summaryrefslogtreecommitdiff
path: root/methods/http.cc
blob: 5f5cd2631234dbcc25dd3014d549e80b3345c440 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
// -*- 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 acquire 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 <config.h>

#include <apt-pkg/fileutl.h>
#include <apt-pkg/acquire-method.h>
#include <apt-pkg/configuration.h>
#include <apt-pkg/error.h>
#include <apt-pkg/hashes.h>
#include <apt-pkg/netrc.h>
#include <apt-pkg/strutl.h>

#include <stddef.h>
#include <stdlib.h>
#include <sys/select.h>
#include <cstring>
#include <sys/stat.h>
#include <sys/time.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <iostream>

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

#include <apti18n.h>
									/*}}}*/
using namespace std;

unsigned long long CircleBuf::BwReadLimit=0;
unsigned long 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 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 long long)-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)
{
   while (1)
   {
      // Woops, buffer is full
      if (InP - OutP == Size)
	 return true;

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

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

	 unsigned long 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
      ssize_t 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 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
      ssize_t 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 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 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;*/
}
									/*}}}*/
CircleBuf::~CircleBuf()
{
   delete [] Buf;
   delete Hash;
}

// HttpServerState::HttpServerState - Constructor			/*{{{*/
HttpServerState::HttpServerState(URI Srv,HttpMethod *Owner) : ServerState(Srv, Owner), In(64*1024), Out(4*1024)
{
   TimeOut = _config->FindI("Acquire::http::Timeout",TimeOut);
   Reset();
}
									/*}}}*/
// HttpServerState::Open - Open a connection to the server		/*{{{*/
// ---------------------------------------------------------------------
/* This opens a connection to the server. */
bool HttpServerState::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;
}
									/*}}}*/
// HttpServerState::Close - Close a connection to the server		/*{{{*/
// ---------------------------------------------------------------------
/* */
bool HttpServerState::Close()
{
   close(ServerFd);
   ServerFd = -1;
   return true;
}
									/*}}}*/
// HttpServerState::RunData - Transfer the data from the socket		/*{{{*/
bool HttpServerState::RunData(FileFd * const File)
{
   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 = Go(false, File)) == true);

	 if (Last == false)
	    return false;
	 	 
	 // See if we are done
	 unsigned long long Len = strtoull(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 = Go(false, File)) == true);
	    if (Last == false)
	       return false;
	    return !_error->PendingError();
	 }
	 
	 // Transfer the block
	 In.Limit(Len);
	 while (Go(true, File) == 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 = Go(false, File)) == 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 (Go(true, File) == true);
   }

   return Owner->Flush() && !_error->PendingError();
}
									/*}}}*/
bool HttpServerState::ReadHeaderLines(std::string &Data)		/*{{{*/
{
   return In.WriteTillEl(Data);
}
									/*}}}*/
bool HttpServerState::LoadNextResponse(bool const ToFile, FileFd * const File)/*{{{*/
{
   return Go(ToFile, File);
}
									/*}}}*/
bool HttpServerState::WriteResponse(const std::string &Data)		/*{{{*/
{
   return Out.Read(Data);
}
									/*}}}*/
APT_PURE bool HttpServerState::IsOpen()					/*{{{*/
{
   return (ServerFd != -1);
}
									/*}}}*/
bool HttpServerState::InitHashes(FileFd &File)				/*{{{*/
{
   delete In.Hash;
   In.Hash = new Hashes;

   // Set the expected size and read file for the hashes
   File.Truncate(StartPos);
   return In.Hash->AddFD(File, StartPos);
}
									/*}}}*/
APT_PURE Hashes * HttpServerState::GetHashes()				/*{{{*/
{
   return In.Hash;
}
									/*}}}*/
// HttpServerState::Die - The server has closed the connection.		/*{{{*/
bool HttpServerState::Die(FileFd &File)
{
   unsigned int LErrno = errno;

   // Dump the buffer to the file
   if (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 (In.WriteSpace() == true)
      {
	 if (In.Write(File.Fd()) == false)
	    return _error->Errno("write",_("Error writing to the file"));

	 // Done
	 if (In.IsLimit() == true)
	    return true;
      }
   }

   // See if this is because the server finished the data stream
   if (In.IsLimit() == false && State != HttpServerState::Header &&
       Encoding != HttpServerState::Closes)
   {
      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
   {
      In.Limit(-1);

      // Nothing left in the buffer
      if (In.WriteSpace() == false)
	 return false;

