Couldn't resolve host Error from curl on NACL - google-chrome

Question

im new to nacl. In my application i have use native curl. I checked out curl through nacl port. im getting "Couldn't resolve host name" error.
Any help will be appriciated.
Below is the example code :
hello_tutorial.cc :
// Copyright (c) 2013 The Chromium 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 <unistd.h>
#include <stdio.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include "nacl_io/nacl_io.h"
#include "ppapi/cpp/instance.h"
#include "ppapi/cpp/module.h"
#include "ppapi/cpp/var.h"
#include "ppapi/utility/completion_callback_factory.h"
#include "ppapi/utility/threading/simple_thread.h"
#include "curl/curl.h"
namespace {
// The expected string sent by the browser.
const char* const kHelloString = "hello";
// The string sent back to the browser upon receipt of a message
// containing "hello".
const char* const kReplyString = "hello from NaCl";
} // namespace
class HelloTutorialInstance : public pp::Instance {
public:
explicit HelloTutorialInstance(PP_Instance instance)
: pp::Instance(instance),
callback_factory_(this),
file_thread_(this){}
virtual ~HelloTutorialInstance() {}
int download_progress_callback(void *clientp, double dltotal, double dlnow, double ultotal, double ulnow) {
fprintf(stderr, "### Progress : %f : %f : %f", dlnow/dltotal, dlnow, dltotal);
return 0;
}
int download_callback(char *buffer, size_t size, size_t nitems, void *outstream) {
static int downloadSize = 0;
downloadSize += (size * nitems);
fprintf(stderr, "SIZE : %d", downloadSize);
return nitems * size;
}
void curlTest(int32_t /* result */)
{
CURLM *multiCurlHandle = NULL;
CURL *curlHandle = NULL;
int res = curl_global_init(CURL_GLOBAL_ALL);
if (res == CURLE_OK) {
multiCurlHandle = curl_multi_init();
curlHandle = curl_easy_init();
curl_easy_setopt(curlHandle, CURLOPT_URL, "www.google.com");
curl_easy_setopt(curlHandle, CURLOPT_VERBOSE, 1);
curl_easy_setopt(curlHandle, CURLOPT_NOPROGRESS, 0);
curl_easy_setopt(curlHandle, CURLOPT_PROGRESSFUNCTION ,&HelloTutorialInstance::download_progress_callback);
curl_easy_setopt(curlHandle, CURLOPT_WRITEFUNCTION, &HelloTutorialInstance::download_callback);
res = curl_easy_perform(curlHandle);
//curl_multi_add_handle(multiCurlHandle, curlHandle);
//curl_multi_perform(multiCurlHandle, &handle_count);
if (CURLE_OK != res) {
fprintf(stderr, "curl_easy_perform failed !!\nReason : %s", curl_easy_strerror((CURLcode)res));
}
} }
virtual void HandleMessage(const pp::Var& var_message) {
// Ignore the message if it is not a string.
if (!var_message.is_string())
return;
// Get the string message and compare it to "hello".
std::string message = var_message.AsString();
if (message == kHelloString) {
// If it matches, send our response back to JavaScript.
pp::Var var_reply(kReplyString);
nacl_io_init_ppapi(pp::Instance::pp_instance(),pp::Module::Get()->get_browser_interface());
file_thread_.Start();
file_thread_.message_loop().PostWork(
callback_factory_.NewCallback(&HelloTutorialInstance::curlTest));
PostMessage(var_reply);
}
}
private:
pp::CompletionCallbackFactory<HelloTutorialInstance> callback_factory_;
pp::SimpleThread file_thread_;
};
class HelloTutorialModule : public pp::Module {
public:
HelloTutorialModule() : pp::Module() {}
virtual ~HelloTutorialModule() {}
virtual pp::Instance* CreateInstance(PP_Instance instance) {
return new HelloTutorialInstance(instance);
}
};
namespace pp {
Module* CreateModule() {
return new HelloTutorialModule();
}
} // namespace pp
makefile :
# Copyright (c) 2013 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
# GNU Makefile based on shared rules provided by the Native Client SDK.
# See README.Makefiles for more details.
VALID_TOOLCHAINS := pnacl newlib glibc
NACL_SDK_ROOT ?= $(abspath $(CURDIR)/../..)
TARGET = part2
include $(NACL_SDK_ROOT)/tools/common.mk
CHROME_ARGS += --allow-nacl-socket-api=localhost
LIBS = ppapi_cpp ppapi pthread nacl_io curl ssl crypto stdc++ z glibc-compat
CFLAGS = -Wall
SOURCES = hello_tutorial.cc
# Build rules generated by macros from common.mk:
$(foreach src,$(SOURCES),$(eval $(call COMPILE_RULE,$(src),$(CFLAGS))))
# The PNaCl workflow uses both an unstripped and finalized/stripped binary.
# On NaCl, only produce a stripped binary for Release configs (not Debug).
ifneq (,$(or $(findstring pnacl,$(TOOLCHAIN)),$(findstring Release,$(CONFIG))))
$(eval $(call LINK_RULE,$(TARGET)_unstripped,$(SOURCES),$(LIBS),$(DEPS)))
$(eval $(call STRIP_RULE,$(TARGET),$(TARGET)_unstripped))
else
$(eval $(call LINK_RULE,$(TARGET),$(SOURCES),$(LIBS),$(DEPS)))
endif
$(eval $(call NMF_RULE,$(TARGET),))
Execution in terminal :
part2$ NACL_SDK_ROOT=~/nacl_sdk/pepper_40 NACL_ARCH=x86_64 TOOLCHAIN=newlib make clean run
~/nacl_sdk/pepper_40/tools/common.mk:495: Using chrome at: /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
CXX newlib/Release/hello_tutorial_x86_64.o
LINK newlib/Release/part2_unstripped_x86_64.nexe
VALIDATE newlib/Release/part2_unstripped_x86_64.nexe
STRIP newlib/Release/part2_x86_64.nexe
CREATE_NMF newlib/Release/part2.nmf
python ~/nacl_sdk/pepper_40/tools/run.py -C ~/nacl_sdk/pepper_40/getting_started/part2 -P "index.html?tc=newlib&config=Release" \
-- /Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome \
--enable-nacl --enable-pnacl --no-first-run --user-data-dir=~/nacl_sdk/pepper_40/getting_started/part2/user-data-dir --allow-nacl-socket-api=localhost \
--register-pepper-plugins="~/nacl_sdk/pepper_40/getting_started/part2/mac/Debug/part2.so;application/x-ppapi-debug~nacl_sdk/pepper_40/getting_started/part2/mac/Release/part2.so;application/x-ppapi-release"
Serving ~/nacl_sdk/pepper_40/getting_started/part2 on http://localhost:5103/...
Running: /Applications/Google Chrome.app/Contents/MacOS/Google Chrome --enable-nacl --enable-pnacl --no-first-run --user-data-dir=~/nacl_sdk/pepper_40/getting_started/part2/user-data-dir --allow-nacl-socket-api=localhost --register-pepper-plugins=~/nacl_sdk/pepper_40/getting_started/part2/mac/Debug/part2.so;application/x-ppapi-debug,~/nacl_sdk/pepper_40/getting_started/part2/mac/Release/part2.so;application/x-ppapi-release http://localhost:5103/index.html?tc=newlib&config=Release...
Output :
127.0.0.1 - - [10/Apr/2015 15:05:26] "GET /index.html?tc=newlib&config=Release HTTP/1.1" 200 -
127.0.0.1 - - [10/Apr/2015 15:05:26] "GET /common.js HTTP/1.1" 200 -
127.0.0.1 - - [10/Apr/2015 15:05:26] "GET /example.js HTTP/1.1" 200 -
127.0.0.1 - - [10/Apr/2015 15:05:26] "GET /newlib/Release/part2.nmf HTTP/1.1" 200 -
127.0.0.1 - - [10/Apr/2015 15:05:26] "GET /newlib/Release/part2_x86_64.nexe HTTP/1.1" 200 -
127.0.0.1 - - [10/Apr/2015 15:05:26] code 404, message File not found
127.0.0.1 - - [10/Apr/2015 15:05:26] "GET /favicon.ico HTTP/1.1" 404 -
[43852,1925374720:15:05:26.885906] Native Client module will be loaded at base address 0x000052a200000000
* Rebuilt URL to: www.google.com/
* timeout on name lookup is not supported
* Hostname was NOT found in DNS cache
* Curl_ipv4_resolve_r failed for www.google.com
* Couldn't resolve host 'www.google.com'
* Closing connection 0
curl_easy_perform failed !!
Reason : Couldn't resolve host name

