conn.c

oscar message protocol stack

/**
 * Low-level connection handling.
 *
 * Does all this gloriously nifty connection handling stuff...
 *
 */

#define FAIM_INTERNAL
#define FAIM_NEED_CONN_INTERNAL
#include <aim.h> 

#ifndef _WIN32
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/in.h>
#endif

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

/**
 * In OSCAR, every connection has a set of SNAC groups associated
 * with it.  These are the groups that you can send over this connection
 * without being guaranteed a "Not supported" SNAC error.  
 *
 * The grand theory of things says that these associations transcend 
 * what libfaim calls "connection types" (conn->type).  You can probably
 * see the elegance here, but since I want to revel in it for a bit, you 
 * get to hear it all spelled out.
 *
 * So let us say that you have your core BOS connection running.  One
 * of your modules has just given you a SNAC of the group 0x0004 to send
 * you.  Maybe an IM destined for some twit in Greenland.  So you start
 * at the top of your connection list, looking for a connection that 
 * claims to support group 0x0004.  You find one.  Why, that neat BOS
 * connection of yours can do that.  So you send it on its way.
 *
 * Now, say, that fellow from Greenland has friends and they all want to
 * meet up with you in a lame chat room.  This has landed you a SNAC
 * in the family 0x000e and you have to admit you're a bit lost.  You've
 * searched your connection list for someone who wants to make your life
 * easy and deliver this SNAC for you, but there isn't one there.
 *
 * Here comes the good bit.  Without even letting anyone know, particularly
 * the module that decided to send this SNAC, and definitely not that twit
 * in Greenland, you send out a service request.  In this request, you have
 * marked the need for a connection supporting group 0x000e.  A few seconds
 * later, you receive a service redirect with an IP address and a cookie in
 * it.  Great, you say.  Now I have something to do.  Off you go, making
 * that connection.  One of the first things you get from this new server
 * is a message saying that indeed it does support the group you were looking
 * for.  So you continue and send rate confirmation and all that.  
 * 
 * Then you remember you had that SNAC to send, and now you have a means to
 * do it, and you do, and everyone is happy.  Except the Greenlander, who is
 * still stuck in the bitter cold.
 *
 * Oh, and this is useful for building the Migration SNACs, too.  In the
 * future, this may help convince me to implement rate limit mitigation
 * for real.  We'll see.
 *
 * Just to make me look better, I'll say that I've known about this great
 * scheme for quite some time now.  But I still haven't convinced myself
 * to make libfaim work that way.  It would take a fair amount of effort,
 * and probably some client API changes as well.  (Whenever I don't want
 * to do something, I just say it would change the client API.  Then I 
 * instantly have a couple of supporters of not doing it.)
 *
 * Generally, addgroup is only called by the internal handling of the
 * server ready SNAC.  So if you want to do something before that, you'll
 * have to be more creative.  That is done rather early, though, so I don't
 * think you have to worry about it.  Unless you're me.  I care deeply
 * about such inane things.
 *
 */
faim_internal void aim_conn_addgroup(aim_conn_t *conn, fu16_t group)
{
	aim_conn_inside_t *ins = (aim_conn_inside_t *)conn->inside;
	struct snacgroup *sg;

	if (!(sg = malloc(sizeof(struct snacgroup))))
		return;

	faimdprintf(aim_conn_getsess(conn), 1, "adding group 0x%04x\n", group);
	sg->group = group;

	sg->next = ins->groups;
	ins->groups = sg;

	return;
}

faim_export aim_conn_t *aim_conn_findbygroup(aim_session_t *sess, fu16_t group)
{
	aim_conn_t *cur;

	for (cur = sess->connlist; cur; cur = cur->next) {
		aim_conn_inside_t *ins = (aim_conn_inside_t *)cur->inside;
		struct snacgroup *sg;

		for (sg = ins->groups; sg; sg = sg->next) {
			if (sg->group == group)
				return cur;
		}
	}

	return NULL;
}

static void connkill_snacgroups(struct snacgroup **head)
{
	struct snacgroup *sg;

	for (sg = *head; sg; ) {
		struct snacgroup *tmp;

		tmp = sg->next;
		free(sg);
		sg = tmp;
	}

	*head = NULL;

	return;
}

static void connkill_rates(struct rateclass **head)
{
	struct rateclass *rc;

	for (rc = *head; rc; ) {
		struct rateclass *tmp;
		struct snacpair *sp;

		tmp = rc->next;

		for (sp = rc->members; sp; ) {
			struct snacpair *tmpsp;

			tmpsp = sp->next;
			free(sp);
			sp = tmpsp;
		}
		free(rc);

		rc = tmp;
	}

	*head = NULL;

	return;
}

static void connkill_real(aim_session_t *sess, aim_conn_t **deadconn)
{

	aim_rxqueue_cleanbyconn(sess, *deadconn);
	aim_tx_cleanqueue(sess, *deadconn);

	if ((*deadconn)->fd != -1) 
		aim_conn_close(*deadconn);

