Adding upstream version 2.2.4.upstream/2.2.4upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1004 insertions, 0 deletions

diff --git a/apt-pkg/acquire-worker.cc b/apt-pkg/acquire-worker.cc
new file mode 100644
index 0000000..3fbc5c0
--- /dev/null
+++ b/apt-pkg/acquire-worker.cc
@@ -0,0 +1,1004 @@
+// -*- mode: cpp; mode: fold -*-
+// Description								/*{{{*/
+/* ######################################################################
+
+   Acquire Worker 
+
+   The worker process can startup either as a Configuration prober
+   or as a queue runner. As a configuration prober it only reads the
+   configuration message and 
+   
+   ##################################################################### */
+									/*}}}*/
+// Include Files							/*{{{*/
+#include <config.h>
+
+#include <apt-pkg/acquire-item.h>
+#include <apt-pkg/acquire-worker.h>
+#include <apt-pkg/acquire.h>
+#include <apt-pkg/configuration.h>
+#include <apt-pkg/error.h>
+#include <apt-pkg/fileutl.h>
+#include <apt-pkg/hashes.h>
+#include <apt-pkg/proxy.h>
+#include <apt-pkg/strutl.h>
+
+#include <algorithm>
+#include <iostream>
+#include <string>
+#include <vector>
+
+#include <sstream>
+#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <apti18n.h>
+									/*}}}*/
+
+using namespace std;
+
+// Worker::Worker - Constructor for Queue startup			/*{{{*/
+pkgAcquire::Worker::Worker(Queue *Q, MethodConfig *Cnf, pkgAcquireStatus *log) :
+   d(NULL), OwnerQ(Q), Log(log), Config(Cnf), Access(Cnf->Access),
+   CurrentItem(nullptr)
+{
+   Construct();
+}
+									/*}}}*/
+// Worker::Worker - Constructor for method config startup		/*{{{*/
+pkgAcquire::Worker::Worker(MethodConfig *Cnf) : Worker(nullptr, Cnf, nullptr)
+{
+}
+									/*}}}*/
+// Worker::Construct - Constructor helper				/*{{{*/
+// ---------------------------------------------------------------------
+/* */
+void pkgAcquire::Worker::Construct()
+{
+   NextQueue = 0;
+   NextAcquire = 0;
+   Process = -1;
+   InFd = -1;
+   OutFd = -1;
+   OutReady = false;
+   InReady = false;
+   Debug = _config->FindB("Debug::pkgAcquire::Worker",false);
+}
+									/*}}}*/
+// Worker::~Worker - Destructor						/*{{{*/
+// ---------------------------------------------------------------------
+/* */
+pkgAcquire::Worker::~Worker()
+{
+   close(InFd);
+   close(OutFd);
+   
+   if (Process > 0)
+   {
+      /* Closing of stdin is the signal to exit and die when the process
+         indicates it needs cleanup */
+      if (Config->NeedsCleanup == false)
+	 kill(Process,SIGINT);
+      ExecWait(Process,Access.c_str(),true);
+   }   
+}
+									/*}}}*/
+// Worker::Start - Start the worker process				/*{{{*/
+// ---------------------------------------------------------------------
+/* This forks the method and inits the communication channel */
+bool pkgAcquire::Worker::Start()
+{
+   // Get the method path
+   constexpr char const * const methodsDir = "Dir::Bin::Methods";
+   std::string const confItem = std::string(methodsDir) + "::" + Access;
+   std::string Method;
+   if (_config->Exists(confItem))
+	 Method = _config->FindFile(confItem.c_str());
+   else if (Access == "ftp" || Access == "rsh" || Access == "ssh")
+      return _error->Error(_("The method '%s' is unsupported and disabled by default. Consider switching to http(s). Set Dir::Bin::Methods::%s to \"%s\" to enable it again."), Access.c_str(), Access.c_str(), Access.c_str());
+   else
+	 Method = _config->FindDir(methodsDir) + Access;
+   if (FileExists(Method) == false)
+   {
+      if (flNotDir(Method) == "false")
+      {
+	 _error->Error(_("The method '%s' is explicitly disabled via configuration."), Access.c_str());
+	 if (Access == "http" || Access == "https")
+	    _error->Notice(_("If you meant to use Tor remember to use %s instead of %s."), ("tor+" + Access).c_str(), Access.c_str());
+	 return false;
+      }
+      _error->Error(_("The method driver %s could not be found."),Method.c_str());
+      std::string const A(Access.cbegin(), std::find(Access.cbegin(), Access.cend(), '+'));
+      std::string pkg;
+      strprintf(pkg, "apt-transport-%s", A.c_str());
+      _error->Notice(_("Is the package %s installed?"), pkg.c_str());
