嵌入式Linux網路程式設計,UDP迴圈伺服器,sendto(),recvfrom()
阿新 • • 發佈:2018-12-14
文章目錄
1,UDP迴圈伺服器模型:
socket(...);
bind(...);
while(1){
recvfrom(...);
process(...);
sendto (...);
}
2,UDP的使用場景
- 實時的音視訊傳輸
- DNS的域名解析
3,UDP資料傳送和接受sendto()、recvfrom()
ssize_t sendto(int socket, void *message, size_t length, int flags, struct sockaddr *dest_addr, socklen_t dest_len);
ssize_t recvfrom(int socket, void *buffer, size_t length, int flags, struct sockaddr *address, socklen_t *address_len);
這兩個函式一般在使用UDP協議時使用
4,UDP迴圈伺服器示例(可同時連線多個客戶端)
4.1,標頭檔案 net.h
#ifndef __NET_H__ #define __NET_H__ #include <stdio.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <strings.h> #include <arpa/inet.h> #include <unistd.h> #include <stdlib.h> #include <errno.h> //#define SERV_IP_ADDR "192.168.31.100" #define SERV_PORT 5005 //#define BACKLOG 5 #define QUIT_STR "quite" #endif
4.2,客戶端程式碼client.c
/* UDP demo */
/*./client serv_ip serv_port */
#include "net.h"
void usage(char *s)
{
printf("this is a UDP demo!\n");
printf("Usage:\n\t%s <serv_ip> <serv_port>\n",s);
printf("\tserv_ip: UDP server ip address\n");
printf("\tserv_port: UDP server port(>5000)\n ");
}
int main(int argc, const char *argv[])
{
int fd;
short port;
struct sockaddr_in sin;
if(argc != 3)
{
usage((char *)argv[0]);
exit(1);
}
if((port = atoi(argv[2])) < 5000)
{
usage((char *)argv[0]);
exit(1);
}
/* 1 建立socket fd */
if((fd = socket(AF_INET,SOCK_DGRAM,0)) < 0)//UDP程式設計
{
perror("socket");
exit(-1);
}
/* 2 連線伺服器 */
/* 2.1 填充struct sockaddr_in結構體變數*/
bzero(&sin,sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_port = htons(port);//轉為網路位元組序埠號
#if 0
#else
if(inet_pton(AF_INET,argv[1],(void *)&sin.sin_addr.s_addr) < 0)
{
perror("inet_pton");
goto _error1;
}
#endif
printf("UDP client starting ...... OK!\n");
/* 3 讀寫*/
char buf[BUFSIZ];
while(1)
{
fprintf(stderr,"Please input the string to server:");
bzero(buf,BUFSIZ);
if(fgets(buf,BUFSIZ-1,stdin) == NULL)
{
perror("fgets");
continue;
}
sendto(fd,buf,strlen(buf),0,(struct sockaddr *)&sin,sizeof(sin));
if(strncasecmp(buf,QUIT_STR,strlen(QUIT_STR)) == 0)
{
printf("client is existed!\n");
break;
}
}
_error1:
close(fd);
return 0;
}
4.3,伺服器端程式碼server.c
#include "net.h"
int main(int argc, const char *argv[])
{
int fd;
struct sockaddr_in sin;
/* 1 建立socket fd */
if((fd = socket(AF_INET,SOCK_DGRAM,0)) < 0)//UDP程式設計,套接字型別為SOCK_DGRAM
{
perror("socket");
exit(-1);
}
/* 2 允許繫結地址快速重用 */
int b_reuse = 1;
setsockopt(fd,SOL_SOCKET,SO_REUSEADDR,&b_reuse,sizeof(int));
/* 3 繫結 */
/* 3.1 填充struct sockaddr_in 結構體變數*/
bzero(&sin,sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_port = htons(SERV_PORT);
#if 1
/* 讓伺服器可以繫結在任意的IP上*/
sin.sin_addr.s_addr = htonl(INADDR_ANY);
#else
if(inet_pton(AF_INET,SERV_IP_ADDR,(void *)&sin.sin_addr.s_addr) < 0)
{
perror("inet_pton");
goto _error1;
}
#endif
/* 3.2 繫結*/
if(bind(fd,(struct sockaddr *)&sin,sizeof(sin)))
{
perror("bind");
goto _error1;
}
printf("UDP server starting .... OK!\n");
char buf[BUFSIZ];
struct sockaddr_in cin;
socklen_t addrlen = sizeof(cin);
while(1)
{
/* 讓系統自動獲取客戶端的資訊*/
bzero(buf,BUFSIZ);
if(recvfrom(fd,buf,BUFSIZ-1,0,(struct sockaddr *)&cin,&addrlen) < 0)
{
perror("recvfrom");
continue ;
}
char cin_ipv4_addr[16];
if(inet_ntop(AF_INET,&cin.sin_addr.s_addr,cin_ipv4_addr,sizeof(cin_ipv4_addr)) < 0)
{
perror("inet_ntop");
goto _error1;
}
printf("Receive from (%s:%d),Data: %s",cin_ipv4_addr,ntohs(cin.sin_port),buf);
if(strncasecmp(buf,QUIT_STR,strlen(QUIT_STR)) == 0)
{
printf("client (%s:%d) is existing!\n",cin_ipv4_addr,ntohs(cin.sin_port));
}
}
_error1:
close(fd);
return 0;
}