ft.c

oscar message protocol stack

/*
 * Oscar File transfer (OFT) and Oscar Direct Connect (ODC).
 * (ODC is also referred to as DirectIM and IM Image.)
 *
 * There are a few static helper functions at the top, then 
 * ODC stuff, then ft stuff.
 *
 * I feel like this is a good place to explain OFT, so I'm going to 
 * do just that.  Each OFT packet has a header type.  I guess this 
 * is pretty similar to the subtype of a SNAC packet.  The type 
 * basically tells the other client the meaning of the OFT packet.  
 * There are two distinct types of file transfer, which I usually 
 * call "sendfile" and "getfile."  Sendfile is when you send a file 
 * to another AIM user.  Getfile is when you share a group of files, 
 * and other users request that you send them the files.
 *
 * A typical sendfile file transfer goes like this:
 *   1) Sender sends a channel 2 ICBM telling the other user that 
 *      we want to send them a file.  At the same time, we open a 
 *      listener socket (this should be done before sending the 
 *      ICBM) on some port, and wait for them to connect to us.  
 *      The ICBM we sent should contain our IP address and the port 
 *      number that we're listening on.
 *   2) The receiver connects to the sender on the given IP address 
 *      and port.  After the connection is established, the receiver 
 *      sends an ICBM signifying that we are ready and waiting.
 *   3) The sender sends an OFT PROMPT message over the OFT 
 *      connection.
 *   4) The receiver of the file sends back an exact copy of this 
 *      OFT packet, except the cookie is filled in with the cookie 
 *      from the ICBM.  I think this might be an attempt to verify 
 *      that the user that is connected is actually the guy that 
 *      we sent the ICBM to.  Oh, I've been calling this the ACK.
 *   5) The sender starts sending raw data across the connection 
 *      until the entire file has been sent.
 *   6) The receiver knows the file is finished because the sender 
 *      sent the file size in an earlier OFT packet.  So then the 
 *      receiver sends the DONE thingy (after filling in the 
 *      "received" checksum and size) and closes the connection.
 */

#define FAIM_INTERNAL
#ifdef HAVE_CONFIG_H
#include  <config.h>
#endif

#include <aim.h>

#ifndef _WIN32
#include <stdio.h>
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/utsname.h> /* for aim_odc_initiate */
#include <arpa/inet.h> /* for inet_ntoa */
#include <limits.h> /* for UINT_MAX */
#define G_DIR_SEPARATOR '/'
#endif

#ifdef _WIN32
#include "win32dep.h"
#endif

/*
 * I really want to switch all our networking code to using IPv6 only,
 * but that really isn't a good idea at all.  Evan S. of Adium says
 * OS X sets all connections as "AF_INET6/PF_INET6," even if there is
 * nothing inherently IPv6 about them.  And I feel like Linux kernel
 * 2.6.5 is doing the same thing.  So we REALLY should accept
 * connections if they're showing up as IPv6.  Old OSes (Solaris?)
 * that might not have full IPv6 support yet will fail if we try
 * to use PF_INET6 but it isn't defined.  --Mark Doliner
 */
#ifndef PF_INET6
#define PF_INET6 PF_INET
#endif

struct aim_odc_intdata {
	fu8_t cookie[8];
	char sn[MAXSNLEN+1];
	char ip[22];
};

/**
 * Convert the directory separator from / (0x2f) to ^A (0x01)
 *
 * @param name The filename to convert.
 */
static void aim_oft_dirconvert_tostupid(char *name)
{
	while (name[0]) {
		if (name[0] == 0x01)
			name[0] = G_DIR_SEPARATOR;
		name++;
	}
}

/**
 * Convert the directory separator from ^A (0x01) to / (0x2f)
 *
 * @param name The filename to convert.
 */
static void aim_oft_dirconvert_fromstupid(char *name)
{
	while (name[0]) {
		if (name[0] == G_DIR_SEPARATOR)
			name[0] = 0x01;
		name++;
	}
}

