From 0fceb64d25ff3d9586549bb43d971c5eef904330 Mon Sep 17 00:00:00 2001
From: Ralf Baechle <ralf@linux-mips.org>
Date: Mon, 7 Jun 1999 10:23:42 +0200
Subject: Import ax25-apps 0.0.1 from tarball

---
 listen/tcpdump.c | 123 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 123 insertions(+)
 create mode 100644 listen/tcpdump.c

(limited to 'listen/tcpdump.c')

diff --git a/listen/tcpdump.c b/listen/tcpdump.c
new file mode 100644
index 0000000..7939f41
--- /dev/null
+++ b/listen/tcpdump.c
@@ -0,0 +1,123 @@
+/* @(#) $Header: tcpdump.c,v 1.5 91/05/09 07:38:56 deyke Exp $ */
+
+/* TCP header tracing routines
+ * Copyright 1991 Phil Karn, KA9Q
+ */
+#include <stdio.h>
+#include <string.h>
+#include "listen.h"
+
+#define	FIN	0x01
+#define	SYN	0x02
+#define	RST	0x04
+#define	PSH	0x08
+#define	ACK	0x10
+#define	URG	0x20
+#define	CE	0x40
+
+/* TCP options */
+#define EOL_KIND	0
+#define NOOP_KIND	1
+#define MSS_KIND	2
+#define MSS_LENGTH	4
+
+#define	TCPLEN	20
+
+#define max(a,b)  ((a) > (b) ? (a) : (b))
+
+/* Dump a TCP segment header. Assumed to be in network byte order */
+void tcp_dump(unsigned char *data, int length, int hexdump)
+{
+	int source, dest;
+	int seq;
+	int ack;
+	int flags;
+	int wnd;
+	int up;
+	int hdrlen;
+	int mss = 0;
+
+	source = get16(data + 0);
+	dest   = get16(data + 2);
+	seq    = get32(data + 4);
+	ack    = get32(data + 8);
+	hdrlen = (data[12] & 0xF0) >> 2;
+	flags  = data[13];
+	wnd    = get16(data + 14);
+	up     = get16(data + 18);
+
+	lprintf(T_PROTOCOL, "TCP:");
+	lprintf(T_TCPHDR, " %s->", servname(source, "tcp"));
+	lprintf(T_TCPHDR, "%s Seq x%x", servname(dest, "tcp"), seq);
+
+	if (flags & ACK) lprintf(T_TCPHDR, " Ack x%x", ack);
+
+	if (flags & CE)  lprintf(T_TCPHDR, " CE");
+
+	if (flags & URG) lprintf(T_TCPHDR, " URG");
+
+	if (flags & ACK) lprintf(T_TCPHDR, " ACK");
+
+	if (flags & PSH) lprintf(T_TCPHDR, " PSH");
+
+	if (flags & RST) lprintf(T_TCPHDR, " RST");
+
+	if (flags & SYN) lprintf(T_TCPHDR, " SYN");
+
+	if (flags & FIN) lprintf(T_TCPHDR, " FIN");
+
+	lprintf(T_TCPHDR, " Wnd %d", wnd);
+
+	if (flags & URG) lprintf(T_TCPHDR, " UP x%x", up);
+
+	/* Process options, if any */
+	if (hdrlen > TCPLEN && length >= hdrlen) {
+		unsigned char *cp = data + TCPLEN;
+		int i = hdrlen - TCPLEN;
+		int kind, optlen;
+
+		while (i > 0) {
+			kind = *cp++;
+
+			/* Process single-byte options */
+			switch (kind) {
+			case EOL_KIND:
+				i--;
+				cp++;
+				break;
+			case NOOP_KIND:
+				i--;
+				cp++;
+				continue;
+			}
+
+			/* All other options have a length field */
+			optlen = *cp++;
+
+			/* Process valid multi-byte options */
+  			switch (kind) {
+			case MSS_KIND:
+			 	if (optlen == MSS_LENGTH)
+					mss = get16(cp);
+				break;
+			}
+
+			optlen = max(2, optlen); /* Enforce legal minimum */
+			i -= optlen;
+			cp += optlen - 2;
+		}
+	}
+
+	if (mss != 0) lprintf(T_TCPHDR," MSS %d", mss);
+
+	length -= hdrlen;
+	data   += hdrlen;
+
+	if (length > 0) {
+		lprintf(T_TCPHDR, " Data %d\n", length);
+		data_dump(data, length, hexdump);
+		return;
+	}
+	
+	lprintf(T_TCPHDR, "\n");
+}
-- 
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