stun.cxx

现在应用最广泛的一种私网穿透方式

   ptr = encode16(ptr, 6 + atr.sizeReason);
   ptr = encode16(ptr, atr.pad);
   *ptr++ = atr.errorClass;
   *ptr++ = atr.number;
   ptr = encode(ptr, atr.reason, atr.sizeReason);
   return ptr;
}


static char* 
encodeAtrUnknown(char* ptr, const StunAtrUnknown& atr)
{
   ptr = encode16(ptr, UnknownAttribute);
   ptr = encode16(ptr, 2+2*atr.numAttributes);
   for (int i=0; i<atr.numAttributes; i++)
   {
      ptr = encode16(ptr, atr.attrType[i]);
   }
   return ptr;
}


static char* 
encodeXorOnly(char* ptr)
{
   ptr = encode16(ptr, XorOnly );
   return ptr;
}


static char* 
encodeAtrString(char* ptr, UInt16 type, const StunAtrString& atr)
{
   assert(atr.sizeValue % 4 == 0);
	
   ptr = encode16(ptr, type);
   ptr = encode16(ptr, atr.sizeValue);
   ptr = encode(ptr, atr.value, atr.sizeValue);
   return ptr;
}


static char* 
encodeAtrIntegrity(char* ptr, const StunAtrIntegrity& atr)
{
   ptr = encode16(ptr, MessageIntegrity);
   ptr = encode16(ptr, 20);
   ptr = encode(ptr, atr.hash, sizeof(atr.hash));
   return ptr;
}


unsigned int
stunEncodeMessage( const StunMessage& msg, 
                   char* buf, 
                   unsigned int bufLen, 
                   const StunAtrString& password, 
                   bool verbose)
{
   assert(bufLen >= sizeof(StunMsgHdr));
   char* ptr = buf;
	
   ptr = encode16(ptr, msg.msgHdr.msgType);
   char* lengthp = ptr;
   ptr = encode16(ptr, 0);
   ptr = encode(ptr, reinterpret_cast<const char*>(msg.msgHdr.id.octet), sizeof(msg.msgHdr.id));
	
   if (verbose) clog << "Encoding stun message: " << endl;
   if (msg.hasMappedAddress)
   {
      if (verbose) clog << "Encoding MappedAddress: " << msg.mappedAddress.ipv4 << endl;
      ptr = encodeAtrAddress4 (ptr, MappedAddress, msg.mappedAddress);
   }
   if (msg.hasResponseAddress)
   {
      if (verbose) clog << "Encoding ResponseAddress: " << msg.responseAddress.ipv4 << endl;
      ptr = encodeAtrAddress4(ptr, ResponseAddress, msg.responseAddress);
   }
   if (msg.hasChangeRequest)
   {
      if (verbose) clog << "Encoding ChangeRequest: " << msg.changeRequest.value << endl;
      ptr = encodeAtrChangeRequest(ptr, msg.changeRequest);
   }
   if (msg.hasSourceAddress)
   {
      if (verbose) clog << "Encoding SourceAddress: " << msg.sourceAddress.ipv4 << endl;
      ptr = encodeAtrAddress4(ptr, SourceAddress, msg.sourceAddress);
   }
   if (msg.hasChangedAddress)
   {
      if (verbose) clog << "Encoding ChangedAddress: " << msg.changedAddress.ipv4 << endl;
      ptr = encodeAtrAddress4(ptr, ChangedAddress, msg.changedAddress);
   }
   if (msg.hasUsername)
   {
      if (verbose) clog << "Encoding Username: " << msg.username.value << endl;
      ptr = encodeAtrString(ptr, Username, msg.username);
   }
   if (msg.hasPassword)
   {
      if (verbose) clog << "Encoding Password: " << msg.password.value << endl;
      ptr = encodeAtrString(ptr, Password, msg.password);
   }
   if (msg.hasErrorCode)
   {
      if (verbose) clog << "Encoding ErrorCode: class=" 
			<< int(msg.errorCode.errorClass)  
			<< " number=" << int(msg.errorCode.number) 
			<< " reason=" 
			<< msg.errorCode.reason 
			<< endl;
		
