3 files changed, 53 insertions, 15 deletions

diff --git a/net/ftp/ftp_network_transaction.cc b/net/ftp/ftp_network_transaction.cc
index 3c49d09..6fd377ed 100644
--- a/net/ftp/ftp_network_transaction.cc
+++ b/net/ftp/ftp_network_transaction.cc
@@ -1098,29 +1098,39 @@ int FtpNetworkTransaction::ProcessResponseCWD(const FtpCtrlResponse& response) {
     case ERROR_CLASS_INFO_NEEDED:
       return Stop(ERR_INVALID_RESPONSE);
     case ERROR_CLASS_TRANSIENT_ERROR:
+      // Some FTP servers send response 451 (not a valid CWD response according
+      // to RFC 959) instead of 550.
+      if (response.status_code == 451)
+        return ProcessResponseCWDNotADirectory();
+
       return Stop(GetNetErrorCodeForFtpResponseCode(response.status_code));
     case ERROR_CLASS_PERMANENT_ERROR:
-      if (response.status_code == 550) {
-        if (resource_type_ == RESOURCE_TYPE_DIRECTORY) {
-          // We're assuming that the resource is a directory, but the server
-          // says it's not true. The most probable interpretation is that it
-          // doesn't exist (with FTP we can't be sure).
-          return Stop(ERR_FILE_NOT_FOUND);
-        }
-
-        // We are here because SIZE failed and we are not sure what the resource
-        // type is. It could still be file, and SIZE could fail because of
-        // an access error (http://crbug.com/56734). Try RETR just to be sure.
-        resource_type_ = RESOURCE_TYPE_FILE;
-        next_state_ = STATE_CTRL_WRITE_RETR;
-        return OK;
-      }
+      if (response.status_code == 550)
+        return ProcessResponseCWDNotADirectory();
 
       return Stop(GetNetErrorCodeForFtpResponseCode(response.status_code));
     default:
       NOTREACHED();
       return Stop(ERR_UNEXPECTED);
   }
+
+  return OK;
+}
+
+int FtpNetworkTransaction::ProcessResponseCWDNotADirectory() {
+  if (resource_type_ == RESOURCE_TYPE_DIRECTORY) {
+    // We're assuming that the resource is a directory, but the server
+    // says it's not true. The most probable interpretation is that it
+    // doesn't exist (with FTP we can't be sure).
+    return Stop(ERR_FILE_NOT_FOUND);
+  }
+
+  // We are here because SIZE failed and we are not sure what the resource
+  // type is. It could still be file, and SIZE could fail because of
+  // an access error (http://crbug.com/56734). Try RETR just to be sure.
+  resource_type_ = RESOURCE_TYPE_FILE;
+  next_state_ = STATE_CTRL_WRITE_RETR;
+
   return OK;
 }
 
diff --git a/net/ftp/ftp_network_transaction.h b/net/ftp/ftp_network_transaction.h
index c47c65f..a1637c2 100644
--- a/net/ftp/ftp_network_transaction.h
+++ b/net/ftp/ftp_network_transaction.h
@@ -175,6 +175,7 @@ class NET_EXPORT_PRIVATE FtpNetworkTransaction : public FtpTransaction {
   int ProcessResponseSIZE(const FtpCtrlResponse& response);
   int DoCtrlWriteCWD();
   int ProcessResponseCWD(const FtpCtrlResponse& response);
+  int ProcessResponseCWDNotADirectory();
   int DoCtrlWriteLIST();
   int ProcessResponseLIST(const FtpCtrlResponse& response);
   int DoCtrlWriteQUIT();
diff --git a/net/ftp/ftp_network_transaction_unittest.cc b/net/ftp/ftp_network_transaction_unittest.cc
index 9427001d..f92561d 100644
--- a/net/ftp/ftp_network_transaction_unittest.cc
+++ b/net/ftp/ftp_network_transaction_unittest.cc
@@ -451,6 +451,28 @@ class FtpSocketDataProviderFileDownloadZeroSize
   DISALLOW_COPY_AND_ASSIGN(FtpSocketDataProviderFileDownloadZeroSize);
 };
 
+class FtpSocketDataProviderFileDownloadCWD451
+    : public FtpSocketDataProviderFileDownload {
+ public:
+  FtpSocketDataProviderFileDownloadCWD451() {
+  }
+
+  virtual MockWriteResult OnWrite(const std::string& data) OVERRIDE {
+    if (InjectFault())
+      return MockWriteResult(true, data.length());
+    switch (state()) {
+      case PRE_CWD:
+        return Verify("CWD /file\r\n", data, PRE_RETR,
+                      "451 not a directory\r\n");
+      default:
+        return FtpSocketDataProviderFileDownload::OnWrite(data);
+    }
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(FtpSocketDataProviderFileDownloadCWD451);
+};
+
 class FtpSocketDataProviderVMSFileDownload : public FtpSocketDataProvider {
  public:
   FtpSocketDataProviderVMSFileDownload() {
@@ -961,6 +983,11 @@ TEST_F(FtpNetworkTransactionTest, DownloadTransactionZeroSize) {
   ExecuteTransaction(&ctrl_socket, "ftp://host/file", OK);
 }
 
+TEST_F(FtpNetworkTransactionTest, DownloadTransactionCWD451) {
+  FtpSocketDataProviderFileDownloadCWD451 ctrl_socket;
+  ExecuteTransaction(&ctrl_socket, "ftp://host/file", OK);
+}
+
 TEST_F(FtpNetworkTransactionTest, DownloadTransactionVMS) {
   FtpSocketDataProviderVMSFileDownload ctrl_socket;
   ExecuteTransaction(&ctrl_socket, "ftp://host/file", OK);