xtunnelsxcipher.cpp

xtunnel nat/fw traversal source code

/*

	File:       XTunnelsXCipher.cpp

	Contains:   X-Cipher protocol definitions and implementation for X-Tunnels server

	Copyright:  (c) 2003 by Xten Networks, Inc., all rights reserved.

*/

#if DEBUG
#include <iostream>
#endif // DEBUG
#include <signal.h>
#include <string.h>
#include <netinet/in.h>
#define BIND_8_COMPAT 1
#include <arpa/nameser.h>
#include <arpa/inet.h>
//#include <arpa/nameser8_compat.h>
#include <resolv.h>
#include "restart.h"
#include "uici.h"
#include "XTunnelsFamilyData.h"
#include "XTunnelsChildData.h"
#include "XTunnelsXCipher.h"

#if DEBUG
using std::cout;
using std::endl;
#endif // DEBUG
using std::list;
using namespace XTunnels;

#ifndef	TRUE
#define TRUE	1
#endif	/* TRUE */

#ifndef	FALSE
#define FALSE	0
#endif	/* FALSE */

namespace {

#if DEBUG

time_t g_tStartTime = 0;

void StartTiming(char* szMessage)
   {
   cout << "Starting timing -- " << szMessage << endl;
   g_tStartTime = time(NULL);
   }

void TimeCheck(char* szMessage)
   {
   time_t tNow = time(NULL);
   cout << "TimeCheck -- " << tNow - g_tStartTime << " seconds -- " << szMessage << endl;
   }

#endif // DEBUG

typedef struct
{
    u_int16_t 	type;
    u_int16_t 	m_usClass;
    u_int32_t 	ttl;
    u_int16_t 	length;

} rr_header;


typedef struct
{
    u_int16_t 	priority;
    u_int16_t 	weight;
    u_int16_t 	port;

} srv_header;


static int decode_name(char** location, char* buffer, int len, char * decodedName)
    // on input, *location is a pointer to the first byte to parse
    // on return, *location is a pointer after the last byte we consumed
   {
    char 		name[64];
    u_int8_t* 	name_loc = (u_int8_t*)*location;
    u_int8_t* 	last_loc = name_loc;
    u_int8_t 	name_len;
    u_int16_t 	offset;
    int 		hit_pointer;
    
    name_len = *name_loc;
    
    hit_pointer = FALSE;
    
    if (decodedName)
    decodedName[0] = '\0';
    
    while (name_len != 0)
    {
        if ((name_len & INDIR_MASK) == INDIR_MASK)
        {
            // If this is the first pointer we've encountered, set 
            // *location to point to after the pointer.
    
            if (!hit_pointer)
                *location = (char *) (name_loc + 2);
    
            hit_pointer = TRUE;
    
            offset = ((*name_loc) & ~INDIR_MASK) << 8 | *(name_loc + 1);
            name_loc = ((u_int8_t *) buffer) + offset;
    
            if ((char *)name_loc >= *location)
            {
#if DEBUG
            cout << "decode error, compression offset invalid!" << endl;
#endif // DEBUG
                return -2;
            }
    
            if (name_loc == last_loc)
               {
#if DEBUG
               cout << "decode error, compression offset yields loop!" << endl;
#endif // DEBUG
               }
    
            last_loc = name_loc;
        }
        else
        {
            int i = 0;
    
            if ( ((char *) name_loc) + name_len > buffer + len)
            {
#if DEBUG
               cout << "decode error, name extends past end of packet" << endl;
#endif // DEBUG
                return -3;
            }
    
            for (i = 0; i < name_len; i++)
                name[i] = name_loc[i + 1];
            name[i] = 0;
    
            if (decodedName)
            {
                strcat(decodedName, name);
                strcat(decodedName, ".");
            }
    
            name_loc += name_len + 1;
        }
    
        name_len = *name_loc;
    }
    
    // If the name contains no pointers, then we have to set 
    // *location to point to after the null terminator.
    
    if (!hit_pointer)
    *location = (char*)(name_loc + 1);
    
    return 0;
   }

int decode_srv(char** location, char* buffer, int len, char * target, u_int16_t * port)
   {
    rr_header* header;
    
    if (*location >= buffer + len || *location < buffer)
      {
#if DEBUG
      cout << "decode error, ran off the buffer" << endl;
#endif // DEBUG
      return -1;
      }

    if (decode_name(location, buffer, len, NULL) != 0)
        return -2;

    header = (rr_header*)*location;

    if (*location + sizeof(rr_header) >= buffer + len)
      {
#if DEBUG
      cout << "decode error, packet too short for type, class, ttl, and length" << endl;
#endif // DEBUG
      return -3;
      }
    
    *location += sizeof(rr_header) - 2;

    if (*location + ntohs(header->length) > buffer + len)
        {
#if DEBUG
         cout << "decode error, packet too short for reported rr length" << endl;
#endif // DEBUG
         }
         
    if (ntohs(header->type) == 33) // SRV
      {
      srv_header * srv = (srv_header *)*location;
      char* name = *location + sizeof(srv_header);

      if (port)
         *port = ntohs(srv->port);

      decode_name(&name, buffer, len, target);
      }
    
    *location += ntohs(header->length);

    return 0;
   }

int skip_question(char** location, char* buffer, int len)
{
    if (*location >= buffer + len || *location < buffer)
    {
#if DEBUG
        cout << "decode error, ran off the buffer" << endl;
#endif // DEBUG
        return -1;
    }

    if (decode_name(location, buffer, len, NULL) != 0)
        return -2;

    if (*location + 4 > buffer + len)
    {
#if DEBUG
        cout << "decode error, packet too short for type and class" << endl;
#endif // DEBUG
        return -4;
    }

