jf! should check that there are enough bytes left in the buffer
		
      StunAtrHdr* attr = reinterpret_cast<StunAtrHdr*>(body);
		
      unsigned int attrLen = ntohs(attr->length);
      int atrType = ntohs(attr->type);
		
      //if (verbose) clog << "Found attribute type=" << AttrNames[atrType] << " length=" << attrLen << endl;
      if ( attrLen+4 > size ) 
      {
         clog << "claims attribute is larger than size of message " <<"(attribute type="<<atrType<<")"<< endl;
         return false;
      }
		
      body += 4; // skip the length and type in attribute header
      size -= 4;
		
      switch ( atrType )
      {
         case MappedAddress:
            msg.hasMappedAddress = true;
            if ( stunParseAtrAddress(  body,  attrLen,  msg.mappedAddress )== false )
            {
               clog << "problem parsing MappedAddress" << endl;
               return false;
            }
            else
            {
               if (verbose) clog << "MappedAddress = " << msg.mappedAddress.ipv4 << endl;
            }
					
            break;  

         case ResponseAddress:
            msg.hasResponseAddress = true;
            if ( stunParseAtrAddress(  body,  attrLen,  msg.responseAddress )== false )
            {
               clog << "problem parsing ResponseAddress" << endl;
               return false;
            }
            else
            {
               if (verbose) clog << "ResponseAddress = " << msg.responseAddress.ipv4 << endl;
            }
            break;  
				
         case ChangeRequest:
            msg.hasChangeRequest = true;
            if (stunParseAtrChangeRequest( body, attrLen, msg.changeRequest) == false)
            {
               clog << "problem parsing ChangeRequest" << endl;
               return false;
            }
            else
            {
               if (verbose) clog << "ChangeRequest = " << msg.changeRequest.value << endl;
            }
            break;
				
         case SourceAddress:
            msg.hasSourceAddress = true;
            if ( stunParseAtrAddress(  body,  attrLen,  msg.sourceAddress )== false )
            {
               clog << "problem parsing SourceAddress" << endl;
               return false;
            }
            else
            {
               if (verbose) clog << "SourceAddress = " << msg.sourceAddress.ipv4 << endl;
            }
            break;  
				
         case ChangedAddress:
            msg.hasChangedAddress = true;
            if ( stunParseAtrAddress(  body,  attrLen,  msg.changedAddress )== false )
            {
               clog << "problem parsing ChangedAddress" << endl;
               return false;
            }
            else
            {
               if (verbose) clog << "ChangedAddress = " << msg.changedAddress.ipv4 << endl;
            }
            break;  
				
         case Username: 
            msg.hasUsername = true;
            if (stunParseAtrString( body, attrLen, msg.username) == false)
            {
               clog << "problem parsing Username" << endl;
               return false;
            }
            else
            {
               if (verbose) clog << "Username = " << msg.username.value << endl;
            }
					
            break;
				
         case Password: 
            msg.hasPassword = true;
            if (stunParseAtrString( body, attrLen, msg.password) == false)
            {
               clog << "problem parsing Password" << endl;
               return false;
            }
            else
            {
               if (verbose) clog << "Password = " << msg.password.value << endl;
            }
            break;
				
         case MessageIntegrity:
            msg.hasMessageIntegrity = true;
            if (stunParseAtrIntegrity( body, attrLen, msg.messageIntegrity) == false)
            {
               clog << "problem parsing MessageIntegrity" << endl;
               return false;
            }
            else
            {
               //if (verbose) clog << "MessageIntegrity = " << msg.messageIntegrity.hash << endl;
            }
					