Answer 1

I managed to get the example working (at least resolving host names)
by changing the LIBS line the Makefile. I removed glibc-compat
and moved nacl_io to the end of the line:
LIBS = ppapi_cpp ppapi pthread curl ssl crypto z nacl_io
The reason it was required is that glibc-compat contains a lot of
stub/dummy/non-working functions whereas nacl_io contains working
implemenations.
-Thanks to Sam (from native google groups) for pointing this

Answer 2

I'm trying to build curl with pepper_49 but there's still some problems when building
Makefile:
LIBS = ppapi_cpp ppapi pthread curl ssl crypto z nacl_io
build with TOOLCHAIN=pnacl make clean run
/Users/fu/nacl_sdk/pepper_49/tools/common.mk:500: Using chrome at: /Applications/Google Chrome.app/Contents/MacOS/Google Chrome
CXX pnacl/Release/hello_tutorial.o
LINK pnacl/Release/curltest_unstripped.bc
/Users/fu/nacl_sdk/pepper_49/toolchain/mac_pnacl/le32-nacl/usr/lib/libcurl.a: error: undefined reference to 'alarm'
make: *** [pnacl/Release/curltest_unstripped.bc] Error 1
It resolved after I changed Makefile to
LIBS = ppapi_cpp ppapi pthread curl ssl crypto z glibc-compat nacl_io
and the example works fine.