C++ 实现HTTP的客户端、服务端demo和HTTP三方库介绍

本文使用C++模拟实现http的客户端请求和http的服务端响应功能，并介绍几种封装HTTP协议的三方库。

1、实现简单HTTP的服务端功能

本程序使用C++ tcp服务端代码模拟HTTP的服务端，服务端返回给客户端的消息内容按照HTTP协议的消息响应格式进行了组装。

demo如下：

#include <iostream>
#include <cstring>
#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h>int main() {int server_fd, new_socket;struct sockaddr_in address;int addrlen = sizeof(address);char buffer[1024] = {0};const char* hello = "HTTP/1.1 200 OK\nContent-Type: text/plain\n\nHello, World!";// 创建套接字if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0) {perror("socket failed");exit(EXIT_FAILURE);}address.sin_family = AF_INET;address.sin_addr.s_addr = INADDR_ANY;address.sin_port = htons(37777);// 绑定套接字到端口if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0) {perror("bind failed");exit(EXIT_FAILURE);}// 监听连接if (listen(server_fd, 3) < 0) {perror("listen");exit(EXIT_FAILURE);}printf("Listening on port 37777\n");while (true) {if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t*)&addrlen)) < 0) {perror("accept");exit(EXIT_FAILURE);}// 读取客户端请求int length = read(new_socket, buffer, 1024);printf("******** HTTP Server recv request length: %d,as follow: ********\n%s\n",length,buffer);// 发送响应send(new_socket, hello, strlen(hello), 0);printf("******** HTTP Server replied to the request ********\n");close(new_socket);}return 0;
}

2、实现简单HTTP的客户端功能

本程序使用C++ tcp客户端代码模拟HTTP的客户端，客户端发给服务端的请求内容按照HTTP协议的请求格式进行了组装。

demo如下：

#include <iostream>
#include <cstring>
#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h>
#include <arpa/inet.h>int main() {int sock = 0, length;struct sockaddr_in serv_addr;char buffer[1024] = {0};const char* get_request = "GET / HTTP/1.1\r\nHost: localhost\r\n\r\n";if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {perror("Socket creation error");exit(EXIT_FAILURE);}serv_addr.sin_family = AF_INET;serv_addr.sin_port = htons(37777);//serv_addr.sin_addr.s_addr = inet_addr("127.0.0.1"); //bind ip method 1// 将IPv4地址从点分十进制转换为二进制形式 bind ip method 2if (inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr) <= 0) {perror("Invalid address/Address not supported");exit(EXIT_FAILURE);}if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {perror("Connection failed");exit(EXIT_FAILURE);}send(sock, get_request, strlen(get_request), 0);printf("HTTP Client GET method has been sent\n");length = read(sock, buffer, 1024);printf("******** HTTP Client receive msg length: %d,context as follow: ********\n%s\n",length,buffer);printf("****************\n");close(sock);return 0;
}

