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示例
基于socket最简单的Server基于socket最简单的Client基于select实现的Server基于poll实现的Serverepoll实现Server测试客户端UDP ServerUDP Client本地套接字Server本地套接字Client
基于socket最简单的Server
#include
#include
#include
#include
#include
#include
#include
#define MAXLINE 80
#define SERV_PORT 6666
int main(void)
{
struct sockaddr_in servaddr, cliaddr;
socklen_t cliaddr_len;
int listenfd, connfd;
char buf[MAXLINE];
char str[INET_ADDRSTRLEN];
int i, n;
listenfd = socket(AF_INET, SOCK_STREAM, 0);
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(SERV_PORT);
bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
listen(listenfd, 20);
printf("Accepting connections ...\n");
while (1) {
cliaddr_len = sizeof(cliaddr);
connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &cliaddr_len);
n = read(connfd, buf, MAXLINE);
printf("received from %s at PORT %d\n",
inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)),
ntohs(cliaddr.sin_port));
for (i = 0; i
fputs("usage: ./client message\n", stderr);
exit(1);
}
str = argv[1];
sockfd = socket(AF_INET, SOCK_STREAM, 0);
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr);
servaddr.sin_port = htons(SERV_PORT);
connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
write(sockfd, str, strlen(str));
n = read(sockfd, buf, MAXLINE);
printf("Response from server:\n");
write(STDOUT_FILENO, buf, n);
close(sockfd);
return 0;
}
注意： 由于客户端不需要固定的端口号，因此不必调用bind()，客户端的端口号由内核自动分配。注意，客户端不是不允许调用bind()，只是没有必要调用bind()固定一个端口号，服务器也不是必须调用bind()，但如果服务器不调用bind()，内核会自动给服务器分配监听端口，每次启动服务器时端口号都不一样，客户端要连接服务器就会遇到麻烦。
基于select实现的Server
/* server.c */
#include
#include
#include
#include
#include
#define MAXLINE 80
#define SERV_PORT 6666
int main(int argc, char *argv[])
{
int i, maxi, maxfd, listenfd, connfd, sockfd;
int nready, client[FD_SETSIZE]; /* FD_SETSIZE 默认为 1024 */
ssize_t n;
fd_set rset, allset;
char buf[MAXLINE];
char str[INET_ADDRSTRLEN]; /* #define INET_ADDRSTRLEN 16 */
socklen_t cliaddr_len;
struct sockaddr_in cliaddr, servaddr;
listenfd = socket(AF_INET, SOCK_STREAM, 0);
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(SERV_PORT);
bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
listen(listenfd, 20); /* 默认最大128 */
maxfd = listenfd; /* 初始化 */
maxi = -1; /* client[]的下标 */
for (i = 0; i /* new client connection */
cliaddr_len = sizeof(cliaddr);
connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &cliaddr_len);
printf("received from %s at PORT %d\n",
inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)),
ntohs(cliaddr.sin_port));
for (i = 0; i
client[i] = connfd; /* 保存accept返回的文件描述符到client[]里 */
break;
}
}
/* 达到select能监控的文件个数上限 1024 */
if (i == FD_SETSIZE) {
fputs("too many clients\n", stderr);
exit(1);
}
FD_SET(connfd, &allset); /* 添加一个新的文件描述符到监控信号集里 */
if (connfd > maxfd)
maxfd = connfd; /* select第一个参数需要 */
if (i > maxi)
maxi = i; /* 更新client[]最大下标值 */
if (--nready == 0)
continue; /* 如果没有更多的就绪文件描述符继续回到上面select阻塞监听,
负责处理未处理完的就绪文件描述符 */
}
for (i = 0; i
if ( (n = read(sockfd, buf, MAXLINE)) == 0) {
close(sockfd); /* 当client关闭链接时，服务器端也关闭对应链接 */
FD_CLR(sockfd, &allset); /* 解除select监控此文件描述符 */
client[i] = -1;
} else {
int j;
for (j = 0; j
nready = poll(client, maxi+1, -1); /* 阻塞 */
if (client[0].revents & POLLIN) { /* 有客户端链接请求 */
clilen = sizeof(cliaddr);
connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &clilen);
printf("received from %s at PORT %d\n",
inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)),
ntohs(cliaddr.sin_port));
for (i = 1; i
client[i].fd = connfd; /* 找到client[]中空闲的位置，存放accept返回的connfd */
break;
}
}
if (i == OPEN_MAX)
