我目前正在学习套接字编程,并且正在尝试制作一个可以处理多个客户端的服务器。我已经用谷歌搜索并将一些模板解决方案合并为一个。但是,它不起作用,我也不知道为什么。
您可以在我的代码中看到,我希望有两个客户端通过向服务器发送一些数据来联系它。我将select
和FD_ISSET
放入了while(1)循环中,以便它始终检查套接字上是否有任何传入的IO操作。我的问题是,如果我同时运行服务器和两个客户端,然后从客户端1发送消息,则只能从客户端1发送消息。这些消息到达服务器,但是如果我以客户端2的身份发送消息,则不会t完全显示在服务器上(即使您在客户端2应用程序中看到“消息已发送”通知)。客户端2同样如此,如果我在客户端2中发送第一条消息,则只有他的消息在服务器上可见,客户端1的消息将被隐藏。
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <sys/select.h>
#include <sys/time.h>
#include <unistd.h>
#define SERVER_IP "192.168.201.95"
#define SERVER_PORT 8888
int main() {
//create server socket
int master_socket;
if ((master_socket = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
perror("Failed to create socket.");
exit(EXIT_FAILURE);
}
//configuring server ip and port
struct sockaddr_in server_address;
server_address.sin_family = AF_INET;
server_address.sin_addr.s_addr = INADDR_ANY;
server_address.sin_port = htons(SERVER_PORT);
int addrlen = sizeof(server_address);
//assign address to socket
if ((bind(master_socket, (struct sockaddr * ) & server_address, sizeof(server_address))) < 0) {
perror("Failed to bind.");
exit(EXIT_FAILURE);
}
//listen for connections
if ((listen(master_socket, 3)) < 0) {
perror("Failed to listen.");
exit(EXIT_FAILURE);
}
//accept incoming connections
int client1;
if ((client1 = accept(master_socket, (struct sockaddr * ) & server_address, (socklen_t * ) & addrlen)) < 0) {
perror("Failed to accept.");
exit(EXIT_FAILURE);
}
int client2;
if ((client2 = accept(master_socket, (struct sockaddr * ) & server_address, (socklen_t * ) & addrlen)) < 0) {
perror("Failed to accept.");
exit(EXIT_FAILURE);
}
char message[64];
fd_set readfds;
FD_ZERO( & readfds);
FD_SET(client1, & readfds);
FD_SET(client2, & readfds);
struct timeval time;
time.tv_sec = 0;
time.tv_usec = 0;
int fd_size = client2 + 1;
int state;
while (1) {
state = select(fd_size, & readfds, NULL, NULL, NULL);
if (state == -1) {
perror("Failed to select.");
exit(EXIT_FAILURE);
} else if (state == 0) {
printf("No data after timeout.");
} else {
if (FD_ISSET(client1, & readfds)) {
recv(client1, & message, sizeof(message), 0);
printf("Client 1: %s\n", message);
}
if (FD_ISSET(client2, & readfds)) {
recv(client2, & message, sizeof(message), 0);
printf("Client 2: %s\n", message);
}
}
}
return 0;
}