udp.cc

达内IT培训Unix C++第一天源码（共四天） 是入门Unix 下C++编程的好东西

#include <iostream>
using namespace std;
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>
#include <fcntl.h>
#include <cstring>

int main()
{
	short port;
	cout << "input your port:";
	cin >> port;
	sockaddr_in si;
	char ip[100];
	char buf[1000];
	socklen_t len=sizeof(si);
	char cmd;
	int s = socket(AF_INET, SOCK_DGRAM, 0);
	if(s<0){
		cout << "socket error!" << endl;
		return -1;
	}
	si.sin_family = AF_INET;
	si.sin_addr.s_addr=htonl(INADDR_ANY);
	si.sin_port = htons(port);
	if(bind(s,(sockaddr*)&si,len)<0){
		cout << "bind error!" << endl;
		return -1;
	}
	for(;;){
		cout << "r/s/q:";
		cin >> cmd;
		if(cmd=='q')
			break;
		if(cmd=='r'){
			int n=recvfrom(s, buf, 1000, 0, (sockaddr*)&si, &len);
			if(n<0) break;
			buf[n] = '\0';
			inet_ntop(AF_INET,&si.sin_addr,ip,100);
			port = ntohs(si.sin_port);
			cout << ip << '@' << port << ':' << buf << endl;
		}
		else if(cmd=='s'){
			cout << "input ip, port and message:";
			cin >> ip >> port;
			cin.getline(buf, 1000);
			si.sin_port = htons(port);
			inet_pton(AF_INET,ip,&si.sin_addr);
			sendto(s,buf,strlen(buf),0,(sockaddr*)&si,len);
		}
		else{
			cout << "invalid command!" << endl;
		}
	}
	close(s);
}