[Networking] Return error on HTTP 4xx and 5xx responses + utils (#64)

This is a bug fix that is also a breaking change. Network requests that
technically succeeded in being performed but resulted in HTTP error
codes (4xx or 5xx) used to be returned as non-errors (`Result::kOk`).
With this change, such responses will be returned with an error status
(`Result::kError`) instead to simplify error handling for library users.

Additionally, a new helper functions were added to `ResourceResponse`
class:

* `base::net::ResourceResponse::DataAsString()`
  * creates a copy of the response data in `std::string` object
* `base::net::ResourceResponse::DataAsStringView()`
  * creates a non-owning view of the response data in `std::string_view`
    object

These should also make it simpler to use response data by library users.

Author: RippeR37

examples/networking/main.cc

@@ -21,9 +21,8 @@ void LogNetResponse(const base::net::ResourceResponse& response) {
   for (const auto& [h, v] : response.headers) {
     LOG(INFO) << "  " << h << ": " << v;
   }
-  LOG_IF(INFO, !response.data.empty())
-      << "Content:\n"
-      << std::string{response.data.begin(), response.data.end()};
+  LOG_IF(INFO, !response.data.empty()) << "Content:\n"
+                                       << response.DataAsStringView();
 }
 
 void NetExampleGet() {

src/CMakeLists.txt

@@ -164,6 +164,7 @@ if(LIBBASE_BUILD_MODULE_NET)
       base/net/request_cancellation_token.h
       base/net/resource_request.cc
       base/net/resource_request.h
+      base/net/resource_response.cc
       base/net/resource_response.h
       base/net/result.h
       base/net/simple_url_loader.cc

src/base/net/impl/net_thread_impl.cc

@@ -20,9 +20,10 @@ Result CurlCodeToNetResult(CURLcode code) {
   }
 }
 
-std::tuple<int, std::string, std::map<std::string, std::string>>
+std::tuple<int, std::string, std::string, std::map<std::string, std::string>>
 GetResponseInfo(CURL* handle, Result result = Result::kOk) {
   int code = -1;
+  std::string scheme;
   std::string final_url;
   std::map<std::string, std::string> headers;
 
@@ -31,6 +32,13 @@ GetResponseInfo(CURL* handle, Result result = Result::kOk) {
     curl_easy_getinfo(handle, CURLINFO_RESPONSE_CODE, &code);
   }
 
+  // Protocol scheme
+  {
+    char* curl_scheme = nullptr;
+    curl_easy_getinfo(handle, CURLINFO_SCHEME, &curl_scheme);
+    scheme = curl_scheme ? curl_scheme : "";
+  }
+
   // Get the URL of the completed transfer
   {
     char* final_url_cstr = nullptr;
@@ -46,7 +54,7 @@ GetResponseInfo(CURL* handle, Result result = Result::kOk) {
     }
   }
 
-  return {code, final_url, headers};
+  return {code, scheme, final_url, headers};
 }
 }  // namespace
 
@@ -323,8 +331,8 @@ void NetThread::NetThreadImpl::EnqueueDownload_NetThread(
           auto response_info = GetResponseInfo(info->handle);
           std::move(info->on_response_started)
               .Run(std::get<0>(response_info),
-                   std::move(std::get<1>(response_info)),
-                   std::move(std::get<2>(response_info)));
+                   std::move(std::get<2>(response_info)),
+                   std::move(std::get<3>(response_info)));
         }
 
         if (info->on_write_data) {
@@ -351,13 +359,18 @@ void NetThread::NetThreadImpl::DownloadFinished_NetThread(CURL* finished_curl,
   CHECK(download_iter != active_downloads_.end());
 
   auto& download = download_iter->second;
+  const auto [code, scheme, final_url, headers] =
+      GetResponseInfo(finished_curl);
+
+  // Override result in case of HTTP status code reporting an error
+  if (result == Result::kOk && (scheme == "http" || scheme == "https") &&
+      (code >= 400 && code < 600)) {
+    result = Result::kError;
+  }
 
   // Handle advanced path and just send status & do cleanup
   if (download.on_response_started) {
-    auto response_info = GetResponseInfo(finished_curl);
-    std::move(download.on_response_started)
-        .Run(std::get<0>(response_info), std::move(std::get<1>(response_info)),
-             std::move(std::get<2>(response_info)));
+    std::move(download.on_response_started).Run(code, final_url, headers);
   }
   if (download.on_finished) {
     std::move(download.on_finished).Run(result);
@@ -372,7 +385,7 @@ void NetThread::NetThreadImpl::DownloadFinished_NetThread(CURL* finished_curl,
 
   // Response info
   std::tie(download.response.code, download.response.final_url,
-           download.response.headers) = GetResponseInfo(finished_curl, result);
+           download.response.headers) = std::tie(code, final_url, headers);
 
   // Get timing data
   {

src/base/net/resource_response.cc

@@ -0,0 +1,16 @@
+#include "base/net/resource_response.h"
+
+namespace base {
+namespace net {
+
+std::string ResourceResponse::DataAsString() const {
+  return std::string{data.begin(), data.end()};
+}
+
+std::string_view ResourceResponse::DataAsStringView() const {
+  return std::string_view{reinterpret_cast<const char*>(data.data()),
+                          data.size()};
+}
+
+}  // namespace net
+}  // namespace base

src/base/net/resource_response.h

@@ -5,6 +5,7 @@
 #include <cstdint>
 #include <map>
 #include <string>
+#include <string_view>
 #include <vector>
 
 #include "base/net/result.h"
@@ -24,6 +25,9 @@ struct ResourceResponse {
   base::TimeDelta timing_connect = base::Seconds(-1);
   base::TimeDelta timing_start_transfer = base::Seconds(-1);
   base::TimeDelta timing_total = base::Seconds(-1);
+
+  std::string DataAsString() const;
+  std::string_view DataAsStringView() const;
 };
 
 }  // namespace net