	/*
	 * XXX ->priv should never be touched by the library. I know
	 * it used to be, but I'm getting rid of all that.  Use
	 * ->internal instead.
	 */
	if ((*deadconn)->priv)
		free((*deadconn)->priv);

	/*
	 * This will free ->internal if it necessary...
	 */
	if ((*deadconn)->type == AIM_CONN_TYPE_CHAT)
		aim_conn_kill_chat(sess, *deadconn);

	if ((*deadconn)->inside) {
		aim_conn_inside_t *inside = (aim_conn_inside_t *)(*deadconn)->inside;

		connkill_snacgroups(&inside->groups);
		connkill_rates(&inside->rates);

		free(inside);
	}

	free(*deadconn);
	*deadconn = NULL;

	return;
}

/**
 * Clears out the connection list, killing remaining connections.
 *
 * @param sess Session to be cleared.
 */
static void aim_connrst(aim_session_t *sess)
{

	if (sess->connlist) {
		aim_conn_t *cur = sess->connlist, *tmp;

		while (cur) {
			tmp = cur->next;
			aim_conn_close(cur);
			connkill_real(sess, &cur);
			cur = tmp;
		}
	}

	sess->connlist = NULL;

	return;
}

/**
 * Initializes and/or resets a connection structure to the default values.
 *
 * @param deadconn Connection to be reset.
 */
static void aim_conn_init(aim_conn_t *deadconn)
{

	if (!deadconn)
		return;

	deadconn->fd = -1;
	deadconn->subtype = -1;
	deadconn->type = -1;
	deadconn->seqnum = 0;
	deadconn->lastactivity = 0;
	deadconn->forcedlatency = 0;
	deadconn->handlerlist = NULL;
	deadconn->priv = NULL;
	memset(deadconn->inside, 0, sizeof(aim_conn_inside_t));

	return;
}

/**
 * Allocate a new empty connection structure.
 *
 * @param sess Session
 * @return Returns the new connection structure.
 */
static aim_conn_t *aim_conn_getnext(aim_session_t *sess)
{
	aim_conn_t *newconn;

	if (!(newconn = malloc(sizeof(aim_conn_t)))) 	
		return NULL;
	memset(newconn, 0, sizeof(aim_conn_t));

	if (!(newconn->inside = malloc(sizeof(aim_conn_inside_t)))) {
		free(newconn);
		return NULL;
	}
	memset(newconn->inside, 0, sizeof(aim_conn_inside_t));

	aim_conn_init(newconn);

	newconn->next = sess->connlist;
	sess->connlist = newconn;

	return newconn;
}

/**
 * Close, clear, and free a connection structure. Should never be
 * called from within libfaim.
 *
 * @param sess Session for the connection.
 * @param deadconn Connection to be freed.
 */
faim_export void aim_conn_kill(aim_session_t *sess, aim_conn_t **deadconn)
{
	aim_conn_t *cur, **prev;

	if (!deadconn || !*deadconn)	
		return;

	for (prev = &sess->connlist; (cur = *prev); ) {
		if (cur == *deadconn) {
			*prev = cur->next;
			break;
		}
		prev = &cur->next;
	}

	if (!cur)
		return; /* oops */

	connkill_real(sess, &cur);

	return;
}

/**
 * Close (but not free) a connection.
 *
 * This leaves everything untouched except for clearing the 
 * handler list and setting the fd to -1 (used to recognize
 * dead connections).  It will also remove cookies if necessary.
 *
 * Why only if fd >= 3?  Seems rather implementation specific...
 * fd's do not have to be distributed in a particular order, do they?
 *
 * @param deadconn The connection to close.
 */
faim_export void aim_conn_close(aim_conn_t *deadconn)
{
	aim_rxcallback_t userfunc;

	if (deadconn->fd >= 3)
		close(deadconn->fd);

	deadconn->fd = -1;

	if ((userfunc = aim_callhandler(deadconn->sessv, deadconn, AIM_CB_FAM_SPECIAL, AIM_CB_SPECIAL_CONNDEAD)))
		userfunc(deadconn->sessv, NULL, deadconn);

	if (deadconn->handlerlist)
		aim_clearhandlers(deadconn);

	return;
}

/**
 * Locates a connection of the specified type in the 
 * specified session.
 *
 * XXX - Except for rendezvous, all uses of this should be removed and
 * aim_conn_findbygroup() should be used instead.
 *
 * @param sess The session to search.
 * @param type The type of connection to look for.
 * @return Returns the first connection found of the given target type,
 *         or NULL if none could be found.
 */
faim_export aim_conn_t *aim_getconn_type(aim_session_t *sess, int type)
{
	aim_conn_t *cur;

	for (cur = sess->connlist; cur; cur = cur->next) {
		if ((cur->type == type) && 
				!(cur->status & AIM_CONN_STATUS_INPROGRESS))
			break;
	}

	return cur;
}

faim_export aim_conn_t *aim_getconn_type_all(aim_session_t *sess, int type)
{
	aim_conn_t *cur;

	for (cur = sess->connlist; cur; cur = cur->next) {
		if (cur->type == type)
			break;
	}

