1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/io/rx_packet.c	Sat Feb 20 21:18:28 2010 -0800
     1.3 @@ -0,0 +1,289 @@
     1.4 +/*
     1.5 + * $Id: rx_packet.c,v 1.7 2004/02/15 04:53:38 hipnod Exp $
     1.6 + *
     1.7 + * Copyright (C) 2003 giFT project (gift.sourceforge.net)
     1.8 + *
     1.9 + * This program is free software; you can redistribute it and/or modify it
    1.10 + * under the terms of the GNU General Public License as published by the
    1.11 + * Free Software Foundation; either version 2, or (at your option) any
    1.12 + * later version.
    1.13 + *
    1.14 + * This program is distributed in the hope that it will be useful, but
    1.15 + * WITHOUT ANY WARRANTY; without even the implied warranty of
    1.16 + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    1.17 + * General Public License for more details.
    1.18 + */
    1.19 +
    1.20 +#include "gt_gnutella.h"
    1.21 +
    1.22 +#include "rx_stack.h"
    1.23 +#include "rx_layer.h"
    1.24 +
    1.25 +#include "gt_packet.h"
    1.26 +#include "rx_packet.h"
    1.27 +
    1.28 +/*****************************************************************************/
    1.29 +
    1.30 +struct rx_packet
    1.31 +{
    1.32 +	struct io_buf       *partial;
    1.33 +	rx_packet_handler_t  handler;
    1.34 +	void                *udata;
    1.35 +};
    1.36 +
    1.37 +/*****************************************************************************/
    1.38 +
    1.39 +#define RX_PACKET(rx) \
    1.40 +	((struct rx_packet *) ((rx)->udata))
    1.41 +
    1.42 +/*****************************************************************************/
    1.43 +
    1.44 +static void null_packet_handler (void *udata, GtPacket *packet)
    1.45 +{
    1.46 +	gt_packet_free (packet);
    1.47 +}
    1.48 +
    1.49 +static BOOL rx_packet_init (struct rx_layer *rx, void *udata)
    1.50 +{
    1.51 +	struct rx_packet *rx_packet;
    1.52 +
    1.53 +	if (!(rx_packet = NEW (struct rx_packet)))
    1.54 +		return FALSE;
    1.55 +
    1.56 +	rx->udata = rx_packet;
    1.57 +
    1.58 +	/* discard the packets received */
    1.59 +	rx_packet->handler = null_packet_handler;
    1.60 +	return TRUE;
    1.61 +}
    1.62 +
    1.63 +static void rx_packet_destroy (struct rx_layer *rx)
    1.64 +{
    1.65 +	struct rx_packet *rx_packet = RX_PACKET(rx);
    1.66 +
    1.67 +	io_buf_free (rx_packet->partial);
    1.68 +	FREE (rx_packet);
    1.69 +}
    1.70 +
    1.71 +static void rx_packet_disable (struct rx_layer *rx)
    1.72 +{
    1.73 +	/* NOP: lower layer will stop sending us data -- it'd better
    1.74 +	 * stop now */
    1.75 +}
    1.76 +
    1.77 +static void rx_packet_enable (struct rx_layer *rx)
    1.78 +{
    1.79 +	/* NOP: the lower layer will start sending us data again */
    1.80 +}
    1.81 +
    1.82 +/*****************************************************************************/
    1.83 +
    1.84 +static GtPacket *make_packet (struct rx_layer *rx, struct rx_packet *rx_packet,
    1.85 +                              size_t packet_size)
    1.86 +{
    1.87 +	GtPacket      *packet;
    1.88 +	struct io_buf *pbuf = rx_packet->partial;
    1.89 +
    1.90 +	assert (io_buf_len (pbuf) == packet_size);
    1.91 +	assert (packet_size < GT_PACKET_MAX);
    1.92 +
    1.93 +	/* construct a complete packet from the data in the binary buf */
    1.94 +	packet = gt_packet_unserialize (pbuf->data, packet_size);
    1.95 +
    1.96 +	/*
    1.97 +	 * TODO: gt_packet_unserialize() currently copies the data, but should
    1.98 +	 * really take ownership of the data in place.  That would also allow the
    1.99 +	 * null terminator in the io_buf to terminate the last string in the
   1.100 +	 * packet, if any.
