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[apt.git] / methods / http.cc

// -*- mode: cpp; mode: fold -*-
// Description                                                          /*{{{*/
// $Id: http.cc,v 1.59 2004/05/08 19:42:35 mdz Exp $
/* ######################################################################

   HTTP Acquire Method - This is the HTTP aquire method for APT.
   
   It uses HTTP/1.1 and many of the fancy options there-in, such as
   pipelining, range, if-range and so on. 

   It is based on a doubly buffered select loop. A groupe of requests are 
   fed into a single output buffer that is constantly fed out the 
   socket. This provides ideal pipelining as in many cases all of the
   requests will fit into a single packet. The input socket is buffered 
   the same way and fed into the fd for the file (may be a pipe in future).
   
   This double buffering provides fairly substantial transfer rates,
   compared to wget the http method is about 4% faster. Most importantly,
   when HTTP is compared with FTP as a protocol the speed difference is
   huge. In tests over the internet from two sites to llug (via ATM) this
   program got 230k/s sustained http transfer rates. FTP on the other 
   hand topped out at 170k/s. That combined with the time to setup the
   FTP connection makes HTTP a vastly superior protocol.
      
   ##################################################################### */
                                                                        /*}}}*/
// Include Files                                                        /*{{{*/
#include <apt-pkg/fileutl.h>
#include <apt-pkg/acquire-method.h>
#include <apt-pkg/error.h>
#include <apt-pkg/hashes.h>

#include <sys/stat.h>
#include <sys/time.h>
#include <utime.h>
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <iostream>
#include <map>
#include <apti18n.h>

// Internet stuff
#include <netdb.h>

#include "config.h"
#include "connect.h"
#include "rfc2553emu.h"
#include "http.h"

                                                                        /*}}}*/
using namespace std;

string HttpMethod::FailFile;
int HttpMethod::FailFd = -1;
time_t HttpMethod::FailTime = 0;
unsigned long PipelineDepth = 10;
unsigned long TimeOut = 120;
bool AllowRedirect = false;
bool Debug = false;
URI Proxy;

unsigned long CircleBuf::BwReadLimit=0;
unsigned long CircleBuf::BwTickReadData=0;
struct timeval CircleBuf::BwReadTick={0,0};
const unsigned int CircleBuf::BW_HZ=10;
  
// CircleBuf::CircleBuf - Circular input buffer                         /*{{{*/
// ---------------------------------------------------------------------
/* */
CircleBuf::CircleBuf(unsigned long Size) : Size(Size), Hash(0)
{
   Buf = new unsigned char[Size];
   Reset();

   CircleBuf::BwReadLimit = _config->FindI("Acquire::http::Dl-Limit",0)*1024;
}
                                                                        /*}}}*/
// CircleBuf::Reset - Reset to the default state                        /*{{{*/
// ---------------------------------------------------------------------
/* */
void CircleBuf::Reset()
{
   InP = 0;
   OutP = 0;
   StrPos = 0;
   MaxGet = (unsigned int)-1;
   OutQueue = string();
   if (Hash != 0)
   {
      delete Hash;
      Hash = new Hashes;
   }   
};
                                                                        /*}}}*/
// CircleBuf::Read - Read from a FD into the circular buffer            /*{{{*/
// ---------------------------------------------------------------------
/* This fills up the buffer with as much data as is in the FD, assuming it
   is non-blocking.. */
bool CircleBuf::Read(int Fd)
{
   unsigned long BwReadMax;

   while (1)
   {
      // Woops, buffer is full
      if (InP - OutP == Size)
         return true;

      // what's left to read in this tick
      BwReadMax = CircleBuf::BwReadLimit/BW_HZ;

      if(CircleBuf::BwReadLimit) {
         struct timeval now;
         gettimeofday(&now,0);

         unsigned long d = (now.tv_sec-CircleBuf::BwReadTick.tv_sec)*1000000 +
            now.tv_usec-CircleBuf::BwReadTick.tv_usec;
         if(d > 1000000/BW_HZ) {
            CircleBuf::BwReadTick = now;
            CircleBuf::BwTickReadData = 0;
         } 
         
         if(CircleBuf::BwTickReadData >= BwReadMax) {
            usleep(1000000/BW_HZ);
            return true;
         }
      }

