From 38ab57afa45a872e53b5221907e34a8a4abed93f Mon Sep 17 00:00:00 2001
From: wb2osz <wb2osz@comcast.net>
Date: Mon, 2 Jul 2018 12:18:23 -0400
Subject: [PATCH] New NOXID option to avoid wasting time to listed station(s)
 which understand SABME but not XID.

---
 ax25_link.c | 11 +++++++++++
 config.c    | 38 ++++++++++++++++++++++++++++++++++++++
 config.h    |  7 +++++++
 3 files changed, 56 insertions(+)

diff --git a/ax25_link.c b/ax25_link.c
index 4d352b48..0e1bb3fa 100644
--- a/ax25_link.c
+++ b/ax25_link.c
@@ -6357,7 +6357,18 @@ static void mdl_negotiate_request (ax25_dlsm_t *S)
 	int p = 1;
 	int nopid = 0;
 	packet_t pp;
+	int n;
+
+// At least one known [partial] v2.2 implementation understands SABME but not XID.
+// Rather than wasting time, sending XID repeatedly until giving up, we have a workaround.
+// The configuration file can contain a list of stations known not to respond to XID.
+// Obviously this applies only to v2.2 because XID was not part of v2.0.
 
+	for (n = 0; n < g_misc_config_p->noxid_count; n++) {
+	  if (strcmp(S->addrs[PEERCALL],g_misc_config_p->noxid_addrs[n]) == 0) {
+	    return;
+	  }
+	}
 
 	switch (S->mdl_state) {
 
diff --git a/config.c b/config.c
index 86a36557..8c367e2c 100644
--- a/config.c
+++ b/config.c
@@ -904,6 +904,8 @@ void config_init (char *fname, struct audio_s *p_audio_config,
 	p_misc_config->maxv22 = AX25_N2_RETRY_DEFAULT / 2;	/* Max SABME before falling back to SABM. */
 	p_misc_config->v20_addrs = NULL;			/* Go directly to v2.0 for stations listed. */
 	p_misc_config->v20_count = 0;
+	p_misc_config->noxid_addrs = NULL;			/* Don't send XID to these stations. */
+	p_misc_config->noxid_count = 0;
 
 /* 
  * Try to extract options from a file.
@@ -4796,6 +4798,42 @@ void config_init (char *fname, struct audio_s *p_audio_config,
 	  }
 
 
+/*
+ * NOXID  address [ address ... ] 	- Stations known not to understand XID.
+ *					  After connecting to these (with v2.2 obviously), don't try using XID commmand.
+ *					  AX.25 for Linux is the one known case so far.
+ *					  Possible to have multiple and they are cummulative.
+ */
+
+	  else if (strcasecmp(t, "NOXID") == 0) {
+
+	    t = split(NULL,0);
+	    if (t == NULL) {
+	      text_color_set(DW_COLOR_ERROR);
+	      dw_printf ("Line %d: Missing address(es) for NOXID.\n", line);
+	      continue;
+	    }
+
+	    while (t != NULL) {
+	      int const strict = 2;
+	      char call_no_ssid[AX25_MAX_ADDR_LEN];
+	      int ssid, heard;
+
+	      if (ax25_parse_addr (AX25_DESTINATION, t, strict, call_no_ssid, &ssid, &heard)) {
+	        p_misc_config->noxid_addrs = (char**)realloc (p_misc_config->noxid_addrs, sizeof(char*) * (p_misc_config->noxid_count + 1));
+	        p_misc_config->noxid_addrs[p_misc_config->noxid_count++] = strdup(t);
+	      }
+	      else {
+	        text_color_set(DW_COLOR_ERROR);
+                dw_printf ("Line %d: Invalid station address for NOXID command.\n", line);
+
+	        // continue processing any others following.
+	      }
+	      t = split(NULL,0);
+	    }
+	  }
+
+
 /*
  * Invalid command.
  */
diff --git a/config.h b/config.h
index 675d2924..8a3c013e 100644
--- a/config.h
+++ b/config.h
@@ -111,6 +111,13 @@ struct misc_config_s {
 
 	int v20_count;		/* Number of station addresses in array above. */
 
+	char **noxid_addrs;	/* Stations known not to understand XID command so don't */
+				/* waste time sending it and eventually giving up. */
+				/* AX.25 for Linux is the one known case, so far, where */
+				/* SABME is implemented but XID is not. */
+
+	int noxid_count;	/* Number of station addresses in array above. */
+
 
 // Beacons.