I discovered that with TCPtrace, only the first fragment includes the
packet header line - subsequent fragments do not. So, I modified the
code to assume that a packet will start almost immediately after the
previous packet. I modified the code so it is more strict in
identifying the start of data in a packet.
-Marc Milgram
Index: vms.c
===================================================================
RCS file: /cvsroot/ethereal/wiretap/vms.c,v
retrieving revision 1.11
diff -u -r1.11 vms.c
--- vms.c 2002/03/07 21:08:33 1.11
+++ vms.c 2002/03/25 20:27:28
@@ -20,6 +20,13 @@
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
+/* Notes:
+ * TCPIPtrace TCP fragments don't have the header line. So, we are never
+ * to look for that line for the first line of a packet except the first
+ * packet. This allows us to read fragmented packets. Define
+ * TCPIPTRACE_FRAGMENTS_HAVE_HEADER_LINE to expect the first line to be
+ * at the start of every packet.
+ */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
@@ -81,6 +88,7 @@
static int parse_vms_rec_hdr(wtap *wth, FILE_T fh, int *err);
+#ifdef TCPIPTRACE_FRAGMENTS_HAVE_HEADER_LINE
/* Seeks to the beginning of the next packet, and returns the
byte offset. Returns -1 on failure, and sets "*err" to the error. */
static long vms_seek_next_packet(wtap *wth, int *err)
@@ -118,6 +126,7 @@
}
return -1;
}
+#endif /* TCPIPTRACE_FRAGMENTS_HAVE_HEADER_LINE */
#define VMS_HEADER_LINES_TO_CHECK 200
#define VMS_LINE_LENGTH 240
@@ -215,7 +224,11 @@
int pkt_len;
/* Find the next packet */
+#ifdef TCPIPTRACE_FRAGMENTS_HAVE_HEADER_LINE
offset = vms_seek_next_packet(wth, err);
+#else
+ offset = file_tell(wth->fh);
+#endif
if (offset < 1)
return FALSE;
@@ -261,31 +274,36 @@
return parse_vms_hex_dump(wth->random_fh, pkt_len, pd, err);
}
-/* isdumpline assumes that dump lines start with some spaces followed by a
- * hex number.
+/* isdumpline assumes that dump lines start with some non-alphanumerics
+ * followed by 4 hex numbers - each 8 digits long, each hex number followed
+ * by 3 spaces.
*/
static int
isdumpline( guchar *line )
{
- int i = 0;
-
- while (i<VMS_LINE_LENGTH && line[i] && !isalnum(line[i]))
- i++;
+ int i, j;
- if (! isxdigit(line[i]))
- return 0;
+ while (*line && !isalnum(*line))
+ line++;
- while (i<VMS_LINE_LENGTH && isxdigit(line[i]))
- i++;
+ for (j=0; j<4; j++) {
+ for (i=0; i<8; i++, line++)
+ if (! isxdigit(*line))
+ return FALSE;
+
+ for (i=0; i<3; i++, line++)
+ if (*line != ' ')
+ return FALSE;
+ }
- return isspace(line[i]);
+ return isspace(*line);
}
/* Parses a packet record header. */
static int
parse_vms_rec_hdr(wtap *wth, FILE_T fh, int *err)
{
- char line[VMS_LINE_LENGTH];
+ char line[VMS_LINE_LENGTH + 1];
int num_items_scanned;
int pkt_len = 0;
int pktnum;
@@ -310,6 +328,8 @@
}
return -1;
}
+ line[VMS_LINE_LENGTH] = '\0';
+
if ((csec == 101) && (p = strstr(line, "packet "))
&& (! strstr(line, "could not save "))) {
/* Find text in line starting with "packet ". */
@@ -360,7 +380,7 @@
static gboolean
parse_vms_hex_dump(FILE_T fh, int pkt_len, guint8* buf, int *err)
{
- guchar line[VMS_LINE_LENGTH];
+ guchar line[VMS_LINE_LENGTH + 1];
int i;
int offset = 0;
@@ -372,8 +392,9 @@
}
return FALSE;
}
+ line[VMS_LINE_LENGTH] = '\0';
if (i == 0) {
- while (! isdumpline(line)) /* advance to start of hex data */
+ while (! isdumpline(line)) { /* advance to start of hex data */
if (file_gets(line, VMS_LINE_LENGTH, fh) == NULL) {
*err = file_error(fh);
if (*err == 0) {
@@ -381,6 +402,8 @@
}
return FALSE;
}
+ line[VMS_LINE_LENGTH] = '\0';
+ }
while (line[offset] && !isxdigit(line[offset]))
offset++;
}
