From cf6f6e2ed7d64a22630080c45147766b3ad9f045 Mon Sep 17 00:00:00 2001
From: Heikki Hannikainen <hessu@hes.iki.fi>
Date: Thu, 19 Dec 2013 08:32:15 +0200
Subject: [PATCH] Drop packets having source callsign of N0CALL, NOCALL, or
 SERVER * NOCALLs being a default on many TNCs and software * potentially
 blocks a message loop between SERVERs

---
 src/incoming.c         | 46 ++++++++++++++++++++++++++++++++++++++++--
 src/worker.h           |  3 ++-
 tests/t/11misc-drops.t |  5 ++++-
 3 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/src/incoming.c b/src/incoming.c
index a4167df..5a9ae0b 100644
--- a/src/incoming.c
+++ b/src/incoming.c
@@ -42,7 +42,7 @@
 #include "dupecheck.h"
 
 /* When adding labels here, remember to add the description strings in
- * web/aprsc.js rx_err_strings
+ * web/aprsc.js rx_err_strings, and worker.h constants
  */
 const char *inerr_labels[] = {
 	"unknown",
@@ -76,11 +76,34 @@ const char *inerr_labels[] = {
 	"q_newq_buffer_small",
 	"q_nonval_multi_q_calls",
 	"q_i_no_viacall",
-	"inerr_empty"
+	"inerr_empty",
+	"dis_srccall"
 };
 
 #define incoming_strerror(i) ((i <= 0 && i >= INERR_MIN) ? inerr_labels[i * -1] : inerr_labels[0])
 
+
+/* a static list of source callsigns which are dropped */
+static const char *disallow_srccalls[] = {
+	"N0CALL", /* default in some apps */
+	"NOCALL", /* default in some apps */
+	"SERVER", /* originated by APRS-IS server */
+	NULL
+};
+
+static const char *disallow_msg_recipients[] = {
+	"USERLIST", /* old aprsd */
+	"JAVATITLE", /* old aprsd */
+	"JAVATITL2", /* old aprsd */
+	NULL
+};
+
+static const char *disallow_data_prefixes[] = {
+	"DX de ", /* DX messages */
+	NULL
+};
+
+
 #ifdef _FOR_VALGRIND_
 typedef struct cellarena_t {
   int dummy;
@@ -523,6 +546,22 @@ int check_invalid_src_dst(const char *call, int len)
 	return 0;
 }
 
+/*
+ *	Check callsign against a list to see if it matches
+ */
+ 
+static int check_call_match(const char **set, const char *call, int len)
+{
+	int i;
+	
+	for (i = 0; (set[i]); i++) {
+		if (strncmp(call, set[i], len) == 0 && strlen(set[i]) == len)
+			return -1;
+	}
+	
+	return 0;
+}
+
 /*
  *	Check if a callsign is good for a digi path entry
  *	(valid APRS-IS callsign, * allowed in end)
@@ -796,6 +835,9 @@ int incoming_parse(struct worker_t *self, struct client_t *c, char *s, int len)
 	if (check_invalid_src_dst(s, src_len) != 0)
 		return INERR_INV_SRCCALL; /* invalid or too long for source callsign */
 	
+	if (check_call_match(disallow_srccalls, s, src_len))
+		return INERR_DIS_SRCCALL; /* disallowed srccall */
+	
 	info_start = path_end+1;	// @":"+1 - first char of the payload
 	if (info_start >= packet_end)
 		return INERR_NO_BODY;
diff --git a/src/worker.h b/src/worker.h
index 02a77ce..4fc52b3 100644
--- a/src/worker.h
+++ b/src/worker.h
@@ -218,8 +218,9 @@ struct client_heard_t {
 #define INERR_Q_NONVAL_MULTI_Q_CALLS		-29
 #define INERR_Q_I_NO_VIACALL			-30
 #define INERR_EMPTY			-31
+#define INERR_DIS_SRCCALL		-32
 
-#define INERR_MIN			-31	/* MINIMUM VALUE FOR INERR, GROW WHEN NEEDED! */
+#define INERR_MIN			-32	/* MINIMUM VALUE FOR INERR, GROW WHEN NEEDED! */
 /* WHEN ADDING STUFF HERE, REMEMBER TO UPDATE inerr_labels IN incoming.c. Thanks! */
 #define INERR_BUCKETS			(INERR_MIN*-1 + 1)
 
diff --git a/tests/t/11misc-drops.t b/tests/t/11misc-drops.t
index 6ee31b2..ac378d0 100644
--- a/tests/t/11misc-drops.t
+++ b/tests/t/11misc-drops.t
@@ -78,10 +78,13 @@ my @pkts = (
 	"SRC2>DST,DIGI,TCPXX,qAR,$login:>Packet from unverified login according to TCPXX in path",
 	"SRC2>DST,DIGI,TCPXX*,qAR,$login:>Packet from unverified login according to TCPXX* in path",
 	"SRC->DST,DIGI-0,qAR,$login:>should drop, too short SSID in srccall",
-	"SRC>DST,DIGI-0,qAR,$login:>should drop, -0 SSID in viacall",
 # javap4 drops these, javap3 allows
 #	"SRC-111>DST,DIGI-0,qAR,$login:>should drop, too long SSID in srccall",
 #	"EL-DH5FFL>DST,DIGI-0,qAR,$login:>should drop, much too long SSID in srccall",
+	# disallowed source callsigns
+	"N0CALL>DST,DIGI,qAR,$login:>should drop, N0CALL as source callsign",
+	"NOCALL>DST,DIGI,qAR,$login:>should drop, NOCALL as source callsign",
+	"SERVER>DST,DIGI,qAR,$login:>should drop, SERVER as source callsign",
 );
 
 # send the packets