udp socket服务端客户端示例

#include <stdio.h>
#include <sys/select.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <string.h>
#include <stdlib.h>

#define PORT 12345
#define BUF_SIZE 65536

void
buf_dump(char *buf, int len)
{
#define PER_LINE 32
printf("--------------------------------\n");
int i;
for (i = 0; i < len; i++) {
printf("%02x ", (unsigned char)buf[i]);
if (((i + 1) % PER_LINE) == 0) {
printf("\n");
}
}
printf("\n--------------------------------\n");
#undef PER_LINE
}

int
main(void)
{
printf("server start\n");

int ret = -1;
int sockfd = -1;
sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd < 0) {
perror("socket()");
}

struct sockaddr_in server_addr;
memset(&server_addr, 0, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(PORT);
server_addr.sin_addr.s_addr = htons(INADDR_ANY);

ret = bind(sockfd, (struct sockaddr *)&server_addr, sizeof(server_addr));
if (ret < 0) {
perror("bind()");
}

int max_fd = sockfd + 1;
fd_set rfds;
char buf[BUF_SIZE];
int n = 0;

while (1) {
FD_ZERO(&rfds);
FD_SET(sockfd, &rfds);

ret = select(max_fd, &rfds, NULL, NULL, NULL);
if (ret > 0) {
if (FD_ISSET(sockfd, &rfds)) {
memset(buf, 0, sizeof(buf));
n = recvfrom(sockfd, buf, sizeof(buf), 0, NULL, NULL);
if (n > 0) {
buf_dump(buf, n);
} else {
perror("recvfrom()");
}
}
} else {
perror("select()");
}

}

return 0;
}

#include <stdio.h>
#include <sys/select.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <string.h>

#define PORT 12345
#define BUF_SIZE 65536

int
main(void)
{
printf("client start\n");

int ret = -1;
int sockfd = -1;
sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd < 0) {
perror("socket()");
}

struct sockaddr_in server_addr;
memset(&server_addr, 0, sizeof(server_addr));
server_addr.sin_family = AF_INET;
server_addr.sin_port = htons(PORT);
server_addr.sin_addr.s_addr = inet_addr("127.0.0.1");

while (1) {
ret = sendto(sockfd, "hello", 5, 0, (struct sockaddr *)&server_addr, sizeof(server_addr));
if (ret < 0) {
perror("sendto()");
}
sleep(2);
}

return 0;
}