proxy1.c

代理

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#include <string.h>
#define BUF_SIZE 1500		/* block transfer size */
#define QUEUE_SIZE 10

int             content_length = -1;
int             head_length = 0;
int             port = 80;
int             len = 0;/*the length of the domain name*/

void
fatal(char *string)
{
	printf("%s\n", string);
	exit(1);
}

void
getDomainName(char name[], char buffer[])
{
	int             i = 0, j = 0, k = 0;
	for (i = 0; i < BUF_SIZE; i++) {
		if (buffer[i] == 'H' && buffer[i + 1] == 'o' && buffer[i + 2] == 's'		/*host*/
		    && buffer[i + 3] == 't') {
			i = i + 6;
			j = i;
			for (; j < BUF_SIZE; j++) {
				if (buffer[j] == '\r' && buffer[j + 1] == '\n') {	/*enter*/
					memcpy(name, buffer + i, j - i);				/*name*/
					len = j - i;

					//printf("j=%d , i=%d\n", j, i);
					return;
				}
			}
		}
	}
}

int
getPort(char name[])
{
	int             i = len - 1;
	for (; i > len - 7; i--) {/*the last 6 char*/
		if (name[i] == ':') {
			int             p = 0;
			char            num[5] = " ";
			memcpy(num, name + i + 1, len - 1 - i);/*port*/

	//delete:	from name
				for (; i <= len - 1; i++)
				name[i] = ' ';
			p = atoi(num);		/*change string to integer*/
			printf("port in loop=%d\n", p);
			return p;
		}
	}
	return 80;
}

int
pickContentLength(char buffer[], int reads)
{
	int             i = 0, j = 0;
	head_length = 0;
	for (; head_length < reads; head_length++) {
		if (buffer[head_length] == '\r' && buffer[head_length + 3] == '\n') {
			head_length += 4;
			break;
		}
	}/* a new line*/
	i = 0;
	j = 0;
	content_length = -1;
	for (; i < reads; i++) {
		if (buffer[i] == '-' && buffer[i + 1] == 'L' && buffer[i + 2] == 'e'		/*-Length:*/
		    && buffer[i + 3] == 'n' && buffer[i + 4] == 'g'
		    && buffer[i + 5] == 't' && buffer[i + 7] == ':') {
			char            length[100] = " ";
			i = i + 9;/*skip -Length:*/
			j = i;
			for (; j < reads; j++) {
				if (buffer[j] == '\r' && buffer[j + 1] == '\n') {/*a new line*/
					memcpy(length, buffer + i, j - i);/*string between*/
					content_length = atoi(length);
					return content_length;
				}
			}
		}
	}
	return -1;
}

int
checkHost(char name[])
{
	int             i = 0;
	int             has = 0;
	for (; i < 100; i++) {
		if (name[i + 6] == '.' && name[i] == 'g' && name[i + 5] == 'e'
		    && name[i + 3] == 'g' && name[i + 1] == 'o')	/*go g e.*/
			has = 1;
		if (name[i] = '.' && name[i + 1] == 'e' && name[i + 2] == 'd'
		    && name[i + 3] == 'u' && name[i + 4] == '.')	/*.edu.*/
			has = 1;
	}
	return has;
}

int
main(int argc, char *argv[])
{
	if (argc < 5) {
		printf("Arguments must like:./proxy1 -l port1 -t machine:port2\nSample:./proxy1 -l 3000 -t localhost:8000\n");
		exit(1);
	}
	if (argc > 5) {
		printf("Arguments must like:./proxy1 -l port1 -t machine:port2\nSample:./proxy1 -l 3000 -t localhost:8000\n");
		exit(2);
	}
	char *myport = argv[2], *deip=argv[4];	

	//server variables
		int             s, b, l, fd, sa, bytes, on = 1;
	char            buf[BUF_SIZE];	/* buffer for outgoing file */
	struct sockaddr_in channel;	/* holds IP address */

	//client variables
		int             c_cli, s_cli, bytes_cli;
	char            buf_cli[BUF_SIZE];	/* buffer for incoming file */
	struct hostent *h_cli;	/* info about server */
	struct sockaddr_in channel_cli;	/* holds IP address */

	/* Build address structure to bind to socket. */
	memset(&channel, 0, sizeof(channel));	/* zerochannel void *memset(void *s, char ch, unsigned n);*/
	channel.sin_family = AF_INET;
	channel.sin_addr.s_addr = htonl(INADDR_ANY);
	channel.sin_port = htons(atoi(myport));		/*3000*/

