tlv.c

Linux下的多协议即时通讯程序源代码

/**
 * Adds the given userinfo struct to a TLV chain.
 *
 * @param list Destination chain.
 * @param type TLV type to add.
 * @return The size of the value added.
 */
int aim_tlvlist_add_userinfo(GSList **list, guint16 type, aim_userinfo_t *userinfo)
{
	guint8 buf[1024]; /* TODO: Don't use a fixed length buffer */
	ByteStream bs;

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

	aim_putuserinfo(&bs, userinfo);

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

/**
 * Adds the given chatroom info to a TLV chain.
 *
 * @param list Destination chain.
 * @param type TLV type to add.
 * @param roomname The name of the chat.
 * @param instance The instance.
 * @return The size of the value added.
 */
int aim_tlvlist_add_chatroom(GSList **list, guint16 type, guint16 exchange, const char *roomname, guint16 instance)
{
	int len;
	ByteStream bs;

	byte_stream_new(&bs, 2 + 1 + strlen(roomname) + 2);

	byte_stream_put16(&bs, exchange);
	byte_stream_put8(&bs, strlen(roomname));
	byte_stream_putstr(&bs, roomname);
	byte_stream_put16(&bs, instance);

	len = aim_tlvlist_add_raw(list, type, byte_stream_curpos(&bs), bs.data);

	g_free(bs.data);

	return len;
}

/**
 * Adds a TLV with a zero length to a TLV chain.
 *
 * @param list Destination chain.
 * @param type TLV type to add.
 * @return The size of the value added.
 */
int aim_tlvlist_add_noval(GSList **list, const guint16 type)
{
	return aim_tlvlist_add_raw(list, type, 0, NULL);
}

/*
 * Note that the inner TLV chain will not be modifiable as a tlvchain once
 * it is written using this.  Or rather, it can be, but updates won't be
 * made to this.
 *
 * TODO: Should probably support sublists for real.
 *
 * This is so neat.
 *
 * @param list Destination chain.
 * @param type TLV type to add.
 * @param t1 The TLV chain you want to write.
 * @return The number of bytes written to the destination TLV chain.
 *         0 is returned if there was an error or if the destination
 *         TLV chain has length 0.
 */
int aim_tlvlist_add_frozentlvlist(GSList **list, guint16 type, GSList **tlvlist)
{
	int buflen;
	ByteStream bs;

	buflen = aim_tlvlist_size(*tlvlist);

	if (buflen <= 0)
		return 0;

	byte_stream_new(&bs, buflen);

	aim_tlvlist_write(&bs, tlvlist);

	aim_tlvlist_add_raw(list, type, byte_stream_curpos(&bs), bs.data);

	g_free(bs.data);

	return buflen;
}

/**
 * Substitute a TLV of a given type with a new TLV of the same type.  If
 * you attempt to replace a TLV that does not exist, this function will
 * just add a new TLV as if you called aim_tlvlist_add_raw().
 *
 * @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 length of the TLV.
 */
int aim_tlvlist_replace_raw(GSList **list, const guint16 type, const guint16 length, const guint8 *value)
{
	GSList *cur;
	aim_tlv_t *tlv;

	if (list == NULL)
		return 0;

	for (cur = *list; cur != NULL; cur = cur->next)
	{
		tlv = cur->data;
		if (tlv->type == type)
			break;
	}

	if (cur == NULL)
		/* TLV does not exist, so add a new one */
		return aim_tlvlist_add_raw(list, type, length, value);

	g_free(tlv->value);
	tlv->length = length;
	if (tlv->length > 0) {
		tlv->value = g_memdup(value, length);
	} else
		tlv->value = NULL;

	return tlv->length;
}

/**
 * Substitute a TLV of a given type with a new TLV of the same type.  If
 * you attempt to replace a TLV that does not exist, this function will
 * just add a new TLV as if you called aim_tlvlist_add_str().
 *
 * @param list Desination chain (%NULL pointer if empty).
 * @param type TLV type.
 * @param str String to add.
 * @return The length of the TLV.
 */
int aim_tlvlist_replace_str(GSList **list, const guint16 type, const char *str)
{
	return aim_tlvlist_replace_raw(list, type, strlen(str), (const guchar *)str);
}

