From: guy <guy>
Date: Sat, 29 Jul 2000 09:06:23 +0000 (+0000)
Subject: Changes from Kevin Steves to print, in an RST segment, the payload as
X-Git-Tag: tcpdump-3.5.1~201
X-Git-Url: https://git.tcpdump.org/tcpdump/commitdiff_plain/674fea664da96caf629c5bdda52a9257d9c7ac91

Changes from Kevin Steves to print, in an RST segment, the payload as
text, as per RFC 1122:

	4.2.2.12  RST Segment: RFC-793 Section 3.4

	   A TCP SHOULD allow a received RST segment to include data.

	   DISCUSSION
		It has been suggested that a RST segment could contain
		ASCII text that encoded and explained the cause of the
		RST.  No standard has yet been established for such
		data.

as some TCP implementations (e.g., HP-UX 11.0) do that.

Clean up the code that prints the payload of non-RST segments.
---

diff --git a/print-tcp.c b/print-tcp.c
index 895cf216..d5790252 100644
--- a/print-tcp.c
+++ b/print-tcp.c
@@ -21,7 +21,7 @@
 
 #ifndef lint
 static const char rcsid[] =
-    "@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.68 2000-07-29 08:03:05 assar Exp $ (LBL)";
+    "@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.69 2000-07-29 09:06:23 guy Exp $ (LBL)";
 #endif
 
 #ifdef HAVE_CONFIG_H
@@ -52,6 +52,10 @@ static const char rcsid[] =
 #include "addrtoname.h"
 #include "extract.h"
 
+static void print_tcp_rst_data(register const u_char *sp, u_int length);
+
+#define MAX_RST_DATA_LEN	30
+
 /* Compatibility */
 #ifndef TCPOPT_WSCALE
 #define	TCPOPT_WSCALE		3	/* window scale factor (rfc1072) */
@@ -518,13 +522,18 @@ tcp_print(register const u_char *bp, register u_int length,
 	 * Decode payload if necessary.
 	 */
 	bp += (tp->th_off * 4);
-	if (!qflag && vflag && length > 0
-	 && (sport == TELNET_PORT || dport == TELNET_PORT))
-		telnet_print(bp, length);
-	else if (sport == BGP_PORT || dport == BGP_PORT)
-		bgp_print(bp, length);
-	else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
-		nbt_tcp_print(bp, length);
+	if (flags & TH_RST) {
+		if (vflag)
+			print_tcp_rst_data(bp, length);
+	} else {
+		if (sport == TELNET_PORT || dport == TELNET_PORT) {
+			if (!qflag && vflag)
+				telnet_print(bp, length);
+		} else if (sport == BGP_PORT || dport == BGP_PORT)
+			bgp_print(bp, length);
+		else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
+			nbt_tcp_print(bp, length);
+	}
 	return;
 bad:
 	fputs("[bad opt]", stdout);
@@ -537,3 +546,41 @@ trunc:
 		putchar('>');
 }
 
+/*
+ * RFC1122 says the following on data in RST segments:
+ *
+ *         4.2.2.12  RST Segment: RFC-793 Section 3.4
+ *
+ *            A TCP SHOULD allow a received RST segment to include data.
+ *
+ *            DISCUSSION
+ *                 It has been suggested that a RST segment could contain
+ *                 ASCII text that encoded and explained the cause of the
+ *                 RST.  No standard has yet been established for such
+ *                 data.
+ *
+ */
+
+static void
+print_tcp_rst_data(register const u_char *sp, u_int length)
+{
+	int c;
+
+	if (TTEST2(*sp, length))
+		printf(" [RST");
+	else
+		printf(" [!RST");
+	if (length > MAX_RST_DATA_LEN) {
+		length = MAX_RST_DATA_LEN;	/* can use -X for longer */
+		putchar('+');			/* indicate we truncate */
+	}
+	putchar(' ');
+	while (length-- && sp <= snapend) {
+		c = *sp++;
+		if (isprint(c))
+			putchar(c);
+		else
+			putchar('.');
+	}
+	putchar(']');
+}