      // Write the buffer segment
      int Res;
      if(CircleBuf::BwReadLimit) {
         Res = read(Fd,Buf + (InP%Size), 
                    BwReadMax > LeftRead() ? LeftRead() : BwReadMax);
      } else
         Res = read(Fd,Buf + (InP%Size),LeftRead());
      
      if(Res > 0 && BwReadLimit > 0) 
         CircleBuf::BwTickReadData += Res;
    
      if (Res == 0)
         return false;
      if (Res < 0)
      {
         if (errno == EAGAIN)
            return true;
         return false;
      }

      if (InP == 0)
         gettimeofday(&Start,0);
      InP += Res;
   }
}
                                                                        /*}}}*/
// CircleBuf::Read - Put the string into the buffer                     /*{{{*/
// ---------------------------------------------------------------------
/* This will hold the string in and fill the buffer with it as it empties */
bool CircleBuf::Read(string Data)
{
   OutQueue += Data;
   FillOut();
   return true;
}
                                                                        /*}}}*/
// CircleBuf::FillOut - Fill the buffer from the output queue           /*{{{*/
// ---------------------------------------------------------------------
/* */
void CircleBuf::FillOut()
{
   if (OutQueue.empty() == true)
      return;
   while (1)
   {
      // Woops, buffer is full
      if (InP - OutP == Size)
         return;
      
      // Write the buffer segment
      unsigned long Sz = LeftRead();
      if (OutQueue.length() - StrPos < Sz)
         Sz = OutQueue.length() - StrPos;
      memcpy(Buf + (InP%Size),OutQueue.c_str() + StrPos,Sz);
      
      // Advance
      StrPos += Sz;
      InP += Sz;
      if (OutQueue.length() == StrPos)
      {
         StrPos = 0;
         OutQueue = "";
         return;
      }
   }
}
                                                                        /*}}}*/
// CircleBuf::Write - Write from the buffer into a FD                   /*{{{*/
// ---------------------------------------------------------------------
/* This empties the buffer into the FD. */
bool CircleBuf::Write(int Fd)
{
   while (1)
   {
      FillOut();
      
      // Woops, buffer is empty
      if (OutP == InP)
         return true;
      
      if (OutP == MaxGet)
         return true;
      
      // Write the buffer segment
      int Res;
      Res = write(Fd,Buf + (OutP%Size),LeftWrite());

      if (Res == 0)
         return false;
      if (Res < 0)
      {
         if (errno == EAGAIN)
            return true;
         
         return false;
      }
      
      if (Hash != 0)
         Hash->Add(Buf + (OutP%Size),Res);
      
      OutP += Res;
   }
}
                                                                        /*}}}*/
// CircleBuf::WriteTillEl - Write from the buffer to a string           /*{{{*/
// ---------------------------------------------------------------------
/* This copies till the first empty line */
bool CircleBuf::WriteTillEl(string &Data,bool Single)
{
   // We cheat and assume it is unneeded to have more than one buffer load
   for (unsigned long I = OutP; I < InP; I++)
   {      
      if (Buf[I%Size] != '\n')
         continue;
      ++I;
      
      if (Single == false)
      {
         if (I < InP  && Buf[I%Size] == '\r')
            ++I;
         if (I >= InP || Buf[I%Size] != '\n')
            continue;
         ++I;
      }
      
      Data = "";
      while (OutP < I)
      {
         unsigned long Sz = LeftWrite();
         if (Sz == 0)
            return false;
         if (I - OutP < Sz)
            Sz = I - OutP;
         Data += string((char *)(Buf + (OutP%Size)),Sz);
         OutP += Sz;
      }
      return true;
   }      
   return false;
}
                                                                        /*}}}*/
// CircleBuf::Stats - Print out stats information                       /*{{{*/
// ---------------------------------------------------------------------
/* */
void CircleBuf::Stats()
{
   if (InP == 0)
      return;
   
   struct timeval Stop;
   gettimeofday(&Stop,0);
/*   float Diff = Stop.tv_sec - Start.tv_sec + 
             (float)(Stop.tv_usec - Start.tv_usec)/1000000;
   clog << "Got " << InP << " in " << Diff << " at " << InP/Diff << endl;*/
}
                                                                        /*}}}*/

// ServerState::ServerState - Constructor                               /*{{{*/
// ---------------------------------------------------------------------
/* */
ServerState::ServerState(URI Srv,HttpMethod *Owner) : Owner(Owner),
                        In(64*1024), Out(4*1024),
                        ServerName(Srv)
{
   Reset();
}
                                                                        /*}}}*/
// ServerState::Open - Open a connection to the server                  /*{{{*/
// ---------------------------------------------------------------------
/* This opens a connection to the server. */
bool ServerState::Open()
{
   // Use the already open connection if possible.
   if (ServerFd != -1)
      return true;
   
   Close();
   In.Reset();
   Out.Reset();
   Persistent = true;
   
   // Determine the proxy setting
   string SpecificProxy = _config->Find("Acquire::http::Proxy::" + ServerName.Host);
   if (!SpecificProxy.empty())
   {
           if (SpecificProxy == "DIRECT")
                   Proxy = "";
           else
                   Proxy = SpecificProxy;
   }
   else
   {
           string DefProxy = _config->Find("Acquire::http::Proxy");
           if (!DefProxy.empty())
           {
                   Proxy = DefProxy;
           }
           else
           {
                   char* result = getenv("http_proxy");
                   Proxy = result ? result : "";
           }
   }
   
