【发布时间】：2020-07-17 12:32:07
【问题描述】：
我正在编写一个程序，它应该充当 Web 服务器和浏览器之间的简单代理。浏览器连接到我的代理程序，我的程序连接到 Web 服务器。我的代理程序应该简单地将它从浏览器接收到的所有数据转发到网络服务器，反之亦然，无需以任何方式修改数据，也无需执行任何缓存。
我已经设法从网络服务器获得回复，但我如何将该回复定向到我的浏览器？还有什么方法可以将它放入某种无限循环中，我可以随意recv 和send？
编辑：
我已经差不多了。我只需要知道如何连续读取套接字。收到 Http 重定向后程序意外关闭。
#include <stdio.h>
#include <stdlib.h>
#include <sys/ioctl.h>
#include <sys/poll.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <errno.h>
#include <pthread.h>
#include <string.h>
#define SERVER_PORT 8080
#define SA struct sockaddr
#define MAX 80
pthread_t ptid, ptidd;
#define TRUE 1
#define FALSE 0
struct sockets_struct {
int server_sd;
int client_sd;
int new_sd;
}socks;
// Function designed to act as client.
void *client_func(void *sockets)
{
char buffer[MAX];
struct sockaddr_in servaddrr;
struct sockets_struct *socks = (struct sockets_struct*)sockets;
int i, len, rc, on = 1;
//bzero(&servaddrr, sizeof(servaddrr));
// assign IP, PORT
servaddrr.sin_family = AF_INET;
servaddrr.sin_addr.s_addr = inet_addr("192.168.0.1");
servaddrr.sin_port = htons(80);
// connect the client socket to server socket
if (connect(socks->client_sd, (SA*)&servaddrr, sizeof(servaddrr)) != 0) {
printf(" client: connection with the server failed...\n");
exit(0);
}
else
printf(" client: connected to the remote server..\n");
do {
rc = recv(socks->client_sd, buffer, sizeof(buffer), 0);
if (rc < 0) {
if (errno != EWOULDBLOCK) {
perror(" client: recv() failed\n");
}
break;
}
if (rc == 0) {
printf(" client: Connection closed\n");
break;
}
len = rc;
printf(" client: %d bytes received\n", len);
rc = send(socks->new_sd, buffer, len, 0);
if (rc < 0) {
perror(" client: send() failed");
break;
}
} while(TRUE);
}
// Function designed to act as server.
void *server_func(void *sockets)
{
int len, rc, on = 1;
int desc_ready, end_server = FALSE, compress_array = FALSE;
int close_conn;
char buffer[80];
struct sockaddr_in6 addr;
int timeout;
struct pollfd fds[200];
int nfds = 1, current_size = 0, i, j;
struct sockets_struct *socks = (struct sockets_struct*)sockets;
rc = setsockopt(socks->server_sd, SOL_SOCKET, SO_REUSEADDR,
(char *)&on, sizeof(on));
if (rc < 0) {
perror(" server: setsockopt() failed\n");
close(socks->server_sd);
exit(-1);
}
rc = ioctl(socks->server_sd, FIONBIO, (char *)&on);
if (rc < 0) {
perror(" server: ioctl() failed\n");
close(socks->server_sd);
exit(-1);
}
memset(&addr, 0, sizeof(addr));
addr.sin6_family = AF_INET;
memcpy(&addr.sin6_addr, &in6addr_any, sizeof(in6addr_any));
addr.sin6_port = htons(SERVER_PORT);
rc = bind(socks->server_sd, (struct sockaddr *)&addr, sizeof(addr));
if (rc < 0) {
perror(" server: bind() failed");
close(socks->server_sd);
exit(-1);
}
rc = listen(socks->server_sd, 32);
if (rc < 0) {
perror(" server: listen() failed");
close(socks->server_sd);
