You have to do the bounds check before the access.

[apt.git] / methods / connect.cc

diff --git a/methods/connect.cc b/methods/connect.cc
index 171622fa570d31a2813dd2f5be4d4ee259e45f2e..f6fb14769861f6cbdfd55fdd7221e70cf201cf6b 100644 (file)
--- a/methods/connect.cc
+++ b/methods/connect.cc
@@ -61,10 +61,25 @@ void RotateDNS()
       LastUsed = LastHostAddr;
 }
                                                                        /*}}}*/
+static bool ConnectionAllowed(char const * const Service, std::string const &Host)/*{{{*/
+{
+   if (unlikely(Host.empty())) // the only legal empty host (RFC2782 '.' target) is detected by caller
+      return false;
+   if (APT::String::Endswith(Host, ".onion") && _config->FindB("Acquire::BlockDotOnion", true))
+   {
+      // TRANSLATOR: %s is e.g. Tor's ".onion" which would likely fail or leak info (RFC7686)
+      _error->Error(_("Direct connection to %s domains is blocked by default."), ".onion");
+      if (strcmp(Service, "http") == 0)
+       _error->Error(_("If you meant to use Tor remember to use %s instead of %s."), "tor+http", "http");
+      return false;
+   }
+   return true;
+}
+                                                                       /*}}}*/
 // DoConnect - Attempt a connect operation                             /*{{{*/
 // ---------------------------------------------------------------------
 /* This helper function attempts a connection to a single address. */
-static bool DoConnect(struct addrinfo *Addr,std::string Host,
+static bool DoConnect(struct addrinfo *Addr,std::string const &Host,
                      unsigned long TimeOut,int &Fd,pkgAcqMethod *Owner)
 {
    // Show a status indicator
@@ -138,6 +153,8 @@ static bool ConnectToHostname(std::string const &Host, int const Port,
       const char * const Service, int DefPort, int &Fd,
       unsigned long const TimeOut, pkgAcqMethod * const Owner)
 {
+   if (ConnectionAllowed(Service, Host) == false)
+      return false;
    // Convert the port name/number
    char ServStr[300];
    if (Port != 0)
@@ -164,7 +181,16 @@ static bool ConnectToHostname(std::string const &Host, int const Port,
       struct addrinfo Hints;
       memset(&Hints,0,sizeof(Hints));
       Hints.ai_socktype = SOCK_STREAM;
-      Hints.ai_flags = AI_ADDRCONFIG;
+      Hints.ai_flags = 0;
+#ifdef AI_IDN
+      if (_config->FindB("Acquire::Connect::IDN", true) == true)
+        Hints.ai_flags |= AI_IDN;
+#endif
+      // see getaddrinfo(3): only return address if system has such a address configured
+      // useful if system is ipv4 only, to not get ipv6, but that fails if the system has
+      // no address configured: e.g. offline and trying to connect to localhost.
+      if (_config->FindB("Acquire::Connect::AddrConfig", true) == true)
+        Hints.ai_flags |= AI_ADDRCONFIG;
       Hints.ai_protocol = 0;
       
       if(_config->FindB("Acquire::ForceIPv4", false) == true)
@@ -267,27 +293,50 @@ bool Connect(std::string Host,int Port,const char *Service,
    if (_error->PendingError() == true)
       return false;
 
+   if (ConnectionAllowed(Service, Host) == false)
+      return false;
+
    if(LastHost != Host || LastPort != Port)
    {
       SrvRecords.clear();
       if (_config->FindB("Acquire::EnableSrvRecords", true) == true)
+      {
          GetSrvRecords(Host, DefPort, SrvRecords);
+        // RFC2782 defines that a lonely '.' target is an abort reason
+        if (SrvRecords.size() == 1 && SrvRecords[0].target.empty())
+           return _error->Error("SRV records for %s indicate that "
+                 "%s service is not available at this domain", Host.c_str(), Service);
+      }
    }
-   // we have no SrvRecords for this host, connect right away
-   if(SrvRecords.size() == 0)
-      return ConnectToHostname(Host, Port, Service, DefPort, Fd, 
-                                    TimeOut, Owner);
 
+   size_t stackSize = 0;
    // try to connect in the priority order of the srv records
-   while(SrvRecords.size() > 0)
+   std::string initialHost{std::move(Host)};
+   while(SrvRecords.empty() == false)
    {
+      _error->PushToStack();
+      ++stackSize;
+      // PopFromSrvRecs will also remove the server
       Host = PopFromSrvRecs(SrvRecords).target;
-      if(ConnectToHostname(Host, Port, Service, DefPort, Fd, TimeOut, Owner))
+      auto const ret = ConnectToHostname(Host, Port, Service, DefPort, Fd, TimeOut, Owner);
+      if (ret)
+      {
+        while(stackSize--)
+           _error->RevertToStack();
          return true;
-
-      // we couldn't connect to this one, use the next
-      SrvRecords.erase(SrvRecords.begin());
+      }
    }
+   Host = std::move(initialHost);
 
-   return false;
+   // we have no (good) SrvRecords for this host, connect right away
+   _error->PushToStack();
+   ++stackSize;
+   auto const ret = ConnectToHostname(Host, Port, Service, DefPort, Fd,
+        TimeOut, Owner);
+   while(stackSize--)
+      if (ret)
+        _error->RevertToStack();
+      else
+        _error->MergeWithStack();
+   return ret;
 }