/**
 * Calculate oft checksum of buffer
 *
 * Prevcheck should be 0xFFFF0000 when starting a checksum of a file.  The 
 * checksum is kind of a rolling checksum thing, so each time you get bytes 
 * of a file you just call this puppy and it updates the checksum.  You can 
 * calculate the checksum of an entire file by calling this in a while or a 
 * for loop, or something.
 *
 * Thanks to Graham Booker for providing this improved checksum routine, 
 * which is simpler and should be more accurate than Josh Myer's original 
 * code. -- wtm
 *
 * This algorithm works every time I have tried it.  The other fails 
 * sometimes.  So, AOL who thought this up?  It has got to be the weirdest 
 * checksum I have ever seen.
 *
 * @param buffer Buffer of data to checksum.  Man I'd like to buff her...
 * @param bufsize Size of buffer.
 * @param prevcheck Previous checksum.
 */
faim_export fu32_t aim_oft_checksum_chunk(const fu8_t *buffer, int bufferlen, fu32_t prevcheck)
{
	fu32_t check = (prevcheck >> 16) & 0xffff, oldcheck;
	int i;
	unsigned short val;

	for (i=0; i<bufferlen; i++) {
		oldcheck = check;
		if (i&1)
			val = buffer[i];
		else
			val = buffer[i] << 8;
		check -= val;
		/*
		 * The following appears to be necessary.... It happens 
		 * every once in a while and the checksum doesn't fail.
		 */
		if (check > oldcheck)
			check--;
	}
	check = ((check & 0x0000ffff) + (check >> 16));
	check = ((check & 0x0000ffff) + (check >> 16));
	return check << 16;
}

faim_export fu32_t aim_oft_checksum_file(char *filename) {
	FILE *fd;
	fu32_t checksum = 0xffff0000;

	if ((fd = fopen(filename, "rb"))) {
		int bytes;
		fu8_t buffer[1024];

		while ((bytes = fread(buffer, 1, 1024, fd)))
			checksum = aim_oft_checksum_chunk(buffer, bytes, checksum);
		fclose(fd);
	}

	return checksum;
}

/**
 * After establishing a listening socket, this is called to accept a connection.  It
 * clones the conn used by the listener, and passes both of these to a signal handler.
 * The signal handler should close the listener conn and keep track of the new conn,
 * since this is what is used for file transfers and what not.
 *
 * @param sess The session.
 * @param cur The conn the incoming connection is on.
 * @return Return 0 if no errors, otherwise return the error number.
 */
faim_export int aim_handlerendconnect(aim_session_t *sess, aim_conn_t *cur)
{
	int acceptfd = 0;
	struct sockaddr addr;
	socklen_t addrlen = sizeof(addr);
	int ret = 0;
	aim_conn_t *newconn;
	char ip[20];
	unsigned short port;

	if ((acceptfd = accept(cur->fd, &addr, &addrlen)) == -1)
		return 0; /* not an error */

	if ((addr.sa_family != PF_INET) && (addr.sa_family != PF_INET6)) {
		close(acceptfd);
		aim_conn_close(cur);
		return -1;
	}

	strncpy(ip, inet_ntoa(((struct sockaddr_in *)&addr)->sin_addr), sizeof(ip));
	port = ntohs(((struct sockaddr_in *)&addr)->sin_port);

	if (!(newconn = aim_cloneconn(sess, cur))) {
		close(acceptfd);
		aim_conn_close(cur);
		return -ENOMEM;
	}

	newconn->type = AIM_CONN_TYPE_RENDEZVOUS;
	newconn->fd = acceptfd;

	if (newconn->subtype == AIM_CONN_SUBTYPE_OFT_DIRECTIM) {
		aim_rxcallback_t userfunc;
		struct aim_odc_intdata *priv;

		priv = (struct aim_odc_intdata *)(newconn->internal = cur->internal);
		cur->internal = NULL;
		snprintf(priv->ip, sizeof(priv->ip), "%s:%hu", ip, port);

		if ((userfunc = aim_callhandler(sess, newconn, AIM_CB_FAM_OFT, AIM_CB_OFT_DIRECTIM_ESTABLISHED)))
			ret = userfunc(sess, NULL, newconn, cur);

