tlv.c

Linux下的多协议即时通讯程序源代码

/*
 * Purple's oscar protocol plugin
 * This file is the legal property of its developers.
 * Please see the AUTHORS file distributed alongside this file.
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include "oscar.h"

static aim_tlv_t *
createtlv(guint16 type, guint16 length, guint8 *value)
{
	aim_tlv_t *ret;

	ret = g_new(aim_tlv_t, 1);
	ret->type = type;
	ret->length = length;
	ret->value = value;

	return ret;
}

static void
freetlv(aim_tlv_t *oldtlv)
{
	g_free(oldtlv->value);
	g_free(oldtlv);
}

static GSList *
aim_tlv_read(GSList *list, ByteStream *bs)
{
	guint16 type, length;
	aim_tlv_t *tlv;

	type = byte_stream_get16(bs);
	length = byte_stream_get16(bs);

#if 0
	/*
	 * This code hasn't been needed in years.  It's been commented
	 * out since 2003, at the latest.  It seems likely that it was
	 * just a bug in their server code that has since been fixed.
	 * In any case, here's the orignal comment, kept for historical
	 * purposes:
	 *
	 * Okay, so now AOL has decided that any TLV of
	 * type 0x0013 can only be two bytes, despite
	 * what the actual given length is.  So here
	 * we dump any invalid TLVs of that sort.  Hopefully
	 * there's no special cases to this special case.
	 *   - mid (30jun2000)
	 */
	if ((type == 0x0013) && (length != 0x0002)) {
		length = 0x0002;
		return list;
	}
#endif
	if (length > byte_stream_empty(bs)) {
		aim_tlvlist_free(list);
		return NULL;
	}

	tlv = createtlv(type, length, NULL);
	if (tlv->length > 0) {
		tlv->value = byte_stream_getraw(bs, length);
		if (!tlv->value) {
			freetlv(tlv);
			aim_tlvlist_free(list);
			return NULL;
		}
	}

	return g_slist_prepend(list, tlv);
}

/**
 * Read a TLV chain from a buffer.
 *
 * Reads and parses a series of TLV patterns from a data buffer; the
 * returned structure is manipulatable with the rest of the TLV
 * routines.  When done with a TLV chain, aim_tlvlist_free() should
 * be called to free the dynamic substructures.
 *
 * TODO: There should be a flag setable here to have the tlvlist contain
 * bstream references, so that at least the ->value portion of each
 * element doesn't need to be malloc/memcpy'd.  This could prove to be
 * just as efficient as the in-place TLV parsing used in a couple places
 * in libfaim.
 *
 * @param bs Input bstream
 * @return Return the TLV chain read
 */
GSList *aim_tlvlist_read(ByteStream *bs)
{
	GSList *list = NULL;

	while (byte_stream_empty(bs) > 0) {
		list = aim_tlv_read(list, bs);
		if (list == NULL)
			return NULL;
	}

	return g_slist_reverse(list);
}

/**
 * Read a TLV chain from a buffer.
 *
 * Reads and parses a series of TLV patterns from a data buffer; the
 * returned structure is manipulatable with the rest of the TLV
 * routines.  When done with a TLV chain, aim_tlvlist_free() should
 * be called to free the dynamic substructures.
 *
 * TODO: There should be a flag setable here to have the tlvlist contain
 * bstream references, so that at least the ->value portion of each
 * element doesn't need to be malloc/memcpy'd.  This could prove to be
 * just as efficient as the in-place TLV parsing used in a couple places
 * in libfaim.
 *
 * @param bs Input bstream
 * @param num The max number of TLVs that will be read, or -1 if unlimited.
 *        There are a number of places where you want to read in a tlvchain,
 *        but the chain is not at the end of the SNAC, and the chain is
 *        preceded by the number of TLVs.  So you can limit that with this.
 * @return Return the TLV chain read
 */
GSList *aim_tlvlist_readnum(ByteStream *bs, guint16 num)
{
	GSList *list = NULL;

