udp_client.c

linux下简单的UDP传输文件功能

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

#define PORT 1234
#define MAXDATASIZE 100

int main(int argc, char **argv)
{
	int fd,numbytes;
	char buf[MAXDATASIZE];
	struct hostent *he;
	struct sockaddr_in server,reply;
	if(argc != 3)
	{
		printf("Usage: %s <IP Address><message>\n",argv[0]);
		exit(1);
	}
	if((he = gethostbyname(argv[1])) == NULL)
	{
		printf("gethostbyname error.\n");
		exit(1);
	}
	if((fd = socket(AF_INET,SOCK_DGRAM,0)) == -1)
	{
		printf("socket error.\n");
		exit(1);
	}
	bzero(&server,sizeof(server));
	server.sin_family = AF_INET;
	server.sin_port = htons(PORT);
	server.sin_addr = *((struct in_addr *)he->h_addr);
	sendto(fd,argv[2],strlen(argv[2]),0,(struct sockaddr *)&server,sizeof(struct sockaddr));
	while(1)
	{
		int len;
		if((numbytes = recvfrom(fd,buf,MAXDATASIZE,0,(struct sockaddr *)&reply,&len)) == -1)
		{
			printf("recvfrom error.\n");
			exit(1);
		}
		if(len != sizeof(struct sockaddr) || memcmp((const void *)&server,(const void *)&reply,len) != 0)
		{
			printf("receive message from oth sever.\n");
			continue;
		}
		buf[numbytes]='\0';
		printf("server message: %s\n",buf);
		break;
	}
	close(fd);
}