Embedded Linux network Programming (III)--UDP programming model

embedded Linux Network Programming (III.)--UDP programming model

UDP programming Model:

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The UDP loop server model is:

Socket (...); Bind (...);   while (1) {recvfrom (...);   Process (...); SendTo (...);}

server.c code:

#include  <stdio.h> #include  <stdlib.h> #include  <string.h> #include  < unistd.h> #include  <sys/socket.h> #include  <netinet/in.h> #include  <arpa/inet.h >  #define  port  8888#define buffer_size 1024 int main (INT&NBSP;ARGC ,  char *argv[]) {int sockfd;sockfd = socket (af_inet, sock_dgram, 0);  //   Create a UDP socket if (sockfd < 0) {fprintf (stderr,  "socket function failed.\n"); exit (-1) ;} Struct sockaddr_in server_addr;bzero (&server_addr, sizeof (SERVER_ADDR)); Server_addr.sin_ Family = af_inet;// ipv4server_addr.sin_port   = htons (port);//  Port server_addr.sin_addr.s_addr = htonl (inaddr_any); // ip//  binding int err;err =  bind (sockfd,  (struct sockaddr*) &server_addr, sizeof (SERVER_ADDR)); if (err !=  0) {fprintf (STDERR,&NBSP; " Bind function failed.\n "); Close (SOCKFD); exit (-1);} fprintf (stdout,  "server runiing on %d\n",  port); char recvbuf[buffer_size];struct  sockaddr_in client_addr;while (1) {Int recvlen;bzero (&recvbuf, sizeof (RECVBUF)); Socklen _t len = sizeof (CLIENT_ADDR); Bzero (&client_addr, sizeof (CLIENT_ADDR)); if (strcmp ( Recvbuf, "exit\n") ==0)             break;         if (strcmp (Recvbuf, "q\n") ==0)              break;        if (strcmp (Recvbuf, " quit\n ") ==0)             break;//  Receive client Data Recvlen = recvfrom (sockfd, recvbuf, sizeof (recvbuf), 0,  (struct  sockaddr*) &client_addr, &len) fprintf (stdout,  "HAVE&NBSP;A&NBSP;NEW&NBSp;client :%s, port:%d\n ",  inet_ntoa (CLIENT_ADDR.SIN_ADDR),  ntohs (Client_addr.sin_port));  //  Client's ipprintf ("message: %s\n",  recvbuf); SendTo (Sockfd, recvbuf, recvlen,  0,  (struct sockaddr*) &client_addr, len);} Close (SOCKFD); return 0;}

CLIENT.C Code:

#include  <sys/types.h> #include  <sys/socket.h> #include  <stdio.h> #include   <netinet/in.h> #include  <arpa/inet.h> #include  <unistd.h> #include  <string.h > #include  <stdlib.h> #include  <fcntl.h> #include  <sys/shm.h>  #define  port  8888#define buffer_size 1024 int main () {    /// Definition Sockfd    int clientsockfd = socket (af_inet, sock_dgram, 0);     ///definition sockaddr_in    struct sockaddr_in servaddr;     bzero (&servaddr, sizeof (SERVADDR));     servaddr.sin_family  = af_inet;    servaddr.sin_port = htons (port);   ///Server port &NBSP;&NBSP;&NBSP;&NBSP;SERVADDR.SIN_ADDR.S_ADDR&NBSP;=&NBSP;INET_ADDR ("192.168.0.200");   ///server IP     ///Connection ServiceSuccessfully returned 0, error returned -1    if  (Connect (clientsockfd,  (struct sockaddr *) & Servaddr, sizeof (SERVADDR))  < 0)     {         fprintf (stderr,  "connect function failed.\n");         exit ( -1);    }    char sendbuf[buffer_size];     char recvbuf[buffer_size];    bzero (Sendbuf, sizeof ( SENDBUF));     bzero (Recvbuf, sizeof (RECVBUF));    while  (1)     {    fgets (Sendbuf, sizeof (SENDBUF),  stdin);     if (strcmp (SendBuf, "exit\n") ==0)              break;        if (strcmp (SendBuf, "q\n") ==0)              break;        if (strcmp (SendBuf, "quit\n") ==0)             break;         send (Clientsockfd, sendbuf, strlen (SENDBUF), 0);  ///send      &NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;&NBSP;RECV (clientsockfd, recvbuf,  sizeof (RECVBUF), 0);  ///reception                  fprintf (stdout,  "%s\n",  recvbuf); Bzero (Sendbuf, sizeof (sendbuf));         bzero (recvbuf, sizeof (recvbuf));    }     close (CLIENTSOCKFD);     return 0;}

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Embedded Linux network Programming (III)--UDP programming model