实现一个HTTP代理程序,该代理接受来自多个Web客户端的请求,并且能够按照需求向Web服务器请求数据并转发给客户端。须使用C语言完成。它应该使用gcc/g++编译并运行,产生一个称为proxy的二进制文件,该文件将其侦听的端口作为第一个参数。服务器可设置为知名的网址,代理使用DNS服务来获得服务器IP,同时不能预设客户端IP且客户端不能来自预先确定的IP。
时间: 2023-11-28 18:47:16 浏览: 47
以下是一个简单的HTTP代理程序的示例代码,使用C语言编写。它使用了libcurl库来进行HTTP请求和响应的处理。
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <curl/curl.h>
#define MAX_CLIENTS 10
#define BUFFER_SIZE 4096
int main(int argc, char *argv[]) {
if (argc < 2) {
printf("Usage: %s <port>\n", argv[0]);
exit(EXIT_FAILURE);
}
int port = atoi(argv[1]);
int server_fd = socket(AF_INET, SOCK_STREAM, 0);
if (server_fd < 0) {
perror("Failed to create socket");
exit(EXIT_FAILURE);
}
struct sockaddr_in server_addr, client_addr;
memset(&server_addr, 0, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_addr.s_addr = INADDR_ANY;
server_addr.sin_port = htons(port);
if (bind(server_fd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
perror("Failed to bind socket");
exit(EXIT_FAILURE);
}
if (listen(server_fd, MAX_CLIENTS) < 0) {
perror("Failed to listen on socket");
exit(EXIT_FAILURE);
}
printf("Listening on port %d...\n", port);
while (1) {
socklen_t client_addr_len = sizeof(client_addr);
int client_fd = accept(server_fd, (struct sockaddr *)&client_addr, &client_addr_len);
if (client_fd < 0) {
perror("Failed to accept client connection");
continue;
}
char buffer[BUFFER_SIZE];
ssize_t num_bytes = recv(client_fd, buffer, BUFFER_SIZE, 0);
if (num_bytes < 0) {
perror("Failed to receive data from client");
close(client_fd);
continue;
}
char *host = NULL;
char *path = NULL;
// Parse HTTP request to extract host and path
if (sscanf(buffer, "GET http://%m[^/]/%ms HTTP/1.1\r\n", &host, &path) < 2) {
perror("Failed to parse HTTP request");
close(client_fd);
continue;
}
// Resolve hostname to IP address
struct hostent *he = gethostbyname(host);
if (he == NULL || he->h_addr_list[0] == NULL) {
perror("Failed to resolve hostname");
close(client_fd);
continue;
}
char ip_address[INET_ADDRSTRLEN];
inet_ntop(AF_INET, he->h_addr_list[0], ip_address, INET_ADDRSTRLEN);
// Send HTTP request to server
CURL *curl = curl_easy_init();
if (curl == NULL) {
perror("Failed to create CURL handle");
close(client_fd);
continue;
}
curl_easy_setopt(curl, CURLOPT_URL, buffer + 4);
curl_easy_setopt(curl, CURLOPT_WRITEDATA, client_fd);
struct curl_slist *headers = NULL;
headers = curl_slist_append(headers, "User-Agent: Mozilla/5.0");
curl_easy_setopt(curl, CURLOPT_HTTPHEADER, headers);
CURLcode res = curl_easy_perform(curl);
if (res != CURLE_OK) {
fprintf(stderr, "Failed to send HTTP request: %s\n", curl_easy_strerror(res));
close(client_fd);
continue;
}
curl_slist_free_all(headers);
curl_easy_cleanup(curl);
close(client_fd);
}
close(server_fd);
return 0;
}
```
该程序使用TCP套接字来侦听客户端连接,并使用libcurl库来发送HTTP请求和处理响应。当客户端连接到代理服务器时,它接收HTTP请求并解析出主机名和路径。然后,它使用gethostbyname函数将主机名解析为IP地址,并使用libcurl发送HTTP请求到该IP地址和路径。最后,它将HTTP响应发送回客户端。
为了编译该程序,请使用以下命令:
```
gcc -o proxy proxy.c -lcurl
```
要运行该程序,请使用以下命令:
```
./proxy <port>
```
其中,`<port>`是代理服务器将侦听的端口号。请注意,客户端不能来自预先确定的IP地址,因为该程序没有实现IP地址过滤。如果您需要实现这个功能,请在程序中添加相应的代码。