methods/connect.cc

   1 // -*- mode: cpp; mode: fold -*-
   2 // Description                                                          /*{{{*/
   3 // $Id: connect.cc,v 1.10.2.1 2004/01/16 18:58:50 mdz Exp $
   4 /* ######################################################################
   5
   6    Connect - Replacement connect call
   7
   8    This was originally authored by Jason Gunthorpe <jgg@debian.org>
   9    and is placed in the Public Domain, do with it what you will.
  10
  11    ##################################################################### */
  12                                                                         /*}}}*/
  13 // Include Files                                                        /*{{{*/
  14 #include <config.h>
  15
  16 #include <apt-pkg/error.h>
  17 #include <apt-pkg/fileutl.h>
  18 #include <apt-pkg/strutl.h>
  19 #include <apt-pkg/acquire-method.h>
  20 #include <apt-pkg/configuration.h>
  21 #include <apt-pkg/srvrec.h>
  22
  23 #include <stdio.h>
  24 #include <errno.h>
  25 #include <unistd.h>
  26 #include <sstream>
  27 #include <string.h>
  28 #include<set>
  29 #include<string>
  30
  31 // Internet stuff
  32 #include <netinet/in.h>
  33 #include <sys/socket.h>
  34 #include <arpa/inet.h>
  35 #include <netdb.h>
  36
  37 #include "connect.h"
  38 #include "rfc2553emu.h"
  39 #include <apti18n.h>
  40                                                                         /*}}}*/
  41
  42 static std::string LastHost;
  43 static int LastPort = 0;
  44 static struct addrinfo *LastHostAddr = 0;
  45 static struct addrinfo *LastUsed = 0;
  46
  47 static std::vector<SrvRec> SrvRecords;
  48
  49 // Set of IP/hostnames that we timed out before or couldn't resolve
  50 static std::set<std::string> bad_addr;
  51
  52 // RotateDNS - Select a new server from a DNS rotation                  /*{{{*/
  53 // ---------------------------------------------------------------------
  54 /* This is called during certain errors in order to recover by selecting a
  55    new server */
  56 void RotateDNS()
  57 {
  58    if (LastUsed != 0 && LastUsed->ai_next != 0)
  59       LastUsed = LastUsed->ai_next;
  60    else
  61       LastUsed = LastHostAddr;
  62 }
  63                                                                         /*}}}*/
  64 static bool ConnectionAllowed(char const * const Service, std::string const &Host)/*{{{*/
  65 {
  66    if (unlikely(Host.empty())) // the only legal empty host (RFC2782 '.' target) is detected by caller
  67       return false;
  68    if (APT::String::Endswith(Host, ".onion") && _config->FindB("Acquire::BlockDotOnion", true))
  69    {
  70       // TRANSLATOR: %s is e.g. Tor's ".onion" which would likely fail or leak info (RFC7686)
  71       _error->Error(_("Direct connection to %s domains is blocked by default."), ".onion");
  72       if (strcmp(Service, "http") == 0)
  73         _error->Error(_("If you meant to use Tor remember to use %s instead of %s."), "tor+http", "http");
  74       return false;
  75    }
  76    return true;
  77 }
  78                                                                         /*}}}*/
  79 // DoConnect - Attempt a connect operation                              /*{{{*/
  80 // ---------------------------------------------------------------------
  81 /* This helper function attempts a connection to a single address. */
  82 static bool DoConnect(struct addrinfo *Addr,std::string const &Host,
  83                       unsigned long TimeOut,int &Fd,pkgAcqMethod *Owner)
  84 {
  85    // Show a status indicator
  86    char Name[NI_MAXHOST];
  87    char Service[NI_MAXSERV];
  88
  89    Name[0] = 0;
  90    Service[0] = 0;
  91    getnameinfo(Addr->ai_addr,Addr->ai_addrlen,
  92                Name,sizeof(Name),Service,sizeof(Service),
  93                NI_NUMERICHOST|NI_NUMERICSERV);
  94    Owner->Status(_("Connecting to %s (%s)"),Host.c_str(),Name);
  95
  96    // if that addr did timeout before, we do not try it again
