[Linux] c语言简单的udp socket 示例

服务端：

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

#include "wrap.h"

#define MAXLINE 80
#define SERV_PORT 8000

int main(void)
{
struct sockaddr_in servaddr, cliaddr;
socklen_t cliaddr_len;
int sockfd;
char buf[MAXLINE];
char str[INET_ADDRSTRLEN];
int i, n;

sockfd = Socket(AF_INET, SOCK_DGRAM, 0);

bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(SERV_PORT);

Bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));

printf("Accepting connections ...\n");

while(1) {
cliaddr_len = sizeof(cliaddr);
n = recvfrom(sockfd, buf, MAXLINE, 0, (struct sockaddr *)&cliaddr, &cliaddr_len);
if (n == -1) {
perr_exit("recvfrom error");
}
printf("received from %s at PORT %d\n", inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)),ntohs(cliaddr.sin_port));
for (i = 0; i < n; i++) {
buf[i] = toupper(buf[i]);
}
n = sendto(sockfd, buf, n, 0, (struct sockaddr *)&cliaddr, sizeof(cliaddr));
if (n == -1) {
perr_exit("sendto error");
}
}
}


客户端：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <unistd.h>

#include "wrap.h"

#define MAXLINE 80
#define SERV_PORT 8000

int main(int argc, char *argv[])
{
struct sockaddr_in servaddr;
int sockfd, n;
char buf[MAXLINE];
char str[INET_ADDRSTRLEN];
socklen_t servaddr_len;

sockfd = Socket(AF_INET, SOCK_DGRAM, 0);

bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
inet_pton(AF_INET, "127.0.0.1", &servaddr.sin_addr);
servaddr.sin_port = htons(SERV_PORT);

while(fgets(buf, MAXLINE, stdin) != NULL) {
n = sendto(sockfd, buf, strlen(buf), 0, (struct sockaddr *)&servaddr, sizeof(servaddr));
if (n == -1) {
perr_exit("sendto error");
}
n = recvfrom(sockfd, buf, MAXLINE, 0, NULL, 0);
if (n == -1 ) {
perr_exit("recvfrom error");
}
Write(STDOUT_FILENO, buf, n);
}
Close(sockfd);
return 0;
}