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path: root/peer.c
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/* $Id$ */
/*
 * Copyright (c) 2005 Dimitri Sokolyuk <demon@dim13.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/param.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/queue.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>

#include <assert.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "meta.h"
#include "peer.h"	/* not used */
#include "tools.h"	/* peerid() */
#include "files.h"

#ifndef lint
static const char rcsid[] = "@(#)$Id$";
#endif /* not lint */

#define HSLEN		68
#define PROTO		"BitTorrent protocol"
#define PROTOLEN	19
#define FLAGSLEN	8

// LIST_HEAD(btplist, btpeer) phead;

char *
btgethandshake(const u_char *info, const u_char *id)
{
	/* Handshake ::= <plen(1)> <pstr(19)> <flags(8)> <info_hash(20)> <peer_id(20)> */
	static char buf[HSLEN];
	int len, off;

	off = 0; len = 1;
	memset(buf, PROTOLEN, len);
	
	off += len; len = PROTOLEN;
	memcpy(buf + off, PROTO, len);
	
	off += len; len = FLAGSLEN;
	memset(buf + off, 0, len);

	off += len; len = SHA1LEN;
	memcpy(buf + off, info, len);

	off += len; len = SHA1LEN;
	if (id == NULL)
		memset(buf + off, 0, len);
	else
		memcpy(buf + off, id, len);

	return buf;
}

int
btchkhandshake(const char *src, const u_char *info, const u_char *id)
{
	char buf[HSLEN], *etalon;

	if (src == NULL)
		return 0;

	/* ignore flags */
	memcpy(buf, src, HSLEN);
	memset(buf + PROTOLEN + 1, 0, FLAGSLEN);
	etalon = btgethandshake(info, id);

	return (memcmp(buf, etalon, id == NULL ? HSLEN - SHA1LEN : HSLEN) == 0);
}

/**********************************************************************/

int
btaddpeer(struct btplist *plist, struct btpeer *peer)
{
	struct btpeer *p;

	LIST_FOREACH(p, plist, link) {
		if (memcmp(&peer->sin, &p->sin, sizeof(struct sockaddr_in)) == 0) {
			/* found same peer, reset its ttl value */
			p->ttl = MAX_TTL;
			return 1;
		}
	}

	/* initial values */
	setbit(&peer->flags, LOCAL_CHOKED);
	clrbit(&peer->flags, LOCAL_INTERESTED);
	setbit(&peer->flags, REMOTE_CHOKED);
	clrbit(&peer->flags, REMOTE_INTERESTED);
	peer->ttl = MAX_TTL;
	peer->state = IDLE;
	LIST_INSERT_HEAD(plist, peer, link);

	return 0;
}

void
btdumpplist(struct btplist *plist)
{
	struct btpeer *p;
	int i = 0;

	LIST_FOREACH(p, plist, link) {
		printf("%2d: %s:%d (%d) %c%c:%c%c\n",
			++i,
			inet_ntoa(p->sin.sin_addr),
			ntohs(p->sin.sin_port),
			p->ttl,
			"cC"[!!isset(&p->flags, LOCAL_CHOKED)],
			"iI"[!!isset(&p->flags, LOCAL_INTERESTED)],
			"cC"[!!isset(&p->flags, REMOTE_CHOKED)],
			"iI"[!!isset(&p->flags, REMOTE_INTERESTED)]
			);
	}
}

int
btclearoldpeers(struct btplist *plist)
{
	struct btpeer *p, *nxt;
	int n = 0;

	for (p = LIST_FIRST(plist); p != NULL; p = nxt) {
		nxt = LIST_NEXT(p, link);
		if (--p->ttl <= 0 && p->state == FAILED) {
			LIST_REMOVE(p, link);
			free(p);
		} else
			++n;
	}

	return n;
}

void
btdelplist(struct btplist *plist)
{
	struct btpeer *p, *nxt;

	for (p = LIST_FIRST(plist); p != NULL; p = nxt) {
		nxt = LIST_NEXT(p, link);
		free(p);
	}
	LIST_INIT(plist);
}

void
btdbg(struct btpeer *p, char *fmt, ...)
{
	va_list ap;

	va_start(ap, fmt);
	fprintf(stderr, "%s:%d ",
		inet_ntoa(p->sin.sin_addr),
		ntohs(p->sin.sin_port));
	vfprintf(stderr, fmt, ap);
	va_end(ap);
}

