path: root/net/phonet/pep.c

/*
 * File: pep.c
 *
 * Phonet pipe protocol end point socket
 *
 * Copyright (C) 2008 Nokia Corporation.
 *
 * Author: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * This program 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 */

#include <linux/kernel.h>
#include <linux/socket.h>
#include <net/sock.h>
#include <net/tcp_states.h>
#include <asm/ioctls.h>

#include <linux/phonet.h>
#include <net/phonet/phonet.h>
#include <net/phonet/pep.h>
#include <net/phonet/gprs.h>

/* sk_state values:
 * TCP_CLOSE		sock not in use yet
 * TCP_CLOSE_WAIT	disconnected pipe
 * TCP_LISTEN		listening pipe endpoint
 * TCP_SYN_RECV		connected pipe in disabled state
 * TCP_ESTABLISHED	connected pipe in enabled state
 *
 * pep_sock locking:
 *  - sk_state, ackq, hlist: sock lock needed
 *  - listener: read only
 *  - pipe_handle: read only
 */

#define CREDITS_MAX	10
#define CREDITS_THR	7

static const struct sockaddr_pn pipe_srv = {
	.spn_family = AF_PHONET,
	.spn_resource = 0xD9, /* pipe service */
};

#define pep_sb_size(s) (((s) + 5) & ~3) /* 2-bytes head, 32-bits aligned */

/* Get the next TLV sub-block. */
static unsigned char *pep_get_sb(struct sk_buff *skb, u8 *ptype, u8 *plen,
					void *buf)
{
	void *data = NULL;
	struct {
		u8 sb_type;
		u8 sb_len;
	} *ph, h;
	int buflen = *plen;

	ph = skb_header_pointer(skb, 0, 2, &h);
	if (ph == NULL || ph->sb_len < 2 || !pskb_may_pull(skb, ph->sb_len))
		return NULL;
	ph->sb_len -= 2;
	*ptype = ph->sb_type;
	*plen = ph->sb_len;

	if (buflen > ph->sb_len)
		buflen = ph->sb_len;
	data = skb_header_pointer(skb, 2, buflen, buf);
	__skb_pull(skb, 2 + ph->sb_len);
	return data;
}

static int pep_reply(struct sock *sk, struct sk_buff *oskb,
			u8 code, const void *data, int len, gfp_t priority)
{
	const struct pnpipehdr *oph = pnp_hdr(oskb);
	struct pnpipehdr *ph;
	struct sk_buff *skb;

	skb = alloc_skb(MAX_PNPIPE_HEADER + len, priority);
	if (!skb)
		return -ENOMEM;
	skb_set_owner_w(skb, sk);

	skb_reserve(skb, MAX_PNPIPE_HEADER);
	__skb_put(skb, len);
	skb_copy_to_linear_data(skb, data, len);
	__skb_push(skb, sizeof(*ph));
	skb_reset_transport_header(skb);
	ph = pnp_hdr(skb);
	ph->utid = oph->utid;
	ph->message_id = oph->message_id + 1; /* REQ -> RESP */
	ph->pipe_handle = oph->pipe_handle;
	ph->error_code = code;

	return pn_skb_send(sk, skb, &pipe_srv);
}

#define PAD 0x00
static int pep_accept_conn(struct sock *sk, struct sk_buff *skb)
{
	static const u8 data[20] = {
		PAD, PAD, PAD, 2 /* sub-blocks */,
		PN_PIPE_SB_REQUIRED_FC_TX, pep_sb_size(5), 3, PAD,
			PN_MULTI_CREDIT_FLOW_CONTROL,
			PN_ONE_CREDIT_FLOW_CONTROL,
			PN_LEGACY_FLOW_CONTROL,
			PAD,
		PN_PIPE_SB_PREFERRED_FC_RX, pep_sb_size(5), 3, PAD,
			PN_MULTI_CREDIT_FLOW_CONTROL,
			PN_ONE_CREDIT_FLOW_CONTROL,
			PN_LEGACY_FLOW_CONTROL,
			PAD,
	};

	might_sleep();
	return pep_reply(sk, skb, PN_PIPE_NO_ERROR, data, sizeof(data),
				GFP_KERNEL);
}

static int pep_reject_conn(struct sock *sk, struct sk_buff *skb, u8 code)
{
	static const u8 data