Linux 网络编程——TCP&UDP范例
TCP基础变成范例
程序功能:服务端启动并接收客户端的连接,客户端连接后,服务端向客户端发送当前时间并显示在客户端上,服务端显示当前连接的客户端的IP地址和port。
服务端代码time_tcp_server.c
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
#include <signal.h>
#include <time.h>
int sockfd;
void sig_handler(int signo)
{
if(signo == SIGINT){
printf("server close\n");
/* 步骤6:关闭socket*/
close(sockfd);
exit();
}
}
/*输出链接上来的客户端信息*/
void out_addr(struct sockaddr_in *clientaddr)
{
//将端口从网络字节序转换成主机字节序
int port = ntohs(clientaddr->sin_port);
char ip[];
memset(ip, , sizeof(ip));
//将IP地址从网络字节序转换成点分十进制
inet_ntop(AF_INET, &clientaddr->sin_addr.s_addr,
ip, sizeof(ip));
printf("client: %s(%d) connected\n",ip,port);
}
void do_service(int fd)
{
//获得系统时间
long t = time();
char *s = ctime(&t);
size_t size = strlen(s) * sizeof(char);
//将服务器获得的系统时间写会客户端
if(write(fd,s,size) != size){
perror("write error\n");
}
}
int main(int argc,char *argv[])
{
if(argc < ){
printf("usage:%s #port\n",argv[]);
exit();
}
if(signal(SIGINT,sig_handler) == SIG_ERR){
perror("signal sigint error\n");
exit();
}
/* 步骤1:创建socket(套接字)
* 注:socket创建在内核中,是一个结构体
* AF_INET:IPV4
* SOCK_STREAM:TCP协议
* */
sockfd = socket(AF_INET,SOCK_STREAM,);
/* 步骤2:调用bind函数将socket和地址
* (包括ip、port)进行绑定
* */
struct sockaddr_in serveraddr;
memset(&serveraddr,,sizeof(serveraddr));
serveraddr.sin_family = AF_INET; //IPV4
serveraddr.sin_port = htons(atoi(argv[])); //port
serveraddr.sin_addr.s_addr = INADDR_ANY;
if(bind(sockfd, (struct sockaddr*)&serveraddr, sizeof(serveraddr)) < ){
perror("bind error\n");
exit();
}
/* 步骤3:调用listen函数启动监听(制定port监听)
* 通知系统去接受来自客户端的链接请求
* (将接受到的客户端对应请求放置到对应的队列中)
* 第二个参数:指定队列的长度
* */
if(listen(sockfd, ) < ){
perror("listen error\n");
exit();
}
/* 步骤4:调用accept函数从队列中获得一个客户端的请求连接,
* 并返回新的socket描述符
* 注意:若没有客户端连接,调用此函数后会阻塞,
* 直到获得一个客户端的链接
* */
struct sockaddr_in clientaddr;
socklen_t clientaddr_len = sizeof(clientaddr);
while(){
int fd = accept(sockfd,(struct sockaddr*)&clientaddr,
&clientaddr_len);
if(fd < ){
perror("accept error\n");
continue;
}
/* 步骤5:调用IO函数(read/write)和链接的客户端进行
* 双向的通信
* */
out_addr(&clientaddr);
do_service(fd);
/* 步骤6:关闭socket*/
close(fd);
}
return ;
}
客户端代码time_tcp_client.c
#include <netdb.h>
#include <sys/socket.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <memory.h>
#include <arpa/inet.h>
#include <unistd.h>
int main(int argc,char *argv[])
{
if(argc < ){
printf("usage:%s ip port\n",argv[]);
exit();
}
/* 步骤1:创建socket*/
int sockfd = socket(AF_INET, SOCK_STREAM, );
if(sockfd < ){
perror("socket error\n");
exit();
}
//往serveraddr中填入ip,port和地址族类型(ipv4)
struct sockaddr_in serveraddr;
memset(&serveraddr, , sizeof(serveraddr));
serveraddr.sin_family = AF_INET;
serveraddr.sin_port = htons(atoi(argv[]));
//将ip地址转换成网络字节序
inet_pton(AF_INET, argv[], &serveraddr.sin_addr.s_addr);
/* 步骤2:客户端调用connect函数连接到服务器端*/
if(connect(sockfd, (struct sockaddr*)&serveraddr, sizeof(serveraddr)) < ){
perror("connect error\n");
exit();
}
/* 步骤3:调用IO函数(read/write)和服务端进行双向通信*/
char buffer[];
memset(buffer, , sizeof(buffer));
size_t size;
if((size = read(sockfd, buffer, sizeof(buffer))) < ){
perror("read error\n");