/**********************************************************************/

// newpeer()
/* alloc space, alloc 68 bytes for msgbuf (handshake length) */

#if 0
int
chkhandshake(struct btpeer *p)
{
	char	buf[20];

	read(p->sockd, buf, 1);
	if (*buf != 19)
		drop(p);
	read(p->sockd, buf, 19);
	if (memcmp(buf, "Bittorrent Protocol", 19) != 0)
		drop(p);
	read(p->sockd, buf, 8);
	read(p->sockd, buf, 20);
	if (memcmp(buf, mp->infohash, 20) != 0)
		drop(p);
	read(p->sockd, buf, 20);
	memcpy(p->peerid, buf, 20);

//	nonblock(p->sockid);
	return 0;
}


int
readmsg(struct btpeer *p)
{
	size_t len, ret;

	if (p->msgbuf == NULL) {
		read(p->sockd, &len, sizeof(size_t));
		p->buflen = ntohl(len);
		p->msgbuf = malloc(p->buflen);
		p->bufoff = 0;
	} else {
		ret = read(p->sockd, p->msgbuf + p->bufoff, p->buflen - p->bufoff);
		p->bufoff += ret;
	}

	if (p->msgbuf != NULL && p->buflen - p->bufoff == 0) {
		dispatch(p);
		free(p->msgbuf);
		p->msgbuf = NULL;
	}
}

int
dispatch(struct btmeta *mp, struct btpeer *p)
{
	int piece, offset, length;

	switch (p->state) {
	case IDLE:
	case CONNECTING:
	case HANDSHAKE:
	case SUCCESS:
		switch (*p->msgbuf) {
		case MSG_CHOKE:
			setbit(&p->flags, REMOTE_CHOKED);
			break;
		case MSG_UNCHOKE:
			clrbit(&p->flags, REMOTE_CHOKED);
			break;
		case MSG_INTERESTED:
			setbit(&p->flags, REMOTE_INTERESTED);
			break;
		case MSG_UNINTERESTED:
			clrbit(&p->flags, REMOTE_INTERESTED);
			break;
		case MSG_HAVE:
			piece = htonl(*(int *)&p->msgbuf[1]);
			btsetbit(p->bitfield, piece);

			sendhave();

			break;
		case MSG_BITFIELD:
			memcpy(p->bitfield, &p->msgbuf[1], p->buflen);
			break;
		case MSG_REQUEST:
			piece = ntohl(*(int *)&p->msgbuf[1]);
			offset = ntohl(*(int *)&p->msgbuf[5]);
			length = ntohl(*(int *)&p->msgbuf[9]);

			btallocrequest(mp, p, piece, offset, length);
			break;
		case MSG_PIECE:
			piece = ntohl(*(int *)&p->msgbuf[1]);
			offset = ntohl(*(int *)&p->msgbuf[5]);
			length = p->length - 9;

			btwriterequest(p, piece, offset, length, &p->msgbuf[9]);
			btfreerequest(mp, p, piece, offset, length);
			break;
		case MSG_CANCEL:
			piece = ntohl(*(int *)&p->msgbuf[1]);
			offset = ntohl(*(int *)&p->msgbuf[5]);
			length = ntohl(*(int *)&p->msgbuf[9]);
			btfreerequest(mp, p, piece, offset, length);
			break;
		}
		break;
	case FAILED:
	}
}


#endif

/**********************************************************************/

/* messages:
-1 keep alive	| length int |
 0 choke	| length int | id char |
 1 unchoke 	| length int | id char |
 2 interested 	| length int | id char |
 3 uninterested	| length int | id char |
 4 bitfield	| length int | id char | bitfield bfsz |
 5 have		| length int | id char | piece int |
 6 request	| length int | id char | piece int | offset int | length int |
 7 piece	| length int | id char | piece int | offset int | data blksz |
 8 cancel	| length int | id char | piece int | offset int | lenght int |
 */

char *
btmessage(struct btmeta *m, struct btpeer *p, size_t *mlen)
{
	size_t	off;
	int	tmp;
	char	*buf;

