Linux Socket編程實例(一個Hello World程序)
在Linux下寫了個小的socket程序，分爲客戶端和服務器端,服務端開一個端口(2000),做爲一個daemon,等待客戶的連接請求.一旦有客戶連接,服務器端打印出客戶端的IP地址和端口,並且向服務器端發送歡迎信息和時間.下面是服務端的代碼(tcpserver.c).由於這只是個簡單的程序，所以只用了單線程實現!
/**
* Tcp Server program, It is a simple example only.
* zhengsh 200520602061 2
* when client connect to server, send a welcome message and timestamp in server.
*/
#include <stdio.h>
#include <sys/socket.h>
#include <unistd.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <stdlib.h>
#include <time.h>
#define SERVER_PORT 20000 // define the defualt connect port id
#define LENGTH_OF_LISTEN_QUEUE 10 //length of listen queue in server
#define BUFFER_SIZE 255
#define WELCOME_MESSAGE "welcome to connect the server. "
int main(int argc, char **argv)
{
int servfd,clifd;
struct sockaddr_in servaddr,cliaddr;
if ((servfd = socket(AF_INET,SOCK_STREAM,0)) < 0)
{
printf("create socket error!/n");
exit(1);
}
bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(SERVER_PORT);
servaddr.sin_addr.s_addr = htons(INADDR_ANY);
if (bind(servfd,(struct sockaddr*)&servaddr,sizeof(servaddr))<0)
{
printf("bind to port %d failure!/n",SERVER_PORT);
exit(1);
}
if (listen(servfd,LENGTH_OF_LISTEN_QUEUE) < 0)
{
printf("call listen failure!/n");
exit(1);
}
while (1)
{//server loop will nerver exit unless any body kill the process
char buf[BUFFER_SIZE];
long timestamp;
socklen_t length = sizeof(cliaddr);
clifd = accept(servfd,(struct sockaddr*)&cliaddr,&length);
if (clifd < 0)
{
printf("error comes when call accept!/n");
break;
}
strcpy(buf,WELCOME_MESSAGE);
//inet_ntop(INET_ADDRSTRLEN,cliaddr.sin_addr,buf,BUFFER_SIZE);
printf("from client,IP:%s,Port:%d/n",inet_ntoa(cliaddr.sin_addr),ntohs(cliaddr.sin_port));
timestamp = time(NULL);
strcat(buf,"timestamp in server:");
strcat(buf,ctime(×tamp));
send(clifd,buf,BUFFER_SIZE,0);
close(clifd);
}//exit
close(servfd);
return 0;
}
客戶每次用一個隨機的端口連接服務器,並接收來自服務器的歡迎信息
,然後打印出來(tcpclient).運行的時候接受一個參數,也就是服務器的ip地址.
/* Tcp client program, It is a simple example only.
* zhengsh 200520602061 2
* connect to server, and echo a message from server.
*/
#include <stdio.h>
#include <sys/socket.h>
#include <unistd.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <stdlib.h>
#define SERVER_PORT 20000 // define the defualt connect port id
#define CLIENT_PORT ((20001+rand())%65536) // define the defualt client port as a random port
#define BUFFER_SIZE 255
#define REUQEST_MESSAGE "welcome to connect the server./n"
void usage(char *name)
{
printf("usage: %s IpAddr/n",name);
}
int main(int argc, char **argv)
{
int servfd,clifd,length = 0;
struct sockaddr_in servaddr,cliaddr;
socklen_t socklen = sizeof(servaddr);
char buf[BUFFER_SIZE];
if (argc < 2)
{
usage(argv[0]);
exit(1);
}
if ((clifd = socket(AF_INET,SOCK_STREAM,0)) < 0)
{
printf("create socket error!/n");
exit(1);
}
srand(time(NULL));//initialize random generator
bzero(&cliaddr,sizeof(cliaddr));
cliaddr.sin_family = AF_INET;
cliaddr.sin_port = htons(CLIENT_PORT);
cliaddr.sin_addr.s_addr = htons(INADDR_ANY);
bzero(&servaddr,sizeof(servaddr));
servaddr.sin_family = AF_INET;
inet_aton(argv[1],&servaddr.sin_addr);
servaddr.sin_port = htons(SERVER_PORT);
//servaddr.sin_addr.s_addr = htons(INADDR_ANY);
if (bind(clifd,(struct sockaddr*)&cliaddr,sizeof(cliaddr))<0)
{
printf("bind to port %d failure!/n",CLIENT_PORT);
exit(1);
}
if (connect(clifd,(struct sockaddr*)&servaddr, socklen) < 0)
{
printf("can't connect to %s!/n",argv[1]);
exit(1);
}
length = recv(clifd,buf,BUFFER_SIZE,0);
if (length < 0)
{
printf("error comes when recieve data from server %s!",argv[1]);
exit(1);
}
printf("from server %s :/n/t%s ",argv[1],buf);
close(clifd);
return 0;
}
程序在Fedora core 4下通過編譯,有幾個warining.但是不影響.
