dns.cpp

/*
  Copyright (c) 2005-2019 by Jakob Schröter <js@camaya.net>
  This file is part of the gloox library. http://camaya.net/gloox

  This software is distributed under a license. The full license
  agreement can be found in the file LICENSE in this distribution.
  This software may not be copied, modified, sold or distributed
  other than expressed in the named license agreement.

  This software is distributed without any warranty.
*/


#include "config.h"

#include "gloox.h"
#include "dns.h"
#include "util.h"

#ifndef _WIN32_WCE
# include <sys/types.h>
#endif

#include <stdio.h>
#include <string.h>

#if ( !defined( _WIN32 ) && !defined( _WIN32_WCE ) ) || defined( __SYMBIAN32__ )
# include <netinet/in.h>
# include <arpa/nameser.h>
# include <resolv.h>
# include <netdb.h>
# include <arpa/inet.h>
# include <sys/socket.h>
# include <sys/un.h>
# include <unistd.h>
# include <errno.h>
#endif

#if defined( _WIN32 ) && !defined( __SYMBIAN32__ )
# include <winsock2.h>
# include <ws2tcpip.h>
#elif defined( _WIN32_WCE )
# include <winsock2.h>
#endif

#ifdef HAVE_WINDNS_H
# include <windns.h>
#endif

#define SRV_COST    (RRFIXEDSZ+0)
#define SRV_WEIGHT  (RRFIXEDSZ+2)
#define SRV_PORT    (RRFIXEDSZ+4)
#define SRV_SERVER  (RRFIXEDSZ+6)
#define SRV_FIXEDSZ (RRFIXEDSZ+6)

#ifndef T_SRV
# define T_SRV 33
#endif

// mingw
#ifndef DNS_TYPE_SRV
# define DNS_TYPE_SRV 33
#endif

#ifndef NS_CMPRSFLGS
# define NS_CMPRSFLGS 0xc0
#endif

#ifndef C_IN
# define C_IN 1
#endif

#ifndef INVALID_SOCKET
# define INVALID_SOCKET -1
#endif

#define XMPP_PORT 5222

namespace gloox
{

#if defined( HAVE_RES_QUERYDOMAIN ) && defined( HAVE_DN_SKIPNAME ) && defined( HAVE_RES_QUERY )
  DNS::HostMap DNS::resolve( const std::string& service, const std::string& proto,
                             const std::string& domain, const LogSink& logInstance )
  {
    buffer srvbuf;
    bool error = false;

    const std::string dname = "_" +  service + "._" + proto;

    if( !domain.empty() )
      srvbuf.len = res_querydomain( dname.c_str(), const_cast<char*>( domain.c_str() ),
                                    C_IN, T_SRV, srvbuf.buf, NS_PACKETSZ );
    else
      srvbuf.len = res_query( dname.c_str(), C_IN, T_SRV, srvbuf.buf, NS_PACKETSZ );

    if( srvbuf.len < 0 )
      return defaultHostMap( domain, logInstance );

    HEADER* hdr = reinterpret_cast<HEADER*>( srvbuf.buf );
    unsigned char* here = srvbuf.buf + NS_HFIXEDSZ;

    if( srvbuf.len < NS_HFIXEDSZ )
      error = true;

    if( hdr->rcode >= 1 && hdr->rcode <= 5 )
      error = true;

    if( ntohs( hdr->ancount ) == 0 )
      error = true;

    if( ntohs( hdr->ancount ) > NS_PACKETSZ )
      error = true;

    int cnt;
    for( cnt = ntohs( hdr->qdcount ); cnt > 0; --cnt )
    {
      int strlen = dn_skipname( here, srvbuf.buf + srvbuf.len );
      here += strlen + NS_QFIXEDSZ;
    }

    unsigned char* srv[NS_PACKETSZ];
    int srvnum = 0;
    for( cnt = ntohs( hdr->ancount ); cnt > 0; --cnt )
    {
      int strlen = dn_skipname( here, srvbuf.buf + srvbuf.len );
      here += strlen;
      srv[srvnum++] = here;
      here += SRV_FIXEDSZ;
      here += dn_skipname( here, srvbuf.buf + srvbuf.len );
    }

    if( error )
    {
      return defaultHostMap( domain, logInstance );
    }

    // (q)sort here

    HostMap servers;
    for( cnt = 0; cnt < srvnum; ++cnt )
    {
      char srvname[NS_MAXDNAME];
      srvname[0] = '\0';

      if( dn_expand( srvbuf.buf, srvbuf.buf + NS_PACKETSZ,
                     srv[cnt] + SRV_SERVER, srvname, NS_MAXDNAME ) < 0
          || !(*srvname) )
        continue;

      unsigned char* c = srv[cnt] + SRV_PORT;
      servers.insert( std::make_pair( static_cast<char*>( srvname ), ntohs( c[1] << 8 | c[0] ) ) );
    }

    if( !servers.size() )
      return defaultHostMap( domain, logInstance );

    return servers;
  }

#elif defined( _WIN32 ) && defined( HAVE_WINDNS_H ) && !defined( __MINGW32__ )
  DNS::HostMap DNS::resolve( const std::string& service, const std::string& proto,
                             const std::string& domain, const LogSink& logInstance )
  {
    const std::string dname = "_" +  service + "._" + proto + "." + domain;
    bool error = false;