exit();
}
if(write(STDOUT_FILENO, buffer, size) != size){
perror("write error\n");
exit();
}
/* 步骤4:关闭socket*/
close(sockfd);
return ;
}
UDP基础变成范例
程序功能:服务端启动并接收客户端的连接,客户端连接后,服务端向客户端发送当前时间并显示在客户端上,服务端显示当前连接的客户端的IP地址和port。
服务端代码time_udp_server.c
#include <stdio.h>
#include <netdb.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <time.h>
int sockfd;
void sig_handler(int signo)
{
if(signo == SIGINT){
printf("server close\n");
close(sockfd);
exit();
}
}
//输出客户端信息
void out_addr(struct sockaddr_in *clientaddr)
{
char ip[];
memset(ip, , sizeof(ip));
inet_ntop(AF_INET, &clientaddr->sin_addr.s_addr, ip, sizeof(ip));
int port = ntohs(clientaddr->sin_port);
printf("client: %s(%d)\n", ip, port);
}
//和客户端进行通信
void do_service()
{
struct sockaddr_in clientaddr;
socklen_t len = sizeof(clientaddr);
char buffer[];
memset(buffer, , sizeof(buffer));
//接收客户端数据报文
if(recvfrom(sockfd, buffer, sizeof(buffer), ,
(struct sockaddr*)&clientaddr, &len) < ){
perror("recvfrom error");
}else{
out_addr(&clientaddr);
printf("client send into: %s\n", buffer);
//向客户端发送数据报文
long int t = time();
char *ptr = ctime(&t);
size_t size = strlen(ptr) * sizeof(char);
if(sendto(sockfd, ptr, size, ,
(struct sockaddr*)&clientaddr, len) < ){
perror("send error");
}
}
}
int main(int argc, char *argv[])
{
if(argc < ){
printf("usage: %s port\n", argv[]);
exit();
}
if(signal(SIGINT, sig_handler) == SIG_ERR){
perror("signal sifint error");
exit();
}
/* 步骤1:创建socket*/
sockfd = socket(AF_INET, SOCK_DGRAM, );
if(sockfd < ){
perror("socket error");
exit();
}
int ret;
int opt = ;
//设置套接字选项
if((ret = setsockopt(sockfd, SOL_SOCKET,
SO_REUSEADDR, &opt, sizeof(opt))) < ){
perror("setsockopt error");
exit();
}
/* 步骤2:调用bind函数对socket和地址进行绑定*/
struct sockaddr_in serveraddr;
memset(&serveraddr, , sizeof(serveraddr));
serveraddr.sin_family = AF_INET; //ipv4
serveraddr.sin_port = htons(atoi(argv[])); //port
serveraddr.sin_addr.s_addr = INADDR_ANY; //ip
if(bind(sockfd, (struct sockaddr*)&serveraddr, sizeof(serveraddr)) < ){
perror("bind error");
exit();
}
/* 步骤3:和客户端进行双向的通信*/
while(){
do_service();
}
return ;
}
客户端代码time_udp_client.c
#include <stdio.h>
#include <arpa/inet.h>
#include <stdlib.h>
#include <sys/socket.h>
#include <netdb.h>
#include <unistd.h>
#include <string.h>
#include <memory.h>
int sockfd;
int main(int argc, char *argv[])
{
if(argc < ){
printf("usage: %s ip,port,msg", argv[]);
exit();
}
/* 步骤1:创建socket*/
if((sockfd = socket(AF_INET, SOCK_DGRAM,)) < ){
perror("socket error");
exit();
}
struct sockaddr_in serveraddr;
memset(&serveraddr, , sizeof(serveraddr));
serveraddr.sin_family = AF_INET;
serveraddr.sin_port = htons(atoi(argv[]));
inet_pton(AF_INET, argv[], &serveraddr.sin_addr.s_addr);
char buffer[];
memset(buffer, , sizeof(buffer));
strcpy(buffer,argv[]);
if(sendto(sockfd, buffer, sizeof(buffer), , (struct sockaddr*)&serveraddr, sizeof(serveraddr)) < ){
perror("send error");
exit();
}else{
memset(buffer, , sizeof(buffer));
if(recv(sockfd, buffer, sizeof(buffer), ) < ){
perror("recv error");
exit();
}else{
printf("%s", buffer);
}
}
close(sockfd);
return ;
}