   // Parse no_proxy, a , separated list of domains
   if (getenv("no_proxy") != 0)
   {
      if (CheckDomainList(ServerName.Host,getenv("no_proxy")) == true)
         Proxy = "";
   }
   
   // Determine what host and port to use based on the proxy settings
   int Port = 0;
   string Host;   
   if (Proxy.empty() == true || Proxy.Host.empty() == true)
   {
      if (ServerName.Port != 0)
         Port = ServerName.Port;
      Host = ServerName.Host;
   }
   else
   {
      if (Proxy.Port != 0)
         Port = Proxy.Port;
      Host = Proxy.Host;
   }
   
   // Connect to the remote server
   if (Connect(Host,Port,"http",80,ServerFd,TimeOut,Owner) == false)
      return false;
   
   return true;
}
                                                                        /*}}}*/
// ServerState::Close - Close a connection to the server                /*{{{*/
// ---------------------------------------------------------------------
/* */
bool ServerState::Close()
{
   close(ServerFd);
   ServerFd = -1;
   return true;
}
                                                                        /*}}}*/
// ServerState::RunHeaders - Get the headers before the data            /*{{{*/
// ---------------------------------------------------------------------
/* Returns 0 if things are OK, 1 if an IO error occurred and 2 if a header
   parse error occurred */
int ServerState::RunHeaders()
{
   State = Header;
   
   Owner->Status(_("Waiting for headers"));

   Major = 0; 
   Minor = 0; 
   Result = 0; 
   Size = 0; 
   StartPos = 0;
   Encoding = Closes;
   HaveContent = false;
   time(&Date);

   do
   {
      string Data;
      if (In.WriteTillEl(Data) == false)
         continue;

      if (Debug == true)
         clog << Data;
      
      for (string::const_iterator I = Data.begin(); I < Data.end(); I++)
      {
         string::const_iterator J = I;
         for (; J != Data.end() && *J != '\n' && *J != '\r';J++);
         if (HeaderLine(string(I,J)) == false)
            return 2;
         I = J;
      }

      // 100 Continue is a Nop...
      if (Result == 100)
         continue;
      
      // Tidy up the connection persistance state.
      if (Encoding == Closes && HaveContent == true)
         Persistent = false;
      
      return 0;
   }
   while (Owner->Go(false,this) == true);
   
   return 1;
}
                                                                        /*}}}*/
// ServerState::RunData - Transfer the data from the socket             /*{{{*/
// ---------------------------------------------------------------------
/* */
bool ServerState::RunData()
{
   State = Data;
   
   // Chunked transfer encoding is fun..
   if (Encoding == Chunked)
   {
      while (1)
      {
         // Grab the block size
         bool Last = true;
         string Data;
         In.Limit(-1);
         do
         {
            if (In.WriteTillEl(Data,true) == true)
               break;
         }
         while ((Last = Owner->Go(false,this)) == true);

         if (Last == false)
            return false;
                 
         // See if we are done
         unsigned long Len = strtol(Data.c_str(),0,16);
         if (Len == 0)
         {
            In.Limit(-1);
            
            // We have to remove the entity trailer
            Last = true;
            do
            {
               if (In.WriteTillEl(Data,true) == true && Data.length() <= 2)
                  break;
            }
            while ((Last = Owner->Go(false,this)) == true);
            if (Last == false)
               return false;
            return !_error->PendingError();
         }
         
         // Transfer the block
         In.Limit(Len);
         while (Owner->Go(true,this) == true)
            if (In.IsLimit() == true)
               break;
         
         // Error
         if (In.IsLimit() == false)
            return false;
         
         // The server sends an extra new line before the next block specifier..
         In.Limit(-1);
         Last = true;
         do
         {
            if (In.WriteTillEl(Data,true) == true)
               break;
         }
         while ((Last = Owner->Go(false,this)) == true);
         if (Last == false)
            return false;
      }
   }
   else
   {
      /* Closes encoding is used when the server did not specify a size, the
         loss of the connection means we are done */
      if (Encoding == Closes)
         In.Limit(-1);
      else
         In.Limit(Size - StartPos);
      
      // Just transfer the whole block.
      do
      {
         if (In.IsLimit() == false)
            continue;
         
         In.Limit(-1);
         return !_error->PendingError();
      }
      while (Owner->Go(true,this) == true);
   }

   return Owner->Flush(this) && !_error->PendingError();
}
                                                                        /*}}}*/
// ServerState::HeaderLine - Process a header line                      /*{{{*/
// ---------------------------------------------------------------------
/* */
bool ServerState::HeaderLine(string Line)
{
   if (Line.empty() == true)
      return true;