	} else if (newconn->subtype == AIM_CONN_SUBTYPE_OFT_GETFILE) {
	} else if (newconn->subtype == AIM_CONN_SUBTYPE_OFT_SENDFILE) {
		aim_rxcallback_t userfunc;

		if ((userfunc = aim_callhandler(sess, newconn, AIM_CB_FAM_OFT, AIM_CB_OFT_ESTABLISHED)))
			ret = userfunc(sess, NULL, newconn, cur);

	} else {
		faimdprintf(sess, 1,"Got a connection on a listener that's not rendezvous.  Closing connection.\n");
		aim_conn_close(newconn);
		ret = -1;
	}

	return ret;
}

/**
 * Send client-to-client typing notification over an established direct connection.
 *
 * @param sess The session.
 * @param conn The already-connected ODC connection.
 * @param typing If 0x0002, sends a "typing" message, 0x0001 sends "typed," and 
 *        0x0000 sends "stopped."
 * @return Return 0 if no errors, otherwise return the error number.
 */
faim_export int aim_odc_send_typing(aim_session_t *sess, aim_conn_t *conn, int typing)
{
	struct aim_odc_intdata *intdata = (struct aim_odc_intdata *)conn->internal;
	aim_frame_t *fr;
	aim_bstream_t *hdrbs;
	fu8_t *hdr;
	int hdrlen = 0x44;

	if (!sess || !conn || (conn->type != AIM_CONN_TYPE_RENDEZVOUS))
		return -EINVAL;

	if (!(fr = aim_tx_new(sess, conn, AIM_FRAMETYPE_OFT, 0x0001, 0)))
		return -ENOMEM;
	memcpy(fr->hdr.rend.magic, "ODC2", 4);
	fr->hdr.rend.hdrlen = hdrlen + 8;

	if (!(hdr = calloc(1, hdrlen))) {
		aim_frame_destroy(fr);
		return -ENOMEM;
	}

	hdrbs = &(fr->data);
	aim_bstream_init(hdrbs, hdr, hdrlen);

	aimbs_put16(hdrbs, 0x0006);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_putraw(hdrbs, intdata->cookie, 8);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put32(hdrbs, 0x00000000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);

	if (typing == 0x0002)
		aimbs_put16(hdrbs, 0x0002 | 0x0008);
	else if (typing == 0x0001)
		aimbs_put16(hdrbs, 0x0002 | 0x0004);
	else
		aimbs_put16(hdrbs, 0x0002);

	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_putraw(hdrbs, sess->sn, strlen(sess->sn));

	aim_bstream_setpos(hdrbs, 52); /* bleeehh */

	aimbs_put8(hdrbs, 0x00);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put8(hdrbs, 0x00);

	/* end of hdr */

	aim_tx_enqueue(sess, fr);

	return 0;
}

/**
 * Send client-to-client IM over an established direct connection.
 * Call this just like you would aim_send_im, to send a directim.
 * 
 * @param sess The session.
 * @param conn The already-connected ODC connection.
 * @param msg Null-terminated string to send.
 * @param len The length of the message to send, including binary data.
 * @param encoding See the AIM_CHARSET_* defines in aim.h
 * @param isawaymsg 0 if this is not an auto-response, 1 if it is.
 * @return Return 0 if no errors, otherwise return the error number.
 */
faim_export int aim_odc_send_im(aim_session_t *sess, aim_conn_t *conn, const char *msg, int len, int encoding, int isawaymsg)
{
	aim_frame_t *fr;
	aim_bstream_t *hdrbs;
	struct aim_odc_intdata *intdata = (struct aim_odc_intdata *)conn->internal;
	int hdrlen = 0x44;
	fu8_t *hdr;