+      return false;
+   }
+   std::string const Calling = _config->FindDir(methodsDir) + Access;
+
+   if (Debug == true)
+   {
+      std::clog << "Starting method '" << Calling << "'";
+      if (Calling != Method)
+	 std::clog << " ( via " << Method << " )";
+      std::clog << endl;
+   }
+
+   // Create the pipes
+   int Pipes[4] = {-1,-1,-1,-1};
+   if (pipe(Pipes) != 0 || pipe(Pipes+2) != 0)
+   {
+      _error->Errno("pipe","Failed to create IPC pipe to subprocess");
+      for (int I = 0; I != 4; I++)
+	 close(Pipes[I]);
+      return false;
+   }
+   for (int I = 0; I != 4; I++)
+      SetCloseExec(Pipes[I],true);
+
+   // Fork off the process
+   Process = ExecFork();
+   if (Process == 0)
+   {
+      // Setup the FDs
+      dup2(Pipes[1],STDOUT_FILENO);
+      dup2(Pipes[2],STDIN_FILENO);
+      SetCloseExec(STDOUT_FILENO,false);
+      SetCloseExec(STDIN_FILENO,false);
+      SetCloseExec(STDERR_FILENO,false);
+
+      const char * const Args[] = { Calling.c_str(), nullptr };
+      execv(Method.c_str() ,const_cast<char **>(Args));
+      std::cerr << "Failed to exec method " << Calling << " ( via " << Method << ")" << endl;
+      _exit(100);
+   }
+
+   // Fix up our FDs
+   InFd = Pipes[0];
+   OutFd = Pipes[3];
+   SetNonBlock(Pipes[0],true);
+   SetNonBlock(Pipes[3],true);
+   close(Pipes[1]);
+   close(Pipes[2]);
+   OutReady = false;
+   InReady = true;
+
+   // Read the configuration data
+   if (WaitFd(InFd) == false ||
+       ReadMessages() == false)
+      return _error->Error(_("Method %s did not start correctly"),Method.c_str());
+
+   RunMessages();
+   if (OwnerQ != 0)
+      SendConfiguration();
+
+   return true;
+}
+									/*}}}*/
+// Worker::ReadMessages - Read all pending messages into the list	/*{{{*/
+// ---------------------------------------------------------------------
+/* */
+bool pkgAcquire::Worker::ReadMessages()
+{
+   if (::ReadMessages(InFd,MessageQueue) == false)
+      return MethodFailure();
+   return true;
+}
+									/*}}}*/
+// Worker::RunMessage - Empty the message queue				/*{{{*/
+// ---------------------------------------------------------------------
+/* This takes the messages from the message queue and runs them through
+   the parsers in order. */
+enum class APT_HIDDEN MessageType
+{
+   CAPABILITIES = 100,
+   LOG = 101,
+   STATUS = 102,
+   REDIRECT = 103,
+   WARNING = 104,
+   URI_START = 200,
+   URI_DONE = 201,
+   AUX_REQUEST = 351,
+   URI_FAILURE = 400,
+   GENERAL_FAILURE = 401,
+   MEDIA_CHANGE = 403
+};
+static bool isDoomedItem(pkgAcquire::Item const * const Itm)
+{
+   auto const TransItm = dynamic_cast<pkgAcqTransactionItem const * const>(Itm);
+   if (TransItm == nullptr)
+      return false;
+   return TransItm->TransactionManager->State != pkgAcqTransactionItem::TransactionStarted;
+}
+static HashStringList GetHashesFromMessage(std::string const &Prefix, std::string const &Message)
+{
+   HashStringList hsl;
+   for (char const *const *type = HashString::SupportedHashes(); *type != NULL; ++type)
+   {
+      std::string const tagname = Prefix + *type + "-Hash";
+      std::string const hashsum = LookupTag(Message, tagname.c_str());
+      if (hashsum.empty() == false)
+	 hsl.push_back(HashString(*type, hashsum));
+   }
+   return hsl;
+}
+static void APT_NONNULL(3) ChangeSiteIsMirrorChange(std::string const &NewURI, pkgAcquire::ItemDesc &desc, pkgAcquire::Item *const Owner)
+{
+   if (URI::SiteOnly(NewURI) == URI::SiteOnly(desc.URI))
+      return;
+
+   auto const firstSpace = desc.Description.find(" ");
+   if (firstSpace != std::string::npos)
+   {
+      std::string const OldSite = desc.Description.substr(0, firstSpace);
+      if (likely(APT::String::Startswith(desc.URI, OldSite)))
+      {
+	 std::string const OldExtra = desc.URI.substr(OldSite.length() + 1);
+	 if (likely(APT::String::Endswith(NewURI, OldExtra)))
+	 {
+	    std::string const NewSite = NewURI.substr(0, NewURI.length() - OldExtra.length());
+	    Owner->UsedMirror = URI::ArchiveOnly(NewSite);
+	    desc.Description.replace(0, firstSpace, Owner->UsedMirror);
+	 }
+      }
+   }
+}
+bool pkgAcquire::Worker::RunMessages()
+{
+   while (MessageQueue.empty() == false)