   // The http server might be trying to do something evil.
   if (Line.length() >= MAXLEN)
      return _error->Error(_("Got a single header line over %u chars"),MAXLEN);

   string::size_type Pos = Line.find(' ');
   if (Pos == string::npos || Pos+1 > Line.length())
   {
      // Blah, some servers use "connection:closes", evil.
      Pos = Line.find(':');
      if (Pos == string::npos || Pos + 2 > Line.length())
         return _error->Error(_("Bad header line"));
      Pos++;
   }

   // Parse off any trailing spaces between the : and the next word.
   string::size_type Pos2 = Pos;
   while (Pos2 < Line.length() && isspace(Line[Pos2]) != 0)
      Pos2++;
      
   string Tag = string(Line,0,Pos);
   string Val = string(Line,Pos2);
   
   if (stringcasecmp(Tag.c_str(),Tag.c_str()+4,"HTTP") == 0)
   {
      // Evil servers return no version
      if (Line[4] == '/')
      {
         if (sscanf(Line.c_str(),"HTTP/%u.%u %u %[^\n]",&Major,&Minor,
                    &Result,Code) != 4)
            return _error->Error(_("The HTTP server sent an invalid reply header"));
      }
      else
      {
         Major = 0;
         Minor = 9;
         if (sscanf(Line.c_str(),"HTTP %u %[^\n]",&Result,Code) != 2)
            return _error->Error(_("The HTTP server sent an invalid reply header"));
      }

      /* Check the HTTP response header to get the default persistance
         state. */
      if (Major < 1)
         Persistent = false;
      else
      {
         if (Major == 1 && Minor <= 0)
            Persistent = false;
         else
            Persistent = true;
      }

      return true;
   }      
      
   if (stringcasecmp(Tag,"Content-Length:") == 0)
   {
      if (Encoding == Closes)
         Encoding = Stream;
      HaveContent = true;
      
      // The length is already set from the Content-Range header
      if (StartPos != 0)
         return true;
      
      if (sscanf(Val.c_str(),"%lu",&Size) != 1)
         return _error->Error(_("The HTTP server sent an invalid Content-Length header"));
      return true;
   }

   if (stringcasecmp(Tag,"Content-Type:") == 0)
   {
      HaveContent = true;
      return true;
   }
   
   if (stringcasecmp(Tag,"Content-Range:") == 0)
   {
      HaveContent = true;
      
      if (sscanf(Val.c_str(),"bytes %lu-%*u/%lu",&StartPos,&Size) != 2)
         return _error->Error(_("The HTTP server sent an invalid Content-Range header"));
      if ((unsigned)StartPos > Size)
         return _error->Error(_("This HTTP server has broken range support"));
      return true;
   }
   
   if (stringcasecmp(Tag,"Transfer-Encoding:") == 0)
   {
      HaveContent = true;
      if (stringcasecmp(Val,"chunked") == 0)
         Encoding = Chunked;      
      return true;
   }

   if (stringcasecmp(Tag,"Connection:") == 0)
   {
      if (stringcasecmp(Val,"close") == 0)
         Persistent = false;
      if (stringcasecmp(Val,"keep-alive") == 0)
         Persistent = true;
      return true;
   }
   
   if (stringcasecmp(Tag,"Last-Modified:") == 0)
   {
      if (StrToTime(Val,Date) == false)
         return _error->Error(_("Unknown date format"));
      return true;
   }

   if (stringcasecmp(Tag,"Location:") == 0)
   {
      Location = Val;
      return true;
   }

   return true;
}
                                                                        /*}}}*/

// HttpMethod::SendReq - Send the HTTP request                          /*{{{*/
// ---------------------------------------------------------------------
/* This places the http request in the outbound buffer */
void HttpMethod::SendReq(FetchItem *Itm,CircleBuf &Out)
{
   URI Uri = Itm->Uri;

   // The HTTP server expects a hostname with a trailing :port
   char Buf[1000];
   string ProperHost = Uri.Host;
   if (Uri.Port != 0)
   {
      sprintf(Buf,":%u",Uri.Port);
      ProperHost += Buf;
   }   
      
   // Just in case.
   if (Itm->Uri.length() >= sizeof(Buf))
       abort();
       