      // We may have got multiple responses back in one packet..
      Close();
      return true;
   }

   return false;
}
									/*}}}*/
// HttpServerState::Flush - Dump the buffer into the file		/*{{{*/
// ---------------------------------------------------------------------
/* This takes the current input buffer from the Server FD and writes it
   into the file */
bool HttpServerState::Flush(FileFd * const File)
{
   if (File != NULL)
   {
      // 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 (In.WriteSpace() == false)
	 return true;
      
      while (In.WriteSpace() == true)
      {
	 if (In.Write(File->Fd()) == false)
	    return _error->Errno("write",_("Error writing to file"));
	 if (In.IsLimit() == true)
	    return true;
      }

      if (In.IsLimit() == true || Encoding == ServerState::Closes)
	 return true;
   }
   return false;
}
									/*}}}*/
// HttpServerState::Go - Run a single loop				/*{{{*/
// ---------------------------------------------------------------------
/* This runs the select loop over the server FDs, Output file FDs and
   stdin. */
bool HttpServerState::Go(bool ToFile, FileFd * const File)
{
   // Server has closed the connection
   if (ServerFd == -1 && (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 (Out.WriteSpace() == true && ServerFd != -1 
       && Persistent == true)
      FD_SET(ServerFd,&wfds);
   if (In.ReadSpace() == true && ServerFd != -1)
      FD_SET(ServerFd,&rfds);
   
   // Add the file
   int FileFD = -1;
   if (File != NULL)
      FileFD = File->Fd();
   
   if (In.WriteSpace() == true && ToFile == true && FileFD != -1)
      FD_SET(FileFD,&wfds);

   // Add stdin
   if (_config->FindB("Acquire::http::DependOnSTDIN", true) == true)
      FD_SET(STDIN_FILENO,&rfds);
	  
   // Figure out the max fd
   int MaxFd = FileFD;
   if (MaxFd < ServerFd)
      MaxFd = 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 Die(*File);
   }
   
   // Handle server IO
   if (ServerFd != -1 && FD_ISSET(ServerFd,&rfds))
   {
      errno = 0;
      if (In.Read(ServerFd) == false)
	 return Die(*File);
   }
	 
   if (ServerFd != -1 && FD_ISSET(ServerFd,&wfds))
   {
      errno = 0;
      if (Out.Write(ServerFd) == false)
	 return Die(*File);
   }

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

   // Handle commands from APT
   if (FD_ISSET(STDIN_FILENO,&rfds))
   {
      if (Owner->Run(true) != -1)
	 exit(100);
   }   
       
   return true;
}
									/*}}}*/

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

   // The HTTP server expects a hostname with a trailing :port
   string Buf;
   string ProperHost;

   if (Uri.Host.find(':') != string::npos)
      ProperHost = '[' + Uri.Host + ']';
   else
      ProperHost = Uri.Host;
   if (Uri.Port != 0)
   {
      strprintf(Buf,":%u",Uri.Port);
      ProperHost += Buf;
   }   
      
   /* RFC 2616 §5.1.2 requires absolute URIs for requests to proxies,
      but while its a must for all servers to accept absolute URIs,
      it is assumed clients will sent an absolute path for non-proxies */
   std::string requesturi;
   if (Server->Proxy.empty() == true || Server->Proxy.Host.empty())
      requesturi = Uri.Path;
   else
      requesturi = Itm->Uri;

   // The "+" is encoded as a workaround for a amazon S3 bug
   // see LP bugs #1003633 and #1086997.
   requesturi = QuoteString(requesturi, "+~ ");

   /* Build the request. No keep-alive is included as it is the default
      in 1.1, can cause problems with proxies, and we are an HTTP/1.1
      client anyway.
      C.f. https://tools.ietf.org/wg/httpbis/trac/ticket/158 */
   strprintf(Buf,"GET %s HTTP/1.1\r\nHost: %s\r\n",
	   requesturi.c_str(),ProperHost.c_str());

   // generate a cache control header (if needed)
   if (_config->FindB("Acquire::http::No-Cache",false) == true) 
   {
      Buf += "Cache-Control: no-cache\r\nPragma: no-cache\r\n";
   }
   else
   {
      if (Itm->IndexFile == true) 
      {
         string Tmp;
	 strprintf(Tmp,"Cache-Control: max-age=%u\r\n",
		 _config->FindI("Acquire::http::Max-Age",0));
         Buf += Tmp;
      }
      else
      {
	 if (_config->FindB("Acquire::http::No-Store",false) == true)
	    Buf += "Cache-Control: no-store\r\n";
      }
   }

