send.c

介绍linux下的发送和接受udp数据报的编程实例。

#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
int port = 9889;
void main() {
  int sockfd, n;
  int circle = 0;
  int process;
  char sendbuf[128]; // for sending messages
  char recvbuf[128]; // for receive messages
  struct sockaddr_in addr;
  
  sockfd = socket(AF_INET, SOCK_DGRAM, 0);
  if (sockfd== -1) {
    perror("Opening socket");
    exit(1);
  }
  memset(&addr, 0, sizeof(addr));
  addr.sin_family = AF_INET;
  addr.sin_addr.s_addr = inet_addr("127.0.0.1");
  addr.sin_port = htons(port);
  process = 1;
  do {
      	sprintf(sendbuf,"data packet with ID %d\n", circle);
      	if (circle >10) {
      		sprintf(sendbuf, "stop\n");
    	  	process = 0;
      	}
	if (sendto(sockfd,sendbuf, sizeof(sendbuf),0,(struct sockaddr *)&addr, sizeof(addr))< 0) {
  	    	perror("Trying to sendto");
      		exit(1);
  	}
	n = recvfrom(sockfd,recvbuf, sizeof(recvbuf),0,NULL,NULL);
	recvbuf[n] = 0;
	fputs(recvbuf,stdout);
    	circle++;
  } while (process);
}