exit(-1);
}
memset(fds, 0 , sizeof(fds));
fds[0].fd = socks->server_sd;
fds[0].events = POLLIN;
timeout = (3 * 60 * 1000);
do {
printf(" server: waiting on poll()...\n");
rc = poll(fds, nfds, timeout);
if (rc < 0) {
perror(" server: poll() failed\n");
break;
}
if (rc == 0) {
printf(" server: poll() timed out. End program.\n");
break;
}
current_size = nfds;
for (i = 0; i < current_size; i++) {
if (fds[i].revents == 0)
continue;
if (fds[i].revents != POLLIN) {
printf(" server: Error! revents = %d\n", fds[i].revents);
end_server = TRUE;
break;
}
if (fds[i].fd == socks->server_sd) {
printf(" server: Listening socket is readable\n");
socks->new_sd = accept(socks->server_sd, NULL, NULL);
if (socks->new_sd < 0) {
if (errno != EWOULDBLOCK) {
perror(" server: accept() failed\n");
end_server = TRUE;
}
break;
}
printf(" server: new incoming connection - %d\n", socks->new_sd);
fds[nfds].fd = socks->new_sd;
fds[nfds].events = POLLIN;
nfds++;
}
else {
printf(" server: Descriptor %d is readable\n", fds[i].fd);
close_conn = FALSE;
do {
rc = recv(fds[i].fd, buffer, sizeof(buffer), 0);
if (rc < 0) {
if (errno != EWOULDBLOCK) {
perror(" recv() failed");
close_conn = TRUE;
}
break;
}
if (rc == 0) {
printf(" server: Connection closed\n");
close_conn = TRUE;
break;
}
len = rc;
printf(" server: %d bytes received \n", len);
rc = send(socks->client_sd, buffer, len, 0);
if (rc < 0) {
perror(" server: send() failed\n");
close_conn = TRUE;
break;
}
} while(TRUE);
if (close_conn) {
close(fds[i].fd);
fds[i].fd = -1;
compress_array = TRUE;
}
} /* End of existing connection is readable */
} /* End of loop through pollable descriptors */
} while (end_server == FALSE); /* End of serving running. */
}
int main (int argc, char *argv[])
{
socks.server_sd = socket(AF_INET, SOCK_STREAM, 0);
socks.client_sd = socket(AF_INET, SOCK_STREAM, 0);
if (socks.server_sd == -1) {
printf("socket \"server_sd\" creation failed...\n");
exit(0);
}
else
printf("Socket \"server_sd\" successfully created..\n");
if (socks.client_sd == -1) {
printf("socket \"client_sd\" creation failed...\n");
exit(0);
}
else
printf("Socket \"client_sd\" successfully created..\n");
pthread_create(&ptidd, NULL, &client_func, &socks);
pthread_create(&ptid, NULL, &server_func, &socks);
pthread_join(ptidd, NULL);
return 0;
}
【问题讨论】：
-
我是否正确理解您的问题，即您的程序充当 Web 客户端（浏览器）和 Web 服务器之间的中间人，以便 Web 客户端连接到您的程序，而您的程序连接到 Web 服务器.建立这些连接后，您的程序应该将从 Web 服务器接收到的所有数据转发到 Web 客户端，反之亦然？
-
你需要密切关注你收到了多少字节。你要求 8080 字节，但如果客户端只发送 200，那么你只需要发送 200 到服务器！ （不是 200 字节，然后是 7880 额外的 0 字节）
-
您使用
recv和write的功能组合有什么特别的原因吗？通常，要么使用套接字函数recv和send，要么使用更通用的函数read和write，但使用recv和write对我来说似乎是一个奇怪的组合。不过，我对 UNIX 编程有点陌生。 -
您是否正在尝试实现一个不知道它所代理的数据的协议的代理？做这两件事的过程是完全不同的，你的代码在中间的某个地方。那肯定行不通。
-
@Madao：我现在已经编辑了您的问题以使其更清楚。如果您不喜欢我的更改，请随时恢复它们。