            // read the current HMAC
            // look up the password given the user of given the transaction id 
            // compute the HMAC on the buffer
            // decide if they match or not
            break;
				
         case ErrorCode:
            msg.hasErrorCode = true;
            if (stunParseAtrError(body, attrLen, msg.errorCode) == false)
            {
               clog << "problem parsing ErrorCode" << endl;
               return false;
            }
            else
            {
               if (verbose) clog << "ErrorCode = " << int(msg.errorCode.errorClass) 
                                 << " " << int(msg.errorCode.number) 
                                 << " " << msg.errorCode.reason << endl;
            }
					
            break;
				
         case UnknownAttribute:
            msg.hasUnknownAttributes = true;
            if (stunParseAtrUnknown(body, attrLen, msg.unknownAttributes) == false)
            {
               clog << "problem parsing UnknownAttribute" << endl;
               return false;
            }
            break;
				
         case ReflectedFrom:
            msg.hasReflectedFrom = true;
            if ( stunParseAtrAddress(  body,  attrLen,  msg.reflectedFrom ) == false )
            {
               clog << "problem parsing ReflectedFrom" << endl;
               return false;
            }
            break;  
				
         case XorMappedAddress:
            msg.hasXorMappedAddress = true;
            if ( stunParseAtrAddress(  body,  attrLen,  msg.xorMappedAddress ) == false )
            {
               clog << "problem parsing XorMappedAddress" << endl;
               return false;
            }
            else
            {
               if (verbose) clog << "XorMappedAddress = " << msg.mappedAddress.ipv4 << endl;
            }
            break;  

         case XorOnly:
            msg.xorOnly = true;
            if (verbose) 
            {
               clog << "xorOnly = true" << endl;
            }
            break;  
				
         case ServerName: 
            msg.hasServerName = true;
            if (stunParseAtrString( body, attrLen, msg.serverName) == false)
            {
               clog << "problem parsing ServerName" << endl;
               return false;
            }
            else
            {
               if (verbose) clog << "ServerName = " << msg.serverName.value << endl;
            }
            break;
				
         case SecondaryAddress:
            msg.hasSecondaryAddress = true;
            if ( stunParseAtrAddress(  body,  attrLen,  msg.secondaryAddress ) == false )
            {
               clog << "problem parsing secondaryAddress" << endl;
               return false;
            }
            else
            {
               if (verbose) clog << "SecondaryAddress = " << msg.secondaryAddress.ipv4 << endl;
            }
            break;  
					
         default:
            if (verbose) clog << "Unknown attribute: " << atrType << endl;
            if ( atrType <= 0x7FFF ) 
            {
               return false;
            }
      }
		
      body += attrLen;
      size -= attrLen;
   }
    
   return true;
}


static char* 
encode16(char* buf, UInt16 data)
{
   UInt16 ndata = htons(data);
   memcpy(buf, reinterpret_cast<void*>(&ndata), sizeof(UInt16));
   return buf + sizeof(UInt16);
}

static char* 
encode32(char* buf, UInt32 data)
{
   UInt32 ndata = htonl(data);
   memcpy(buf, reinterpret_cast<void*>(&ndata), sizeof(UInt32));
   return buf + sizeof(UInt32);
}


static char* 
encode(char* buf, const char* data, unsigned int length)
{
   memcpy(buf, data, length);
   return buf + length;
}


static char* 
encodeAtrAddress4(char* ptr, UInt16 type, const StunAtrAddress4& atr)
{
   ptr = encode16(ptr, type);
   ptr = encode16(ptr, 8);
   *ptr++ = atr.pad;
   *ptr++ = IPv4Family;
   ptr = encode16(ptr, atr.ipv4.port);
   ptr = encode32(ptr, atr.ipv4.addr);
	
   return ptr;
}

static char* 
encodeAtrChangeRequest(char* ptr, const StunAtrChangeRequest& atr)
{
   ptr = encode16(ptr, ChangeRequest);
   ptr = encode16(ptr, 4);
   ptr = encode32(ptr, atr.value);
   return ptr;
}

static char* 
encodeAtrError(char* ptr, const StunAtrError& atr)
{
   ptr = encode16(ptr, ErrorCode);