   // If we ask for uncompressed files servers might respond with content-
   // negotiation which lets us end up with compressed files we do not support,
   // see 657029, 657560 and co, so if we have no extension on the request
   // ask for text only. As a sidenote: If there is nothing to negotate servers
   // seem to be nice and ignore it.
   if (_config->FindB("Acquire::http::SendAccept", true) == true)
   {
      size_t const filepos = Itm->Uri.find_last_of('/');
      string const file = Itm->Uri.substr(filepos + 1);
      if (flExtension(file) == file)
	 Buf += "Accept: text/*\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
      strprintf(Buf,"Range: bytes=%lli-\r\nIf-Range: %s\r\n",(long long)SBuf.st_size,
	      TimeRFC1123(SBuf.st_mtime).c_str());
      Req += Buf;
   }
   else
   {
      if (Itm->LastModified != 0)
      {
	 strprintf(Buf,"If-Modified-Since: %s\r\n",TimeRFC1123(Itm->LastModified).c_str());
	 Req += Buf;
      }
   }

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


   maybe_add_auth (Uri, _config->FindFile("Dir::Etc::netrc"));
   if(Uri.User.empty() || Uri.Password.empty())
   {
      std::string const netrcparts = _config->FindDir("Dir::Etc::netrcparts");
      if (not netrcparts.empty())
      {
	 _error->PushToStack();
	 std::vector<std::string> files = GetListOfFilesInDir(netrcparts, "conf", true, true);
	 for (std::vector<std::string>::const_iterator netrc = files.begin(); netrc != files.end(); netrc++)
	 {
	    maybe_add_auth (Uri, *netrc);
	    if (Uri.User.empty() == false || Uri.Password.empty() == false)
	       break;
	 }
	 _error->RevertToStack();
      }
   }

   if (Uri.User.empty() == false || Uri.Password.empty() == false)
   {
      Req += string("Authorization: Basic ") + 
          Base64Encode(Uri.User + ":" + Uri.Password) + "\r\n";
   }
   Req += "User-Agent: " + _config->Find("Acquire::http::User-Agent",
		"Debian APT-HTTP/1.3 (" PACKAGE_VERSION ")") + "\r\n\r\n";
   
   if (Debug == true)
      cerr << Req << endl;

   Server->WriteResponse(Req);
}
									/*}}}*/
// HttpMethod::Configuration - Handle a configuration message		/*{{{*/
// ---------------------------------------------------------------------
/* We stash the desired pipeline depth */
bool HttpMethod::Configuration(string Message)
{
   if (ServerMethod::Configuration(Message) == false)
      return false;

   AllowRedirect = _config->FindB("Acquire::http::AllowRedirect",true);
   PipelineDepth = _config->FindI("Acquire::http::Pipeline-Depth",
				  PipelineDepth);
   Debug = _config->FindB("Debug::Acquire::http",false);

   // Get the proxy to use
   AutoDetectProxy();

   return true;
}
									/*}}}*/
// HttpMethod::AutoDetectProxy - auto detect proxy			/*{{{*/
// ---------------------------------------------------------------------
/* */
bool HttpMethod::AutoDetectProxy()
{
   // option is "Acquire::http::Proxy-Auto-Detect" but we allow the old
   // name without the dash ("-")
   AutoDetectProxyCmd = _config->Find("Acquire::http::Proxy-Auto-Detect",
                                      _config->Find("Acquire::http::ProxyAutoDetect"));

   if (AutoDetectProxyCmd.empty())
      return true;

   if (Debug)
      clog << "Using auto proxy detect command: " << AutoDetectProxyCmd << endl;

   int Pipes[2] = {-1,-1};
   if (pipe(Pipes) != 0)
      return _error->Errno("pipe", "Failed to create Pipe");

   pid_t Process = ExecFork();
   if (Process == 0)
   {
      close(Pipes[0]);
      dup2(Pipes[1],STDOUT_FILENO);
      SetCloseExec(STDOUT_FILENO,false);

      const char *Args[2];
      Args[0] = AutoDetectProxyCmd.c_str();
      Args[1] = 0;
      execv(Args[0],(char **)Args);
      cerr << "Failed to exec method " << Args[0] << endl;
      _exit(100);
   }
   char buf[512];
   int InFd = Pipes[0];
   close(Pipes[1]);
   int res = read(InFd, buf, sizeof(buf)-1);
   ExecWait(Process, "ProxyAutoDetect", true);

   if (res < 0)
      return _error->Errno("read", "Failed to read");
   if (res == 0)
      return _error->Warning("ProxyAutoDetect returned no data");

   // add trailing \0
   buf[res] = 0;

   if (Debug)
      clog << "auto detect command returned: '" << buf << "'" << endl;

   if (strstr(buf, "http://") == buf)
      _config->Set("Acquire::http::proxy", _strstrip(buf));

   return true;
}
									/*}}}*/
ServerState * HttpMethod::CreateServerState(URI uri)			/*{{{*/
{
   return new HttpServerState(uri, this);
}
									/*}}}*/
void HttpMethod::RotateDNS()						/*{{{*/
{
   ::RotateDNS();
}
									/*}}}*/