    DNS::HostMap servers;
    DNS_RECORD* pRecord = NULL;
    DNS_STATUS status = DnsQuery_UTF8( dname.c_str(), DNS_TYPE_SRV, DNS_QUERY_STANDARD, NULL, &pRecord, NULL );
    if( status == ERROR_SUCCESS )
    {
      // NOTE: DnsQuery_UTF8 and DnsQuery_A really should have been defined with
      // PDNS_RECORDA instead of PDNS_RECORD, since that's what it is (even with _UNICODE defined).
      // We'll correct for that mistake with a cast.
      DNS_RECORDA* pRec = (DNS_RECORDA*)pRecord;
      do
      {
        if( pRec->wType == DNS_TYPE_SRV )
        {
          servers[pRec->Data.SRV.pNameTarget] = pRec->Data.SRV.wPort;
        }
        pRec = pRec->pNext;
      }
      while( pRec != NULL );
      DnsRecordListFree( pRecord, DnsFreeRecordList );
    }
    else
    {
      logInstance.warn( LogAreaClassDns, "DnsQuery_UTF8() failed: " + util::int2string( status ) );
      error = true;
    }

    if( error || !servers.size() )
    {
      servers = defaultHostMap( domain, logInstance );
    }

    return servers;
  }

#else
  DNS::HostMap DNS::resolve( const std::string& /*service*/, const std::string& /*proto*/,
                             const std::string& domain, const LogSink& logInstance )
  {
    logInstance.warn( LogAreaClassDns, "Notice: gloox does not support SRV "
                        "records on this platform. Using A records instead." );
    return defaultHostMap( domain, logInstance );
  }
#endif

  DNS::HostMap DNS::defaultHostMap( const std::string& domain, const LogSink& logInstance )
  {
    HostMap server;

    logInstance.warn( LogAreaClassDns, "Notice: no SRV record found for "
                                          + domain + ", using default port." );

    if( !domain.empty() )
      server[domain] = XMPP_PORT;

    return server;
  }

#ifdef HAVE_GETADDRINFO
  void DNS::resolve( struct addrinfo** res, const std::string& service, const std::string& proto,
                     const std::string& domain, const LogSink& logInstance )
  {
    logInstance.dbg( LogAreaClassDns, "Resolving: _" +  service + "._" + proto + "." + domain );
    struct addrinfo hints;
    if( proto == "tcp" )
      hints.ai_socktype = SOCK_STREAM;
    else if( proto == "udp" )
      hints.ai_socktype = SOCK_DGRAM;
    else
    {
      logInstance.err( LogAreaClassDns, "Unknown/Invalid protocol: " + proto );
    }
    memset( &hints, '\0', sizeof( hints ) );
    hints.ai_flags = AI_ADDRCONFIG | AI_CANONNAME;
    hints.ai_socktype = SOCK_STREAM;
    int e = getaddrinfo( domain.c_str(), service.c_str(), &hints, res );
    if( e )
      logInstance.err( LogAreaClassDns, "getaddrinfo() failed" );
  }

  int DNS::connect( const std::string& host, const LogSink& logInstance )
  {
    struct addrinfo* results = 0;

    resolve( &results, host, logInstance );
    if( !results )
    {
      logInstance.err( LogAreaClassDns, "host not found: " + host );
      return -ConnDnsError;
    }

    struct addrinfo* runp = results;
    while( runp )
    {
      int fd = DNS::connect( runp, logInstance );
      if( fd >= 0 )
      {
        freeaddrinfo( results );
        return fd;
      }

      runp = runp->ai_next;
    }

    freeaddrinfo( results );

    return -ConnConnectionRefused;
  }

  int DNS::connect( struct addrinfo* res, const LogSink& logInstance )
  {
    if( !res )
      return -1;

    int fd = getSocket( res->ai_family, res->ai_socktype, res->ai_protocol, logInstance );
    if( fd < 0 )
      return fd;

    if( ::connect( fd, res->ai_addr, res->ai_addrlen ) == 0 )
    {
      char ip[NI_MAXHOST];
      char port[NI_MAXSERV];

