Best practices for HTTPDNS C SDK and Alibaba Cloud OSS C++ SDK

2.1 Build HTTPDNS C SDK

git clone https://github.com/aliyun/alibabacloud-httpdns-c-sdk.git
cd alibabacloud-httpdns-c-sdk
mkdir build && cd build
cmake -DCMAKE_BUILD_TYPE=Release ..
make
sudo make install

2.2 Build OSS C++ SDK

git clone https://github.com/aliyun/aliyun-oss-cpp-sdk.git
cd aliyun-oss-cpp-sdk
mkdir build && cd build
cmake ..
make
sudo make install

2.3 Configure your project CMakeLists.txt

You can add both SDKs to your project's CMakeLists.txt file:

# Add HTTPDNS C SDK
find_library(HTTPDNS_LIBRARY httpdns_c_sdk_static)
include_directories(${CMAKE_INSTALL_PREFIX}/include/httpdns)

# Add OSS C++ SDK
find_library(OSS_LIBRARY alibabacloud-oss-cpp-sdk)
include_directories(${CMAKE_INSTALL_PREFIX}/include)

# Link libraries
target_link_libraries(your_target 
    ${HTTPDNS_LIBRARY}
    ${OSS_LIBRARY}
    curl
    pthread
)

Step 1: Add the HTTPDNS adapter

The OSS C++ SDK provides an HttpInterceptor extension point that lets you intercept and modify HTTP requests before they are sent. You can implement this interface to inject HTTPDNS resolution results into the request.

You can download the adapter file hdns_oss_interceptor.h and copy it into your project. This adapter implements the OSS SDK's HttpInterceptor interface. Its core logic is as follows:

void preSendRequest(void *handler, 
                    const std::shared_ptr<OSS::HttpRequest> &request) override {
    // Get the request domain name
    std::string host = request->url().host();
    
    // Resolve the domain name using HTTPDNS
    hdns_list_head_t *results = nullptr;
    hdns_status_t status = hdns_get_result_for_host_sync_with_cache(
        hdnsClient_, host.c_str(), queryType_, nullptr, &results);

    // Get the resolved IP address
    char ip[HDNS_IP_ADDRESS_STRING_LENGTH] = {0};
    hdns_select_ip_randomly(results, queryType_, ip);

    // Inject the resolution result into the request
    char resolveEntry[512];
    snprintf(resolveEntry, sizeof(resolveEntry), "%s:%d:%s", host.c_str(), port, ip);
    struct curl_slist *resolveList = curl_slist_append(nullptr, resolveEntry);
    curl_easy_setopt(curl, CURLOPT_RESOLVE, resolveList);
}

Step 2: Integrate with OSS SDK

You can integrate the adapter into the OSS SDK to complete the HTTPDNS integration.

Integration code example:

#include <iostream>
#include <memory>

// HTTPDNS SDK
extern "C" {
#include "hdns_api.h"
}

// OSS SDK
#include <alibabacloud/oss/OssClient.h>

// HTTPDNS-OSS adapter
#include "hdns_oss_interceptor.h"

using namespace AlibabaCloud::OSS;

int main() {
    std::string accessKeyId = "your_access_key_id";
    std::string accessKeySecret = "your_access_key_secret";
    std::string endpoint = "oss-cn-hangzhou.aliyuncs.com";

    // ============ 1. Initialize HTTPDNS ============
    hdns_sdk_init();

    hdns_client_t *hdnsClient = hdns_client_create("your_httpdns_account_id", "your_secret_key");

    // Configure the HTTPDNS client
    hdns_client_set_timeout(hdnsClient, 2000);
    hdns_client_set_using_cache(hdnsClient, true);
    hdns_client_set_using_https(hdnsClient, true);
    hdns_client_enable_expired_ip(hdnsClient, true);
    hdns_client_enable_failover_localdns(hdnsClient, true);
    hdns_client_add_pre_resolve_host(hdnsClient, endpoint.c_str());

    hdns_client_start(hdnsClient);

    // ============ 2. Initialize OSS and inject the adapter ============
    InitializeSdk();

    // Create the adapter
    auto hdnsInterceptor = std::make_shared<AlibabaCloud::HDNS::HdnsOssInterceptor>(hdnsClient);

    // Configure the OSS client
    ClientConfiguration conf;
    conf.httpInterceptor = hdnsInterceptor;  // Key: inject the adapter

    // Create the OSS client
    OssClient ossClient("https://" + endpoint, accessKeyId, accessKeySecret, conf);

    // ============ 3. Use the OSS client ============
    auto outcome = ossClient.ListBuckets();
    if (outcome.isSuccess()) {
        std::cout << "Request succeeded. Bucket list:" << std::endl;
        for (const auto &bucket : outcome.result().Buckets()) {
            std::cout << "  - " << bucket.Name() << std::endl;
        }
    } else {
        std::cerr << "Request failed: " << outcome.error().Message() << std::endl;
    }

    // ============ 4. Release resources ============
    // Note: Release the OSS client before releasing the HTTPDNS client
    ShutdownSdk();
    hdns_client_cleanup(hdnsClient);
    hdns_sdk_cleanup();

    return 0;
}