距离详解Linux下的UDP方式通讯

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <errno.h>
#include <stdlib.h>
#include <arpa/inet.h>

int main(int argc,char **argv)
{
struct sockaddr_in s_addr;
struct sockaddr_in c_addr;
int sock;
socklen_t addr_len;
int len;
char buff[128];

/* 创建 socket,关键在于这个 SOCK_DGRAM */
if ((sock = socket(AF_INET,SOCK_DGRAM,0)) == -1) {
perror("socket");
exit(errno);
} else
printf("create socket.nr");

memset(&s_addr,sizeof(struct sockaddr_in));
/* 设置地址和端口信息 */
s_addr.sin_family = AF_INET;
if (argv[2])
s_addr.sin_port = htons(atoi(argv[2]));
else
s_addr.sin_port = htons(7838);
if (argv[1])
s_addr.sin_addr.s_addr = inet_addr(argv[1]);
else
s_addr.sin_addr.s_addr = INADDR_ANY;

/* 绑定地址和端口信息 */
if ((bind(sock,(struct sockaddr *) &s_addr,sizeof(s_addr))) == -1) {
perror("bind");
exit(errno);
} else
printf("bind address to socket.nr");

/* 循环接收数据 */
addr_len = sizeof(c_addr);
while (1) {
len = recvfrom(sock,buff,sizeof(buff) - 1,(struct sockaddr *) &c_addr,&addr_len);
if (len < 0) {
perror("recvfrom");
exit(errno);
}

buff[len] = '';
printf("收到来自%s:%d的消息:%snr",inet_ntoa(c_addr.sin_addr),ntohs(c_addr.sin_port),buff);
}
return 0;
}

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <errno.h>
#include <stdlib.h>
#include <arpa/inet.h>


int main(int argc,char **argv)
{
struct sockaddr_in s_addr;
int sock;
int addr_len;
int len;
char buff[128];

/* 创建 socket,0)) == -1) {
perror("socket");
exit(errno);
} else
printf("create socket.nr");

/* 设置对方地址和端口信息 */
s_addr.sin_family = AF_INET;
if (argv[2])
s_addr.sin_port = htons(atoi(argv[2]));
else
s_addr.sin_port = htons(7838);
if (argv[1])
s_addr.sin_addr.s_addr = inet_addr(argv[1]);
else {
printf("消息必须有一个接收者！n");
exit(0);
}

/* 发送UDP消息 */
addr_len = sizeof(s_addr);
strcpy(buff,"hello i'm here");
len = sendto(sock,strlen(buff),addr_len);
if (len < 0) {
printf("nrsend error.nr");
return 3;
}

printf("send success.nr");
return 0;
}

gcc -Wall simple-udpserver.c -o server
gcc -Wall simple-udpclient.c -o client

./server 127.0.0.1 7838

./client 127.0.0.1 7838

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <errno.h>
#include <stdlib.h>
#include <arpa/inet.h>

int main(int argc,char **argv)
{
struct sockaddr_in s_addr;
int sock;
int addr_len;
int len;
char buff[128];
int yes;

/* 创建 socket */
if ((sock = socket(AF_INET,0)) == -1) {
perror("socket");
exit(errno);
} else
printf("create socket.nr");

/* 设置通讯方式对广播，即本程序发送的一个消息，网络上所有主机均可以收到 */
yes = 1;
setsockopt(sock,SOL_SOCKET,SO_BROADCAST,&yes,sizeof(yes));
/* 唯一变化就是这一点了 */

/* 设置对方地址和端口信息 */
s_addr.sin_family = AF_INET;
if (argv[2])
s_addr.sin_port = htons(atoi(argv[2]));
else
s_addr.sin_port = htons(7838);
if (argv[1])
s_addr.sin_addr.s_addr = inet_addr(argv[1]);
else {
printf("消息必须有一个接收者！n");
exit(0);
}

/* 发送UDP消息 */
addr_len = sizeof(s_addr);
strcpy(buff,addr_len);
if (len < 0) {
printf("nrsend error.nr");
return 3;
}

printf("send success.nr");
return 0;
}

gcc -Wall broadc-udpclient.c -o client

./client 192.168.0.255 7838

./server 自己的IP地址 7838