/**
 * Substitute a TLV of a given type with a new TLV of the same type.  If
 * you attempt to replace a TLV that does not exist, this function will
 * just add a new TLV as if you called aim_tlvlist_add_raw().
 *
 * @param list Desination chain (%NULL pointer if empty).
 * @param type TLV type.
 * @return The length of the TLV.
 */
int aim_tlvlist_replace_noval(GSList **list, const guint16 type)
{
	return aim_tlvlist_replace_raw(list, type, 0, NULL);
}

/**
 * Substitute a TLV of a given type with a new TLV of the same type.  If
 * you attempt to replace a TLV that does not exist, this function will
 * just add a new TLV as if you called aim_tlvlist_add_raw().
 *
 * @param list Desination chain (%NULL pointer if empty).
 * @param type TLV type.
 * @param value 8 bit value to add.
 * @return The length of the TLV.
 */
int aim_tlvlist_replace_8(GSList **list, const guint16 type, const guint8 value)
{
	guint8 v8[1];

	aimutil_put8(v8, value);

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

/**
 * Substitute a TLV of a given type with a new TLV of the same type.  If
 * you attempt to replace a TLV that does not exist, this function will
 * just add a new TLV as if you called aim_tlvlist_add_raw().
 *
 * @param list Desination chain (%NULL pointer if empty).
 * @param type TLV type.
 * @param value 32 bit value to add.
 * @return The length of the TLV.
 */
int aim_tlvlist_replace_32(GSList **list, const guint16 type, const guint32 value)
{
	guint8 v32[4];

	aimutil_put32(v32, value);

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

/**
 * Remove all TLVs of a given type.  If you attempt to remove a TLV
 * that does not exist, nothing happens.
 *
 * @param list Desination chain (%NULL pointer if empty).
 * @param type TLV type.
 */
void aim_tlvlist_remove(GSList **list, const guint16 type)
{
	GSList *cur, *next;
	aim_tlv_t *tlv;

	if (list == NULL || *list == NULL)
		return;

	cur = *list;
	while (cur != NULL)
	{
		tlv = cur->data;
		next = cur->next;

		if (tlv->type == type)
		{
			/* Delete this TLV */
			*list = g_slist_delete_link(*list, cur);
			g_free(tlv->value);
			g_free(tlv);
		}

		cur = next;
	}
}

/**
 * Write a TLV chain into a data buffer.
 *
 * Copies a TLV chain into a raw data buffer, writing only the number
 * of bytes specified. This operation does not free the chain;
 * aim_tlvlist_free() must still be called to free up the memory used
 * by the chain structures.
 *
 * TODO: Clean this up, make better use of bstreams
 *
 * @param bs Input bstream
 * @param list Source TLV chain
 * @return Return 0 if the destination bstream is too small.
 */
int aim_tlvlist_write(ByteStream *bs, GSList **list)
{
	int goodbuflen;
	GSList *cur;
	aim_tlv_t *tlv;

	/* do an initial run to test total length */
	goodbuflen = aim_tlvlist_size(*list);

	if (goodbuflen > byte_stream_empty(bs))
		return 0; /* not enough buffer */

	/* do the real write-out */
	for (cur = *list; cur; cur = cur->next) {
		tlv = cur->data;
		byte_stream_put16(bs, tlv->type);
		byte_stream_put16(bs, tlv->length);
		if (tlv->length > 0)
			byte_stream_putraw(bs, tlv->value, tlv->length);
	}

