socket，linux用c语言实现
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Socket通信创建步骤：
（1）通过socket()函数创建socket
（2）通过bind函数绑定socket于设备地址
（3）进行读写操作read/recv/recvfrom write/send/sendto
（4）close方法关闭套接字
例子如下：
test1.c
#include <stdio.h>#include <stdlib.h>
#include <unistd.h>
#include <netinet/in.h>
#include <arpa/inet.h>
int main(void)
{
//create socket
int fd = socket(AF_INET, SOCK_DGRAM, 0);
if(fd==-1)
{
perror("socket\n");
exit(-1);
}
printf("socket fd=%d\n",fd);
//build connection address
struct sockaddr_in addr;
addr.sin_family = AF_INET;
addr.sin_port = htons(6666);
addr.sin_addr.s_addr = inet_addr("127.0.0.1");
int r;
r = bind(fd,(struct sockaddr*)&addr,sizeof(addr));
if(r==-1)
{
perror("bind");
close(fd);
exit(-1);
}
printf("bind address successful!\n");
//accept or send message
char buf[255];
struct sockaddr_in from;
socklen_t len;
len = sizeof(from);
while(1)
{
r = recvfrom(fd,buf,sizeof(buf)-1,0,(struct sockaddr*)&from,&len);
if(r>0)
{
buf[r]=0;
printf("The message from %s is:%s\n",inet_ntoa(from.sin_addr),buf);
}
else
{
break;
}
}
//close socket
close(fd);
return 0;
}
test2.c
#include <stdio.h>#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
int main(void)
{
//create socket
int fd = socket(AF_INET,SOCK_DGRAM,0);
if(fd==-1)
{
perror("socket");
exit(-1);
}
printf("create socket OK!\n");
//create an send address
struct sockaddr_in addr={};
addr.sin_family = AF_INET;
addr.sin_port = htons(6666);
addr.sin_addr.s_addr=inet_addr("127.0.0.1");
//send the message to the specify address
int r;
char buf[255];
while(1)
{
r = read(0,buf,sizeof(buf)-1);
if(r<=0)
break;
sendto(fd,buf,r,0,(struct sockaddr*)&addr,sizeof(addr));
}
//close socket
close(fd);
return 0;
}
先运行test1.c，然后运行test2.c，在test2.c运行后输入内容，在test1.c所在终端中就会显示信息
运行结果如下：
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//服务端server.c
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <sys/wait.h>
#define SERVPORT 6000 /*服务器监听端口号 */
#define BACKLOG 10 /* 最大同时连接请求数 */
#define MAXDATASIZE 100
main()
{
char buf[MAXDATASIZE];
int sockfd,client_fd; /*sock_fd：监听socket；client_fd：数据传输socket */
struct sockaddr_in my_addr; /* 本机地址信息 */
struct sockaddr_in remote_addr; /* 客户端地址信息 */
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
perror("socket创建出错！");
exit(1);
}
my_addr.sin_family=AF_INET;
my_addr.sin_port=htons(SERVPORT);
my_addr.sin_addr.s_addr = INADDR_ANY;
bzero(&(my_addr.sin_zero),8);
if (bind(sockfd, (struct sockaddr *)&my_addr, sizeof(struct sockaddr)) == -1)
{
perror("bind出错！");
exit(1);
}
if (listen(sockfd, BACKLOG) == -1)
{
perror("listen出错！");
exit(1);
}
while(1)
{
sin_size = sizeof(struct sockaddr_in);
if ((client_fd = accept(sockfd, (struct sockaddr *)&remote_addr, &sin_size)) == -1)
{
perror("accept出错");
continue;
}
printf("received a connection from %s\n", inet_ntoa(remote_addr.sin_addr));
if (!fork())
{ /* 子进程代码段 */
if ((recvbytes=recv(client_fd, buf, MAXDATASIZE, 0)) ==-1)
{
perror("recv出错！");
close(client_fd);
exit(0);
}
buf[recvbytes] = '\0';
printf("from client Received: %s",buf);
if (send(client_fd, "thanks!\n", 8, 0) == -1)
perror("send出错！");
close(client_fd);
exit(0);
}
close(client_fd);
}
}
//客户端client.c
#include<stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <netdb.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#define SERVPORT 6000
#define MAXDATASIZE 100
main(int argc, char *argv[])
{
int sockfd, recvbytes;
char buf[MAXDATASIZE];
struct hostent *host;
struct sockaddr_in serv_addr;
if (argc < 2)
{
fprintf(stderr,"Please enter the server's hostname!\n");
exit(1);
}
if((host=gethostbyname(argv[1]))==NULL)
{
herror("gethostbyname出错！");
exit(1);
}
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1)
{
perror("socket创建出错！");
exit(1);
}
serv_addr.sin_family=AF_INET;
serv_addr.sin_port=htons(SERVPORT);
serv_addr.sin_addr = *((struct in_addr *)host->h_addr);
bzero(&(serv_addr.sin_zero),8);
if (connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(struct sockaddr)) == -1)
{
perror("connect出错！");
exit(1);
}
if (send(sockfd, "hello!\n", 7, 0) == -1)
{
perror("send出错！");
exit(1);
}
if ((recvbytes=recv(sockfd, buf, MAXDATASIZE, 0)) ==-1)
{
perror("recv出错！");
exit(1);
}
buf[recvbytes] = '\0';
printf("Received: %s",buf);
close(sockfd);
}
