feat: Add HTTP/HTTPS client module

Implement HTTP client with libcurl for fetching web pages:
- Support for HTTP and HTTPS protocols
- Configurable timeout and user agent
- Automatic redirect following
- SSL certificate verification
- Pimpl pattern for implementation hiding

This module provides the foundation for web page retrieval
in the terminal browser.

src/http_client.cpp

@@ -0,0 +1,111 @@
+#include "http_client.h"
+#include <curl/curl.h>
+#include <stdexcept>
+
+// 回调函数用于接收数据
+static size_t write_callback(void* contents, size_t size, size_t nmemb, std::string* userp) {
+    size_t total_size = size * nmemb;
+    userp->append(static_cast<char*>(contents), total_size);
+    return total_size;
+}
+
+class HttpClient::Impl {
+public:
+    CURL* curl;
+    long timeout;
+    std::string user_agent;
+    bool follow_redirects;
+
+    Impl() : timeout(30),
+             user_agent("TUT-Browser/1.0 (Terminal User Interface Browser)"),
+             follow_redirects(true) {
+        curl = curl_easy_init();
+        if (!curl) {
+            throw std::runtime_error("Failed to initialize CURL");
+        }
+    }
+
+    ~Impl() {
+        if (curl) {
+            curl_easy_cleanup(curl);
+        }
+    }
+};
+
+HttpClient::HttpClient() : pImpl(std::make_unique<Impl>()) {}
+
+HttpClient::~HttpClient() = default;
+
+HttpResponse HttpClient::fetch(const std::string& url) {
+    HttpResponse response;
+    response.status_code = 0;
+
+    if (!pImpl->curl) {
+        response.error_message = "CURL not initialized";
+        return response;
+    }
+
+    // 重置选项
+    curl_easy_reset(pImpl->curl);
+
+    // 设置URL
+    curl_easy_setopt(pImpl->curl, CURLOPT_URL, url.c_str());
+
+    // 设置写回调
+    std::string response_body;
+    curl_easy_setopt(pImpl->curl, CURLOPT_WRITEFUNCTION, write_callback);
+    curl_easy_setopt(pImpl->curl, CURLOPT_WRITEDATA, &response_body);
+
+    // 设置超时
+    curl_easy_setopt(pImpl->curl, CURLOPT_TIMEOUT, pImpl->timeout);
+    curl_easy_setopt(pImpl->curl, CURLOPT_CONNECTTIMEOUT, 10L);
+
+    // 设置用户代理
+    curl_easy_setopt(pImpl->curl, CURLOPT_USERAGENT, pImpl->user_agent.c_str());
+
+    // 设置是否跟随重定向
+    if (pImpl->follow_redirects) {
+        curl_easy_setopt(pImpl->curl, CURLOPT_FOLLOWLOCATION, 1L);
+        curl_easy_setopt(pImpl->curl, CURLOPT_MAXREDIRS, 10L);
+    }
+
+    // 支持 HTTPS
+    curl_easy_setopt(pImpl->curl, CURLOPT_SSL_VERIFYPEER, 1L);
+    curl_easy_setopt(pImpl->curl, CURLOPT_SSL_VERIFYHOST, 2L);
+
+    // 执行请求
+    CURLcode res = curl_easy_perform(pImpl->curl);
+
+    if (res != CURLE_OK) {
+        response.error_message = curl_easy_strerror(res);
+        return response;
+    }
+
+    // 获取响应码
+    long http_code = 0;
+    curl_easy_getinfo(pImpl->curl, CURLINFO_RESPONSE_CODE, &http_code);
+    response.status_code = static_cast<int>(http_code);
+
+    // 获取 Content-Type
+    char* content_type = nullptr;
+    curl_easy_getinfo(pImpl->curl, CURLINFO_CONTENT_TYPE, &content_type);
+    if (content_type) {
+        response.content_type = content_type;
+    }
+
+    response.body = std::move(response_body);
+
+    return response;
+}
+
+void HttpClient::set_timeout(long timeout_seconds) {
+    pImpl->timeout = timeout_seconds;
+}
+
+void HttpClient::set_user_agent(const std::string& user_agent) {
+    pImpl->user_agent = user_agent;
+}
+
+void HttpClient::set_follow_redirects(bool follow) {
+    pImpl->follow_redirects = follow;
+}

src/http_client.h

@@ -0,0 +1,37 @@
+#pragma once
+
+#include <string>
+#include <memory>
+
+struct HttpResponse {
+    int status_code;
+    std::string body;
+    std::string content_type;
+    std::string error_message;
+
+    bool is_success() const {
+        return status_code >= 200 && status_code < 300;
+    }
+};
+
+class HttpClient {
+public:
+    HttpClient();
+    ~HttpClient();
+
+    // 获取网页内容
+    HttpResponse fetch(const std::string& url);
+
+    // 设置超时（秒）
+    void set_timeout(long timeout_seconds);
+
+    // 设置用户代理
+    void set_user_agent(const std::string& user_agent);
+
+    // 设置是否跟随重定向
+    void set_follow_redirects(bool follow);
+
+private:
+    class Impl;
+    std::unique_ptr<Impl> pImpl;
+};