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Commit e21ce8c7 authored by Ralf Baechle's avatar Ralf Baechle Committed by David S. Miller
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[NETROM]: Implement G8PZT Circuit reset for NET/ROM 



NET/ROM is lacking a connection reset like TCP's RST flag which at times
may result in a connecting having to slowly timing out instead of just being
reset.  An earlier attempt to reset the connection by sending a
NR_CONNACK | NR_CHOKE_FLAG transport was inacceptable as it did result in
crashes of BPQ systems.  An alternative approach of introducing a new
transport type 7 (NR_RESET) has be implemented several years ago in
Paula Jayne Dowie G8PZT's Xrouter.

Implement NR_RESET for Linux's NET/ROM but like any messing with the state
engine consider this experimental for now and thus control it by a sysctl
(net.netrom.reset) which for the time being defaults to off.

Signed-off-by: default avatarRalf Baechle DL5RB <ralf@linux-mips.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d2ce4bc3

include/linux/sysctl.h

+2 −1
Original line number Diff line number Diff line
@@ -544,7 +544,8 @@ enum { 
	NET_NETROM_TRANSPORT_REQUESTED_WINDOW_SIZE=8,

	NET_NETROM_TRANSPORT_NO_ACTIVITY_TIMEOUT=9,

	NET_NETROM_ROUTING_CONTROL=10,

	NET_NETROM_LINK_FAILS_COUNT=11

	NET_NETROM_LINK_FAILS_COUNT=11,

	NET_NETROM_RESET=12

};



/* /proc/sys/net/ax25 */

include/net/netrom.h

+26 −1
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ 
#define	NR_DISCACK			0x04

#define	NR_INFO				0x05

#define	NR_INFOACK			0x06

#define	NR_RESET			0x07



#define	NR_CHOKE_FLAG			0x80

#define	NR_NAK_FLAG			0x40
@@ -51,6 +52,7 @@ enum { 
#define	NR_DEFAULT_TTL			16		/* Default Time To Live - 16 */

#define	NR_DEFAULT_ROUTING		1		/* Is routing enabled ? */

#define	NR_DEFAULT_FAILS		2		/* Link fails until route fails */

#define	NR_DEFAULT_RESET		0		/* Sent / accept reset cmds? */



#define NR_MODULUS 			256

#define NR_MAX_WINDOW_SIZE		127			/* Maximum Window Allowable - 127 */
@@ -176,6 +178,8 @@ extern int sysctl_netrom_transport_requested_window_size; 
extern int  sysctl_netrom_transport_no_activity_timeout;

extern int  sysctl_netrom_routing_control;

extern int  sysctl_netrom_link_fails_count;

extern int  sysctl_netrom_reset_circuit;



extern int  nr_rx_frame(struct sk_buff *, struct net_device *);

extern void nr_destroy_socket(struct sock *);
@@ -218,7 +222,28 @@ extern void nr_requeue_frames(struct sock *); 
extern int  nr_validate_nr(struct sock *, unsigned short);

extern int  nr_in_rx_window(struct sock *, unsigned short);

extern void nr_write_internal(struct sock *, int);

extern void nr_transmit_refusal(struct sk_buff *, int);



extern void __nr_transmit_reply(struct sk_buff *skb, int mine,

	unsigned char cmdflags);



/*

 * This routine is called when a Connect Acknowledge with the Choke Flag

 * set is needed to refuse a connection.

 */

#define nr_transmit_refusal(skb, mine)					\

do {									\

	__nr_transmit_reply((skb), (mine), NR_CONNACK | NR_CHOKE_FLAG);	\

} while (0)



/*

 * This routine is called when we don't have a circuit matching an incoming

 * NET/ROM packet.  This is an G8PZT Xrouter extension.

