[net/http auth] Use strings to identify authentication schemes.

net/http/http_auth.cc

Index: net/http/http_auth.cc
diff --git a/net/http/http_auth.cc b/net/http/http_auth.cc
index 7752d743a22a356ea659577e858ad8aa3f2c017b..28fa76b006123a9de1d6464641956b99e34914e0 100644
--- a/net/http/http_auth.cc
+++ b/net/http/http_auth.cc
@@ -7,49 +7,120 @@
 #include <algorithm>
 
 #include "base/basictypes.h"
+#include "base/bind.h"
 #include "base/strings/string_tokenizer.h"
 #include "base/strings/string_util.h"
+#include "base/values.h"
 #include "net/base/net_errors.h"
 #include "net/http/http_auth_challenge_tokenizer.h"
 #include "net/http/http_auth_handler.h"
 #include "net/http/http_auth_handler_factory.h"
+#include "net/http/http_auth_scheme_set.h"
 #include "net/http/http_request_headers.h"
 #include "net/http/http_response_headers.h"
 #include "net/http/http_util.h"
 
 namespace net {
 
+namespace {
+
+// Hardcoded map of HTTP authentication scheme priorities. Higher priorities are
+// preferred over lower.
+struct SchemePriority {
+  const char* scheme;
+  int priority;
+} kSchemeScores[] = {
+    {"basic", 1},
+    {"digest", 2},
+    {"ntlm", 3},
+    {"negotiate", 4},
+};
+
+// Priority assigned to unknown authentication schemes. They are currently
+// ranked lower than Basic, which might be a bit too conservative.
+const int kSchemePriorityDefault = 0;
+
+// Not a valid priority.
+const int kSchemePriorityInvalid = -1;
+
+// Higher priority schemes are preferred over lower priority schemes.
+int GetSchemePriority(const std::string& scheme) {
+  DCHECK(HttpAuth::IsValidNormalizedScheme(scheme));
+  for (const auto& iter : kSchemeScores) {
+    if (scheme == iter.scheme)
+      return iter.priority;
+  }
+  return kSchemePriorityDefault;
+}
+
+scoped_ptr<base::Value> AuthHandlerCreationFailureParams(
+    const std::string* challenge,
+    int error,
+    NetLogCaptureMode capture_mode) {
+  scoped_ptr<base::DictionaryValue> dict(new base::DictionaryValue());
+  dict->SetString("challenge", *challenge);
+  dict->SetInteger("net_error", error);
+  return dict.Pass();
+}
+
+}  // namespace
+
 HttpAuth::Identity::Identity() : source(IDENT_SRC_NONE), invalid(true) {}
 
+HttpAuth::Identity::~Identity() {}
+
 // static
 void HttpAuth::ChooseBestChallenge(
     HttpAuthHandlerFactory* http_auth_handler_factory,
     const HttpResponseHeaders* headers,
     Target target,
     const GURL& origin,
-    const std::set<Scheme>& disabled_schemes,
+    const HttpAuthSchemeSet& disabled_schemes,
     const BoundNetLog& net_log,
     scoped_ptr<HttpAuthHandler>* handler) {
   DCHECK(http_auth_handler_factory);
-  DCHECK(handler->get() == NULL);
+  DCHECK(!handler->get());
 