+   {
+      string Message = MessageQueue.front();
+      MessageQueue.erase(MessageQueue.begin());
+
+      if (Debug == true)
+	 clog << " <- " << Access << ':' << QuoteString(Message,"\n") << endl;
+
+      // Fetch the message number
+      char *End;
+      MessageType const Number = static_cast<MessageType>(strtoul(Message.c_str(),&End,10));
+      if (End == Message.c_str())
+	 return _error->Error("Invalid message from method %s: %s",Access.c_str(),Message.c_str());
+
+      string URI = LookupTag(Message,"URI");
+      pkgAcquire::Queue::QItem *Itm = NULL;
+      if (URI.empty() == false)
+	 Itm = OwnerQ->FindItem(URI,this);
+
+      if (Itm != NULL)
+      {
+	 // update used mirror
+	 string UsedMirror = LookupTag(Message,"UsedMirror", "");
+	 if (UsedMirror.empty() == false)
+	 {
+	    for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
+	       (*O)->UsedMirror = UsedMirror;
+
+	    if (Itm->Description.find(" ") != string::npos)
+	       Itm->Description.replace(0, Itm->Description.find(" "), UsedMirror);
+	 }
+      }
+
+      // Determine the message number and dispatch
+      switch (Number)
+      {
+	 case MessageType::CAPABILITIES:
+	 if (Capabilities(Message) == false)
+	    return _error->Error("Unable to process Capabilities message from %s",Access.c_str());
+	 break;
+
+	 case MessageType::LOG:
+	 if (Debug == true)
+	    clog << " <- (log) " << LookupTag(Message,"Message") << endl;
+	 break;
+
+	 case MessageType::STATUS:
+	 Status = LookupTag(Message,"Message");
+	 break;
+
+	 case MessageType::REDIRECT:
+         {
+            if (Itm == nullptr)
+            {
+               _error->Error("Method gave invalid 103 Redirect message");
+               break;
+            }
+
+	    std::string const GotNewURI = LookupTag(Message,"New-URI",URI.c_str());
+	    if (Config->GetSendURIEncoded())
+	       Itm->URI = GotNewURI;
+	    else
+	    {
+	       ::URI tmpuri{GotNewURI};
+	       tmpuri.Path = pkgAcquire::URIEncode(tmpuri.Path);
+	       Itm->URI = tmpuri;
+	    }
+	    auto NewURI = Itm->URI;
+
+	    auto const AltUris = VectorizeString(LookupTag(Message, "Alternate-URIs"), '\n');
+
+	    ItemDone();
+
+	    // Change the status so that it can be dequeued
+	    for (auto const &O: Itm->Owners)
+	       O->Status = pkgAcquire::Item::StatIdle;
+	    // Mark the item as done (taking care of all queues)
+	    // and then put it in the main queue again
+	    std::vector<Item*> const ItmOwners = Itm->Owners;
+	    OwnerQ->ItemDone(Itm);
+	    Itm = nullptr;
+	    for (auto const &Owner: ItmOwners)
+	    {
+	       pkgAcquire::ItemDesc &desc = Owner->GetItemDesc();
+
+	       // for a simplified retry a method might redirect without URI change
+	       // see also IsRedirectionLoop implementation
+	       bool simpleRetry = false;
+	       if (Config->GetSendURIEncoded())
+	       {
+		  for (auto alt = AltUris.crbegin(); alt != AltUris.crend(); ++alt)
+		     Owner->PushAlternativeURI(std::string(*alt), {}, false);
+		  if (desc.URI == GotNewURI)
+		     simpleRetry = true;
+	       }
+	       else
+	       {
+		  for (auto alt = AltUris.crbegin(); alt != AltUris.crend(); ++alt)
+		  {
+		     ::URI tmpuri{*alt};
+		     tmpuri.Path = pkgAcquire::URIEncode(tmpuri.Path);
+		     Owner->PushAlternativeURI(std::string(tmpuri), {}, false);
+		  }
+		  ::URI tmpuri{desc.URI};
+		  tmpuri.Path = DeQuoteString(tmpuri.Path);
+		  if (GotNewURI == std::string(tmpuri))
+		     simpleRetry = true;
+	       }
+
+	       if (not simpleRetry)
+	       {
+		  if (Owner->IsGoodAlternativeURI(NewURI) == false && Owner->PopAlternativeURI(NewURI) == false)
+		     NewURI.clear();
+		  if (NewURI.empty() || Owner->IsRedirectionLoop(NewURI))
+		  {
+		     std::string msg = Message;
+		     msg.append("\nFailReason: RedirectionLoop");
+		     Owner->Failed(msg, Config);
+		     if (Log != nullptr)
+			Log->Fail(Owner->GetItemDesc());
+		     continue;
+		  }
+
+		  if (Log != nullptr)
+		     Log->Done(desc);
+
+		  ChangeSiteIsMirrorChange(NewURI, desc, Owner);
+		  desc.URI = NewURI;
+	       }
+	       if (isDoomedItem(Owner) == false)
+		  OwnerQ->Owner->Enqueue(desc);
+	    }
+            break;