	if (!sess || !conn || (conn->type != AIM_CONN_TYPE_RENDEZVOUS) || !msg)
		return -EINVAL;

	if (!(fr = aim_tx_new(sess, conn, AIM_FRAMETYPE_OFT, 0x01, 0)))
		return -ENOMEM;

	memcpy(fr->hdr.rend.magic, "ODC2", 4);
	fr->hdr.rend.hdrlen = hdrlen + 8;

	if (!(hdr = calloc(1, hdrlen + len))) {
		aim_frame_destroy(fr);
		return -ENOMEM;
	}

	hdrbs = &(fr->data);
	aim_bstream_init(hdrbs, hdr, hdrlen + len);

	aimbs_put16(hdrbs, 0x0006);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_putraw(hdrbs, intdata->cookie, 8);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put32(hdrbs, len);
	aimbs_put16(hdrbs, encoding);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);

	/* flags - used for typing notification and to mark if this is an away message */
	aimbs_put16(hdrbs, 0x0000 | isawaymsg);

	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_putraw(hdrbs, sess->sn, strlen(sess->sn));

	aim_bstream_setpos(hdrbs, 52); /* bleeehh */

	aimbs_put8(hdrbs, 0x00);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put8(hdrbs, 0x00);

	/* end of hdr2 */

#if 0 /* XXX - this is how you send buddy icon info... */	
	aimbs_put16(hdrbs, 0x0008);
	aimbs_put16(hdrbs, 0x000c);
	aimbs_put16(hdrbs, 0x0000);
	aimbs_put16(hdrbs, 0x1466);
	aimbs_put16(hdrbs, 0x0001);
	aimbs_put16(hdrbs, 0x2e0f);
	aimbs_put16(hdrbs, 0x393e);
	aimbs_put16(hdrbs, 0xcac8);
#endif
	aimbs_putraw(hdrbs, msg, len);

	aim_tx_enqueue(sess, fr);

	return 0;
}

/**
 * Get the screen name of the peer of a direct connection.
 *
 * @param conn The ODC connection.
 * @return The screen name of the dude, or NULL if there was an anomaly.
 */
faim_export const char *aim_odc_getsn(aim_conn_t *conn)
{
	struct aim_odc_intdata *intdata;

	if (!conn || !conn->internal)
		return NULL;

	if ((conn->type != AIM_CONN_TYPE_RENDEZVOUS) ||
			(conn->subtype != AIM_CONN_SUBTYPE_OFT_DIRECTIM))
		return NULL;

	intdata = (struct aim_odc_intdata *)conn->internal;

	return intdata->sn;
}

/**
 * Get the cookie of a direct connection.
 *
 * @param conn The ODC connection.
 * @return The cookie, an 8 byte unterminated string, or NULL if there was an anomaly.
 */
faim_export const char *aim_odc_getcookie(aim_conn_t *conn)
{
	struct aim_odc_intdata *intdata;

	if (!conn || !conn->internal)
		return NULL;

	intdata = (struct aim_odc_intdata *)conn->internal;

	return intdata->cookie;
}

/**
 * Find the conn of a direct connection with the given buddy.
 *
 * @param sess The session.
 * @param sn The screen name of the buddy whose direct connection you want to find.
 * @return The conn for the direct connection with the given buddy, or NULL if no 
 *         connection was found.
 */
faim_export aim_conn_t *aim_odc_getconn(aim_session_t *sess, const char *sn)
{
	aim_conn_t *cur;
	struct aim_odc_intdata *intdata;

	if (!sess || !sn || !strlen(sn))
		return NULL;

	for (cur = sess->connlist; cur; cur = cur->next) {
		if ((cur->type == AIM_CONN_TYPE_RENDEZVOUS) && (cur->subtype == AIM_CONN_SUBTYPE_OFT_DIRECTIM)) {
			intdata = cur->internal;
			if (!aim_sncmp(intdata->sn, sn))
				return cur;
		}
	}

	return NULL;
}