Getting Brian's proposal, preparing for a few little changes

Merge branch 'multiple_external_handlers' of https://github.com/bbockelm/xrootd into bbockelm-multiple_external_handlers

src/XrdHttp/XrdHttpProtocol.cc

@@ -93,7 +93,7 @@ SSL_CTX *XrdHttpProtocol::sslctx = 0;
 BIO *XrdHttpProtocol::sslbio_err = 0;
 XrdCryptoFactory *XrdHttpProtocol::myCryptoFactory = 0;
 XrdHttpSecXtractor *XrdHttpProtocol::secxtractor = 0;
-XrdHttpExtHandler *XrdHttpProtocol::exthandler = 0;
+std::vector<XrdHttpExtHandler *> XrdHttpProtocol::exthandler;
 std::map< std::string, std::string > XrdHttpProtocol::hdr2cgimap; 
 
 static const unsigned char *s_server_session_id_context = (const unsigned char *) "XrdHTTPSessionCtx";
@@ -739,7 +739,7 @@ int XrdHttpProtocol::Process(XrdLink *lp) // We ignore the argument here
   // Now we have everything that is needed to try the login
   // Remember that if there is an exthandler then it has the responsibility
   // for authorization in the paths that it manages
-  if (!exthandler || !exthandler->MatchesPath(CurrentReq.requestverb.c_str(), CurrentReq.resource.c_str())) {
+  if (FindMatchingExtHandler(CurrentReq)) {
     if (!Bridge) {
       if (SecEntity.name)
         Bridge = XrdXrootd::Bridge::Login(&CurrentReq, Link, &SecEntity, SecEntity.name, "XrdHttp");
@@ -2437,20 +2437,32 @@ int XrdHttpProtocol::LoadExtHandler(XrdSysError *myeDest, const char *libName,
                                     const char *configFN, const char *libParms,
                                     XrdOucEnv *myEnv) {
 
-  // We don't want to load it more than once
-  if (exthandler) return 1;
-
   XrdVersionInfo *myVer = &XrdVERSIONINFOVAR(XrdgetProtocol);
   XrdOucPinLoader myLib(myeDest, myVer, "exthandlerlib", libName);
   XrdHttpExtHandler *(*ep)(XrdHttpExtHandlerArgs);
 
   // Get the entry point of the object creator
   //
   ep = (XrdHttpExtHandler *(*)(XrdHttpExtHandlerArgs))(myLib.Resolve("XrdHttpGetExtHandler"));
-  if (ep && (exthandler = ep(myeDest, configFN, libParms, myEnv))) return 0;
+
+  XrdHttpExtHandler *newhandler;
+  if (ep && (newhandler = ep(myeDest, configFN, libParms, myEnv))) {
+    exthandler.push_back(newhandler);
+    return 0;
+  }
+
   myLib.Unload();
   return 1;
 }
 
 
-
+// Locates a matching external handler for a given request, if available
+XrdHttpExtHandler * XrdHttpProtocol::FindMatchingExtHandler(const XrdHttpReq &req) {
+  std::vector<XrdHttpExtHandler *>::const_iterator it;
+  for (it = exthandler.begin(); it != exthandler.end(); it++) {
+    if ((*it)->MatchesPath(req.requestverb.c_str(), req.resource.c_str())) {
+      return *it;
+    }
+  }
+  return nullptr;
+}

src/XrdHttp/XrdHttpProtocol.hh

@@ -50,6 +50,8 @@
 
 #include <openssl/ssl.h>
 
+#include <vector>
+
 #include "XrdHttpReq.hh"
 
 /******************************************************************************/
@@ -170,7 +172,7 @@ private:
   static int xheader2cgi(XrdOucStream &Config);
 
   static XrdHttpSecXtractor *secxtractor;
-  static XrdHttpExtHandler *exthandler;
+  static std::vector<XrdHttpExtHandler *> exthandler;
 
   // Loads the SecXtractor plugin, if available
   static int LoadSecXtractor(XrdSysError *eDest, const char *libName,
@@ -181,6 +183,12 @@ private:
                             const char *configFN, const char *libParms,
                             XrdOucEnv *myEnv);
 
+  // Determines whether one of the loaded ExtHandlers are interested in
+  // handling a given request.
+  //
+  // Returns NULL if there is no matching handler.
+  static XrdHttpExtHandler *FindMatchingExtHandler(const XrdHttpReq &);
+
   /// Circular Buffer used to read the request
   XrdBuffer *myBuff;
   /// The circular pointers

src/XrdHttp/XrdHttpReq.cc

@@ -776,9 +776,11 @@ int XrdHttpReq::ProcessHTTPReq() {
 
 
   // Verify if we have an external handler for this request
-  if (prot->exthandler && prot->exthandler->MatchesPath(this->requestverb.c_str(), this->resource.c_str())) {
+
+  XrdHttpExtHandler *exthandler = prot->FindMatchingExtHandler(*this);
+  if (exthandler) {
     XrdHttpExtReq xreq(this, prot);
-    int r = prot->exthandler->ProcessReq(xreq);
+    int r = exthandler->ProcessReq(xreq);
     reset();
     if (!r) return 1; // All went fine, response sent
     if (r < 0) return -1; // There was a hard error... close the connection