  97    if(bad_addr.find(std::string(Name)) != bad_addr.end())
  98       return false;
  99
 100    /* If this is an IP rotation store the IP we are using.. If something goes
 101       wrong this will get tacked onto the end of the error message */
 102    if (LastHostAddr->ai_next != 0)
 103    {
 104       std::stringstream ss;
 105       ioprintf(ss, _("[IP: %s %s]"),Name,Service);
 106       Owner->SetIP(ss.str());
 107    }
 108
 109    // Get a socket
 110    if ((Fd = socket(Addr->ai_family,Addr->ai_socktype,
 111                     Addr->ai_protocol)) < 0)
 112       return _error->Errno("socket",_("Could not create a socket for %s (f=%u t=%u p=%u)"),
 113                            Name,Addr->ai_family,Addr->ai_socktype,Addr->ai_protocol);
 114
 115    SetNonBlock(Fd,true);
 116    if (connect(Fd,Addr->ai_addr,Addr->ai_addrlen) < 0 &&
 117        errno != EINPROGRESS)
 118       return _error->Errno("connect",_("Cannot initiate the connection "
 119                            "to %s:%s (%s)."),Host.c_str(),Service,Name);
 120
 121    /* This implements a timeout for connect by opening the connection
 122       nonblocking */
 123    if (WaitFd(Fd,true,TimeOut) == false) {
 124       bad_addr.insert(bad_addr.begin(), std::string(Name));
 125       Owner->SetFailReason("Timeout");
 126       return _error->Error(_("Could not connect to %s:%s (%s), "
 127                            "connection timed out"),Host.c_str(),Service,Name);
 128    }
 129
 130    // Check the socket for an error condition
 131    unsigned int Err;
 132    unsigned int Len = sizeof(Err);
 133    if (getsockopt(Fd,SOL_SOCKET,SO_ERROR,&Err,&Len) != 0)
 134       return _error->Errno("getsockopt",_("Failed"));
 135
 136    if (Err != 0)
 137    {
 138       errno = Err;
 139       if(errno == ECONNREFUSED)
 140          Owner->SetFailReason("ConnectionRefused");
 141       else if (errno == ETIMEDOUT)
 142          Owner->SetFailReason("ConnectionTimedOut");
 143       bad_addr.insert(bad_addr.begin(), std::string(Name));
 144       return _error->Errno("connect",_("Could not connect to %s:%s (%s)."),Host.c_str(),
 145                            Service,Name);
 146    }
 147
 148    return true;
 149 }
 150                                                                         /*}}}*/
 151 // Connect to a given Hostname                                          /*{{{*/
 152 static bool ConnectToHostname(std::string const &Host, int const Port,
 153       const char * const Service, int DefPort, int &Fd,
 154       unsigned long const TimeOut, pkgAcqMethod * const Owner)
 155 {
 156    if (ConnectionAllowed(Service, Host) == false)
 157       return false;
 158    // Convert the port name/number
 159    char ServStr[300];
 160    if (Port != 0)
 161       snprintf(ServStr,sizeof(ServStr),"%i", Port);
 162    else
 163       snprintf(ServStr,sizeof(ServStr),"%s", Service);
 164
 165    /* We used a cached address record.. Yes this is against the spec but
 166       the way we have setup our rotating dns suggests that this is more
 167       sensible */
 168    if (LastHost != Host || LastPort != Port)
 169    {
 170       Owner->Status(_("Connecting to %s"),Host.c_str());
 171
 172       // Free the old address structure
 173       if (LastHostAddr != 0)
 174       {
 175          freeaddrinfo(LastHostAddr);
 176          LastHostAddr = 0;
 177          LastUsed = 0;
 178       }
 179
 180       // We only understand SOCK_STREAM sockets.
 181       struct addrinfo Hints;
 182       memset(&Hints,0,sizeof(Hints));
 183       Hints.ai_socktype = SOCK_STREAM;
 184       Hints.ai_flags = 0;
 185 #ifdef AI_IDN
 186       if (_config->FindB("Acquire::Connect::IDN", true) == true)
 187          Hints.ai_flags |= AI_IDN;
 188 #endif
 189       // see getaddrinfo(3): only return address if system has such a address configured
 190       // useful if system is ipv4 only, to not get ipv6, but that fails if the system has
 191       // no address configured: e.g. offline and trying to connect to localhost.