   1.101 +	 */
   1.102 +	io_buf_free (pbuf);
   1.103 +	rx_packet->partial = NULL;
   1.104 +
   1.105 +	if (!packet)
   1.106 +	{
   1.107 +		gt_rx_stack_abort (rx->stack);
   1.108 +		return NULL;
   1.109 +	}
   1.110 +
   1.111 +	return packet;
   1.112 +}
   1.113 +
   1.114 +static BOOL fill_up_to (struct rx_layer *rx, struct io_buf *dst,
   1.115 +                        struct io_buf *src, size_t fill_size)
   1.116 +{
   1.117 +	size_t     new_len;
   1.118 +	size_t     old_len;
   1.119 +	size_t     len_to_read;
   1.120 +
   1.121 +	old_len = io_buf_len (dst);
   1.122 +	new_len = io_buf_len (src);
   1.123 +
   1.124 +	/* skip if we already have enough */
   1.125 +	if (old_len >= fill_size)
   1.126 +		return TRUE;
   1.127 +
   1.128 +	len_to_read = MIN (fill_size - old_len, new_len);
   1.129 +
   1.130 +	/* ensure the packet has enough room */
   1.131 +	if (!io_buf_resize (dst, old_len + len_to_read))
   1.132 +	{
   1.133 +		gt_rx_stack_abort (rx->stack);
   1.134 +		return FALSE;
   1.135 +	}
   1.136 +
   1.137 +	io_buf_copy (dst, src, len_to_read);
   1.138 +
   1.139 +	if (io_buf_len (dst) >= fill_size)
   1.140 +		return TRUE;
   1.141 +
   1.142 +	return FALSE;
   1.143 +}
   1.144 +
   1.145 +static BOOL fill_header (struct rx_layer *rx, struct rx_packet *rx_packet,
   1.146 +                         struct io_buf *io_buf)
   1.147 +{
   1.148 +	struct io_buf *dst = rx_packet->partial;
   1.149 +	struct io_buf *src = io_buf;
   1.150 +
   1.151 +	if (!fill_up_to (rx, dst, src, GNUTELLA_HDR_LEN))
   1.152 +	{
   1.153 +		/* this would fail if there was an alloc failure */
   1.154 +		assert (io_buf_read_avail (io_buf) == 0);
   1.155 +		return FALSE;
   1.156 +	}
   1.157 +
   1.158 +	return TRUE;
   1.159 +}
   1.160 +
   1.161 +/*
   1.162 + * We must read all the data the lower layer has sent and buffer
   1.163 + * partial packets, because otherwise we would poll the CPU if the
   1.164 + * packet were bigger than the buffer size of one of the layer
   1.165 + * layers under this one.
   1.166 + */
   1.167 +static BOOL read_packet (struct rx_layer *rx, struct rx_packet *rx_packet,
   1.168 +                         struct io_buf *io_buf, GtPacket **ret)
   1.169 +{
   1.170 +	uint32_t       payload_len;
   1.171 +	size_t         partial_len;
   1.172 +	uint32_t       packet_size;
   1.173 +	struct io_buf *partial     = rx_packet->partial;
   1.174 +	GtPacket      *pkt;
   1.175 +
   1.176 +	*ret = NULL;
   1.177 +
   1.178 +	partial_len = io_buf_len (partial);
   1.179 +	assert (partial_len >= GNUTELLA_HDR_LEN);
   1.180 +
   1.181 +	/*
   1.182 +	 * The partial packet is now at least 23 bytes.  Look in the header for
   1.183 +	 * the payload length so we know how much we need to read before the
   1.184 +	 * packet is complete.
   1.185 +	 */
   1.186 +	payload_len = get_payload_len (partial->data);
   1.187 +	packet_size = payload_len + GNUTELLA_HDR_LEN;
   1.188 +
   1.189 +	/*
   1.190 +	 * Check for wraparound, and reset the packet size to its payload len.
   1.191 +	 * Its likely we've experienced a protocol de-sync here.  Set the size so
   1.192 +	 * the connection will be closed.
