/******************************************************************************//* This file has been written by Sergio Perez Alca駃z <serpeal@upvnet.upv.es> *//*            Departamento de Inform醫ica de Sistemas y Computadores          *//*            Universidad Polit閏nica de Valencia                             *//*            Valencia (Spain)                                                *//*                                                                            *//* The RTL-lwIP project has been supported by the Spanish Government Research *//* Office (CICYT) under grant TIC2002-04123-C03-03                            *//******************************************************************************/#include <sys/types.h>#include <sys/socket.h>#include <netinet/in.h>#include <arpa/inet.h>#include <netdb.h>#include <stdio.h>#include <unistd.h> /* close() */#include <string.h> /* memset() */#define LOCAL_SERVER_PORT 7#define MAX_MSG 100int main(int argc, char *argv[]) {    int sd, rc, n, cliLen;  struct sockaddr_in cliAddr, servAddr;  char msg[MAX_MSG];  /* socket creation */  sd=socket(AF_INET, SOCK_DGRAM, 0);  if(sd<0) {    printf("%s: cannot open socket \n",argv[0]);    exit(1);  }  /* bind local server port */  servAddr.sin_family = AF_INET;  servAddr.sin_addr.s_addr = htonl(INADDR_ANY);  servAddr.sin_port = htons(LOCAL_SERVER_PORT);  rc = bind (sd, (struct sockaddr *) &servAddr,sizeof(servAddr));  if(rc<0) {    printf("%s: cannot bind port number %d \n", 	   argv[0], LOCAL_SERVER_PORT);    exit(1);  }  printf("%s: waiting for data on port UDP %u\n", 	   argv[0],LOCAL_SERVER_PORT);  /* server infinite loop */  while(1) {        /* init buffer */    memset(msg,0x0,MAX_MSG);    /* receive message */    cliLen = sizeof(cliAddr);    n = recvfrom(sd, msg, MAX_MSG, 0, 		 (struct sockaddr *) &cliAddr, &cliLen);    if(n<0) {      printf("%s: cannot receive data \n",argv[0]);      continue;    }          /* print received message */    printf("%s: from %s:UDP%u : %s \n", 	   argv[0],inet_ntoa(cliAddr.sin_addr),	   ntohs(cliAddr.sin_port),msg);      }/* end of server infinite loop */return 0;}