-  // Choose the challenge whose authentication handler gives the maximum score.
+  int best_priority = kSchemePriorityInvalid;
   scoped_ptr<HttpAuthHandler> best;
   const std::string header_name = GetChallengeHeaderName(target);
   std::string cur_challenge;
-  void* iter = NULL;
+  void* iter = nullptr;
+
   while (headers->EnumerateHeader(&iter, header_name, &cur_challenge)) {
-    scoped_ptr<HttpAuthHandler> cur;
-    int rv = http_auth_handler_factory->CreateAuthHandlerFromString(
-        cur_challenge, target, origin, net_log, &cur);
+    HttpAuthChallengeTokenizer challenge_tokenizer(cur_challenge.begin(),
+                                                   cur_challenge.end());
+    std::string cur_auth_scheme = challenge_tokenizer.NormalizedScheme();
+    if (cur_auth_scheme.empty())
+      continue;
+
+    if (disabled_schemes.Contains(cur_auth_scheme))
+      continue;
+
+    // Always prefer the highest priority scheme available. If two handlers are
+    // of equal priority, then the handler based on the earlier challenge wins.
+    int cur_priority = GetSchemePriority(cur_auth_scheme);
+    if (best.get() && best_priority >= cur_priority)
+      continue;
+
+    // Immediately trying to create a handler may be wasteful because we may see
+    // a higher ranking challenge later on in the headers. However, this is
+    // rare. Servers typically specify higher priority schemes before lower
+    // priority schemes.
+    scoped_ptr<HttpAuthHandler> current_handler;
+    int rv = http_auth_handler_factory->CreateAuthHandler(
+        &challenge_tokenizer, target, origin,
+        HttpAuthHandlerFactory::CREATE_CHALLENGE, 1, net_log, &current_handler);
     if (rv != OK) {
-      VLOG(1) << "Unable to create AuthHandler. Status: "
-              << ErrorToString(rv) << " Challenge: " << cur_challenge;
+      net_log.AddEvent(
+          NetLog::TYPE_AUTH_HANDLER_CREATION_FAILURE,
+          base::Bind(&AuthHandlerCreationFailureParams, &cur_challenge, rv));
       continue;
     }
-    if (cur.get() && (!best.get() || best->score() < cur->score()) &&
-        (disabled_schemes.find(cur->auth_scheme()) == disabled_schemes.end()))
-      best.swap(cur);
+    DCHECK(current_handler.get());
+    DCHECK_EQ(cur_auth_scheme, current_handler->auth_scheme());
+    best.swap(current_handler);
+    best_priority = cur_priority;
   }
   handler->swap(best);
 }
@@ -59,16 +130,15 @@ HttpAuth::AuthorizationResult HttpAuth::HandleChallengeResponse(
     HttpAuthHandler* handler,
     const HttpResponseHeaders* headers,
     Target target,
-    const std::set<Scheme>& disabled_schemes,
+    const HttpAuthSchemeSet& disabled_schemes,
     std::string* challenge_used) {
   DCHECK(handler);
   DCHECK(headers);
   DCHECK(challenge_used);
   challenge_used->clear();
-  HttpAuth::Scheme current_scheme = handler->auth_scheme();
-  if (disabled_schemes.find(current_scheme) != disabled_schemes.end())
+  const std::string& current_scheme = handler->auth_scheme();
+  if (disabled_schemes.Contains(current_scheme))
     return HttpAuth::AUTHORIZATION_RESULT_REJECT;
-  std::string current_scheme_name = SchemeToString(current_scheme);
   const std::string header_name = GetChallengeHeaderName(target);
   void* iter = NULL;
   std::string challenge;
@@ -76,8 +146,7 @@ HttpAuth::AuthorizationResult HttpAuth::HandleChallengeResponse(
       HttpAuth::AUTHORIZATION_RESULT_INVALID;
   while (headers->EnumerateHeader(&iter, header_name, &challenge)) {
     HttpAuthChallengeTokenizer props(challenge.begin(), challenge.end());
-    if (!base::LowerCaseEqualsASCII(props.scheme(),
-                                    current_scheme_name.c_str()))
+    if (!props.SchemeIs(current_scheme))
       continue;
     authorization_result = handler->HandleAnotherChallenge(&props);
     if (authorization_result != HttpAuth::AUTHORIZATION_RESULT_INVALID) {
@@ -129,22 +198,9 @@ std::string HttpAuth::GetAuthTargetString(Target target) {
 }
 
 // static
-const char* HttpAuth::SchemeToString(Scheme scheme) {
-  static const char* const kSchemeNames[] = {
-    "basic",
-    "digest",
-    "ntlm",
-    "negotiate",
-    "spdyproxy",
-    "mock",
-  };
-  static_assert(arraysize(kSchemeNames) == AUTH_SCHEME_MAX,
-                "http auth scheme names incorrect size");
-  if (scheme < AUTH_SCHEME_BASIC || scheme >= AUTH_SCHEME_MAX) {
-    NOTREACHED();
-    return "invalid_scheme";
-  }
-  return kSchemeNames[scheme];
+bool HttpAuth::IsValidNormalizedScheme(const std::string& scheme) {
+  return HttpUtil::IsToken(scheme.begin(), scheme.end()) &&
+         base::ToLowerASCII(scheme) == scheme;
 }
 
 }  // namespace net