perr_exit("too many clients");
client[i].events = POLLIN; /* 设置刚刚返回的connfd，监控读事件 */
if (i > maxi)
maxi = i; /* 更新client[]中最大元素下标 */
if (--nready
if ((n = read(sockfd, buf, MAXLINE)) /* 当收到 RST标志时 */
/* connection reset by client */
printf("client[%d] aborted connection\n", i);
close(sockfd);
client[i].fd = -1;
} else {
perr_exit("read error");
}
} else if (n == 0) {
/* connection closed by client */
printf("client[%d] closed connection\n", i);
close(sockfd);
client[i].fd = -1;
} else {
for (j = 0; j
nready = epoll_wait(efd, ep, OPEN_MAX, -1); /* 阻塞监听 */
if (nready == -1)
perr_exit("epoll_wait");
for (i = 0; i
clilen = sizeof(cliaddr);
connfd = accept(listenfd, (struct sockaddr *)&cliaddr, &clilen);
printf("received from %s at PORT %d\n",
inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)),
ntohs(cliaddr.sin_port));
for (j = 0; j
client[j] = connfd; /* save descriptor */
break;
}
}
if (j == OPEN_MAX)
perr_exit("too many clients");
if (j > maxi)
maxi = j; /* max index in client[] array */
tep.events = EPOLLIN;
tep.data.fd = connfd;
res = epoll_ctl(efd, EPOLL_CTL_ADD, connfd, &tep);
if (res == -1)
perr_exit("epoll_ctl");
} else {
sockfd = ep[i].data.fd;
n = read(sockfd, buf, MAXLINE);
if (n == 0) {
for (j = 0; j
client[j] = -1;
break;
}
}
res = epoll_ctl(efd, EPOLL_CTL_DEL, sockfd, NULL);
if (res == -1)
perr_exit("epoll_ctl");
close(sockfd);
printf("client[%d] closed connection\n", j);
} else {
for (j = 0; j
write(sockfd, buf, strlen(buf));
n = read(sockfd, buf, MAXLINE);
if (n == 0)
printf("the other side has been closed.\n");
else
write(STDOUT_FILENO, buf, n);
}
close(sockfd);
return 0;
}
UDP Server
#include
#include
#include
#include
#include
#include
#include
#define MAXLINE 80
#define SERV_PORT 6666
int main(void)
{
struct sockaddr_in servaddr, cliaddr;
socklen_t cliaddr_len;
int sockfd;
char buf[MAXLINE];
char str[INET_ADDRSTRLEN];
int i, n;
sockfd = socket(AF_INET, SOCK_DGRAM, 0);
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(SERV_PORT);
bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
printf("Accepting connections ...\n");
while (1) {
cliaddr_len = sizeof(cliaddr);
n = recvfrom(sockfd, buf, MAXLINE,0, (struct sockaddr *)&cliaddr, &cliaddr_len);
if (n == -1)
perror("recvfrom error");
printf("received from %s at PORT %d\n",
inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)),
ntohs(cliaddr.sin_port));
for (i = 0; i
n = sendto(sockfd, buf, strlen(buf), 0, (struct sockaddr *)&servaddr, sizeof(servaddr));
if (n == -1)
perror("sendto error");
n = recvfrom(sockfd, buf, MAXLINE, 0, NULL, 0);
if (n == -1)
perror("recvfrom error");
write(STDOUT_FILENO, buf, n);
}
close(sockfd);
return 0;
}
本地套接字Server
#include
#include
#include
#include
#include
#include
#include
#include
int main(){
//创建socket
int lfd = socket(AF_UNIX,SOCK_STREAM,0);//SOCK_STREAM:tcp流程
if(lfd
perror("bind error");
return -1;
}
//监听
listen(lfd,10);
//接收新的链接-accept
struct sockaddr_un client;
bzero(&client,sizeof(client));
socklen_t len = sizeof(client);
int cfd = accept(lfd,(struct sockaddr*)&client,&len);
if(cfd
//读取数据
memset(buf,0x00,sizeof(buf));
n = read(cfd,buf,sizeof(buf));
if(n
//创建socket
int cfd = socket(AF_UNIX,SOCK_STREAM,0);//tcp流程
if(cfd
perror("bind error");
return -1;
}
struct sockaddr_un serv;
bzero(&serv,sizeof(serv));
serv.sun_family = AF_UNIX;
strcpy(serv.sun_path,"./server.sock");
ret = connect(cfd,(struct sockaddr*)&serv,sizeof(serv));
if(ret
memset(buf,0x00,sizeof(buf));
n = read(STDIN_FILENO,buf,sizeof(buf));
//发送数据
write(cfd,buf,n);
//读取数据
memset(buf,0x00,sizeof(buf));
n = read(cfd,buf,sizeof(buf));
if(n |