      if( getnameinfo( res->ai_addr, res->ai_addrlen,
                       ip, sizeof( ip ),
                       port, sizeof( port ),
                       NI_NUMERICHOST | NI_NUMERICSERV ) )
      {
        //FIXME do we need to handle this? How? Can it actually happen at all?
//         printf( "could not get numeric hostname");
      }

      if( res->ai_canonname )
        logInstance.dbg( LogAreaClassDns, std::string( "Connecting to " ).append( res->ai_canonname ).append( " (" ).append( ip ).append( "), port  " ).append( port ) );
      else
        logInstance.dbg( LogAreaClassDns, std::string( "Connecting to " ).append( ip ).append( ":" ).append( port ) );

      return fd;
    }

    std::string message = "connect() failed. "
#if defined( _WIN32 ) && !defined( __SYMBIAN32__ )
        "WSAGetLastError: " + util::int2string( ::WSAGetLastError() );
#else
        "errno: " + util::int2string( errno ) + ": " + strerror( errno );
#endif
    logInstance.dbg( LogAreaClassDns, message );

    closeSocket( fd, logInstance );
    return -ConnConnectionRefused;
  }

#else

  int DNS::connect( const std::string& host, const LogSink& logInstance )
  {
    HostMap hosts = resolve( host, logInstance );
    if( hosts.size() == 0 )
      return -ConnDnsError;

    HostMap::const_iterator it = hosts.begin();
    for( ; it != hosts.end(); ++it )
    {
      int fd = DNS::connect( (*it).first, (*it).second, logInstance );
      if( fd >= 0 )
        return fd;
    }

    return -ConnConnectionRefused;
  }
#endif

  int DNS::getSocket( const LogSink& logInstance )
  {
#if defined( _WIN32 ) && !defined( __SYMBIAN32__ )
    WSADATA wsaData;
    if( WSAStartup( MAKEWORD( 1, 1 ), &wsaData ) != 0 )
    {
      logInstance.dbg( LogAreaClassDns, "WSAStartup() failed. WSAGetLastError: "
                                        + util::int2string( ::WSAGetLastError() ) );
      return -ConnDnsError;
    }
#endif

    int protocol = IPPROTO_TCP;
#if !defined( __APPLE__ )  // Sandboxing on Apple doesn't like you to use getprotobyname
    struct protoent* prot;
    if( ( prot = getprotobyname( "tcp" ) ) != 0 )
    {
      protocol = prot->p_proto;
    }
    else
    {
      std::string message = "getprotobyname( \"tcp\" ) failed. "
#if defined( _WIN32 ) && !defined( __SYMBIAN32__ )
          "WSAGetLastError: " + util::int2string( ::WSAGetLastError() )
#else
          "errno: " + util::int2string( errno ) + ": " + strerror( errno );
#endif
          + ". Falling back to IPPROTO_TCP: " + util::int2string( IPPROTO_TCP );
      logInstance.dbg( LogAreaClassDns, message );

      // Do not return an error. We'll fall back to IPPROTO_TCP.
    }
#endif // !defined( __APPLE__ )

    return getSocket( PF_INET, SOCK_STREAM, protocol, logInstance );
  }

  int DNS::getSocket( int af, int socktype, int proto, const LogSink& logInstance )
  {
#if defined( _WIN32 ) && !defined( __SYMBIAN32__ )
    SOCKET fd;
#else
    int fd;
#endif
    if( ( fd = socket( af, socktype, proto ) ) == INVALID_SOCKET )
    {
      std::string message = "getSocket( "
          + util::int2string( af ) + ", "
          + util::int2string( socktype ) + ", "
          + util::int2string( proto )
          + " ) failed. "
#if defined( _WIN32 ) && !defined( __SYMBIAN32__ )
          "WSAGetLastError: " + util::int2string( ::WSAGetLastError() );
#else
          "errno: " + util::int2string( errno ) + ": " + strerror( errno );
#endif
      logInstance.dbg( LogAreaClassDns, message );

      cleanup( logInstance );
      return -ConnConnectionRefused;
    }

#ifdef HAVE_SETSOCKOPT
    int timeout = 5000;
    int reuseaddr = 1;
    setsockopt( fd, SOL_SOCKET, SO_SNDTIMEO, reinterpret_cast<char*>( &timeout ), sizeof( timeout ) );
    setsockopt( fd, SOL_SOCKET, SO_REUSEADDR, reinterpret_cast<char*>( &reuseaddr ), sizeof( reuseaddr ) );
#endif

    return static_cast<int>( fd );
  }

#ifdef HAVE_GETADDRINFO
  int DNS::connect( const std::string& host, int port, const LogSink& logInstance )
  {
    struct addrinfo hints, *servinfo, *p;
    int rv = 0;
    int fd = 0;