	return 1; /* TODO: This is a nonsensical return */
}


/**
 * Grab the Nth TLV of type type in the TLV list list.
 *
 * Returns a pointer to an aim_tlv_t of the specified type;
 * %NULL on error.  The @nth parameter is specified starting at %1.
 * In most cases, there will be no more than one TLV of any type
 * in a chain.
 *
 * @param list Source chain.
 * @param type Requested TLV type.
 * @param nth Index of TLV of type to get.
 * @return The TLV you were looking for, or NULL if one could not be found.
 */
aim_tlv_t *aim_tlv_gettlv(GSList *list, const guint16 type, const int nth)
{
	GSList *cur;
	aim_tlv_t *tlv;
	int i;

	for (cur = list, i = 0; cur != NULL; cur = cur->next) {
		tlv = cur->data;
		if (tlv != NULL) { /* TODO: This NULL check shouldn't be needed */
			if (tlv->type == type)
				i++;
			if (i >= nth)
				return tlv;
		}
	}

	return NULL;
}

/**
 * Get the length of the data of the nth TLV in the given TLV chain.
 *
 * @param list Source chain.
 * @param type Requested TLV type.
 * @param nth Index of TLV of type to get.
 * @return The length of the data in this TLV, or -1 if the TLV could not be
 *         found.  Unless -1 is returned, this value will be 2 bytes.
 */
int aim_tlv_getlength(GSList *list, const guint16 type, const int nth)
{
	aim_tlv_t *tlv;

	tlv = aim_tlv_gettlv(list, type, nth);
	if (tlv == NULL)
		return -1;

	return tlv->length;
}

char *
aim_tlv_getvalue_as_string(aim_tlv_t *tlv)
{
	char *ret;

	ret = g_malloc(tlv->length + 1);
	memcpy(ret, tlv->value, tlv->length);
	ret[tlv->length] = '\0';

	return ret;
}

/**
 * Retrieve the data from the nth TLV in the given TLV chain as a string.
 *
 * @param list Source TLV chain.
 * @param type TLV type to search for.
 * @param nth Index of TLV to return.
 * @return The value of the TLV you were looking for, or NULL if one could
 *         not be found.  This is a dynamic buffer and must be freed by the
 *         caller.
 */
char *aim_tlv_getstr(GSList *list, const guint16 type, const int nth)
{
	aim_tlv_t *tlv;

	tlv = aim_tlv_gettlv(list, type, nth);
	if (tlv == NULL)
		return NULL;

	return aim_tlv_getvalue_as_string(tlv);
}

/**
 * Retrieve the data from the nth TLV in the given TLV chain as an 8bit
 * integer.
 *
 * @param list Source TLV chain.
 * @param type TLV type to search for.
 * @param nth Index of TLV to return.
 * @return The value the TLV you were looking for, or 0 if one could
 *         not be found.
 */
guint8 aim_tlv_get8(GSList *list, const guint16 type, const int nth)
{
	aim_tlv_t *tlv;

	tlv = aim_tlv_gettlv(list, type, nth);
	if (tlv == NULL)
		return 0; /* erm */

	return aimutil_get8(tlv->value);
}

/**
 * Retrieve the data from the nth TLV in the given TLV chain as a 16bit
 * integer.
 *
 * @param list Source TLV chain.
 * @param type TLV type to search for.
 * @param nth Index of TLV to return.
 * @return The value the TLV you were looking for, or 0 if one could
 *         not be found.
 */
guint16 aim_tlv_get16(GSList *list, const guint16 type, const int nth)
{
	aim_tlv_t *tlv;

	tlv = aim_tlv_gettlv(list, type, nth);
	if (tlv == NULL)
		return 0; /* erm */

	return aimutil_get16(tlv->value);
}

/**
 * Retrieve the data from the nth TLV in the given TLV chain as a 32bit
 * integer.
 *
 * @param list Source TLV chain.
 * @param type TLV type to search for.
 * @param nth Index of TLV to return.
 * @return The value the TLV you were looking for, or 0 if one could
 *         not be found.
 */
guint32 aim_tlv_get32(GSList *list, const guint16 type, const int nth)
{
	aim_tlv_t *tlv;

	tlv = aim_tlv_gettlv(list, type, nth);
	if (tlv == NULL)
		return 0; /* erm */

	return aimutil_get32(tlv->value);
}