 192       if (_config->FindB("Acquire::Connect::AddrConfig", true) == true)
 193          Hints.ai_flags |= AI_ADDRCONFIG;
 194       Hints.ai_protocol = 0;
 195
 196       if(_config->FindB("Acquire::ForceIPv4", false) == true)
 197          Hints.ai_family = AF_INET;
 198       else if(_config->FindB("Acquire::ForceIPv6", false) == true)
 199          Hints.ai_family = AF_INET6;
 200       else
 201          Hints.ai_family = AF_UNSPEC;
 202
 203       // if we couldn't resolve the host before, we don't try now
 204       if(bad_addr.find(Host) != bad_addr.end())
 205          return _error->Error(_("Could not resolve '%s'"),Host.c_str());
 206
 207       // Resolve both the host and service simultaneously
 208       while (1)
 209       {
 210          int Res;
 211          if ((Res = getaddrinfo(Host.c_str(),ServStr,&Hints,&LastHostAddr)) != 0 ||
 212              LastHostAddr == 0)
 213          {
 214             if (Res == EAI_NONAME || Res == EAI_SERVICE)
 215             {
 216                if (DefPort != 0)
 217                {
 218                   snprintf(ServStr, sizeof(ServStr), "%i", DefPort);
 219                   DefPort = 0;
 220                   continue;
 221                }
 222                bad_addr.insert(bad_addr.begin(), Host);
 223                Owner->SetFailReason("ResolveFailure");
 224                return _error->Error(_("Could not resolve '%s'"),Host.c_str());
 225             }
 226
 227             if (Res == EAI_AGAIN)
 228             {
 229                Owner->SetFailReason("TmpResolveFailure");
 230                return _error->Error(_("Temporary failure resolving '%s'"),
 231                                     Host.c_str());
 232             }
 233             if (Res == EAI_SYSTEM)
 234                return _error->Errno("getaddrinfo", _("System error resolving '%s:%s'"),
 235                                       Host.c_str(),ServStr);
 236             return _error->Error(_("Something wicked happened resolving '%s:%s' (%i - %s)"),
 237                                  Host.c_str(),ServStr,Res,gai_strerror(Res));
 238          }
 239          break;
 240       }
 241
 242       LastHost = Host;
 243       LastPort = Port;
 244    }
 245
 246    // When we have an IP rotation stay with the last IP.
 247    struct addrinfo *CurHost = LastHostAddr;
 248    if (LastUsed != 0)
 249        CurHost = LastUsed;
 250
 251    while (CurHost != 0)
 252    {
 253       if (DoConnect(CurHost,Host,TimeOut,Fd,Owner) == true)
 254       {
 255          LastUsed = CurHost;
 256          return true;
 257       }
 258       close(Fd);
 259       Fd = -1;
 260
 261       // Ignore UNIX domain sockets
 262       do
 263       {
 264          CurHost = CurHost->ai_next;
 265       }
 266       while (CurHost != 0 && CurHost->ai_family == AF_UNIX);
 267
 268       /* If we reached the end of the search list then wrap around to the
 269          start */
 270       if (CurHost == 0 && LastUsed != 0)
 271          CurHost = LastHostAddr;
 272
 273       // Reached the end of the search cycle
 274       if (CurHost == LastUsed)
 275          break;
 276
 277       if (CurHost != 0)
 278          _error->Discard();
 279    }
 280
 281    if (_error->PendingError() == true)
 282       return false;
 283    return _error->Error(_("Unable to connect to %s:%s:"),Host.c_str(),ServStr);
 284 }
 285                                                                         /*}}}*/
 286 // Connect - Connect to a server                                        /*{{{*/
 287 // ---------------------------------------------------------------------
 288 /* Performs a connection to the server (including SRV record lookup) */
 289 bool Connect(std::string Host,int Port,const char *Service,
 290                             int DefPort,int &Fd,
 291                             unsigned long TimeOut,pkgAcqMethod *Owner)
 292 {
 293    if (_error->PendingError() == true)
 294       return false;
 295
 296    if (ConnectionAllowed(Service, Host) == false)
 297       return false;
 298
 299    if(LastHost != Host || LastPort != Port)
 300    {
 301       SrvRecords.clear();
 302       if (_config->FindB("Acquire::EnableSrvRecords", true) == true)
 303       {
 304          GetSrvRecords(Host, DefPort, SrvRecords);
 305          // RFC2782 defines that a lonely '.' target is an abort reason
 306          if (SrvRecords.size() == 1 && SrvRecords[0].target.empty())
 307             return _error->Error("SRV records for %s indicate that "
 308                   "%s service is not available at this domain", Host.c_str(), Service);
 309       }
 310    }
 311
 312    size_t stackSize = 0;
 313    // try to connect in the priority order of the srv records
 314    std::string initialHost{std::move(Host)};
 315    while(SrvRecords.empty() == false)
 316    {
 317       _error->PushToStack();
 318       ++stackSize;
 319       // PopFromSrvRecs will also remove the server
 320       Host = PopFromSrvRecs(SrvRecords).target;
 321       auto const ret = ConnectToHostname(Host, Port, Service, DefPort, Fd, TimeOut, Owner);
 322       if (ret)
 323       {
 324          while(stackSize--)
 325             _error->RevertToStack();
 326          return true;
 327       }
 328    }
 329    Host = std::move(initialHost);
 330
 331    // we have no (good) SrvRecords for this host, connect right away
 332    _error->PushToStack();
 333    ++stackSize;
 334    auto const ret = ConnectToHostname(Host, Port, Service, DefPort, Fd,
 335          TimeOut, Owner);
 336    while(stackSize--)
 337       if (ret)
 338          _error->RevertToStack();
 339       else
 340          _error->MergeWithStack();
 341    return ret;
 342 }