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 (APT::String::Endswith(Host, ".onion") && _config->FindB("Acquire::BlockDotOnion", true))
  67    {
  68       // TRANSLATOR: %s is e.g. Tor's ".onion" which would likely fail or leak info (RFC7686)
  69       _error->Error(_("Direct connection to %s domains is blocked by default."), ".onion");
  70       if (strcmp(Service, "http") == 0)
  71         _error->Error(_("If you meant to use Tor remember to use %s instead of %s."), "tor+http", "http");
  72       return false;
  73    }
  74    return true;
  75 }
  76                                                                         /*}}}*/
  77 // DoConnect - Attempt a connect operation                              /*{{{*/
  78 // ---------------------------------------------------------------------
  79 /* This helper function attempts a connection to a single address. */
  80 static bool DoConnect(struct addrinfo *Addr,std::string const &Host,
  81                       unsigned long TimeOut,int &Fd,pkgAcqMethod *Owner)
  82 {
  83    // Show a status indicator
  84    char Name[NI_MAXHOST];
  85    char Service[NI_MAXSERV];
  86
  87    Name[0] = 0;
  88    Service[0] = 0;
  89    getnameinfo(Addr->ai_addr,Addr->ai_addrlen,
  90                Name,sizeof(Name),Service,sizeof(Service),
  91                NI_NUMERICHOST|NI_NUMERICSERV);
  92    Owner->Status(_("Connecting to %s (%s)"),Host.c_str(),Name);
  93
  94    // if that addr did timeout before, we do not try it again
  95    if(bad_addr.find(std::string(Name)) != bad_addr.end())
  96       return false;
  97
  98    /* If this is an IP rotation store the IP we are using.. If something goes
  99       wrong this will get tacked onto the end of the error message */
 100    if (LastHostAddr->ai_next != 0)
 101    {
 102       std::stringstream ss;
 103       ioprintf(ss, _("[IP: %s %s]"),Name,Service);
 104       Owner->SetIP(ss.str());
 105    }
 106
 107    // Get a socket
 108    if ((Fd = socket(Addr->ai_family,Addr->ai_socktype,
 109                     Addr->ai_protocol)) < 0)
 110       return _error->Errno("socket",_("Could not create a socket for %s (f=%u t=%u p=%u)"),
 111                            Name,Addr->ai_family,Addr->ai_socktype,Addr->ai_protocol);
 112
 113    SetNonBlock(Fd,true);
 114    if (connect(Fd,Addr->ai_addr,Addr->ai_addrlen) < 0 &&
 115        errno != EINPROGRESS)
 116       return _error->Errno("connect",_("Cannot initiate the connection "
 117                            "to %s:%s (%s)."),Host.c_str(),Service,Name);
 118
 119    /* This implements a timeout for connect by opening the connection
 120       nonblocking */
 121    if (WaitFd(Fd,true,TimeOut) == false) {
 122       bad_addr.insert(bad_addr.begin(), std::string(Name));
 123       Owner->SetFailReason("Timeout");
 124       return _error->Error(_("Could not connect to %s:%s (%s), "
 125                            "connection timed out"),Host.c_str(),Service,Name);
 126    }
 127
 128    // Check the socket for an error condition
 129    unsigned int Err;
 130    unsigned int Len = sizeof(Err);
 131    if (getsockopt(Fd,SOL_SOCKET,SO_ERROR,&Err,&Len) != 0)
 132       return _error->Errno("getsockopt",_("Failed"));
 133
 134    if (Err != 0)
 135    {
 136       errno = Err;
 137       if(errno == ECONNREFUSED)
 138          Owner->SetFailReason("ConnectionRefused");
 139       else if (errno == ETIMEDOUT)
 140          Owner->SetFailReason("ConnectionTimedOut");
 141       bad_addr.insert(bad_addr.begin(), std::string(Name));
 142       return _error->Errno("connect",_("Could not connect to %s:%s (%s)."),Host.c_str(),
 143                            Service,Name);
 144    }
 145
 146    return true;
 147 }
 148                                                                         /*}}}*/
 149 // Connect to a given Hostname                                          /*{{{*/
 150 static bool ConnectToHostname(std::string const &Host, int const Port,
 151       const char * const Service, int DefPort, int &Fd,
 152       unsigned long const TimeOut, pkgAcqMethod * const Owner)
 153 {
 154    if (ConnectionAllowed(Service, Host) == false)
 155       return false;
 156    // Convert the port name/number
 157    char ServStr[300];
 158    if (Port != 0)
 159       snprintf(ServStr,sizeof(ServStr),"%i", Port);
 160    else
 161       snprintf(ServStr,sizeof(ServStr),"%s", Service);
 162
 163    /* We used a cached address record.. Yes this is against the spec but
 164       the way we have setup our rotating dns suggests that this is more
 165       sensible */
 166    if (LastHost != Host || LastPort != Port)
 167    {
 168       Owner->Status(_("Connecting to %s"),Host.c_str());
 169
 170       // Free the old address structure
 171       if (LastHostAddr != 0)
 172       {
 173          freeaddrinfo(LastHostAddr);
 174          LastHostAddr = 0;
 175          LastUsed = 0;
 176       }
 177
 178       // We only understand SOCK_STREAM sockets.
 179       struct addrinfo Hints;
 180       memset(&Hints,0,sizeof(Hints));
 181       Hints.ai_socktype = SOCK_STREAM;
 182       Hints.ai_flags = 0;
 183       if (_config->FindB("Acquire::Connect::IDN", true) == true)
 184          Hints.ai_flags |= AI_IDN;
 185       // see getaddrinfo(3): only return address if system has such a address configured
 186       // useful if system is ipv4 only, to not get ipv6, but that fails if the system has
 187       // no address configured: e.g. offline and trying to connect to localhost.
