implement generic config fallback for methods

The https method implemented for a long while now a hardcoded fallback
to the same options in http, which, while it works, is rather inflexible
if we want to allow the methods to use another name to change their
behavior slightly, like apt-transport-tor does to https – most of the
diff being s#https#tor#g which then fails to do the full circle
fallthrough tor -> https -> http for https sources. With this config
infrastructure this could be implemented now.

1 files changed, 49 insertions, 8 deletions

diff --git a/methods/server.cc b/methods/server.cc
index 66551b893..7c85c8abb 100644
--- a/methods/server.cc
+++ b/methods/server.cc
@@ -313,10 +313,30 @@ ServerMethod::DealWithHeaders(FetchResult &Res)
       {
 	 NextURI = DeQuoteString(Server->Location);
 	 URI tmpURI = NextURI;
-	 if (tmpURI.Access == "http" && Binary == "https+http")
+	 if (tmpURI.Access.find('+') != std::string::npos)
 	 {
-	    tmpURI.Access = "https+http";
-	    NextURI = tmpURI;
+	    _error->Error("Server tried to trick us into using a specific implementation: %s", tmpURI.Access.c_str());
+	    if (Server->HaveContent == true)
+	       return ERROR_WITH_CONTENT_PAGE;
+	    return ERROR_UNRECOVERABLE;
+	 }
+	 URI Uri = Queue->Uri;
+	 if (Binary.find('+') != std::string::npos)
+	 {
+	    auto base = Binary.substr(0, Binary.find('+'));
+	    if (base != tmpURI.Access)
+	    {
+	       tmpURI.Access = base + '+' + tmpURI.Access;
+	       if (tmpURI.Access == Binary)
+	       {
+		  std::string tmpAccess = Uri.Access;
+		  std::swap(tmpURI.Access, Uri.Access);
+		  NextURI = tmpURI;
+		  std::swap(tmpURI.Access, Uri.Access);
+	       }
+	       else
+		  NextURI = tmpURI;
+	    }
 	 }
 	 if (Queue->Uri == NextURI)
 	 {
@@ -326,7 +346,7 @@ ServerMethod::DealWithHeaders(FetchResult &Res)
 	       return ERROR_WITH_CONTENT_PAGE;
 	    return ERROR_UNRECOVERABLE;
 	 }
-	 URI Uri = Queue->Uri;
+	 Uri.Access = Binary;
 	 // same protocol redirects are okay
 	 if (tmpURI.Access == Uri.Access)
 	    return TRY_AGAIN_OR_REDIRECT;
@@ -334,7 +354,22 @@ ServerMethod::DealWithHeaders(FetchResult &Res)
 	 else if ((Uri.Access == "http" || Uri.Access == "https+http") && tmpURI.Access == "https")
 	    return TRY_AGAIN_OR_REDIRECT;
 	 else
-	    _error->Error("Redirection from %s to '%s' is forbidden", Uri.Access.c_str(), NextURI.c_str());
+	 {
+	    auto const tmpplus = tmpURI.Access.find('+');
+	    if (tmpplus != std::string::npos && tmpURI.Access.substr(tmpplus + 1) == "https")
+	    {
+	       auto const uriplus = Uri.Access.find('+');
+	       if (uriplus == std::string::npos)
+	       {
+		  if (Uri.Access == tmpURI.Access.substr(0, tmpplus)) // foo -> foo+https
+		     return TRY_AGAIN_OR_REDIRECT;
+	       }
+	       else if (Uri.Access.substr(uriplus + 1) == "http" &&
+		     Uri.Access.substr(0, uriplus) == tmpURI.Access.substr(0, tmpplus)) // foo+http -> foo+https
+		  return TRY_AGAIN_OR_REDIRECT;
+	    }
+	 }
+	 _error->Error("Redirection from %s to '%s' is forbidden", Uri.Access.c_str(), NextURI.c_str());
       }
       /* else pass through for error message */
    }
@@ -513,7 +548,7 @@ int ServerMethod::Loop()
       if (Result != -1 && (Result != 0 || Queue == 0))
       {
 	 if(FailReason.empty() == false ||
-	    _config->FindB("Acquire::http::DependOnSTDIN", true) == true)
+	    ConfigFindB("DependOnSTDIN", true) == true)
 	    return 100;
 	 else
 	    return 0;
@@ -524,7 +559,13 @@ int ServerMethod::Loop()
       
       // Connect to the server
       if (Server == 0 || Server->Comp(Queue->Uri) == false)
+      {
 	 Server = CreateServerState(Queue->Uri);
+	 setPostfixForMethodNames(::URI(Queue->Uri).Host.c_str());
+	 AllowRedirect = ConfigFindB("AllowRedirect", true);
+	 PipelineDepth = ConfigFindI("Pipeline-Depth", 10);
+	 Debug = DebugEnabled();
+      }
 
       /* If the server has explicitly said this is the last connection
          then we pre-emptively shut down the pipeline and tear down 
@@ -747,8 +788,8 @@ unsigned long long ServerMethod::FindMaximumObjectSizeInQueue() const	/*{{{*/
    return MaxSizeInQueue;
 }
 									/*}}}*/
-ServerMethod::ServerMethod(char const * const Binary, char const * const Ver,unsigned long const Flags) :/*{{{*/
-   aptMethod(Binary, Ver, Flags), Server(nullptr), File(NULL), PipelineDepth(10),
+ServerMethod::ServerMethod(std::string &&Binary, char const * const Ver,unsigned long const Flags) :/*{{{*/
+   aptMethod(std::move(Binary), Ver, Flags), Server(nullptr), File(NULL), PipelineDepth(10),
    AllowRedirect(false), Debug(false)
 {
 }