path: root/net/dccp/options.c

/*
 *  net/dccp/options.c
 *
 *  An implementation of the DCCP protocol
 *  Copyright (c) 2005 Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org>
 *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
 *  Copyright (c) 2005 Ian McDonald <iam4@cs.waikato.ac.nz>
 *
 *      This program is free software; you can redistribute it and/or
 *      modify it under the terms of the GNU General Public License
 *      as published by the Free Software Foundation; either version
 *      2 of the License, or (at your option) any later version.
 */
#include <linux/config.h>
#include <linux/dccp.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>

#include "ccid.h"
#include "dccp.h"

static void dccp_ackpkts_check_rcv_ackvector(struct dccp_ackpkts *ap,
					     struct sock *sk,
					     const u64 ackno,
					     const unsigned char len,
					     const unsigned char *vector);

/* stores the default values for new connection. may be changed with sysctl */
static const struct dccp_options dccpo_default_values = {
	.dccpo_sequence_window	  = DCCPF_INITIAL_SEQUENCE_WINDOW,
	.dccpo_ccid		  = DCCPF_INITIAL_CCID,
	.dccpo_send_ack_vector	  = DCCPF_INITIAL_SEND_ACK_VECTOR,
	.dccpo_send_ndp_count	  = DCCPF_INITIAL_SEND_NDP_COUNT,
};

void dccp_options_init(struct dccp_options *dccpo)
{
	memcpy(dccpo, &dccpo_default_values, sizeof(*dccpo));
}

static u32 dccp_decode_value_var(const unsigned char *bf, const u8 len)
{
	u32 value = 0;

	if (len > 3)
		value += *bf++ << 24;
	if (len > 2)
		value += *bf++ << 16;
	if (len > 1)
		value += *bf++ << 8;
	if (len > 0)
		value += *bf;

	return value;
}

int dccp_parse_options(struct sock *sk, struct sk_buff *skb)
{
	struct dccp_sock *dp = dccp_sk(sk);
#ifdef CONFIG_IP_DCCP_DEBUG
	const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
					"CLIENT rx opt: " : "server rx opt: ";
#endif
	const struct dccp_hdr *dh = dccp_hdr(skb);
	const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
	unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
	unsigned char *opt_ptr = options;
	const unsigned char *opt_end = (unsigned char *)dh +
					(dh->dccph_doff * 4);
	struct dccp_options_received *opt_recv = &dp->dccps_options_received;
	unsigned char opt, len;
	unsigned char *value;
	u32 elapsed_time;

	memset(opt_recv, 0, sizeof(*opt_recv));

	while (opt_ptr != opt_end) {
		opt   = *opt_ptr++;
		len   = 0;
		value = NULL;

		/* Check if this isn't a single byte option */
		if (opt > DCCPO_MAX_RESERVED) {
			if (opt_ptr == opt_end)
				goto out_invalid_option;

			len = *opt_ptr++;
			if (len < 3)
				goto out_invalid_option;
			/*
			 * Remove the type and len fields, leaving
			 * just the value size
			 */
			len	-= 2;
			value	= opt_ptr;
			opt_ptr += len;

			if (opt_ptr > opt_end)
				goto out_invalid_option;
		}

		switch (opt) {
		case DCCPO_PADDING:
			break;
		case DCCPO_NDP_COUNT:
			if (len > 3)
				goto out_invalid_option;

			opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
			dccp_pr_debug("%sNDP count=%d\n", debug_prefix,
				      opt_recv->dccpor_ndp);
			break;
		case DCCPO_ACK_VECTOR_0:
			if (len > DCCP_MAX_ACK_VECTOR_LEN)
				goto out_invalid_option;

			if (pkt_type == DCCP_PKT_DATA)
				continue;

			opt_recv->dccpor_ack_vector_len = len;
			opt_recv->dccpor_ack_vector_idx = value - options;

			dccp_pr_debug("%sACK vector 0, len=%d, ack_ackno=%llu\n",
				      debug_prefix, len,
				      (unsigned long long)
				      DCCP_SKB_CB(skb)->dccpd_ack_seq);
			dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq,
					     value, len);
			dccp_ackpkts_check_rcv_ackvector(dp->dccps_hc_rx_ackpkts,
							 sk,
						 DCCP_SKB_CB(skb)->dccpd_ack_seq,
							 len, value);
			break;
		case DCCPO_TIMESTAMP:
			if (len != 4)
				goto out_invalid_option;

			opt_recv->dccpor_timestamp = ntohl(*(u32 *)value);

			dp->dccps_timestamp_echo = opt_recv->dccpor_timestamp;
			dccp_timestamp(sk, &dp->dccps_timestamp_time);

			dccp_pr_debug("%sTIMESTAMP=%u, ackno=%llu\n",
				      debug_prefix, opt_recv->dccpor_timestamp,
				      (unsigned long long)
				      DCCP_SKB_CB(skb)->dccpd_ack_seq);
			break;
		case DCCPO_TIMESTAMP_ECHO:
			if (len != 4 && len != 6 && len != 8)
				goto out_invalid_option;

			opt_recv->dccpor_timestamp_echo = ntohl(*(u32 *)value);

			dccp_pr_debug