      ptr = encodeAtrError(ptr, msg.errorCode);
   }
   if (msg.hasUnknownAttributes)
   {
      if (verbose) clog << "Encoding UnknownAttribute: ???" << endl;
      ptr = encodeAtrUnknown(ptr, msg.unknownAttributes);
   }
   if (msg.hasReflectedFrom)
   {
      if (verbose) clog << "Encoding ReflectedFrom: " << msg.reflectedFrom.ipv4 << endl;
      ptr = encodeAtrAddress4(ptr, ReflectedFrom, msg.reflectedFrom);
   }
   if (msg.hasXorMappedAddress)
   {
      if (verbose) clog << "Encoding XorMappedAddress: " << msg.xorMappedAddress.ipv4 << endl;
      ptr = encodeAtrAddress4 (ptr, XorMappedAddress, msg.xorMappedAddress);
   }
   if (msg.xorOnly)
   {
      if (verbose) clog << "Encoding xorOnly: " << endl;
      ptr = encodeXorOnly( ptr );
   }
   if (msg.hasServerName)
   {
      if (verbose) clog << "Encoding ServerName: " << msg.serverName.value << endl;
      ptr = encodeAtrString(ptr, ServerName, msg.serverName);
   }
   if (msg.hasSecondaryAddress)
   {
      if (verbose) clog << "Encoding SecondaryAddress: " << msg.secondaryAddress.ipv4 << endl;
      ptr = encodeAtrAddress4 (ptr, SecondaryAddress, msg.secondaryAddress);
   }

   if (password.sizeValue > 0)
   {
      if (verbose) clog << "HMAC with password: " << password.value << endl;
		
      StunAtrIntegrity integrity;
      computeHmac(integrity.hash, buf, int(ptr-buf) , password.value, password.sizeValue);
      ptr = encodeAtrIntegrity(ptr, integrity);
   }
   if (verbose) clog << endl;
	
   encode16(lengthp, UInt16(ptr - buf - sizeof(StunMsgHdr)));
   return int(ptr - buf);
}

int 
stunRand()
{
   // return 32 bits of random stuff
   assert( sizeof(int) == 4 );
   static bool init=false;
   if ( !init )
   { 
      init = true;
		
      UInt64 tick;
		
#if defined(WIN32) 
      volatile unsigned int lowtick=0,hightick=0;
      __asm
         {
            rdtsc 
               mov lowtick, eax
               mov hightick, edx
               }
      tick = hightick;
      tick <<= 32;
      tick |= lowtick;
#elif defined(__GNUC__) && ( defined(__i686__) || defined(__i386__) )
      asm("rdtsc" : "=A" (tick));
#elif defined (__SUNPRO_CC) || defined( __sparc__ )	
      tick = gethrtime();
#elif defined(__MACH__) 
      int fd=open("/dev/random",O_RDONLY);
      read(fd,&tick,sizeof(tick));
      closesocket(fd);
#else
#     error Need some way to seed the random number generator 
#endif 
      int seed = int(tick);
#ifdef WIN32
      srand(seed);
#else
      srandom(seed);
#endif
   }
	
#ifdef WIN32
   assert( RAND_MAX == 0x7fff );
   int r1 = rand();
   int r2 = rand();
	
   int ret = (r1<<16) + r2;
	
   return ret;
#else
   return random(); 
#endif
}


/// return a random number to use as a port 
static int
randomPort()
{
   int min=0x4000;
   int max=0x7FFF;
	
   int ret = stunRand();
   ret = ret|min;
   ret = ret&max;
	
   return ret;
}


#ifdef NOSSL
static void
computeHmac(char* hmac, const char* input, int length, const char* key, int sizeKey)
{
   strncpy(hmac,"hmac-not-implemented",20);
}
#else
#include <openssl/hmac.h>

static void
computeHmac(char* hmac, const char* input, int length, const char* key, int sizeKey)
{
   unsigned int resultSize=0;
   HMAC(EVP_sha1(), 
        key, sizeKey, 
        reinterpret_cast<const unsigned char*>(input), length, 
        reinterpret_cast<unsigned char*>(hmac), &resultSize);
   assert(resultSize == 20);
}
#endif


static void
toHex(const char* buffer, int bufferSize, char* output) 
{
   static char hexmap[] = "0123456789abcdef";
	
   const char* p = buffer;
   char* r = output;
   for (int i=0; i < bufferSize; i++)
   {
      unsigned char temp = *p++;
		
      int hi = (temp & 0xf0)>>4;
      int low = (temp & 0xf);
		
      *r++ = hexmap[hi];
      *r++ = hexmap[low];
   }
   *r = 0;
}

void
stunCreateUserName(const StunAddress4& source, StunAtrString* username)
{
   UInt64 time = stunGetSystemTimeSecs();
   time -= (time % 20*60);
   //UInt64 hitime = time >> 32;
   UInt64 lotime = time & 0xFFFFFFFF;
	
   char buffer[1024];
   sprintf(buffer,
           "%08x:%08x:%08x:", 
           UInt32(source.addr),
           UInt32(stunRand()),
           UInt32(lotime));
   assert( strlen(buffer) < 1024 );
	
   assert(strlen(buffer) + 41 < STUN_MAX_STRING);
	
   char hmac[20];
   char key[] = "Jason";
   computeHmac(hmac, buffer, strlen(buffer), key, strlen(key) );
   char hmacHex[41];
   toHex(hmac, 20, hmacHex );
   hmacHex[40] =0;
	
   strcat(buffer,hmacHex);
	
   int l = strlen(buffer);
   assert( l+1 < STUN_MAX_STRING );
   assert( l%4 == 0 );
   
   username->sizeValue = l;
   memcpy(username->value,buffer,l);
   username->value[l]=0;
	