+         }
+
+	 case MessageType::WARNING:
+	    _error->Warning("%s: %s", Itm ? Itm->Owner ? Itm->Owner->DescURI().c_str() : Access.c_str() : Access.c_str(), LookupTag(Message, "Message").c_str());
+	    break;
+
+	 case MessageType::URI_START:
+	 {
+	    if (Itm == nullptr)
+	    {
+	       _error->Error("Method gave invalid 200 URI Start message");
+	       break;
+	    }
+
+	    CurrentItem = Itm;
+	    Itm->CurrentSize = 0;
+	    Itm->TotalSize = strtoull(LookupTag(Message,"Size","0").c_str(), NULL, 10);
+	    Itm->ResumePoint = strtoull(LookupTag(Message,"Resume-Point","0").c_str(), NULL, 10);
+	    for (auto const Owner: Itm->Owners)
+	    {
+	       Owner->Start(Message, Itm->TotalSize);
+	       // Display update before completion
+	       if (Log != nullptr)
+	       {
+		  if (Log->MorePulses == true)
+		     Log->Pulse(Owner->GetOwner());
+		  Log->Fetch(Owner->GetItemDesc());
+	       }
+	    }
+
+	    break;
+	 }
+
+	 case MessageType::URI_DONE:
+	 {
+	    if (Itm == nullptr)
+	    {
+	       _error->Error("Method gave invalid 201 URI Done message");
+	       break;
+	    }
+
+	    PrepareFiles("201::URIDone", Itm);
+
+	    // Display update before completion
+	    if (Log != 0 && Log->MorePulses == true)
+	       for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
+		  Log->Pulse((*O)->GetOwner());
+
+	    HashStringList ReceivedHashes;
+	    {
+	       std::string const givenfilename = LookupTag(Message, "Filename");
+	       std::string const filename = givenfilename.empty() ? Itm->Owner->DestFile : givenfilename;
+	       // see if we got hashes to verify
+	       ReceivedHashes = GetHashesFromMessage("", Message);
+	       // not all methods always sent Hashes our way
+	       if (ReceivedHashes.usable() == false)
+	       {
+		  HashStringList const ExpectedHashes = Itm->GetExpectedHashes();
+		  if (ExpectedHashes.usable() == true && RealFileExists(filename))
+		  {
+		     Hashes calc(ExpectedHashes);
+		     FileFd file(filename, FileFd::ReadOnly, FileFd::None);
+		     calc.AddFD(file);
+		     ReceivedHashes = calc.GetHashStringList();
+		  }
+	       }
+
+	       // only local files can refer other filenames and counting them as fetched would be unfair
+	       if (Log != NULL && Itm->Owner->Complete == false && Itm->Owner->Local == false && givenfilename == filename)
+		  Log->Fetched(ReceivedHashes.FileSize(),atoi(LookupTag(Message,"Resume-Point","0").c_str()));
+	    }
+
+	    std::vector<Item*> const ItmOwners = Itm->Owners;
+	    OwnerQ->ItemDone(Itm);
+	    Itm = NULL;
+
+	    bool const isIMSHit = StringToBool(LookupTag(Message,"IMS-Hit"),false) ||
+	       StringToBool(LookupTag(Message,"Alt-IMS-Hit"),false);
+	    auto const forcedHash = _config->Find("Acquire::ForceHash");
+	    for (auto const Owner: ItmOwners)
+	    {
+	       HashStringList const ExpectedHashes = Owner->GetExpectedHashes();
+	       if(_config->FindB("Debug::pkgAcquire::Auth", false) == true)
+	       {
+		  std::clog << "201 URI Done: " << Owner->DescURI() << endl
+		     << "ReceivedHash:" << endl;
+		  for (HashStringList::const_iterator hs = ReceivedHashes.begin(); hs != ReceivedHashes.end(); ++hs)
+		     std::clog <<  "\t- " << hs->toStr() << std::endl;
+		  std::clog << "ExpectedHash:" << endl;
+		  for (HashStringList::const_iterator hs = ExpectedHashes.begin(); hs != ExpectedHashes.end(); ++hs)
+		     std::clog <<  "\t- " << hs->toStr() << std::endl;
+		  std::clog << endl;
+	       }
+
+	       // decide if what we got is what we expected
+	       bool consideredOkay = false;
+	       if ((forcedHash.empty() && ExpectedHashes.empty() == false) ||
+		     (forcedHash.empty() == false && ExpectedHashes.usable()))
+	       {
+		  if (ReceivedHashes.empty())
+		  {
+		     /* IMS-Hits can't be checked here as we will have uncompressed file,
+			but the hashes for the compressed file. What we have was good through
+			so all we have to ensure later is that we are not stalled. */
+		     consideredOkay = isIMSHit;
+		  }
+		  else if (ReceivedHashes == ExpectedHashes)
+		     consideredOkay = true;
+		  else
+		     consideredOkay = false;
+
+	       }
+	       else
+		  consideredOkay = !Owner->HashesRequired();
