转载:https://www.cnblogs.com/zkfopen/p/9382705.html
环境:Linux
语言:C/C++
通信方式:UDP
1. socket: 建立一个socket
2. bind: 将这个socket绑定在某个端口上(AF_INET)
3. recvfrom: 如果没有客户端发起请求,则会阻塞在这个函数里
4. close: 通信完成后关闭socket
1. socket: 建立一个socket
2. sendto: 向服务器的某个端口发起请求(AF_INET)
3. close: 通信完成后关闭socket
int recvfrom(int sockfd, void * buf, size_t len, int flags, struct sockaddr * src_addr, socklen_t * addrlen);
int sendto(int sockfd, const void * buf, size_t len, int flags, const struct sockaddr * dest_addr, socklen_t addrlen);
UDP套接字不会保持连接状态,每次传输数据都要添加目标地址信息,这相当于在邮寄包裹前填写收件人地址。
recvfrom用于接收数据,sendto用于发送数据
recvfrom:
sendto:
Server.cpp
#include
#include
#include
#include
#include
#include
#include
#include
#define SERV_PORT 8000
int main()
{
/* sock_fd --- socket文件描述符 创建udp套接字*/
int sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
if(sock_fd < 0)
{
perror("socket");
exit(1);
}
/* 将套接字和IP、端口绑定 */
struct sockaddr_in addr_serv;
int len;
memset(&addr_serv, 0, sizeof(struct sockaddr_in)); //每个字节都用0填充
addr_serv.sin_family = AF_INET; //使用IPV4地址
addr_serv.sin_port = htons(SERV_PORT); //端口
/* INADDR_ANY表示不管是哪个网卡接收到数据,只要目的端口是SERV_PORT,就会被该应用程序接收到 */
addr_serv.sin_addr.s_addr = htonl(INADDR_ANY); //自动获取IP地址
len = sizeof(addr_serv);
/* 绑定socket */
if(bind(sock_fd, (struct sockaddr *)&addr_serv, sizeof(addr_serv)) < 0)
{
perror("bind error:");
exit(1);
}
int recv_num;
int send_num;
char send_buf[20] = "i am server!";
char recv_buf[20];
struct sockaddr_in addr_client;
while(1)
{
printf("server wait:\n");
recv_num = recvfrom(sock_fd, recv_buf, sizeof(recv_buf), 0, (struct sockaddr *)&addr_client, (socklen_t *)&len);
if(recv_num < 0)
{
perror("recvfrom error:");
exit(1);
}
recv_buf[recv_num] = '\0';
printf("server receive %d bytes: %s\n", recv_num, recv_buf);
send_num = sendto(sock_fd, send_buf, recv_num, 0, (struct sockaddr *)&addr_client, len);
if(send_num < 0)
{
perror("sendto error:");
exit(1);
}
}
close(sock_fd);
return 0;
}
Client.cpp
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define DEST_PORT 8000
#define DSET_IP_ADDRESS "127.0.0.1"
int main()
{
/* socket文件描述符 */
int sock_fd;
/* 建立udp socket */
sock_fd = socket(AF_INET, SOCK_DGRAM, 0);
if(sock_fd < 0)
{
perror("socket");
exit(1);
}
/* 设置address */
struct sockaddr_in addr_serv;
int len;
memset(&addr_serv, 0, sizeof(addr_serv));
addr_serv.sin_family = AF_INET;
addr_serv.sin_addr.s_addr = inet_addr(DSET_IP_ADDRESS);
addr_serv.sin_port = htons(DEST_PORT);
len = sizeof(addr_serv);
int send_num;
int recv_num;
char send_buf[20] = "hey, who are you?";
char recv_buf[20];
printf("client send: %s\n", send_buf);
send_num = sendto(sock_fd, send_buf, strlen(send_buf), 0, (struct sockaddr *)&addr_serv, len);
if(send_num < 0)
{
perror("sendto error:");
exit(1);
}
recv_num = recvfrom(sock_fd, recv_buf, sizeof(recv_buf), 0, (struct sockaddr *)&addr_serv, (socklen_t *)&len);
if(recv_num < 0)
{
perror("recvfrom error:");
exit(1);
}
recv_buf[recv_num] = '\0';
printf("client receive %d bytes: %s\n", recv_num, recv_buf);
close(sock_fd);
return 0;
}
程序运行截图:
client向服务器发送了“hey, who are you?”的字符串,server返回"i am server!"的字符串。