	while ((byte_stream_empty(bs) > 0) && (num != 0)) {
		list = aim_tlv_read(list, bs);
		if (list == NULL)
			return NULL;
		num--;
	}

	return g_slist_reverse(list);
}

/**
 * Read a TLV chain from a buffer.
 *
 * Reads and parses a series of TLV patterns from a data buffer; the
 * returned structure is manipulatable with the rest of the TLV
 * routines.  When done with a TLV chain, aim_tlvlist_free() should
 * be called to free the dynamic substructures.
 *
 * TODO: There should be a flag setable here to have the tlvlist contain
 * bstream references, so that at least the ->value portion of each
 * element doesn't need to be malloc/memcpy'd.  This could prove to be
 * just as efficient as the in-place TLV parsing used in a couple places
 * in libfaim.
 *
 * @param bs Input bstream
 * @param len The max length in bytes that will be read.
 *        There are a number of places where you want to read in a tlvchain,
 *        but the chain is not at the end of the SNAC, and the chain is
 *        preceded by the length of the TLVs.  So you can limit that with this.
 * @return Return the TLV chain read
 */
GSList *aim_tlvlist_readlen(ByteStream *bs, guint16 len)
{
	GSList *list = NULL;

	while ((byte_stream_empty(bs) > 0) && (len > 0)) {
		list = aim_tlv_read(list, bs);
		if (list == NULL)
			return NULL;

		len -= 2 + 2 + ((aim_tlv_t *)list->data)->length;
	}

	return g_slist_reverse(list);
}

/**
 * Duplicate a TLV chain.
 * This is pretty self explanatory.
 *
 * @param orig The TLV chain you want to make a copy of.
 * @return A newly allocated TLV chain.
 */
GSList *aim_tlvlist_copy(GSList *orig)
{
	GSList *new = NULL;
	aim_tlv_t *tlv;

	while (orig != NULL) {
		tlv = orig->data;
		aim_tlvlist_add_raw(&new, tlv->type, tlv->length, tlv->value);
		orig = orig->next;
	}

	return new;
}

/*
 * Compare two TLV lists for equality.  This probably is not the most
 * efficient way to do this.
 *
 * @param one One of the TLV chains to compare.
 * @param two The other TLV chain to compare.
 * @return Return 0 if the lists are the same, return 1 if they are different.
 */
int aim_tlvlist_cmp(GSList *one, GSList *two)
{
	ByteStream bs1, bs2;

	if (aim_tlvlist_size(one) != aim_tlvlist_size(two))
		return 1;

	byte_stream_new(&bs1, aim_tlvlist_size(one));
	byte_stream_new(&bs2, aim_tlvlist_size(two));

	aim_tlvlist_write(&bs1, &one);
	aim_tlvlist_write(&bs2, &two);

	if (memcmp(bs1.data, bs2.data, bs1.len)) {
		g_free(bs1.data);
		g_free(bs2.data);
		return 1;
	}

	g_free(bs1.data);
	g_free(bs2.data);

	return 0;
}

/**
 * Free a TLV chain structure
 *
 * Walks the list of TLVs in the passed TLV chain and
 * frees each one. Note that any references to this data
 * should be removed before calling this.
 *
 * @param list Chain to be freed
 */
void aim_tlvlist_free(GSList *list)
{
	while (list != NULL)
	{
		freetlv(list->data);
		list = g_slist_delete_link(list, list);
	}
}