+
+	       if (consideredOkay == true)
+		  consideredOkay = Owner->VerifyDone(Message, Config);
+	       else // hashsum mismatch
+		  Owner->Status = pkgAcquire::Item::StatAuthError;
+
+
+	       if (consideredOkay == true)
+	       {
+		  if (isDoomedItem(Owner) == false)
+		     Owner->Done(Message, ReceivedHashes, Config);
+		  if (Log != nullptr)
+		  {
+		     if (isIMSHit)
+			Log->IMSHit(Owner->GetItemDesc());
+		     else
+			Log->Done(Owner->GetItemDesc());
+		  }
+	       }
+	       else
+	       {
+		  auto SavedDesc = Owner->GetItemDesc();
+		  if (isDoomedItem(Owner) == false)
+		  {
+		     if (Message.find("\nFailReason:") == std::string::npos)
+		     {
+			if (ReceivedHashes != ExpectedHashes)
+			   Message.append("\nFailReason: HashSumMismatch");
+			else
+			   Message.append("\nFailReason: WeakHashSums");
+		     }
+		     Owner->Failed(Message,Config);
+		  }
+		  if (Log != nullptr)
+		     Log->Fail(SavedDesc);
+	       }
+	    }
+	    ItemDone();
+	    break;
+	 }
+
+	 case MessageType::AUX_REQUEST:
+	 {
+	    if (Itm == nullptr)
+	    {
+	       _error->Error("Method gave invalid Aux Request message");
+	       break;
+	    }
+	    else if (Config->GetAuxRequests() == false)
+	    {
+	       std::vector<Item *> const ItmOwners = Itm->Owners;
+	       Message.append("\nMessage: Method tried to make an Aux Request while not being allowed to do them");
+	       OwnerQ->ItemDone(Itm);
+	       Itm = nullptr;
+	       HandleFailure(ItmOwners, Config, Log, Message, false, false);
+	       ItemDone();
+
+	       std::string Msg = "600 URI Acquire\n";
+	       Msg.reserve(200);
+	       Msg += "URI: " + LookupTag(Message, "Aux-URI", "");
+	       Msg += "\nFilename: /nonexistent/auxrequest.blocked";
+	       Msg += "\n\n";
+	       if (Debug == true)
+		  clog << " -> " << Access << ':' << QuoteString(Msg, "\n") << endl;
+	       OutQueue += Msg;
+	       OutReady = true;
+	       break;
+	    }
+
+	    auto maxsizestr = LookupTag(Message, "MaximumSize", "");
+	    unsigned long long const MaxSize = maxsizestr.empty() ? 0 : strtoull(maxsizestr.c_str(), nullptr, 10);
+	    new pkgAcqAuxFile(Itm->Owner, this, LookupTag(Message, "Aux-ShortDesc", ""),
+			      LookupTag(Message, "Aux-Description", ""), LookupTag(Message, "Aux-URI", ""),
+			      GetHashesFromMessage("Aux-", Message), MaxSize);
+	    break;
+	 }
+
+	 case MessageType::URI_FAILURE:
+	 {
+	    if (Itm == nullptr)
+	    {
+	       std::string const msg = LookupTag(Message,"Message");
+	       _error->Error("Method gave invalid 400 URI Failure message: %s", msg.c_str());
+	       break;
+	    }
+
+	    PrepareFiles("400::URIFailure", Itm);
+
+	    // Display update before completion
+	    if (Log != nullptr && Log->MorePulses == true)
+	       for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
+		  Log->Pulse((*O)->GetOwner());
+
+	    std::vector<Item*> const ItmOwners = Itm->Owners;
+	    OwnerQ->ItemDone(Itm);
+	    Itm = nullptr;
+
+	    bool errTransient = false, errAuthErr = false;
+	    if (StringToBool(LookupTag(Message, "Transient-Failure"), false) == true)
+	       errTransient = true;
+	    else
+	    {
+	       std::string const failReason = LookupTag(Message, "FailReason");
+	       {
+		  auto const reasons = { "Timeout", "ConnectionRefused",
+		     "ConnectionTimedOut", "ResolveFailure", "TmpResolveFailure" };
+		  errTransient = std::find(std::begin(reasons), std::end(reasons), failReason) != std::end(reasons);
+	       }
+	       if (errTransient == false)
+	       {
+		  auto const reasons = { "HashSumMismatch", "WeakHashSums", "MaximumSizeExceeded" };
+		  errAuthErr = std::find(std::begin(reasons), std::end(reasons), failReason) != std::end(reasons);
+	       }
+	    }
+	    HandleFailure(ItmOwners, Config, Log, Message, errTransient, errAuthErr);
+	    ItemDone();
+
+	    break;
+	 }
+
+	 case MessageType::GENERAL_FAILURE:
+	 _error->Error("Method %s General failure: %s",Access.c_str(),LookupTag(Message,"Message").c_str());
+	 break;
+
+	 case MessageType::MEDIA_CHANGE:
+	 MediaChange(Message);
+	 break;
+      }
+   }
+   return true;
+}
+									/*}}}*/
