AU: Support redirects.

libcurl_http_fetcher.cc

 // Copyright (c) 2009 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "update_engine/libcurl_http_fetcher.h"
 #include <algorithm>
 #include "base/logging.h"
 
 using std::max;
 using std::make_pair;
@@ skipping 43 matching lines @@
   CHECK_EQ(curl_easy_setopt(curl_handle_, CURLOPT_WRITEFUNCTION,
                             StaticLibcurlWrite), CURLE_OK);
   CHECK_EQ(curl_easy_setopt(curl_handle_, CURLOPT_URL, url_.c_str()), CURLE_OK);
 
   // If the connection drops under 10 bytes/sec for 3 minutes, reconnect.
   CHECK_EQ(curl_easy_setopt(curl_handle_, CURLOPT_LOW_SPEED_LIMIT, 10),
            CURLE_OK);
   CHECK_EQ(curl_easy_setopt(curl_handle_, CURLOPT_LOW_SPEED_TIME, 3 * 60),
            CURLE_OK);
 
+  // By default, libcurl doesn't follow redirections. Allow up to
+  // |kMaxRedirects| redirections.
+  CHECK_EQ(curl_easy_setopt(curl_handle_, CURLOPT_FOLLOWLOCATION, 1),
+           CURLE_OK);
+  CHECK_EQ(curl_easy_setopt(curl_handle_, CURLOPT_MAXREDIRS, kMaxRedirects),
+           CURLE_OK);
+
   CHECK_EQ(curl_multi_add_handle(curl_multi_handle_, curl_handle_), CURLM_OK);
   transfer_in_progress_ = true;
 }
 
 // Begins the transfer, which must not have already been started.
 void LibcurlHttpFetcher::BeginTransfer(const std::string& url) {
   transfer_size_ = -1;
   bytes_downloaded_ = 0;
   resume_offset_ = 0;
   retry_count_ = 0;
@@ skipping 199 matching lines @@
     curl_handle_ = NULL;
   }
   if (curl_multi_handle_) {
     CHECK_EQ(curl_multi_cleanup(curl_multi_handle_), CURLM_OK);
     curl_multi_handle_ = NULL;
   }
   transfer_in_progress_ = false;
 }
 
 }  // namespace chromeos_update_engine