 188       if (_config->FindB("Acquire::Connect::AddrConfig", true) == true)
 189          Hints.ai_flags |= AI_ADDRCONFIG;
 190       Hints.ai_protocol = 0;
 191
 192       if(_config->FindB("Acquire::ForceIPv4", false) == true)
 193          Hints.ai_family = AF_INET;
 194       else if(_config->FindB("Acquire::ForceIPv6", false) == true)
 195          Hints.ai_family = AF_INET6;
 196       else
 197          Hints.ai_family = AF_UNSPEC;
 198
 199       // if we couldn't resolve the host before, we don't try now
 200       if(bad_addr.find(Host) != bad_addr.end())
 201          return _error->Error(_("Could not resolve '%s'"),Host.c_str());
 202
 203       // Resolve both the host and service simultaneously
 204       while (1)
 205       {
 206          int Res;
 207          if ((Res = getaddrinfo(Host.c_str(),ServStr,&Hints,&LastHostAddr)) != 0 ||
 208              LastHostAddr == 0)
 209          {
 210             if (Res == EAI_NONAME || Res == EAI_SERVICE)
 211             {
 212                if (DefPort != 0)
 213                {
 214                   snprintf(ServStr, sizeof(ServStr), "%i", DefPort);
 215                   DefPort = 0;
 216                   continue;
 217                }
 218                bad_addr.insert(bad_addr.begin(), Host);
 219                Owner->SetFailReason("ResolveFailure");
 220                return _error->Error(_("Could not resolve '%s'"),Host.c_str());
 221             }
 222
 223             if (Res == EAI_AGAIN)
 224             {
 225                Owner->SetFailReason("TmpResolveFailure");
 226                return _error->Error(_("Temporary failure resolving '%s'"),
 227                                     Host.c_str());
 228             }
 229             if (Res == EAI_SYSTEM)
 230                return _error->Errno("getaddrinfo", _("System error resolving '%s:%s'"),
 231                                       Host.c_str(),ServStr);
 232             return _error->Error(_("Something wicked happened resolving '%s:%s' (%i - %s)"),
 233                                  Host.c_str(),ServStr,Res,gai_strerror(Res));
 234          }
 235          break;
 236       }
 237
 238       LastHost = Host;
 239       LastPort = Port;
 240    }
 241
 242    // When we have an IP rotation stay with the last IP.
 243    struct addrinfo *CurHost = LastHostAddr;
 244    if (LastUsed != 0)
 245        CurHost = LastUsed;
 246
 247    while (CurHost != 0)
 248    {
 249       if (DoConnect(CurHost,Host,TimeOut,Fd,Owner) == true)
 250       {
 251          LastUsed = CurHost;
 252          return true;
 253       }
 254       close(Fd);
 255       Fd = -1;
 256
 257       // Ignore UNIX domain sockets
 258       do
 259       {
 260          CurHost = CurHost->ai_next;
 261       }
 262       while (CurHost != 0 && CurHost->ai_family == AF_UNIX);
 263
 264       /* If we reached the end of the search list then wrap around to the
 265          start */
 266       if (CurHost == 0 && LastUsed != 0)
 267          CurHost = LastHostAddr;
 268
 269       // Reached the end of the search cycle
 270       if (CurHost == LastUsed)
 271          break;
 272
 273       if (CurHost != 0)
 274          _error->Discard();
 275    }
 276
 277    if (_error->PendingError() == true)
 278       return false;
 279    return _error->Error(_("Unable to connect to %s:%s:"),Host.c_str(),ServStr);
 280 }
 281                                                                         /*}}}*/
 282 // Connect - Connect to a server                                        /*{{{*/
 283 // ---------------------------------------------------------------------
 284 /* Performs a connection to the server (including SRV record lookup) */
 285 bool Connect(std::string Host,int Port,const char *Service,
 286                             int DefPort,int &Fd,
 287                             unsigned long TimeOut,pkgAcqMethod *Owner)
 288 {
 289    if (_error->PendingError() == true)
 290       return false;
 291
 292    if (ConnectionAllowed(Service, Host) == false)
 293       return false;
 294
 295    if(LastHost != Host || LastPort != Port)
 296    {
 297       SrvRecords.clear();
 298       if (_config->FindB("Acquire::EnableSrvRecords", true) == true)
 299          GetSrvRecords(Host, DefPort, SrvRecords);
 300    }
 301
 302    size_t stackSize = 0;
 303    // try to connect in the priority order of the srv records
 304    std::string initialHost{std::move(Host)};
 305    while(SrvRecords.empty() == false)
 306    {
 307       _error->PushToStack();
 308       ++stackSize;
 309       // PopFromSrvRecs will also remove the server
 310       Host = PopFromSrvRecs(SrvRecords).target;
 311       auto const ret = ConnectToHostname(Host, Port, Service, DefPort, Fd, TimeOut, Owner);
 312       if (ret)
 313       {
 314          while(stackSize--)
 315             _error->RevertToStack();
 316          return true;
 317       }
 318    }
 319    Host = std::move(initialHost);
 320
 321    // we have no (good) SrvRecords for this host, connect right away
 322    _error->PushToStack();
 323    ++stackSize;
 324    auto const ret = ConnectToHostname(Host, Port, Service, DefPort, Fd,
 325          TimeOut, Owner);
 326    while(stackSize--)
 327       if (ret)
 328          _error->RevertToStack();
 329       else
 330          _error->MergeWithStack();
 331    return ret;
 332 }