+void pkgAcquire::Worker::HandleFailure(std::vector<pkgAcquire::Item *> const &ItmOwners, /*{{{*/
+				       pkgAcquire::MethodConfig *const Config, pkgAcquireStatus *const Log,
+				       std::string const &Message, bool const errTransient, bool const errAuthErr)
+{
+   for (auto const Owner : ItmOwners)
+   {
+      std::string NewURI;
+      if (errTransient == true && Config->LocalOnly == false && Owner->Retries != 0)
+      {
+	 --Owner->Retries;
+	 Owner->FailMessage(Message);
+	 auto SavedDesc = Owner->GetItemDesc();
+	 if (Log != nullptr)
+	    Log->Fail(SavedDesc);
+	 if (isDoomedItem(Owner) == false)
+	    OwnerQ->Owner->Enqueue(SavedDesc);
+      }
+      else
+      {
+	 if (errAuthErr)
+	    Owner->RemoveAlternativeSite(URI::SiteOnly(Owner->GetItemDesc().URI));
+	 if (Owner->PopAlternativeURI(NewURI))
+	 {
+	    Owner->FailMessage(Message);
+	    auto &desc = Owner->GetItemDesc();
+	    if (Log != nullptr)
+	       Log->Fail(desc);
+	    ChangeSiteIsMirrorChange(NewURI, desc, Owner);
+	    desc.URI = NewURI;
+	    if (isDoomedItem(Owner) == false)
+	       OwnerQ->Owner->Enqueue(desc);
+	 }
+	 else
+	 {
+	    if (errAuthErr && Owner->GetExpectedHashes().empty() == false)
+	       Owner->Status = pkgAcquire::Item::StatAuthError;
+	    else if (errTransient)
+	       Owner->Status = pkgAcquire::Item::StatTransientNetworkError;
+	    auto SavedDesc = Owner->GetItemDesc();
+	    if (isDoomedItem(Owner) == false)
+	       Owner->Failed(Message, Config);
+	    if (Log != nullptr)
+	       Log->Fail(SavedDesc);
+	 }
+      }
+   }
+}
+									/*}}}*/
+// Worker::Capabilities - 100 Capabilities handler			/*{{{*/
+// ---------------------------------------------------------------------
+/* This parses the capabilities message and dumps it into the configuration
+   structure. */
+bool pkgAcquire::Worker::Capabilities(string Message)
+{
+   if (Config == 0)
+      return true;
+
+   Config->Version = LookupTag(Message,"Version");
+   Config->SingleInstance = StringToBool(LookupTag(Message,"Single-Instance"),false);
+   Config->Pipeline = StringToBool(LookupTag(Message,"Pipeline"),false);
+   Config->SendConfig = StringToBool(LookupTag(Message,"Send-Config"),false);
+   Config->LocalOnly = StringToBool(LookupTag(Message,"Local-Only"),false);
+   Config->NeedsCleanup = StringToBool(LookupTag(Message,"Needs-Cleanup"),false);
+   Config->Removable = StringToBool(LookupTag(Message,"Removable"),false);
+   Config->SetAuxRequests(StringToBool(LookupTag(Message, "AuxRequests"), false));
+   if (_config->FindB("Acquire::Send-URI-Encoded", true))
+      Config->SetSendURIEncoded(StringToBool(LookupTag(Message, "Send-URI-Encoded"), false));
+
+   // Some debug text
+   if (Debug == true)
+   {
+      clog << "Configured access method " << Config->Access << endl;
+      clog << "Version:" << Config->Version << " SingleInstance:" << Config->SingleInstance
+	   << " Pipeline:" << Config->Pipeline << " SendConfig:" << Config->SendConfig
+	   << " LocalOnly: " << Config->LocalOnly << " NeedsCleanup: " << Config->NeedsCleanup
+	   << " Removable: " << Config->Removable << " AuxRequests: " << Config->GetAuxRequests()
+	   << " SendURIEncoded: " << Config->GetSendURIEncoded() << '\n';
+   }
+
+   return true;
+}
+									/*}}}*/
+// Worker::MediaChange - Request a media change				/*{{{*/
+// ---------------------------------------------------------------------
+/* */
+bool pkgAcquire::Worker::MediaChange(string Message)
+{
+   int status_fd = _config->FindI("APT::Status-Fd",-1);
+   if(status_fd > 0)
+   {
+      string Media = LookupTag(Message,"Media");
+      string Drive = LookupTag(Message,"Drive");
+      ostringstream msg,status;
+      ioprintf(msg,_("Please insert the disc labeled: "
+		     "'%s' "
+		     "in the drive '%s' and press [Enter]."),
+	       Media.c_str(),Drive.c_str());
+      status << "media-change: "  // message
+	     << Media  << ":"     // media
+	     << Drive  << ":"     // drive
+	     << msg.str()         // l10n message
+	     << endl;
+
+      std::string const dlstatus = status.str();
+      FileFd::Write(status_fd, dlstatus.c_str(), dlstatus.size());
+   }
+
+   if (Log == 0 || Log->MediaChange(LookupTag(Message,"Media"),