	/* Passive open. Wait for connection. */
	s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);	/* createsocket */
	if (s < 0)
		fatal("socket failed");
	setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (char *) &on, sizeof(on));
	b = bind(s, (struct sockaddr *) & channel, sizeof(channel));
	if (b < 0)
		fatal("bind failed");
	l = listen(s, QUEUE_SIZE);	/* specify queue size */
	if (l < 0)
		fatal("listen failed");

	/*
	 * Socket is now set up and bound. Wait for connection and process
	 * it.
	 */
	while (1) {
		printf("Listening for socket connection...\n");
		sa = accept(s, 0, 0);	/* block for connection request */
		printf("accept\n");
		if (sa < 0) {
			printf("sa failed\n");
			continue;
		}
		int             r1 = read(sa, buf, BUF_SIZE);	/* read file name from * socket */
		char            domainName[250] = " ";
		getDomainName(domainName, buf);
		printf("before get port!\nThe domainName=%s\n",domainName);
		port = getPort(domainName);
		if (port != 80) {
			printf("Unsupported port !%d \n", port);
			continue;
		}
		h_cli = gethostbyname(domainName);	/* look up host's IP
							 * address */
		
		if (!h_cli) {
			printf("gethostbyname failed\n");
			continue;
		}
		
		s_cli = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
		if (s_cli < 0) {
			printf("socket error\n");
			continue;
		}

		printf("\nstart hostent\n");
		struct hostent *h_udp;
		char udp_name[50]=" ";
		char udp_port[50]=" ";
		int i=0,j=0;
		while(!(deip[j]=='\0')){
			if(deip[j]==':'){
				i=j;			
			}		
			j++;
			//printf("The char in domainname:%c ",deip[i]);		
		}
		memcpy(udp_name, deip, i);
		printf("The domain name = %s",udp_name);
		memcpy(udp_port, deip+i+1,j-i-1);
		printf("The port = %s",udp_port);
		h_udp = gethostbyname(udp_name);
		
		if(!h_udp){
			printf("gethostbyname failed\n");
			continue;		
		}
		/*memset(&channel_cli, 0, sizeof(channel_cli));
		channel_cli.sin_family = AF_INET;
		memcpy(&channel_cli.sin_addr.s_addr, h_cli->h_addr, h_cli->h_length);
		channel_cli.sin_port = htons(port);*/		
		
		memset(&channel_cli, 0, sizeof(channel_cli));
		channel_cli.sin_family = AF_INET;
		memcpy(&channel_cli.sin_addr.s_addr, h_udp->h_addr, h_udp->h_length);
		channel_cli.sin_port = htons(atoi(udp_port));		

		int addr_len=sizeof(channel_cli);
		c_cli = sendto(s_cli, buf, BUF_SIZE, 0, (struct sockaddr *)&channel_cli,addr_len);

		if (c_cli < 0) {
			printf("Failed to send to UDP\n");
			continue;
		}
		int             check = checkHost(domainName);
		
		bytes_cli = recvfrom(s_cli,buf_cli,BUF_SIZE,0 ,(struct sockaddr *)&channel_cli ,&addr_len);
		content_length = pickContentLength(buf_cli, bytes_cli);
		printf("content_length=%d\n", content_length);
		int             content_length_fixed = content_length;

			write(sa, buf_cli, bytes_cli);
		int             tail = bytes_cli - head_length;/*head_length=1*/
		content_length = content_length - tail;
		if (content_length_fixed <= -1) {
			while (1) {
				/*bytes_cli = read(s_cli, buf_cli, BUF_SIZE);	/* read from socket */
				bytes_cli = recvfrom(s_cli,buf_cli,BUF_SIZE,0 ,(struct sockaddr *)&channel_cli ,&addr_len);
				printf("[Chunck: Bytes Read]: %d \n", bytes_cli);
				write(sa, buf_cli, bytes_cli);	/* write back to host */
				if (bytes_cli <= 0) {
					printf("Chunck:Read data OK!\n");
					break;	/* check for end of file */
				}
			}
		}
		if (content_length > 0) {
			while (content_length > 0) {
				/*bytes_cli = read(s_cli, buf_cli, BUF_SIZE);	/* read from socket */
				bytes_cli = recvfrom(s_cli,buf_cli,BUF_SIZE,0 ,(struct sockaddr *)&channel_cli ,&addr_len);
				write(sa, buf_cli, bytes_cli);	/* write back to host */
				content_length -= bytes_cli;
				printf("Bytes Read: %d\n", bytes_cli);
				if (bytes_cli <= 0) {
					printf("Read data OK!\n");
					break;	/* check for end of file */
				}
			}
		}
		printf("Now close sa\n");
		close(sa);	/* close connection */
	}
}