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Commit be0c52bf authored by Remi Denis-Courmont's avatar Remi Denis-Courmont Committed by David S. Miller
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Phonet: emit errors when a packet cannot be delivered locally 



When there is no listener socket for a received packet, send an error
back to the sender.

Signed-off-by: default avatarRemi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 87ab4e20

include/linux/phonet.h

+32 −0
Original line number Diff line number Diff line
@@ -45,6 +45,38 @@ struct phonethdr { 
	__u8	pn_sobj;

} __attribute__((packed));



/* Common Phonet payload header */

struct phonetmsg {

	__u8	pn_trans_id;	/* transaction ID */

	__u8	pn_msg_id;	/* message type */

	union {

		struct {

			__u8	pn_submsg_id;	/* message subtype */

			__u8	pn_data[5];

		} base;

		struct {

			__u16	pn_e_res_id;	/* extended resource ID */

			__u8	pn_e_submsg_id;	/* message subtype */

			__u8	pn_e_data[3];

		} ext;

	} pn_msg_u;

};

#define PN_COMMON_MESSAGE	0xF0

#define PN_PREFIX		0xE0 /* resource for extended messages */

#define pn_submsg_id		pn_msg_u.base.pn_submsg_id

#define pn_e_submsg_id		pn_msg_u.ext.pn_e_submsg_id

#define pn_e_res_id		pn_msg_u.ext.pn_e_res_id

#define pn_data			pn_msg_u.base.pn_data

#define pn_e_data		pn_msg_u.ext.pn_e_data



/* data for unreachable errors */

#define PN_COMM_SERVICE_NOT_IDENTIFIED_RESP	0x01

#define PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP	0x14

#define pn_orig_msg_id		pn_data[0]

#define pn_status		pn_data[1]

#define pn_e_orig_msg_id	pn_e_data[0]

#define pn_e_status		pn_e_data[1]



/* Phonet socket address structure */

struct sockaddr_pn {

	sa_family_t spn_family;

include/net/phonet/phonet.h

+5 −0
Original line number Diff line number Diff line
@@ -60,6 +60,11 @@ static inline struct phonethdr *pn_hdr(struct sk_buff *skb) 
	return (struct phonethdr *)skb_network_header(skb);

}



static inline struct phonetmsg *pn_msg(struct sk_buff *skb)

{

	return (struct phonetmsg *)skb_transport_header(skb);

}



/*

 * Get the other party's sockaddr from received skb. The skb begins

 * with a Phonet header.

net/phonet/af_phonet.c

+92 −4
Original line number Diff line number Diff line
@@ -132,7 +132,7 @@ EXPORT_SYMBOL(phonet_header_ops); 
 * Prepends an ISI header and sends a datagram.

 */

static int pn_send(struct sk_buff *skb, struct net_device *dev,

			u16 dst, u16 src, u8 res)

			u16 dst, u16 src, u8 res, u8 irq)

{

	struct phonethdr *ph;

	int err;
@@ -163,6 +163,9 @@ static int pn_send(struct sk_buff *skb, struct net_device *dev, 
		skb_reset_mac_header(skb);

		skb->pkt_type = PACKET_LOOPBACK;

		skb_orphan(skb);

		if (irq)

			netif_rx(skb);

		else

			netif_rx_ni(skb);

		err = 0;

	} else {
@@ -181,6 +184,19 @@ static int pn_send(struct sk_buff *skb, struct net_device *dev, 
	return err;

}



static int pn_raw_send(const void *data, int len, struct net_device *dev,

			u16 dst, u16 src, u8 res)

{

	struct sk_buff *skb = alloc_skb(MAX_PHONET_HEADER + len, GFP_ATOMIC);

	if (skb == NULL)

		return -ENOMEM;



	skb_reserve(skb, MAX_PHONET_HEADER);

	__skb_put(skb, len);

	skb_copy_to_linear_data(skb, data, len);

	return pn_send(skb, dev, dst, src, res, 1);