+				    LookupTag(Message,"Drive")) == false)
+   {
+      char S[300];
+      snprintf(S,sizeof(S),"603 Media Changed\nFailed: true\n\n");
+      if (Debug == true)
+	 clog << " -> " << Access << ':' << QuoteString(S,"\n") << endl;
+      OutQueue += S;
+      OutReady = true;
+      return true;
+   }
+
+   char S[300];
+   snprintf(S,sizeof(S),"603 Media Changed\n\n");
+   if (Debug == true)
+      clog << " -> " << Access << ':' << QuoteString(S,"\n") << endl;
+   OutQueue += S;
+   OutReady = true;
+   return true;
+}
+									/*}}}*/
+// Worker::SendConfiguration - Send the config to the method		/*{{{*/
+// ---------------------------------------------------------------------
+/* */
+bool pkgAcquire::Worker::SendConfiguration()
+{
+   if (Config->SendConfig == false)
+      return true;
+
+   if (OutFd == -1)
+      return false;
+
+   /* Write out all of the configuration directives by walking the
+      configuration tree */
+   std::ostringstream Message;
+   Message << "601 Configuration\n";
+   if (not _config->Exists("Acquire::Send-URI-Encoded"))
+      Message << "Config-Item: Acquire::Send-URI-Encoded=1\n";
+   _config->Dump(Message, NULL, "Config-Item: %F=%V\n", false);
+   Message << '\n';
+
+   if (Debug == true)
+      clog << " -> " << Access << ':' << QuoteString(Message.str(),"\n") << endl;
+   OutQueue += Message.str();
+   OutReady = true;
+
+   return true;
+}
+									/*}}}*/
+// Worker::QueueItem - Add an item to the outbound queue		/*{{{*/
+// ---------------------------------------------------------------------
+/* Send a URI Acquire message to the method */
+bool pkgAcquire::Worker::QueueItem(pkgAcquire::Queue::QItem *Item)
+{
+   if (OutFd == -1)
+      return false;
+
+   if (isDoomedItem(Item->Owner))
+      return true;
+
+   Item->SyncDestinationFiles();
+
+   string Message = "600 URI Acquire\n";
+   Message.reserve(300);
+   URI URL(Item->URI);
+   if (Config->GetSendURIEncoded())
+      Message += "URI: " + Item->URI;
+   else
+   {
+      URL.Path = DeQuoteString(URL.Path);
+      Message += "URI: " + std::string(URL);
+   }
+   Message += "\nFilename: " + Item->Owner->DestFile;
+
+   // FIXME: We should not hard code proxy protocols here.
+   if (URL.Access == "http" || URL.Access == "https")
+   {
+      AutoDetectProxy(URL);
+      if (_config->Exists("Acquire::" + URL.Access + "::proxy::" + URL.Host))
+      {
+	 Message += "\nProxy: " + _config->Find("Acquire::" + URL.Access + "::proxy::" + URL.Host);
+      }
+   }
+
+   HashStringList const hsl = Item->GetExpectedHashes();
+   for (HashStringList::const_iterator hs = hsl.begin(); hs != hsl.end(); ++hs)
+      Message += "\nExpected-" + hs->HashType() + ": " + hs->HashValue();
+
+   Message += Item->Custom600Headers();
+
+   if (hsl.FileSize() == 0 && Message.find("\nMaximum-Size: ") == std::string::npos)
+   {
+      unsigned long long FileSize = Item->GetMaximumSize();
+      if(FileSize > 0)
+      {
+	 string MaximumSize;
+	 strprintf(MaximumSize, "%llu", FileSize);
+	 Message += "\nMaximum-Size: " + MaximumSize;
+      }
+   }
+
+   Message += "\n\n";
+
+   if (RealFileExists(Item->Owner->DestFile))
+   {
+      std::string const SandboxUser = _config->Find("APT::Sandbox::User");
+      ChangeOwnerAndPermissionOfFile("Item::QueueURI", Item->Owner->DestFile.c_str(),
+                                     SandboxUser.c_str(), ROOT_GROUP, 0600);
+   }
+
+   if (Debug == true)
+      clog << " -> " << Access << ':' << QuoteString(Message,"\n") << endl;
+   OutQueue += Message;
+   OutReady = true;
+
+   return true;
+}
+									/*}}}*/
+// Worker::ReplyAux - reply to an aux request from this worker		/*{{{*/
+bool pkgAcquire::Worker::ReplyAux(pkgAcquire::ItemDesc const &Item)
+{
+   if (OutFd == -1)
+      return false;
+
+   if (isDoomedItem(Item.Owner))
+      return true;
+
+   string Message = "600 URI Acquire\n";
+   Message.reserve(200);
+   Message += "URI: " + Item.URI;
+   if (RealFileExists(Item.Owner->DestFile))
+   {
+      if (Item.Owner->Status == pkgAcquire::Item::StatDone)
+      {
+	 std::string const SandboxUser = _config->Find("APT::Sandbox::User");
+	 ChangeOwnerAndPermissionOfFile("Worker::ReplyAux", Item.Owner->DestFile.c_str(),