分别运行上面的服务端和客户端程序，服务端程序运行结果如下：

客户端程序运行结果如下：

3、实现HTTP的客户端访问百度功能

本程序使用C++ tcp客户端代码模拟HTTP的客户端，按照http协议请求格式对百度网页进行GET请求消息的组装。

实现demo如下：

#include <iostream>
#include <cstring>
#include <sys/socket.h>
#include <netinet/in.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <netdb.h>#define URL  "/"                            //资源
#define HTTP_VESTION "HTTP/1.1"
#define HOST "www.baidu.com"                //域名
#define	CONNETION  "Connection: close\r\n"  //短链接
#define BUFFER_SIZE		1024
std::string strBuffer = "";
int getIpAddress(char** ip)
{int ret = -1;struct  hostent *ht = NULL;ht = gethostbyname(HOST);if(ht) {printf("type:%s\n", ht->h_addrtype == AF_INET ? "AF_INET" : "AF_INET6");for(int i=0; ;i++) {if(ht->h_addr_list[i]!=NULL) {*ip = inet_ntoa(*((struct in_addr *)ht->h_addr_list[i]));ret = 1;break;}}}return ret;
}char* receiveNew(int sockfd, size_t& len) {char* buffer = nullptr; // 初始化为nullptrssize_t totalBytesReceived = 0; // 累计接收的字节数ssize_t bytesReceived; // 当前接收的字节数// 循环接收数据，直到对方关闭连接或发生错误do {// 分配额外的空间以容纳更多数据char* newBuffer = new char[totalBytesReceived + 1024]; // 假设每次额外分配1024字节，用于接受下次数据if (buffer) {// 如果有旧的数据，复制到新的缓冲区，每次所有内容复制一遍std::memcpy(newBuffer, buffer, totalBytesReceived);delete[] buffer; // 释放旧缓冲区}buffer = newBuffer; // 更新指针以指向新的缓冲区，指向的内容可以任意大，即只要可分配// 接收数据bytesReceived = recv(sockfd, buffer + totalBytesReceived, 1024, 0);if (bytesReceived == -1) {// 错误处理，例如检查errnostd::cerr << "Error receiving data: " << strerror(errno) << std::endl;delete[] buffer; // 释放已分配的缓冲区return nullptr; // 返回nullptr表示错误}totalBytesReceived += bytesReceived; // 累计已接收的字节数// 如果需要，可以在此处设置接收的最大字节数限制} while (bytesReceived > 0); // 当recv返回0时，表示对方已关闭连接// 调整缓冲区的大小以匹配实际接收的数据量char* finalBuffer = new char[totalBytesReceived + 1]; // +1为了字符串终止符'\0'std::memcpy(finalBuffer, buffer, totalBytesReceived);finalBuffer[totalBytesReceived] = '\0'; // 添加字符串终止符delete[] buffer; // 释放中间缓冲区len = totalBytesReceived; // 更新len以反映实际接收的数据长度return finalBuffer; // 返回最终缓冲区
}void receiveString(int sockfd, size_t& len) {char buffer[BUFFER_SIZE] = {}; // 初始化为nullptrssize_t totalBytesReceived = 0; // 累计接收的字节数ssize_t bytesReceived; // 当前接收的字节数// 循环接收数据，直到对方关闭连接或发生错误do {// 接收数据bytesReceived = recv(sockfd, buffer, BUFFER_SIZE, 0);if (bytesReceived == -1) {// 错误处理，例如检查errnoprintf("Error receiving data:%s", strerror(errno));}strBuffer += buffer;totalBytesReceived += bytesReceived; // 累计已接收的字节数memset(buffer,0,BUFFER_SIZE);// 如果需要，可以在此处设置接收的最大字节数限制} while (bytesReceived > 0); // 当recv返回0时，表示对方已关闭连接len = totalBytesReceived;
}void MakeSocketConnect()
{char* ipAddr = nullptr;getIpAddress(&ipAddr);int sock = 0;struct sockaddr_in serv_addr;serv_addr.sin_family = AF_INET;serv_addr.sin_port = htons(80);if (inet_pton(AF_INET, ipAddr, &serv_addr.sin_addr) <= 0) {perror("Invalid address/Address not supported");exit(EXIT_FAILURE);}if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0) {perror("Socket creation error");exit(EXIT_FAILURE);}if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0) {perror("Connection failed");exit(EXIT_FAILURE);}char get_request[1024] = {};sprintf(get_request,"GET %s %s\r\n""Host: %s\r\n""%s\r\n""\r\n",URL,HTTP_VESTION,HOST,CONNETION);send(sock, get_request, strlen(get_request), 0);printf("HTTP Client GET method has been sent\n");size_t len = 0; // 用于保存接收到的数据的长度/* 由于HTTP服务端回复的消息客户端一次接收不完，需要多次接收，直到数据接收完毕*  本文采用下面两种C++方法进行接收*  方法1：采用new方法分配内存，缺点：需要多次分配，并且需要多次memcpy（可以使用c语言malloc分配内存，realloc扩容）*  方法2：采用string容器（stinrg是字符串容器），动态的存储数据，也可以采用vector<char>容器存储*/
#if 0char* receivedData = receiveNew(sock,len);if (receivedData) {// 处理接收到的数据printf("******** HTTP Client receive msg length: %d,context as follow: ********\n%s\n",len,receivedData);printf("****************\n");// 释放动态分配的内存delete[] receivedData;} else {// 错误处理printf("Failed to receive data.\n");}
#elsereceiveString(sock,len);printf("******** HTTP Client receive msg length: %d,context as follow: ********\n%s\n",len,strBuffer.c_str());printf("****************\n");
#endifclose(sock);
}int main() {MakeSocketConnect();return 0;
}

上面程序运行结果如下：

上面接收的响应正文太长，上面图片没有截完。