[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 532a6c5c24e9cc105b30accf34f4a6e792967988..3a29a9f9b451d7f3b0e6135ff7d4fcc0fa886027 100644 (file)
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -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 */

diff --git a/include/net/netrom.h b/include/net/netrom.h
index 45f2c7616d8b8566e690aedbdecb66db9ccea9d3..ad05d7a3c55d85b2547a02df78567b53d719a996 100644 (file)
--- 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 @@ 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 */

diff --git a/net/netrom/af_netrom.c b/net/netrom/af_netrom.c
index 02b1ab52dbbf1b363174faf7111d61a6156304e6..8c3d3a78481eb8bf4401d21600a6c245da3820ab 100644 (file)
--- a/net/netrom/af_netrom.c
+++ b/net/netrom/af_netrom.c
@@ -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;
        }
 

diff --git a/net/netrom/nr_in.c b/net/netrom/nr_in.c
index 64b81a7969077c706353e76309a67698380f2095..004e8599b8fe595f5b72c92b0b51bb203b99a44d 100644 (file)
--- a/net/netrom/nr_in.c
+++ b/net/netrom/nr_in.c
@@ -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;
        }

diff --git a/net/netrom/nr_subr.c b/net/netrom/nr_subr.c
index 587bed2674bfb4dcb09e40f13ae0d33b8342e053..bcb9946b4f5628f59276cfed1082c33135d95119 100644 (file)
--- a/net/netrom/nr_subr.c
+++ b/net/netrom/nr_subr.c
@@ -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))

diff --git a/net/netrom/sysctl_net_netrom.c b/net/netrom/sysctl_net_netrom.c
index c9ed50382ea7bb067766173207bafbade894f984..6bb8dda849dc71d1de1bd13ca8942eb6d607316f 100644 (file)
--- a/net/netrom/sysctl_net_netrom.c
+++ b/net/netrom/sysctl_net_netrom.c
@@ -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 }
 };