   /* Build the request. We include a keep-alive header only for non-proxy
      requests. This is to tweak old http/1.0 servers that do support keep-alive
      but not HTTP/1.1 automatic keep-alive. Doing this with a proxy server 
      will glitch HTTP/1.0 proxies because they do not filter it out and 
      pass it on, HTTP/1.1 says the connection should default to keep alive
      and we expect the proxy to do this */
   if (Proxy.empty() == true || Proxy.Host.empty())
      sprintf(Buf,"GET %s HTTP/1.1\r\nHost: %s\r\nConnection: keep-alive\r\n",
              QuoteString(Uri.Path,"~").c_str(),ProperHost.c_str());
   else
   {
      /* Generate a cache control header if necessary. We place a max
         cache age on index files, optionally set a no-cache directive
         and a no-store directive for archives. */
      sprintf(Buf,"GET %s HTTP/1.1\r\nHost: %s\r\n",
              Itm->Uri.c_str(),ProperHost.c_str());
      // only generate a cache control header if we actually want to 
      // use a cache
      if (_config->FindB("Acquire::http::No-Cache",false) == false)
      {
         if (Itm->IndexFile == true)
            sprintf(Buf+strlen(Buf),"Cache-Control: max-age=%u\r\n",
                    _config->FindI("Acquire::http::Max-Age",0));
         else
         {
            if (_config->FindB("Acquire::http::No-Store",false) == true)
               strcat(Buf,"Cache-Control: no-store\r\n");
         }       
      }
   }
   // generate a no-cache header if needed
   if (_config->FindB("Acquire::http::No-Cache",false) == true)
      strcat(Buf,"Cache-Control: no-cache\r\nPragma: no-cache\r\n");

   
   string Req = Buf;

   // Check for a partial file
   struct stat SBuf;
   if (stat(Itm->DestFile.c_str(),&SBuf) >= 0 && SBuf.st_size > 0)
   {
      // In this case we send an if-range query with a range header
      sprintf(Buf,"Range: bytes=%li-\r\nIf-Range: %s\r\n",(long)SBuf.st_size - 1,
              TimeRFC1123(SBuf.st_mtime).c_str());
      Req += Buf;
   }
   else
   {
      if (Itm->LastModified != 0)
      {
         sprintf(Buf,"If-Modified-Since: %s\r\n",TimeRFC1123(Itm->LastModified).c_str());
         Req += Buf;
      }
   }

   if (Proxy.User.empty() == false || Proxy.Password.empty() == false)
      Req += string("Proxy-Authorization: Basic ") + 
          Base64Encode(Proxy.User + ":" + Proxy.Password) + "\r\n";

   if (Uri.User.empty() == false || Uri.Password.empty() == false)
      Req += string("Authorization: Basic ") + 
          Base64Encode(Uri.User + ":" + Uri.Password) + "\r\n";
   
   Req += "User-Agent: Debian APT-HTTP/1.3 ("VERSION")\r\n\r\n";
   
   if (Debug == true)
      cerr << Req << endl;

   Out.Read(Req);
}
                                                                        /*}}}*/
// HttpMethod::Go - Run a single loop                                   /*{{{*/
// ---------------------------------------------------------------------
/* This runs the select loop over the server FDs, Output file FDs and
   stdin. */
bool HttpMethod::Go(bool ToFile,ServerState *Srv)
{
   // Server has closed the connection
   if (Srv->ServerFd == -1 && (Srv->In.WriteSpace() == false || 
                               ToFile == false))
      return false;
   
   fd_set rfds,wfds;
   FD_ZERO(&rfds);
   FD_ZERO(&wfds);
   
   /* Add the server. We only send more requests if the connection will 
      be persisting */
   if (Srv->Out.WriteSpace() == true && Srv->ServerFd != -1 
       && Srv->Persistent == true)
      FD_SET(Srv->ServerFd,&wfds);
   if (Srv->In.ReadSpace() == true && Srv->ServerFd != -1)
      FD_SET(Srv->ServerFd,&rfds);
   
   // Add the file
   int FileFD = -1;
   if (File != 0)
      FileFD = File->Fd();
   
   if (Srv->In.WriteSpace() == true && ToFile == true && FileFD != -1)
      FD_SET(FileFD,&wfds);
   
   // Add stdin
   FD_SET(STDIN_FILENO,&rfds);
          
   // Figure out the max fd
   int MaxFd = FileFD;
   if (MaxFd < Srv->ServerFd)
      MaxFd = Srv->ServerFd;

   // Select
   struct timeval tv;
   tv.tv_sec = TimeOut;
   tv.tv_usec = 0;
   int Res = 0;
   if ((Res = select(MaxFd+1,&rfds,&wfds,0,&tv)) < 0)
   {
      if (errno == EINTR)
         return true;
      return _error->Errno("select",_("Select failed"));
   }
   
   if (Res == 0)
   {
      _error->Error(_("Connection timed out"));
      return ServerDie(Srv);
   }
   