   1.193 +	 */
   1.194 +	if (packet_size < GNUTELLA_HDR_LEN)
   1.195 +		packet_size = GT_PACKET_MAX;
   1.196 +
   1.197 +	if (packet_size >= GT_PACKET_MAX)
   1.198 +	{
   1.199 +		if (IO_DEBUG)
   1.200 +			GT->dbg (GT, "received too large packet(%d)", packet_size);
   1.201 +
   1.202 +		/* TODO: should send a BYE message here */
   1.203 +		gt_rx_stack_abort (rx->stack);
   1.204 +		return FALSE;
   1.205 +	}
   1.206 +
   1.207 +	if (!fill_up_to (rx, partial, io_buf, packet_size))
   1.208 +	{
   1.209 +		/* this would fail if there was an alloc failure */
   1.210 +		assert (io_buf_read_avail (io_buf) == 0);
   1.211 +		return FALSE;
   1.212 +	}
   1.213 +
   1.214 +	/* yay, read a packet */
   1.215 +	pkt = make_packet (rx, rx_packet, packet_size);
   1.216 +	*ret = pkt;
   1.217 +
   1.218 +	return (pkt == NULL ? FALSE : TRUE);
   1.219 +}
   1.220 +
   1.221 +/*
   1.222 + * Receive a message buffer from the lower layer, parse it into as many
   1.223 + * packets as it contains, and pass those to our handler function.
   1.224 + *
   1.225 + * This is meant to be the top layer of the rx stack only.
   1.226 + *
   1.227 + * TODO: A handler could be implemented as another layer, should think
   1.228 + * about this approach instead.
   1.229 + */
   1.230 +static void rx_packet_recv (struct rx_layer *rx, struct io_buf *io_buf)
   1.231 +{
   1.232 +	GtPacket          *packet = NULL;
   1.233 +	struct rx_packet  *rx_packet;
   1.234 +
   1.235 +	rx_packet = RX_PACKET(rx);
   1.236 +
   1.237 +	while (rx->enabled && io_buf_read_avail (io_buf) > 0)
   1.238 +	{
   1.239 +		/* allocate a new partial buffer, if one is not present yet */
   1.240 +		if (!rx_packet->partial &&
   1.241 +		    !(rx_packet->partial = io_buf_new (GNUTELLA_HDR_LEN)))
   1.242 +		{
   1.243 +			gt_rx_stack_abort (rx->stack);
   1.244 +			break;
   1.245 +		}
   1.246 +
   1.247 +		/* try to read the first 23 bytes */
   1.248 +		if (!fill_header (rx, rx_packet, io_buf))
   1.249 +			break;
   1.250 +
   1.251 +		/*
   1.252 +		 * Read the payload. If there arent enough bytes to complete the
   1.253 +		 * packet, we finish it later.
   1.254 +		 */
   1.255 +		if (!read_packet (rx, rx_packet, io_buf, &packet))
   1.256 +		{
   1.257 +			assert (packet == NULL);
   1.258 +			break;
   1.259 +		}
   1.260 +
   1.261 +		assert (packet != NULL);
   1.262 +		(*rx_packet->handler) (rx_packet->udata, packet);
   1.263 +
   1.264 +		/* freeing the packet here means the callback must make its own
   1.265 +		 * provisions for storing the packet's data */
   1.266 +		gt_packet_free (packet);
   1.267 +		packet = NULL;
   1.268 +	}
   1.269 +
   1.270 +	io_buf_free (io_buf);
   1.271 +}
   1.272 +
   1.273 +/*****************************************************************************/
   1.274 +
   1.275 +struct rx_layer_ops gt_rx_packet_ops =
   1.276 +{
   1.277 +	rx_packet_init,
   1.278 +	rx_packet_destroy,
   1.279 +	rx_packet_enable,
   1.280 +	rx_packet_disable,
   1.281 +	rx_packet_recv,
   1.282 +};
   1.283 +
   1.284 +void gt_rx_packet_set_handler (struct rx_layer *rx,
   1.285 +                               rx_packet_handler_t handler,
   1.286 +                               void *udata)
   1.287 +{
   1.288 +	struct rx_packet *rx_packet = RX_PACKET(rx);
   1.289 +
   1.290 +	rx_packet->handler = handler;
   1.291 +	rx_packet->udata   = udata;
   1.292 +}