}



/*

 * Create a Phonet header for the skb and send it out. Returns

 * non-zero error code if failed. The skb is freed then.
@@ -211,7 +227,7 @@ int pn_skb_send(struct sock *sk, struct sk_buff *skb, 
		src = pn_object(saddr, pn_obj(src));



	err = pn_send(skb, dev, pn_sockaddr_get_object(target),

			src, pn_sockaddr_get_resource(target));

			src, pn_sockaddr_get_resource(target), 0);

	dev_put(dev);

	return err;
@@ -223,6 +239,73 @@ int pn_skb_send(struct sock *sk, struct sk_buff *skb, 
}

EXPORT_SYMBOL(pn_skb_send);



/* Do not send an error message in response to an error message */

static inline int can_respond(struct sk_buff *skb)

{

	const struct phonethdr *ph;

	const struct phonetmsg *pm;

	u8 submsg_id;



	if (!pskb_may_pull(skb, 3))

		return 0;



	ph = pn_hdr(skb);

	if (phonet_address_get(skb->dev, ph->pn_rdev) != ph->pn_rdev)

		return 0; /* we are not the destination */

	if (ph->pn_res == PN_PREFIX && !pskb_may_pull(skb, 5))

		return 0;



	ph = pn_hdr(skb); /* re-acquires the pointer */

	pm = pn_msg(skb);

	if (pm->pn_msg_id != PN_COMMON_MESSAGE)

		return 1;

	submsg_id = (ph->pn_res == PN_PREFIX)

		? pm->pn_e_submsg_id : pm->pn_submsg_id;

	if (submsg_id != PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP &&

		pm->pn_e_submsg_id != PN_COMM_SERVICE_NOT_IDENTIFIED_RESP)

		return 1;

	return 0;

}



static int send_obj_unreachable(struct sk_buff *rskb)

{

	const struct phonethdr *oph = pn_hdr(rskb);

	const struct phonetmsg *opm = pn_msg(rskb);

	struct phonetmsg resp;



	memset(&resp, 0, sizeof(resp));

	resp.pn_trans_id = opm->pn_trans_id;

	resp.pn_msg_id = PN_COMMON_MESSAGE;

	if (oph->pn_res == PN_PREFIX) {

		resp.pn_e_res_id = opm->pn_e_res_id;

		resp.pn_e_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;

		resp.pn_e_orig_msg_id = opm->pn_msg_id;

		resp.pn_e_status = 0;

	} else {

		resp.pn_submsg_id = PN_COMM_ISA_ENTITY_NOT_REACHABLE_RESP;

		resp.pn_orig_msg_id = opm->pn_msg_id;

		resp.pn_status = 0;

	}

	return pn_raw_send(&resp, sizeof(resp), rskb->dev,

				pn_object(oph->pn_sdev, oph->pn_sobj),

				pn_object(oph->pn_rdev, oph->pn_robj),

				oph->pn_res);

}



static int send_reset_indications(struct sk_buff *rskb)

{

	struct phonethdr *oph = pn_hdr(rskb);

	static const u8 data[4] = {

		0x00 /* trans ID */, 0x10 /* subscribe msg */,

		0x00 /* subscription count */, 0x00 /* dummy */

	};



	return pn_raw_send(data, sizeof(data), rskb->dev,

				pn_object(oph->pn_sdev, 0x00),

				pn_object(oph->pn_rdev, oph->pn_robj), 0x10);

}





/* packet type functions */



/*
@@ -260,8 +343,13 @@ static int phonet_rcv(struct sk_buff *skb, struct net_device *dev, 
		goto out; /* currently, we cannot be device 0 */



	sk = pn_find_sock_by_sa(&sa);

	if (sk == NULL)

	if (sk == NULL) {

		if (can_respond(skb)) {

			send_obj_unreachable(skb);

			send_reset_indications(skb);

		}

		goto out;

	}



	/* Push data to the socket (or other sockets connected to it). */

	return sk_receive_skb(sk, skb, 0);