wastecat的博客

#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
 
typedef struct sockaddr SA;
 
const unsigned short PORT = 38000;
 
const unsigned char LOGIN = 0x01;
const unsigned char PEER = 0x02;
 
void wait_login(int sock, struct sockaddr_in* remoteaddr, socklen_t* paddrlen)
{
	int index = 0;
 
	while (index < 2)
	{
		int n;
		char buf[16];
 
		if ((n = recvfrom(sock, buf, 16, 0, (SA*)&remoteaddr[index], paddrlen)) < 0)
		{
			perror("recvfrom");
			exit(errno);
		}
		if (n != 1 || buf[0] != LOGIN)
			continue;	/* ignore it */
		++index;
	}
}
 
void send_peer(int sock, struct sockaddr_in* remoteaddr, int from, int to)
{
	char ip[INET_ADDRSTRLEN];
	char buf[1024];
	buf[0] = PEER;
 
	if (inet_ntop(AF_INET, &remoteaddr[from].sin_addr, ip, INET_ADDRSTRLEN) == NULL)
	{
		perror("inet_ntop");
		exit(errno);
	}
	snprintf(buf + 1, 1023, "%s:%d", ip, ntohs(remoteaddr[from].sin_port));
	printf("sending message: %s\n", buf + 1);
	if (sendto(sock, buf, strlen(buf + 1) + 1, 0, (SA*)&remoteaddr[to], sizeof(remoteaddr[to])) < 0)
	{
		perror("sendto");
		exit(errno);
	}
}
 
int main()
{
	int sock;
	struct sockaddr_in localaddr;
	struct sockaddr_in remoteaddr[2];
	socklen_t addrlen = sizeof(remoteaddr[0]);
 
	sock = socket(AF_INET, SOCK_DGRAM, 0);
	if (sock < 0)
	{
		perror("socket");
		exit(errno);
	}
 
	bzero(&localaddr, sizeof(localaddr));
	localaddr.sin_family = AF_INET;
	localaddr.sin_addr.s_addr = htonl(INADDR_ANY);
	localaddr.sin_port = htons(PORT);
	if (bind(sock, (SA*)&localaddr, sizeof(localaddr)) < 0)
	{
		perror("bind");
		exit(errno);
	}
 
	while (1)
	{
		wait_login(sock, remoteaddr, &addrlen);
		send_peer(sock, remoteaddr, 0, 1);
		send_peer(sock, remoteaddr, 1, 0);
	}
 
	return 0;
}

#include <netdb.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <sys/socket.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
 
#define max(a, b) ((a) > (b)?(a):(b))
 
const unsigned short PORT = 38000;
 
const unsigned char LOGIN = 0x01;
const unsigned char PEER = 0x02;
const unsigned char HELLO = 0x03;
const unsigned char MSG = 0x04;
 
typedef struct sockaddr SA;
 
int init_svraddr(const char* server, struct sockaddr_in* svrAddr, socklen_t len)
{
	struct hostent* ent = gethostbyname(server);
	if (ent == NULL)
	{
		fprintf(stderr, "gethostbyname:%s\n", hstrerror(h_errno));
		return -1;
	}
 
	bzero(svrAddr, len);
	svrAddr->sin_family = AF_INET;
	svrAddr->sin_port = htons(PORT);
	svrAddr->sin_addr = *(in_addr*)*ent->h_addr_list;
	return 0;
}
 
int login(int sock, struct sockaddr_in* svrAddr, socklen_t len)
{
	if (connect(sock, (SA*)svrAddr, len) < 0)
		return -1;
	if (write(sock, &LOGIN, sizeof(LOGIN)) < 0)
		return -1;
	return 0;
}
 
int get_peer_info(int sock, char* addrport, int len)
{
	int i, j;
	if ((i = read(sock, addrport, len)) < 0)
		return -1;
	if (*addrport != PEER)
		return -1;
 
	for (j = 0; j < i - 1; ++j)
		addrport[j] = addrport[j + 1];
	addrport[j] = '\0';
	return 0;
}
 
int say_hello_peer(int sock, struct sockaddr* addr, socklen_t len)
{
	if (connect(sock, addr, len) < 0)
		return -1;
	if (write(sock, &HELLO, sizeof(HELLO)) < 0)
 		return -1;
 	return 0; 
} 
 
int ptoap(char* str, struct sockaddr_in* addr, socklen_t len) 
{
 	char* p;
 	bzero(addr, len);
 	addr->sin_family = AF_INET;
 
	p = strchr(str, ':');
	*p = '\0';
	if (inet_pton(AF_INET, str, &addr->sin_addr) < 0)
 		return -1;
 	addr->sin_port = htons(atoi(p + 1));
	return 0;
}
 
const char* SERVER = "198.56.248.214";
 
int main()
{
	int sock;
	char addrport[256];
	struct sockaddr_in svrAddr;
	struct sockaddr_in peeraddr;
 
	sock = socket(AF_INET, SOCK_DGRAM, 0);
	if (sock < 0)
	{
		perror("socket");
		exit(errno);
	}
 
	if (init_svraddr(SERVER, &svrAddr, sizeof(svrAddr)) == -1)
		exit(-1);
 
	printf("Sending login\n");
	if (login(sock, &svrAddr, sizeof(svrAddr)) == -1)
	{
		perror("login");
		exit(errno);
	}
 
	printf("Getting peer info\n");
	if (get_peer_info(sock, addrport, 256) == -1)
	{
		perror("get_peer_info");
		exit(errno);
	}
	printf("Peer info: %s\n", addrport);
 
	if (ptoap(addrport, &peeraddr, sizeof(peeraddr)) == -1)
	{
		perror("ptoap");
		exit(errno);
	}
 
	if (say_hello_peer(sock, (SA*)&peeraddr, sizeof(peeraddr)) == -1)
	{
		perror("say_hello_peer");
		exit(errno);
	}
 
	while (true)
	{
		fd_set sockstdin;
		int maxFd;
		int n;
		char buf[4096];
 
		FD_ZERO(&sockstdin);
		FD_SET(STDIN_FILENO, &sockstdin);
		FD_SET(sock, &sockstdin);
		maxFd = max(sock, STDIN_FILENO);
 
		if (select(maxFd + 1, &sockstdin, NULL, NULL, NULL) < 0)
		{
			perror("select");
			exit(errno);
		}
 
		if (FD_ISSET(STDIN_FILENO, &sockstdin))
		{
 
			if ((n = read(STDIN_FILENO, buf, 4096)) < 0)
			{
				perror("read");
				exit(errno);
			}
			else if (n == 0)
			{
				exit(0);	/* exit normally */
			}
			if (write(sock, buf, n) < 0)
			{
				perror("sendto");
				exit(errno);
			}
		}
		if (FD_ISSET(sock, &sockstdin))
		{
			if ((n = read(sock, buf, 4096)) < 0)
			{
				perror("read");
				exit(errno);
			}
			if (write(STDOUT_FILENO, buf, n) < 0)
			{
				perror("write");
				exit(errno);
			}
		}
	}
 
	return 0;
}