   // Handle server IO
   if (Srv->ServerFd != -1 && FD_ISSET(Srv->ServerFd,&rfds))
   {
      errno = 0;
      if (Srv->In.Read(Srv->ServerFd) == false)
         return ServerDie(Srv);
   }
         
   if (Srv->ServerFd != -1 && FD_ISSET(Srv->ServerFd,&wfds))
   {
      errno = 0;
      if (Srv->Out.Write(Srv->ServerFd) == false)
         return ServerDie(Srv);
   }

   // Send data to the file
   if (FileFD != -1 && FD_ISSET(FileFD,&wfds))
   {
      if (Srv->In.Write(FileFD) == false)
         return _error->Errno("write",_("Error writing to output file"));
   }

   // Handle commands from APT
   if (FD_ISSET(STDIN_FILENO,&rfds))
   {
      if (Run(true) != -1)
         exit(100);
   }   
       
   return true;
}
                                                                        /*}}}*/
// HttpMethod::Flush - Dump the buffer into the file                    /*{{{*/
// ---------------------------------------------------------------------
/* This takes the current input buffer from the Server FD and writes it
   into the file */
bool HttpMethod::Flush(ServerState *Srv)
{
   if (File != 0)
   {
      // on GNU/kFreeBSD, apt dies on /dev/null because non-blocking
      // can't be set
      if (File->Name() != "/dev/null")
         SetNonBlock(File->Fd(),false);
      if (Srv->In.WriteSpace() == false)
         return true;
      
      while (Srv->In.WriteSpace() == true)
      {
         if (Srv->In.Write(File->Fd()) == false)
            return _error->Errno("write",_("Error writing to file"));
         if (Srv->In.IsLimit() == true)
            return true;
      }

      if (Srv->In.IsLimit() == true || Srv->Encoding == ServerState::Closes)
         return true;
   }
   return false;
}
                                                                        /*}}}*/
// HttpMethod::ServerDie - The server has closed the connection.        /*{{{*/
// ---------------------------------------------------------------------
/* */
bool HttpMethod::ServerDie(ServerState *Srv)
{
   unsigned int LErrno = errno;
   
   // Dump the buffer to the file
   if (Srv->State == ServerState::Data)
   {
      // on GNU/kFreeBSD, apt dies on /dev/null because non-blocking
      // can't be set
      if (File->Name() != "/dev/null")
         SetNonBlock(File->Fd(),false);
      while (Srv->In.WriteSpace() == true)
      {
         if (Srv->In.Write(File->Fd()) == false)
            return _error->Errno("write",_("Error writing to the file"));

         // Done
         if (Srv->In.IsLimit() == true)
            return true;
      }
   }
   
   // See if this is because the server finished the data stream
   if (Srv->In.IsLimit() == false && Srv->State != ServerState::Header && 
       Srv->Encoding != ServerState::Closes)
   {
      Srv->Close();
      if (LErrno == 0)
         return _error->Error(_("Error reading from server. Remote end closed connection"));
      errno = LErrno;
      return _error->Errno("read",_("Error reading from server"));
   }
   else
   {
      Srv->In.Limit(-1);

      // Nothing left in the buffer
      if (Srv->In.WriteSpace() == false)
         return false;
      
      // We may have got multiple responses back in one packet..
      Srv->Close();
      return true;
   }
   
   return false;
}
                                                                        /*}}}*/
// HttpMethod::DealWithHeaders - Handle the retrieved header data       /*{{{*/
// ---------------------------------------------------------------------
/* We look at the header data we got back from the server and decide what
   to do. Returns 
     0 - File is open,
     1 - IMS hit
     3 - Unrecoverable error 
     4 - Error with error content page
     5 - Unrecoverable non-server error (close the connection) 
     6 - Try again with a new or changed URI
 */
int HttpMethod::DealWithHeaders(FetchResult &Res,ServerState *Srv)
{
   // Not Modified
   if (Srv->Result == 304)
   {
      unlink(Queue->DestFile.c_str());
      Res.IMSHit = true;
      Res.LastModified = Queue->LastModified;
      return 1;
   }
   
   /* Redirect
    *
    * Note that it is only OK for us to treat all redirection the same
    * because we *always* use GET, not other HTTP methods.  There are
    * three redirection codes for which it is not appropriate that we
    * redirect.  Pass on those codes so the error handling kicks in.
    */
   if (AllowRedirect
       && (Srv->Result > 300 && Srv->Result < 400)
       && (Srv->Result != 300       // Multiple Choices
           && Srv->Result != 304    // Not Modified
           && Srv->Result != 306))  // (Not part of HTTP/1.1, reserved)
   {
      if (!Srv->Location.empty())
      {
         NextURI = Srv->Location;
         return 6;
      }
      /* else pass through for error message */
   }
 