    /* move past "type" */
    *location += sizeof(u_int16_t);

    /* move past "class" */
    *location += sizeof(u_int16_t);

    return 0;
}

#if DEBUG
void CheckResult(int iResult, char* szMessage)
   {
   if (!iResult)
      return;
   if ((iResult >= XCipher::EErrorBadRemoteHost) && (iResult < XCipher::ELastProtocolError))
      return;
   cout << "X-Cipher: WARNING: CheckResult got unknown " << iResult << " error from '" << szMessage << "'! " << endl;
   }
#endif DEBUG

int ConnectToGlobalServer()
   {
   static bool s_bCalledResInit = false;
   if (!s_bCalledResInit)
      res_init();
   
#define HARDCODE_GLOBAL_SERVER 0
#if HARDCODE_GLOBAL_SERVER   
   return u_connect(
      XCipher::EGlobalServer_PORT_XCIPHER_GLOBAL_SERVER,
      "192.168.2.110"
   );
#endif // HARDCODE_GLOBAL_SERVER   

   int iGlobalServerSocket = -1;
   
   // get ip and port here using SRV lookup


   //const char* szSRVRequest = "_xcipherglobal._tcp.xten.net";
   const char* szSRVRequest = XCipher::g_szXCipherGlobalServerSRVRequest;
/*
AlexG5:~ alex$ dig _xtunnels._tcp.xten.net SRV IN

; <<>> DiG 9.2.2 <<>> _xtunnels._tcp.xten.net SRV IN
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 3452
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; QUESTION SECTION:
;_xtunnels._tcp.xten.net.       IN      SRV

;; ANSWER SECTION:
_xtunnels._tcp.xten.net. 3600   IN      SRV     10 0 13838 xtunnels.xten.net.

;; ADDITIONAL SECTION:
xtunnels.xten.net.      3600    IN      A       64.69.91.5

;; Query time: 29 msec
;; SERVER: 64.69.91.10#53(64.69.91.10)
;; WHEN: Mon Nov 10 13:10:39 2003
;; MSG SIZE  rcvd: 86


; <<>> DiG 9.2.2 <<>> _xcipherglobal._tcp.test.xten.net SRV IN
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 62669
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 1

;; QUESTION SECTION:
;_xcipherglobal._tcp.test.xten.net. IN  SRV

;; ANSWER SECTION:
_xcipherglobal._tcp.test.xten.net. 3600 IN SRV  10 0 13842 dsl.xten.net.

;; AUTHORITY SECTION:
xten.net.               135642  IN      NS      dns2.gridfx.com.
xten.net.               135642  IN      NS      dns1.gridfx.com.

;; ADDITIONAL SECTION:
dsl.xten.net.           3600    IN      A       64.180.255.194

;; Query time: 42 msec
;; SERVER: 192.168.2.1#53(192.168.2.1)
;; WHEN: Wed Nov 26 09:39:29 2003
;; MSG SIZE  rcvd: 147
*/

   if (!szSRVRequest || !szSRVRequest[0])
      return -1;
   
   unsigned char pSRVReply[10 * 1024] = { 0 };
   HEADER* hdr = (HEADER*)pSRVReply;

   int iResultLength = res_query(szSRVRequest, C_ANY, /* SRV */ 33, pSRVReply, sizeof(pSRVReply));

   if (iResultLength < (int)sizeof(HEADER))
      {
#if DEBUG
    cout << "res_query() FAILED!" << endl;
#endif // DEBUG
      return -1;
      }
   
   // need to swap these from big endian
   hdr->qdcount = ntohs(hdr->qdcount);
   hdr->ancount = ntohs(hdr->ancount);
   hdr->nscount = ntohs(hdr->nscount);
   hdr->arcount = ntohs(hdr->arcount);

   /*
#if DEBUG
   cout << "X-Cipher: ConnectToGlobalServer got " << iResultLength << " byte SRV record for " << szSRVRequest << endl;
   cout << "   hdr->id " << (unsigned long)hdr->id << endl;
   cout << "   hdr->qr " << (unsigned long)hdr->qr << endl;
   cout << "   hdr->opcode " << (unsigned long)hdr->opcode << endl;
   cout << "   hdr->aa " << (unsigned long)hdr->aa << endl;
   cout << "   hdr->tc " << (unsigned long)hdr->tc << endl;
   cout << "   hdr->rd " << (unsigned long)hdr->rd << endl;
   cout << "   hdr->ra " << (unsigned long)hdr->ra << endl;
   cout << "   hdr->unused " << (unsigned long)hdr->unused << endl;
   cout << "   hdr->rcode " << (unsigned long)hdr->rcode << endl;
   cout << "   hdr->qdcount " << (unsigned long)hdr->qdcount << endl;
   cout << "   hdr->ancount " << (unsigned long)hdr->ancount << endl;
   cout << "   hdr->nscount " << (unsigned long)hdr->nscount << endl;
   cout << "   hdr->arcount " <<(unsigned long)hdr->arcount << endl;
#endif // DEBUG