 */

#define nr_transmit_reset(skb, mine)					\

do {									\

	__nr_transmit_reply((skb), (mine), NR_RESET);			\

} while (0)



extern void nr_disconnect(struct sock *, int);



/* nr_timer.c */

net/netrom/af_netrom.c

+11 −10
Original line number Diff line number Diff line
@@ -56,6 +56,7 @@ int sysctl_netrom_transport_requested_window_size = NR_DEFAULT_WINDOW; 
int sysctl_netrom_transport_no_activity_timeout   = NR_DEFAULT_IDLE;

int sysctl_netrom_routing_control                 = NR_DEFAULT_ROUTING;

int sysctl_netrom_link_fails_count                = NR_DEFAULT_FAILS;

int sysctl_netrom_reset_circuit                   = NR_DEFAULT_RESET;



static unsigned short circuit = 0x101;
@@ -908,17 +909,17 @@ int nr_rx_frame(struct sk_buff *skb, struct net_device *dev) 
	if (frametype != NR_CONNREQ) {

		/*

		 * Here it would be nice to be able to send a reset but

		 * NET/ROM doesn't have one. The following hack would

		 * have been a way to extend the protocol but apparently

		 * it kills BPQ boxes... :-(

		 * NET/ROM doesn't have one.  We've tried to extend the protocol

		 * by sending NR_CONNACK | NR_CHOKE_FLAGS replies but that

		 * apparently kills BPQ boxes... :-(

		 * So now we try to follow the established behaviour of

		 * G8PZT's Xrouter which is sending packets with command type 7

		 * as an extension of the protocol.

		 */

#if 0

		/*

		 * Never reply to a CONNACK/CHOKE.

		 */

		if (frametype != NR_CONNACK || flags != NR_CHOKE_FLAG)

			nr_transmit_refusal(skb, 1);

#endif

		if (sysctl_netrom_reset_circuit &&

		    (frametype != NR_RESET || flags != 0))

			nr_transmit_reset(skb, 1);



		return 0;

	}

net/netrom/nr_in.c

+15 −0
Original line number Diff line number Diff line
@@ -98,6 +98,11 @@ static int nr_state1_machine(struct sock *sk, struct sk_buff *skb, 
		nr_disconnect(sk, ECONNREFUSED);

		break;



	case NR_RESET:

		if (sysctl_netrom_reset_circuit);

			nr_disconnect(sk, ECONNRESET);

		break;



	default:

		break;

	}
@@ -124,6 +129,11 @@ static int nr_state2_machine(struct sock *sk, struct sk_buff *skb, 
		nr_disconnect(sk, 0);

		break;



	case NR_RESET:

		if (sysctl_netrom_reset_circuit);

			nr_disconnect(sk, ECONNRESET);

		break;



	default:

		break;

	}
@@ -254,6 +264,11 @@ static int nr_state3_machine(struct sock *sk, struct sk_buff *skb, int frametype 
		}

		break;



	case NR_RESET:

		if (sysctl_netrom_reset_circuit);

			nr_disconnect(sk, ECONNRESET);

		break;



	default:

		break;

	}

net/netrom/nr_subr.c

+3 −4
Original line number Diff line number Diff line
@@ -210,10 +210,9 @@ void nr_write_internal(struct sock *sk, int frametype) 
}



/*

 * This routine is called when a Connect Acknowledge with the Choke Flag

 * set is needed to refuse a connection.

 * This routine is called to send an error reply.

 */

void nr_transmit_refusal(struct sk_buff *skb, int mine)

void __nr_transmit_reply(struct sk_buff *skb, int mine, unsigned char cmdflags)

{

	struct sk_buff *skbn;

	unsigned char *dptr;
@@ -254,7 +253,7 @@ void nr_transmit_refusal(struct sk_buff *skb, int mine) 
		*dptr++ = 0;

	}



	*dptr++ = NR_CONNACK | NR_CHOKE_FLAG;

	*dptr++ = cmdflags;

	*dptr++ = 0;



	if (!nr_route_frame(skbn, NULL))