Question

linux下socket编程，只需要实现服务器端能接收多个用户端发来的消息这个功能就行，求代码，最好有相应解释

Answer 1

这些都是自己写的，由于我很粗心调试了好久，要是有任何问题我都可以帮你解决，包教会，而且可以进一步一起完善他的功能

#include<stdio.h>
#include<sys/types.h>
#include<sys/socket.h>
#include<arpa/inet.h>
#include<unistd.h>
#include<string.h>
#include<stdlib.h>
#include<sys/time.h>

#define BUFF_SIZE 1024
#define PORT 8888
#define LSN_NUM 10

int main()
{
int sockfd = -1;
int clt_sockfd = -1;
int i = 0, fd;
fd_set inset, tmp_inset;
struct sockaddr_in *server_addr, *client_addr;
int addr_len = sizeof(struct sockaddr_in);
int len;
char buff[BUFF_SIZE];

if((sockfd = socket(AF_INET, SOCK_STREAM, 0)) < 1){
printf("Create socket error!\n");
exit(0);
}else{
printf("Create socket success! sockfd = %d\n", sockfd);
}

server_addr = malloc(addr_len);
client_addr = malloc(addr_len);
memset(server_addr, 0, sizeof(server_addr));
memset(client_addr, 0, sizeof(client_addr));
server_addr->sin_family = AF_INET;
server_addr->sin_port = htons(PORT); //此处要将主机字节序转为网络字节序
server_addr->sin_addr.s_addr = INADDR_ANY;
if(bind(sockfd, (struct sockaddr*)server_addr, sizeof(struct sockaddr_in)) < 0){
printf("Bind error!\n");
exit(0);
}else{
printf("Bind success!\n");
}

if(listen(sockfd, LSN_NUM) < 0){
printf("Listen error!\n");
exit(0);
}else{
printf("Listen success!\n");
}

printf("Waiting for connect ...\n");

i = 1;
FD_ZERO(&inset);
FD_SET(sockfd, &inset);
while(1){
printf("------ The %dth turning ------- \n", i++);
tmp_inset = inset;
memset(buff, 0, BUFF_SIZE);
//select
if(select(FD_SETSIZE, &tmp_inset, NULL, NULL, NULL) <= 0){
printf("Select failed!\n");
exit(0);
}else{
printf("Select success!\n");
}//end select
for(fd = 0; fd < FD_SETSIZE; fd++){
if(FD_ISSET(fd, &tmp_inset) > 0){
printf("crrent fd: %d\n", fd);
if(sockfd == fd){
if((clt_sockfd = accept(sockfd, (struct sockaddr*)client_addr, &addr_len)) < 0){
printf("Accept error!\n");
exit(0);
}else{
printf("Get connection from %s, port: %d. socket: %d\n", \
inet_ntoa(client_addr->sin_addr), ntohs(client_addr->sin_port), clt_sockfd);
}
FD_SET(clt_sockfd, &inset);
}else{
if((len = recv(fd, buff, BUFF_SIZE, 0)) < 0){
printf("Recv failed!\b");
close(fd);
FD_CLR(fd, &inset);
}else if(0 == len || !strncmp("quit", buff, 4)){
printf("Clt_sockfd %d has quited!\n", clt_sockfd);
close(fd);
FD_CLR(fd, &inset);
continue;
}else{
printf("Clt_sockfd %d got message: %s\n", clt_sockfd, buff);
}
}
}
}
continue;
}
}
free(server_addr);
free(client_addr);

}

Answer 2

这个具体应用具体编码，最简单的是多线程，来个客户frok一个线程收发，操作简单，但是耗资源，一般也用的少，客户端一多就不行了；再来是IO多路复用的方法，用得较多，具体用法参考select和poll这2个函数。