bingrequest.cpp

/***
 * Copyright (C) Microsoft. All rights reserved.
 * Licensed under the MIT license. See LICENSE.txt file in the project root for full license information.
 *
 * =+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+
 *
 * bingrequest.cpp - Simple cmd line application that makes an HTTP GET request to bing searching and outputting
 *       the resulting HTML response body into a file.
 *
 * =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
 ****/

#include <cpprest/filestream.h>
#include <cpprest/http_client.h>

using namespace utility;
using namespace web::http;
using namespace web::http::client;
using namespace concurrency::streams;

/* Can pass proxy information via environment variable http_proxy.
   Example:
   Linux:   export http_proxy=http://192.1.8.1:8080
 */
web::http::client::http_client_config client_config_for_proxy()
{
    web::http::client::http_client_config client_config;
#ifdef _WIN32
    wchar_t* pValue = nullptr;
    std::unique_ptr<wchar_t, void (*)(wchar_t*)> holder(nullptr, [](wchar_t* p) { free(p); });
    size_t len = 0;
    auto err = _wdupenv_s(&pValue, &len, L"http_proxy");
    if (pValue) holder.reset(pValue);
    if (!err && pValue && len)
    {
        std::wstring env_http_proxy_string(pValue, len - 1);
#else
    if (const char* env_http_proxy = std::getenv("http_proxy"))
    {
        std::string env_http_proxy_string(env_http_proxy);
#endif
        if (env_http_proxy_string == U("auto"))
            client_config.set_proxy(web::web_proxy::use_auto_discovery);
        else
            client_config.set_proxy(web::web_proxy(env_http_proxy_string));
    }

    return client_config;
}

#ifdef _WIN32
int wmain(int argc, wchar_t* args[])
#else
int main(int argc, char* args[])
#endif
{
    if (argc != 3)
    {
        printf("Usage: BingRequest.exe search_term output_file\n");
        return -1;
    }
    const string_t searchTerm = args[1];
    const string_t outputFileName = args[2];

    // Open a stream to the file to write the HTTP response body into.
    auto fileBuffer = std::make_shared<streambuf<uint8_t>>();
    file_buffer<uint8_t>::open(outputFileName, std::ios::out)
        .then([=](streambuf<uint8_t> outFile) -> pplx::task<http_response> {
            *fileBuffer = outFile;

            // Create an HTTP request.
            // Encode the URI query since it could contain special characters like spaces.
            http_client client(U("http://www.bing.com/"), client_config_for_proxy());
            return client.request(methods::GET, uri_builder(U("/search")).append_query(U("q"), searchTerm).to_string());
        })

        // Write the response body into the file buffer.
        .then([=](http_response response) -> pplx::task<size_t> {
            printf("Response status code %u returned.\n", response.status_code());

            return response.body().read_to_end(*fileBuffer);
        })

        // Close the file buffer.
        .then([=](size_t) { return fileBuffer->close(); })

        // Wait for the entire response body to be written into the file.
        .wait();

    return 0;
}