   //if (verbose) clog << "computed username=" << username.value << endl;
}

void
stunCreatePassword(const StunAtrString& username, StunAtrString* password)
{
   char hmac[20];
   char key[] = "Fluffy";
   //char buffer[STUN_MAX_STRING];
   computeHmac(hmac, username.value, strlen(username.value), key, strlen(key));
   toHex(hmac, 20, password->value);
   password->sizeValue = 40;
   password->value[40]=0;
	
   //clog << "password=" << password->value << endl;
}


UInt64
stunGetSystemTimeSecs()
{
   UInt64 time=0;
#if defined(WIN32)  
   SYSTEMTIME t;
   // CJ TODO - this probably has bug on wrap around every 24 hours
   GetSystemTime( &t );
   time = (t.wHour*60+t.wMinute)*60+t.wSecond; 
#else
   struct timeval now;
   gettimeofday( &now , NULL );
   //assert( now );
   time = now.tv_sec;
#endif
   return time;
}


ostream& operator<< ( ostream& strm, const UInt128& r )
{
   strm << int(r.octet[0]);
   for ( int i=1; i<16; i++ )
   {
      strm << ':' << int(r.octet[i]);
   }
    
   return strm;
}

ostream& 
operator<<( ostream& strm, const StunAddress4& addr)
{
   UInt32 ip = addr.addr;
   strm << ((int)(ip>>24)&0xFF) << ".";
   strm << ((int)(ip>>16)&0xFF) << ".";
   strm << ((int)(ip>> 8)&0xFF) << ".";
   strm << ((int)(ip>> 0)&0xFF) ;
	
   strm << ":" << addr.port;
	
   return strm;
}


// returns true if it scucceeded
bool 
stunParseHostName( char* peerName,
               UInt32& ip,
               UInt16& portVal,
               UInt16 defaultPort )
{
   in_addr sin_addr;
    
   char host[512];
   strncpy(host,peerName,512);
   host[512-1]='\0';
   char* port = NULL;
	
   int portNum = defaultPort;
	
   // pull out the port part if present.
   char* sep = strchr(host,':');
	
   if ( sep == NULL )
   {
      portNum = defaultPort;
   }
   else
   {
      *sep = '\0';
      port = sep + 1;
      // set port part
		
      char* endPtr=NULL;
		
      portNum = strtol(port,&endPtr,10);
		
      if ( endPtr != NULL )
      {
         if ( *endPtr != '\0' )
         {
            portNum = defaultPort;
         }
      }
   }
    
   if ( portNum < 1024 ) return false;
   if ( portNum >= 0xFFFF ) return false;
	
   // figure out the host part 
   struct hostent* h;
	
#ifdef WIN32
   assert( strlen(host) >= 1 );
   if ( isdigit( host[0] ) )
   {
      // assume it is a ip address 
      unsigned long a = inet_addr(host);
      //cerr << "a=0x" << hex << a << dec << endl;
		
      ip = ntohl( a );
   }
   else
   {
      // assume it is a host name 
      h = gethostbyname( host );
		
      if ( h == NULL )
      {
         int err = getErrno();
         std::cerr << "error was " << err << std::endl;
         assert( err != WSANOTINITIALISED );
			
         ip = ntohl( 0x7F000001L );
			
         return false;
      }
      else
      {
         sin_addr = *(struct in_addr*)h->h_addr;
         ip = ntohl( sin_addr.s_addr );
      }
   }
	
#else
   h = gethostbyname( host );
   if ( h == NULL )
   {
      int err = getErrno();
      std::cerr << "error was " << err << std::endl;
      ip = ntohl( 0x7F000001L );
      return false;
   }
   else
   {
      sin_addr = *(struct in_addr*)h->h_addr;
      ip = ntohl( sin_addr.s_addr );
   }
#endif
	
   portVal = portNum;
	
   return true;
}


bool
stunParseServerName( char* name, StunAddress4& addr)
{
   assert(name);
	
   // TODO - put in DNS SRV stuff.
	
   bool ret = stunParseHostName( name, addr.addr, addr.port, 3478); 
   if ( ret != true ) 
   {
       addr.port=0xFFFF;
   }	
   return ret;
}