   /* We have a reply we dont handle. This should indicate a perm server
      failure */
   if (Srv->Result < 200 || Srv->Result >= 300)
   {
      _error->Error("%u %s",Srv->Result,Srv->Code);
      if (Srv->HaveContent == true)
         return 4;
      return 3;
   }

   // This is some sort of 2xx 'data follows' reply
   Res.LastModified = Srv->Date;
   Res.Size = Srv->Size;
   
   // Open the file
   delete File;
   File = new FileFd(Queue->DestFile,FileFd::WriteAny);
   if (_error->PendingError() == true)
      return 5;

   FailFile = Queue->DestFile;
   FailFile.c_str();   // Make sure we dont do a malloc in the signal handler
   FailFd = File->Fd();
   FailTime = Srv->Date;
      
   // Set the expected size
   if (Srv->StartPos >= 0)
   {
      Res.ResumePoint = Srv->StartPos;
      if (ftruncate(File->Fd(),Srv->StartPos) < 0)
         _error->Errno("ftruncate", _("Failed to truncate file"));
   }
      
   // Set the start point
   lseek(File->Fd(),0,SEEK_END);

   delete Srv->In.Hash;
   Srv->In.Hash = new Hashes;
   
   // Fill the Hash if the file is non-empty (resume)
   if (Srv->StartPos > 0)
   {
      lseek(File->Fd(),0,SEEK_SET);
      if (Srv->In.Hash->AddFD(File->Fd(),Srv->StartPos) == false)
      {
         _error->Errno("read",_("Problem hashing file"));
         return 5;
      }
      lseek(File->Fd(),0,SEEK_END);
   }
   
   SetNonBlock(File->Fd(),true);
   return 0;
}
                                                                        /*}}}*/
// HttpMethod::SigTerm - Handle a fatal signal                          /*{{{*/
// ---------------------------------------------------------------------
/* This closes and timestamps the open file. This is neccessary to get 
   resume behavoir on user abort */
void HttpMethod::SigTerm(int)
{
   if (FailFd == -1)
      _exit(100);
   close(FailFd);
   
   // Timestamp
   struct utimbuf UBuf;
   UBuf.actime = FailTime;
   UBuf.modtime = FailTime;
   utime(FailFile.c_str(),&UBuf);
   
   _exit(100);
}
                                                                        /*}}}*/
// HttpMethod::Fetch - Fetch an item                                    /*{{{*/
// ---------------------------------------------------------------------
/* This adds an item to the pipeline. We keep the pipeline at a fixed
   depth. */
bool HttpMethod::Fetch(FetchItem *)
{
   if (Server == 0)
      return true;

   // Queue the requests
   int Depth = -1;
   for (FetchItem *I = Queue; I != 0 && Depth < (signed)PipelineDepth; 
        I = I->Next, Depth++)
   {
      // If pipelining is disabled, we only queue 1 request
      if (Server->Pipeline == false && Depth >= 0)
         break;
      
      // Make sure we stick with the same server
      if (Server->Comp(I->Uri) == false)
         break;
      if (QueueBack == I)
      {
         QueueBack = I->Next;
         SendReq(I,Server->Out);
         continue;
      }
   }
   
   return true;
};
                                                                        /*}}}*/
// HttpMethod::Configuration - Handle a configuration message           /*{{{*/
// ---------------------------------------------------------------------
/* We stash the desired pipeline depth */
bool HttpMethod::Configuration(string Message)
{
   if (pkgAcqMethod::Configuration(Message) == false)
      return false;
   
   AllowRedirect = _config->FindB("Acquire::http::AllowRedirect",true);
   TimeOut = _config->FindI("Acquire::http::Timeout",TimeOut);
   PipelineDepth = _config->FindI("Acquire::http::Pipeline-Depth",
                                  PipelineDepth);
   Debug = _config->FindB("Debug::Acquire::http",false);
   
   return true;
}
                                                                        /*}}}*/
// HttpMethod::Loop - Main loop                                         /*{{{*/
// ---------------------------------------------------------------------
/* */
int HttpMethod::Loop()
{
   typedef vector<string> StringVector;
   typedef vector<string>::iterator StringVectorIterator;
   map<string, StringVector> Redirected;

   signal(SIGTERM,SigTerm);
   signal(SIGINT,SigTerm);
   
   Server = 0;
   
   int FailCounter = 0;
   while (1)
   {      
      // We have no commands, wait for some to arrive
      if (Queue == 0)
      {
         if (WaitFd(STDIN_FILENO) == false)
            return 0;
      }
      
      /* Run messages, we can accept 0 (no message) if we didn't
         do a WaitFd above.. Otherwise the FD is closed. */
      int Result = Run(true);
      if (Result != -1 && (Result != 0 || Queue == 0))
         return 100;

      if (Queue == 0)
         continue;
      
