[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: Ralf Baechle DL5RB <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/sysctl.h b/include/linux/sysctl.h
index 532a6c5..3a29a9f 100644
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -544,7 +544,8 @@
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 */
diff --git a/include/net/netrom.h b/include/net/netrom.h
index 45f2c76..ad05d7a 100644
--- a/include/net/netrom.h
+++ b/include/net/netrom.h
@@ -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 @@
#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_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 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 */
diff --git a/net/netrom/af_netrom.c b/net/netrom/af_netrom.c
index 02b1ab5..8c3d3a7 100644
--- a/net/netrom/af_netrom.c
+++ b/net/netrom/af_netrom.c
@@ -56,6 +56,7 @@
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 @@
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;
}
diff --git a/net/netrom/nr_in.c b/net/netrom/nr_in.c
index 64b81a7..004e859 100644
--- a/net/netrom/nr_in.c
+++ b/net/netrom/nr_in.c
@@ -98,6 +98,11 @@
nr_disconnect(sk, ECONNREFUSED);
break;
+ case NR_RESET:
+ if (sysctl_netrom_reset_circuit);
+ nr_disconnect(sk, ECONNRESET);
+ break;
+
default:
break;
}
@@ -124,6 +129,11 @@
nr_disconnect(sk, 0);
break;
+ case NR_RESET:
+ if (sysctl_netrom_reset_circuit);
+ nr_disconnect(sk, ECONNRESET);
+ break;
+
default:
break;
}
@@ -254,6 +264,11 @@
}
break;
+ case NR_RESET:
+ if (sysctl_netrom_reset_circuit);
+ nr_disconnect(sk, ECONNRESET);
+ break;
+
default:
break;
}
diff --git a/net/netrom/nr_subr.c b/net/netrom/nr_subr.c
index 587bed2..bcb9946 100644
--- a/net/netrom/nr_subr.c
+++ b/net/netrom/nr_subr.c
@@ -210,10 +210,9 @@
}
/*
- * 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 @@
*dptr++ = 0;
}
- *dptr++ = NR_CONNACK | NR_CHOKE_FLAG;
+ *dptr++ = cmdflags;
*dptr++ = 0;
if (!nr_route_frame(skbn, NULL))
diff --git a/net/netrom/sysctl_net_netrom.c b/net/netrom/sysctl_net_netrom.c
index c9ed503..6bb8dda 100644
--- a/net/netrom/sysctl_net_netrom.c
+++ b/net/netrom/sysctl_net_netrom.c
@@ -30,6 +30,7 @@
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 @@
.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 }
};