	return cur;
}

/* If you pass -1 for the fd, you'll get what you ask for.  Gibberish. */
faim_export aim_conn_t *aim_getconn_fd(aim_session_t *sess, int fd)
{
	aim_conn_t *cur;

	for (cur = sess->connlist; cur; cur = cur->next) {
		if (cur->fd == fd)
			break;
	}

	return cur;
}

/**
 * Handle normal connections or SOCKS5 via an extrememly quick and 
 * dirty SOCKS5 interface. 
 *
 * Attempts to connect to the specified host via the configured
 * proxy settings, if present.  If no proxy is configured for
 * this session, the connection is done directly.
 *
 * XXX - this is really awful.
 * XXX - Split the SOCKS5 and the normal connection stuff into two
 *        separate functions.
 *
 * @param sess Session to connect.
 * @param host Host to connect to.
 * @param port Port to connect to.
 * @param statusret Return value of the connection.
 */
static int aim_proxyconnect(aim_session_t *sess, const char *host, fu16_t port, fu32_t *statusret)
{
	int fd = -1;

	if (strlen(sess->socksproxy.server)) { /* connecting via proxy */
		int i;
		unsigned char buf[512];
		struct sockaddr_in sa;
		struct hostent *hp;
		char *proxy;
		unsigned short proxyport = 1080;

		for(i=0;i<(int)strlen(sess->socksproxy.server);i++) {
			if (sess->socksproxy.server[i] == ':') {
				proxyport = atoi(&(sess->socksproxy.server[i+1]));
				break;
			}
		}

		proxy = (char *)malloc(i+1);
		strncpy(proxy, sess->socksproxy.server, i);
		proxy[i] = '\0';

		if (!(hp = gethostbyname(proxy))) {
			faimdprintf(sess, 0, "proxyconnect: unable to resolve proxy name\n");
			*statusret = (h_errno | AIM_CONN_STATUS_RESOLVERR);
			return -1;
		}
		free(proxy);

		memset(&sa.sin_zero, 0, 8);
		sa.sin_port = htons(proxyport);
		memcpy(&sa.sin_addr, hp->h_addr, hp->h_length);
		sa.sin_family = hp->h_addrtype;

		fd = socket(hp->h_addrtype, SOCK_STREAM, 0);
		if (connect(fd, (struct sockaddr *)&sa, sizeof(struct sockaddr_in)) < 0) {
			faimdprintf(sess, 0, "proxyconnect: unable to connect to proxy\n");
			close(fd);
			return -1;
		}

		i = 0;
		buf[0] = 0x05; /* SOCKS version 5 */
		if (strlen(sess->socksproxy.username)) {
			buf[1] = 0x02; /* two methods */
			buf[2] = 0x00; /* no authentication */
			buf[3] = 0x02; /* username/password authentication */
			i = 4;
		} else {
			buf[1] = 0x01;
			buf[2] = 0x00;
			i = 3;
		}
		if (write(fd, buf, i) < i) {
			*statusret = errno;
			close(fd);
			return -1;
		}
		if (read(fd, buf, 2) < 2) {
			*statusret = errno;
			close(fd);
			return -1;
		}

		if ((buf[0] != 0x05) || (buf[1] == 0xff)) {
			*statusret = EINVAL;
			close(fd);
			return -1;
		}

		/* check if we're doing username authentication */
		if (buf[1] == 0x02) {
			i  = aimutil_put8(buf, 0x01); /* version 1 */
			i += aimutil_put8(buf+i, strlen(sess->socksproxy.username));
			i += aimutil_putstr(buf+i, sess->socksproxy.username, strlen(sess->socksproxy.username));
			i += aimutil_put8(buf+i, strlen(sess->socksproxy.password));
			i += aimutil_putstr(buf+i, sess->socksproxy.password, strlen(sess->socksproxy.password));
			if (write(fd, buf, i) < i) {
				*statusret = errno;
				close(fd);
				return -1;
			}
			if (read(fd, buf, 2) < 2) {
				*statusret = errno;
				close(fd);
				return -1;
			}
			if ((buf[0] != 0x01) || (buf[1] != 0x00)) {
				*statusret = EINVAL;
				close(fd);
				return -1;
			}
		}

		i  = aimutil_put8(buf, 0x05);
		i += aimutil_put8(buf+i, 0x01); /* CONNECT */
		i += aimutil_put8(buf+i, 0x00); /* reserved */
		i += aimutil_put8(buf+i, 0x03); /* address type: host name */
		i += aimutil_put8(buf+i, strlen(host));
		i += aimutil_putstr(buf+i, host, strlen(host));
		i += aimutil_put16(buf+i, port);

		if (write(fd, buf, i) < i) {
			*statusret = errno;
			close(fd);
			return -1;
		}

		if (read(fd, buf, 10) < 10) {
			*statusret = errno;
			close(fd);
			return -1;
		}
		if ((buf[0] != 0x05) || (buf[1] != 0x00)) {
			*statusret = EINVAL;
			close(fd);