+					SandboxUser.c_str(), ROOT_GROUP, 0600);
+	 Message += "\nFilename: " + Item.Owner->DestFile;
+      }
+      else
+      {
+	 // we end up here in case we would need root-rights to delete a file,
+	 // but we run the command as non-root… (yes, it is unlikely)
+	 Message += "\nFilename: " + flCombine("/nonexistent", Item.Owner->DestFile);
+      }
+   }
+   else
+      Message += "\nFilename: " + Item.Owner->DestFile;
+   Message += "\n\n";
+
+   if (Debug == true)
+      clog << " -> " << Access << ':' << QuoteString(Message, "\n") << endl;
+   OutQueue += Message;
+   OutReady = true;
+
+   return true;
+}
+									/*}}}*/
+// Worker::OutFdRead - Out bound FD is ready				/*{{{*/
+// ---------------------------------------------------------------------
+/* */
+bool pkgAcquire::Worker::OutFdReady()
+{
+   int Res;
+   do
+   {
+      Res = write(OutFd,OutQueue.c_str(),OutQueue.length());
+   }
+   while (Res < 0 && errno == EINTR);
+
+   if (Res <= 0)
+      return MethodFailure();
+
+   OutQueue.erase(0,Res);
+   if (OutQueue.empty() == true)
+      OutReady = false;
+
+   return true;
+}
+									/*}}}*/
+// Worker::InFdRead - In bound FD is ready				/*{{{*/
+// ---------------------------------------------------------------------
+/* */
+bool pkgAcquire::Worker::InFdReady()
+{
+   if (ReadMessages() == false)
+      return false;
+   RunMessages();
+   return true;
+}
+									/*}}}*/
+// Worker::MethodFailure - Called when the method fails			/*{{{*/
+// ---------------------------------------------------------------------
+/* This is called when the method is believed to have failed, probably because
+   read returned -1. */
+bool pkgAcquire::Worker::MethodFailure()
+{
+   _error->Error("Method %s has died unexpectedly!",Access.c_str());
+
+   // do not reap the child here to show meaningful error to the user
+   ExecWait(Process,Access.c_str(),false);
+   Process = -1;
+   close(InFd);
+   close(OutFd);
+   InFd = -1;
+   OutFd = -1;
+   OutReady = false;
+   InReady = false;
+   OutQueue = string();
+   MessageQueue.erase(MessageQueue.begin(),MessageQueue.end());
+
+   return false;
+}
+									/*}}}*/
+// Worker::Pulse - Called periodically					/*{{{*/
+// ---------------------------------------------------------------------
+/* */
+void pkgAcquire::Worker::Pulse()
+{
+   if (CurrentItem == 0)
+      return;
+
+   struct stat Buf;
+   if (stat(CurrentItem->Owner->DestFile.c_str(),&Buf) != 0)
+      return;
+   CurrentItem->CurrentSize = Buf.st_size;
+}
+									/*}}}*/
+// Worker::ItemDone - Called when the current item is finished		/*{{{*/
+// ---------------------------------------------------------------------
+/* */
+void pkgAcquire::Worker::ItemDone()
+{
+   CurrentItem = nullptr;
+   Status = string();
+}
+									/*}}}*/
+void pkgAcquire::Worker::PrepareFiles(char const * const caller, pkgAcquire::Queue::QItem const * const Itm)/*{{{*/
+{
+   if (RealFileExists(Itm->Owner->DestFile))
+   {
+      ChangeOwnerAndPermissionOfFile(caller, Itm->Owner->DestFile.c_str(), "root", ROOT_GROUP, 0644);
+      std::string const filename = Itm->Owner->DestFile;
+      for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
+      {
+	 pkgAcquire::Item const * const Owner = *O;
+	 if (Owner->DestFile == filename || filename == "/dev/null")
+	    continue;
+	 RemoveFile("PrepareFiles", Owner->DestFile);
+	 if (link(filename.c_str(), Owner->DestFile.c_str()) != 0)
+	 {
+	    // different mounts can't happen for us as we download to lists/ by default,
+	    // but if the system is reused by others the locations can potentially be on
+	    // different disks, so use symlink as poor-men replacement.
+	    // FIXME: Real copying as last fallback, but that is costly, so offload to a method preferable
+	    if (symlink(filename.c_str(), Owner->DestFile.c_str()) != 0)
+	       _error->Error("Can't create (sym)link of file %s to %s", filename.c_str(), Owner->DestFile.c_str());
+	 }
+      }
+   }
+   else
+   {
+      for (pkgAcquire::Queue::QItem::owner_iterator O = Itm->Owners.begin(); O != Itm->Owners.end(); ++O)
+	 RemoveFile("PrepareFiles", (*O)->DestFile);
+   }
+}
+									/*}}}*/