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[NETROM]: Implement G8PZT Circuit reset for NET/ROM

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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: Ralf Baechle DL5RB <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Ralf Baechle 2005-09-12 14:27:37 -07:00 committed by David S. Miller
parent d2ce4bc340
commit e21ce8c7c0
6 changed files with 69 additions and 16 deletions
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3
include/linux/sysctl.h
View File

@ -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 */

27
include/net/netrom.h
View File

@ -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 */

21
net/netrom/af_netrom.c
View File

@ -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;
}

15
net/netrom/nr_in.c
View File

@ -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;
}

7
net/netrom/nr_subr.c
View File

@ -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))

12
net/netrom/sysctl_net_netrom.c
View File

@ -30,6 +30,7 @@ static int min_idle[] = {0 * HZ};
static int max_idle[] = {65535 * HZ};
static int min_route[] = {0}, max_route[] = {1};
static int min_fails[] = {1}, max_fails[] = {10};
static int min_reset[] = {0}, max_reset[] = {1};
static struct ctl_table_header *nr_table_header;
@ -155,6 +156,17 @@ static ctl_table nr_table[] = {
.extra1 = &min_fails,
.extra2 = &max_fails
},
{
.ctl_name = NET_NETROM_RESET,
.procname = "reset",
.data = &sysctl_netrom_reset_circuit,
.maxlen = sizeof(int),
.mode = 0644,
.proc_handler = &proc_dointvec_minmax,
.strategy = &sysctl_intvec,
.extra1 = &min_reset,
.extra2 = &max_reset
},
{ .ctl_name = 0 }
};