/**
 * Count the number of TLVs in a chain.
 *
 * @param list Chain to be counted.
 * @return The number of TLVs stored in the passed chain.
 */
int aim_tlvlist_count(GSList *list)
{
	GSList *cur;
	int count;

	if (list == NULL)
		return 0;

	for (cur = list, count = 0; cur; cur = cur->next)
		count++;

	return count;
}

/**
 * Count the number of bytes in a TLV chain.
 *
 * @param list Chain to be sized
 * @return The number of bytes that would be needed to
 *         write the passed TLV chain to a data buffer.
 */
int aim_tlvlist_size(GSList *list)
{
	GSList *cur;
	int size;

	if (list == NULL)
		return 0;

	for (cur = list, size = 0; cur; cur = cur->next)
		size += (4 + ((aim_tlv_t *)cur->data)->length);

	return size;
}

/**
 * Adds the passed string as a TLV element of the passed type
 * to the TLV chain.
 *
 * @param list Desination chain (%NULL pointer if empty).
 * @param type TLV type.
 * @param length Length of string to add (not including %NULL).
 * @param value String to add.
 * @return The size of the value added.
 */
int aim_tlvlist_add_raw(GSList **list, const guint16 type, const guint16 length, const guint8 *value)
{
	aim_tlv_t *tlv;

	if (list == NULL)
		return 0;

	tlv = createtlv(type, length, NULL);
	if (tlv->length > 0)
		tlv->value = g_memdup(value, length);

	*list = g_slist_append(*list, tlv);

	return tlv->length;
}

/**
 * Add a one byte integer to a TLV chain.
 *
 * @param list Destination chain.
 * @param type TLV type to add.
 * @param value Value to add.
 * @return The size of the value added.
 */
int aim_tlvlist_add_8(GSList **list, const guint16 type, const guint8 value)
{
	guint8 v8[1];

	aimutil_put8(v8, value);

	return aim_tlvlist_add_raw(list, type, 1, v8);
}

/**
 * Add a two byte integer to a TLV chain.
 *
 * @param list Destination chain.
 * @param type TLV type to add.
 * @param value Value to add.
 * @return The size of the value added.
 */
int aim_tlvlist_add_16(GSList **list, const guint16 type, const guint16 value)
{
	guint8 v16[2];

	aimutil_put16(v16, value);

	return aim_tlvlist_add_raw(list, type, 2, v16);
}

/**
 * Add a four byte integer to a TLV chain.
 *
 * @param list Destination chain.
 * @param type TLV type to add.
 * @param value Value to add.
 * @return The size of the value added.
 */
int aim_tlvlist_add_32(GSList **list, const guint16 type, const guint32 value)
{
	guint8 v32[4];

	aimutil_put32(v32, value);

	return aim_tlvlist_add_raw(list, type, 4, v32);
}

/**
 * Add a string to a TLV chain.
 *
 * @param list Destination chain.
 * @param type TLV type to add.
 * @param value Value to add.
 * @return The size of the value added.
 */
int aim_tlvlist_add_str(GSList **list, const guint16 type, const char *value)
{
	return aim_tlvlist_add_raw(list, type, strlen(value), (guint8 *)value);
}

/**
 * Adds a block of capability blocks to a TLV chain. The bitfield
 * passed in should be a bitwise %OR of any of the %AIM_CAPS constants:
 *
 *     %OSCAR_CAPABILITY_BUDDYICON   Supports Buddy Icons
 *     %OSCAR_CAPABILITY_TALK        Supports Voice Chat
 *     %OSCAR_CAPABILITY_IMIMAGE     Supports DirectIM/IMImage
 *     %OSCAR_CAPABILITY_CHAT        Supports Chat
 *     %OSCAR_CAPABILITY_GETFILE     Supports Get File functions
 *     %OSCAR_CAPABILITY_SENDFILE    Supports Send File functions
 *
 * @param list Destination chain
 * @param type TLV type to add
 * @param caps Bitfield of capability flags to send
 * @return The size of the value added.
 */
int aim_tlvlist_add_caps(GSList **list, const guint16 type, const guint32 caps)
{
	guint8 buf[256]; /* TODO: Don't use a fixed length buffer */
	ByteStream bs;

	if (caps == 0)
		return 0; /* nothing there anyway */

	byte_stream_init(&bs, buf, sizeof(buf));

	byte_stream_putcaps(&bs, caps);

	return aim_tlvlist_add_raw(list, type, byte_stream_curpos(&bs), buf);
}