	*mlen = sizeof(int);
	if (p->msg >= MSG_CHOKE)
		*mlen += sizeof(char);
	if (p->msg == MSG_BITFIELD)
		*mlen += m->bitlen;
	if (p->msg >= MSG_HAVE)
		*mlen += sizeof(int);
	if (p->msg >= MSG_REQUEST) {
		*mlen += sizeof(int);
		if (p->msg == MSG_PIECE)
			*mlen += BLOCKSZ;
		else
			*mlen += sizeof(int);
	}

	buf = calloc(*mlen, sizeof(char));
	if (buf == NULL)
		return NULL;

	tmp = htonl(*mlen - sizeof(int));
	memcpy(buf, &tmp, sizeof(int));
	off = sizeof(int);

	if (p->msg >= MSG_CHOKE) {
		memcpy(buf + off, &p->msg, sizeof(char));
		off += sizeof(char);
	}
	if (p->msg == MSG_BITFIELD)
		memcpy(buf + off, m->bitfield, m->bitlen);
	if (p->msg >= MSG_HAVE) {
		tmp = htonl(p->piece);
		memcpy(buf + off, &tmp, sizeof(int));
		off += sizeof(int);
	}
	if (p->msg >= MSG_REQUEST) {
		tmp = htonl(p->offset);
		memcpy(buf + off, &tmp, sizeof(int));
		off += sizeof(int);
		if (p->msg == MSG_PIECE)
			memcpy(buf + off, p->data, BLOCKSZ);
		else {
			tmp = htonl(p->length);
			memcpy(buf + off, &tmp, sizeof(int));
		}
	}

	return buf;
}

void
handlemsg(struct btmeta *mp, struct btpeer *p, char *buf, size_t buflen)
{
	size_t length;
	enum msg msg;
	int piece, offset, blklen;

	length = ntohl(*(int *)buf);
	buf += sizeof(int);

	if (length == 0)
		return;

	msg = *(char *)buf;
	buf += sizeof(char);
	length -= sizeof(char);

	switch (msg) {
	case MSG_CHOKE:
		setbit(&p->flags, REMOTE_CHOKED);
		break;
	case MSG_UNCHOKE:
		clrbit(&p->flags, REMOTE_CHOKED);
		break;
	case MSG_INTERESTED:
		setbit(&p->flags, REMOTE_INTERESTED);
		break;
	case MSG_UNINTERESTED:
		clrbit(&p->flags, REMOTE_INTERESTED);
		break;
	case MSG_HAVE:
		assert(p->bitfield);
		piece = htonl(*(int *)buf);
		btsetbit(p->bitfield, piece);
		break;
	case MSG_BITFIELD:
		if (p->bitfield == NULL) {
			p->bitfield = calloc(length, sizeof(char));
			assert(p->bitfield);
		}
		memcpy(p->bitfield, buf, length);
		break;
	case MSG_REQUEST:
		piece = htonl(*(int *)buf);
		buf += sizeof(int);
		offset = htonl(*(int *)buf);
		buf += sizeof(int);
		blklen = htonl(*(int *)buf);

	 	if (p->data == NULL) {
			p->data = calloc(mp->plength, sizeof(char));
			assert(p->data);
		//	btread(mp, p->data, piece);
		}

		/* XXX send, put on queue */

		break;
	case MSG_PIECE:
		piece = htonl(*(int *)buf);
		buf += sizeof(int);
		offset = htonl(*(int *)buf);
		blklen = buflen - sizeof(int) * 2;

	 	if (p->data == NULL) {
			p->data = calloc(mp->plength, sizeof(char));
			assert(p->data);
		}

		/* XXX recieve, put on queue */

		break;
	case MSG_CANCEL:
		piece = htonl(*(int *)buf);
		buf += sizeof(int);
		offset = htonl(*(int *)buf);
		buf += sizeof(int);
		blklen = htonl(*(int *)buf);

		/* XXX remove from queue */

		break;
	default:
		break;
	}
}

#if 0
payload(enum msg *msg)
{
	switch (msg) {
	case MSG_CHOKE:
	case MSG_UNCHOKE:
	case MSG_INTERESTED:
	case MSG_UNINTERESTED:
		buf[0] = (int)4;
		buf[3] = (char)msg;
	}
}

btsndchoked(struct btpeer *p)
{
	/* | length | id */
	int buf[2];

	p->msg = MSG_CHOKE;

	buf[0] = sizeof(p->msg);
	buf[1] = p->msg;
}

btsndhave(struct btpeer *p)
{
	int buf[3];
	p->msg = MSG_HAVE;

	buf[0] = sizeof(p->msg) + sizeof(p->piece);
	buf[1] = p->msg;
	buf[2] = p->piece;
}
#endif