- UDP客户端的实现流程:
- 一、创建用户数据报套接字(socket函数):
- 通信域选择
IPV4网络协议
、数据报式套接字
;
int sockfd = socket(AF_INET,SOCK_DGRAM,0);
- 二、填充服务器的网络信息结构体:
- 1.定义网络信息结构体
变量
; - 2.求出结构体变量的
内存空间大小
; - 3.结构体清零;
- 4.使用
IPV4网络协议
; - 5.预留给在终端输入的
网络字节序的端口号
; - 6.预留给在终端输入的
IP地址
;
struct sockaddr_in serveraddr; socklen_t serveraddrlen = sizeof(serveraddr);memset(&serveraddr,0,serveraddrlen);serveraddr.sin_family = AF_INET; serveraddr.sin_addr.s_addr = inet_addr(argv[1]);serveraddr.sin_port = htons(atoi(argv[2]));
- 三、向服务器发送数据(sendto函数)和接收来自服务器端的应答消息(recvfrom函数):
- 注意:接收来自
服务器端的应答消息
,不需要保存再次保存服务器的网络信息结构体
,因为未曾修改过
;
sendto(sockfd,buf,sizeof(buf),0,(struct sockaddr *)&serveraddr,serveraddrlen);memset(buf,0,sizeof(buf));recvfrom(sockfd,buf,sizeof(buf),0,NULL,NULL); printf("应答:[%s]\n",buf);
close(sockfd);
#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <string.h>
#include <arpa/inet.h>
#include <unistd.h>#define ERRLOG(msg) do{\printf("%s:%s:%d\n", __FILE__, __func__, __LINE__);\perror(msg);\exit(-1);\}while(0)int main(int argc, const char *argv[])
{if(3 != argc){printf("Usage : %s <IP> <prot>\n", argv[0]);exit(-1);}int sockfd = socket(AF_INET,SOCK_DGRAM,0);if(-1 == sockfd){ERRLOG("socket error");}struct sockaddr_in serveraddr;socklen_t serveraddrlen = sizeof(serveraddr);memset(&serveraddr,0,serveraddrlen);serveraddr.sin_family = AF_INET;serveraddr.sin_addr.s_addr = inet_addr(argv[1]);serveraddr.sin_port = htons(atoi(argv[2]));char buf[128] = {0};while(1){memset(buf,0,sizeof(buf));fgets(buf,sizeof(buf),stdin);buf[strlen(buf)-1] = '\0';if(!strcmp(buf, "quit")){break;}if(-1 == sendto(sockfd,buf,sizeof(buf),0,(struct sockaddr *)&serveraddr,serveraddrlen)){ERRLOG("sendto error");}memset(buf,0,sizeof(buf));if(-1 == recvfrom(sockfd,buf,sizeof(buf),0,NULL,NULL)){ERRLOG("recvfrom error");}printf("应答:[%s]\n",buf);}close(sockfd);return 0;
}