      // Connect to the server
      if (Server == 0 || Server->Comp(Queue->Uri) == false)
      {
         delete Server;
         Server = new ServerState(Queue->Uri,this);
      }
      /* If the server has explicitly said this is the last connection
         then we pre-emptively shut down the pipeline and tear down 
         the connection. This will speed up HTTP/1.0 servers a tad
         since we don't have to wait for the close sequence to
         complete */
      if (Server->Persistent == false)
         Server->Close();
      
      // Reset the pipeline
      if (Server->ServerFd == -1)
         QueueBack = Queue;      
         
      // Connnect to the host
      if (Server->Open() == false)
      {
         Fail(true);
         delete Server;
         Server = 0;
         continue;
      }

      // Fill the pipeline.
      Fetch(0);
      
      // Fetch the next URL header data from the server.
      switch (Server->RunHeaders())
      {
         case 0:
         break;
         
         // The header data is bad
         case 2:
         {
            _error->Error(_("Bad header data"));
            Fail(true);
            RotateDNS();
            continue;
         }
         
         // The server closed a connection during the header get..
         default:
         case 1:
         {
            FailCounter++;
            _error->Discard();
            Server->Close();
            Server->Pipeline = false;
            
            if (FailCounter >= 2)
            {
               Fail(_("Connection failed"),true);
               FailCounter = 0;
            }
            
            RotateDNS();
            continue;
         }
      };

      // Decide what to do.
      FetchResult Res;
      Res.Filename = Queue->DestFile;
      switch (DealWithHeaders(Res,Server))
      {
         // Ok, the file is Open
         case 0:
         {
            URIStart(Res);

            // Run the data
            bool Result =  Server->RunData();

            /* If the server is sending back sizeless responses then fill in
               the size now */
            if (Res.Size == 0)
               Res.Size = File->Size();
            
            // Close the file, destroy the FD object and timestamp it
            FailFd = -1;
            delete File;
            File = 0;
            
            // Timestamp
            struct utimbuf UBuf;
            time(&UBuf.actime);
            UBuf.actime = Server->Date;
            UBuf.modtime = Server->Date;
            utime(Queue->DestFile.c_str(),&UBuf);

            // Send status to APT
            if (Result == true)
            {
               Res.TakeHashes(*Server->In.Hash);
               URIDone(Res);
            }
            else
            {
               if (Server->ServerFd == -1)
               {
                  FailCounter++;
                  _error->Discard();
                  Server->Close();
                  
                  if (FailCounter >= 2)
                  {
                     Fail(_("Connection failed"),true);
                     FailCounter = 0;
                  }
                  
                  QueueBack = Queue;
               }
               else
                  Fail(true);
            }
            break;
         }
         
         // IMS hit
         case 1:
         {
            URIDone(Res);
            break;
         }
         
         // Hard server error, not found or something
         case 3:
         {
            Fail();
            break;
         }
          
         // Hard internal error, kill the connection and fail
         case 5:
         {
            delete File;
            File = 0;

            Fail();
            RotateDNS();
            Server->Close();
            break;
         }

         // We need to flush the data, the header is like a 404 w/ error text
         case 4:
         {
            Fail();
            
            // Send to content to dev/null
            File = new FileFd("/dev/null",FileFd::WriteExists);
            Server->RunData();
            delete File;
            File = 0;
            break;
         }
         
         // Try again with a new URL
         case 6:
         {
            // Clear rest of response if there is content
            if (Server->HaveContent)
            {
               File = new FileFd("/dev/null",FileFd::WriteExists);
               Server->RunData();
               delete File;
               File = 0;
            }

            /* Detect redirect loops.  No more redirects are allowed
               after the same URI is seen twice in a queue item. */
            StringVector &R = Redirected[Queue->DestFile];
            bool StopRedirects = false;
            if (R.size() == 0)
               R.push_back(Queue->Uri);
            else if (R[0] == "STOP" || R.size() > 10)
               StopRedirects = true;
            else
            {
               for (StringVectorIterator I = R.begin(); I != R.end(); I++)
                  if (Queue->Uri == *I)
                  {
                     R[0] = "STOP";
                     break;
                  }
 
               R.push_back(Queue->Uri);
            }
 
            if (StopRedirects == false)
               Redirect(NextURI);
            else
               Fail();
 
            break;
         }

         default:
         Fail(_("Internal error"));
         break;
      }
      
      FailCounter = 0;
   }
   
   return 0;
}
                                                                        /*}}}*/

int main()
{
   setlocale(LC_ALL, "");
   // ignore SIGPIPE, this can happen on write() if the socket
   // closes the connection (this is dealt with via ServerDie())
   signal(SIGPIPE, SIG_IGN);

   HttpMethod Mth;
   return Mth.Loop();
}