1.服務器端實現
程序在收到客戶端發送來的消息後，給客戶端發送消息，提示客戶端收到了該消息
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#include <unistd.h>
int main(int argc, char *argv[])
{
int sock, length, fromlen, n;
struct sockaddr_in server;
struct sockaddr_in from;
char buf[1024];
//要求執行是輸入端口信息
if (argc!= 2) {
printf( "Usage: %s port_num\n",argv[0]);
return 1;
}
//創建通信所需的套接字，並與地址和端口信息幫定
sock=socket(AF_INET, SOCK_DGRAM, 0);
if (sock < 0){
perror("cannot create communicating socket");
return 1;
}
length = sizeof(server);
bzero(&server,length);
server.sin_family=AF_INET;
server.sin_addr.s_addr=INADDR_ANY;
server.sin_port=htons(atoi(argv[1]));
if (bind(sock,(struct sockaddr *)&server,length)<0){
perror("cannot bind the socket");
close(sock);
return 1;
}
fromlen = sizeof(struct sockaddr_in);
//讀取客戶端發送來的信息，顯示後，發回相關信息給客戶端
while (1) {
n = recvfrom(sock,buf,sizeof(buf),0,(struct sockaddr *)&from,&fromlen);
if (n < 0) {
perror("cannot receive date from client");
break;
}
write(STDOUT_FILENO,"server: Received a datagram: ",29);
write(STDOUT_FILENO,buf,n);
n = sendto(sock,"send message to client\n",22,
0,(struct sockaddr *)&from,fromlen);
if (n < 0) {
perror("cannot send data to the client");
break;
}
}
close(sock);
return 0;
}
2.客戶端實現
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>
#include <unistd.h>
int main(int argc, char *argv[])
{
int sock, length, n;
struct sockaddr_in server, from;
struct hostent *hp;
char buffer[256];
//判斷輸入參數是否符合要求
if (argc != 3) {
printf("Usage: %s server_ip port_num\n",argv[0]);
return 1;
}
//創建通信套接字
sock= socket(AF_INET, SOCK_DGRAM, 0);
if (sock < 0) {
perror("cannot create communicating socket");
return 1;
}
server.sin_family = AF_INET;
hp = gethostbyname(argv[1]);
if (hp==0) {
perror("cannot get the server ip address");
return 1;
}
bcopy((char *)hp->h_addr,
(char *)&server.sin_addr,
hp->h_length);
server.sin_port = htons(atoi(argv[2]));
length=sizeof(struct sockaddr_in);
printf("(client) enter the message: ");
bzero(buffer,256);
fgets(buffer,255,stdin);
//發送數據給指定服務器
n=sendto(sock,buffer,strlen(buffer),0,&server,length);
if (n < 0){
perror("cannot get message from the client");
return 1;
}
//從服務器中接受數據
bzero(buffer,256);
n = recvfrom(sock,buffer,256,0,&from, &length);
if (n < 0) {
perror("cannot send message to the server");
return 1;
}
printf("client got message : %s\n",buffer);
close(sock);
return 0;
}