    memset( &hints, 0, sizeof( hints ) );
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;

    if( ( rv = getaddrinfo( host.c_str(), util::int2string( port ).c_str(), &hints, &servinfo ) ) != 0 )
    {
      logInstance.dbg( LogAreaClassDns, "getaddrinfo() failed for " + host + "." );
      return -ConnDnsError;
    }

    for( p = servinfo; p != 0; p = p->ai_next )
    {
      if( ( fd = getSocket( p->ai_family, p->ai_socktype, p->ai_protocol, logInstance ) ) == -1 )
      {
        continue;
      }

      if( ::connect( fd, p->ai_addr, p->ai_addrlen ) == -1 )
      {
        closeSocket( fd, logInstance );
        continue;
      }

      break;
    }

    if( p == 0 )
    {
      freeaddrinfo( servinfo );
      std::string message = "Connection to " + host + ":" + util::int2string( port ) + " failed. "
#if defined( _WIN32 ) && !defined( __SYMBIAN32__ )
      "WSAGetLastError: " + util::int2string( ::WSAGetLastError() );
#else
      "errno: " + util::int2string( errno ) + ": " + strerror( errno );
#endif
      logInstance.dbg( LogAreaClassDns, message );
      return -ConnConnectionRefused;
    }

    freeaddrinfo( servinfo );
    return fd;
  }

#else // HAVE_GETADDRINFO
  int DNS::connect( const std::string& host, int port, const LogSink& logInstance )
  {
    int fd = getSocket( logInstance );
    if( fd < 0 )
      return fd;

    struct hostent* h;
    if( ( h = gethostbyname( host.c_str() ) ) == 0 )
    {
      logInstance.dbg( LogAreaClassDns, "gethostbyname() failed for " + host + "." );
      cleanup( logInstance );
      closeSocket( fd, logInstance );
      return -ConnDnsError;
    }

    struct sockaddr_in target;
    target.sin_family = AF_INET;
    target.sin_port = htons( static_cast<unsigned short int>( port ) );

    if( h->h_length != sizeof( struct in_addr ) )
    {
      logInstance.dbg( LogAreaClassDns, "gethostbyname() returned unexpected structure." );
      cleanup( logInstance );
      closeSocket( fd, logInstance );
      return -ConnDnsError;
    }
    else
    {
      memcpy( &target.sin_addr, h->h_addr, sizeof( struct in_addr ) );
    }

    logInstance.dbg( LogAreaClassDns, "Connecting to " + host
        + " (" + inet_ntoa( target.sin_addr ) + ":" + util::int2string( port ) + ")" );

    memset( target.sin_zero, '\0', 8 );
    if( ::connect( fd, reinterpret_cast<struct sockaddr *>( &target ), sizeof( struct sockaddr ) ) == 0 )
    {
      logInstance.dbg( LogAreaClassDns, "Connected to " + host + " ("
          + inet_ntoa( target.sin_addr ) + ":" + util::int2string( port ) + ")" );
      return fd;
    }

    std::string message = "Connection to " + host + " ("
        + inet_ntoa( target.sin_addr ) + ":" + util::int2string( port ) + ") failed. "
#if defined( _WIN32 ) && !defined( __SYMBIAN32__ )
        "WSAGetLastError: " + util::int2string( ::WSAGetLastError() );
#else
        "errno: " + util::int2string( errno ) + ": " + strerror( errno );
#endif
    logInstance.dbg( LogAreaClassDns, message );

    closeSocket( fd, logInstance );
    return -ConnConnectionRefused;
  }
#endif // HAVE_GETADDRINFO

  void DNS::closeSocket( int fd, const LogSink& logInstance )
  {
#if defined( _WIN32 ) && !defined( __SYMBIAN32__ )
    int result = closesocket( fd );
#else
    int result = close( fd );
#endif

    if( result != 0 )
    {
      std::string message = "closeSocket() failed. "
#if defined( _WIN32 ) && !defined( __SYMBIAN32__ )
          "WSAGetLastError: " + util::int2string( ::WSAGetLastError() );
#else
          "errno: " + util::int2string( errno ) + ": " + strerror( errno );
#endif
      logInstance.dbg( LogAreaClassDns, message );
    }
  }

  void DNS::cleanup( const LogSink& logInstance )
  {
#if defined( _WIN32 ) && !defined( __SYMBIAN32__ )
    if( WSACleanup() != 0 )
    {
      logInstance.dbg( LogAreaClassDns, "WSACleanup() failed. WSAGetLastError: "
          + util::int2string( ::WSAGetLastError() ) );
    }
#else
    (void)logInstance;
#endif
  }

}