Date: Fri, 11 Feb 2000 09:00:04 -0800 (PST) From: bmah@CA.Sandia.GOV (Bruce A. Mah) To: freebsd-bugs@FreeBSD.org Subject: bin/13691: tcpslice problems Message-ID: <200002111700.JAA07442@freefall.freebsd.org>
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The following reply was made to PR bin/13691; it has been noted by GNATS. From: bmah@CA.Sandia.GOV (Bruce A. Mah) To: sheldonh@uunet.co.za, tate@spa.is.uec.ac.jp, freebsd-gnats-submit@freebsd.org Cc: bmah@CA.Sandia.GOV, vern@ee.lbl.gov, obrien@freebsd.org Subject: bin/13691: tcpslice problems Date: Fri, 11 Feb 2000 08:50:46 -0800 Hi all-- Came across PR bin/13691 while I was researching a Y2K bug in tcpslice. Right now I see three problems with the version of tcpslice in the FreeBSD base distribution: 1. tcpslice doesn't work correctly on >2GB files. 2. Timezone conversions aren't right. (See PR bin/10633, filed by me.) 3. Y2K bug (tcpslice doesn't handle dates correctly on traces that start in year 2000 or later). To fix all three of these, I propose the following: A. Contribify tcpslice-1.1a3, as I described in bin/10633. This fixes #2 and, according to Tateoka-san's follow-up to bin/13691, will fix part of #1 by giving us a tcpslice that uses off_t instead of long for file offsets. B. Apply the patch attached here, to replace all of the fseek/ftell calls with fsetpos/fgetpos calls. Another way to do this is to replace fseek/ftell with fseeko/ftello. The patch from Vern (cited by Sheldon) replaces two of the ftell calls with ftello, but doesn't touch any of the fseek calls. (My patch uses fsetpos/fgetpos because that's what I was familiar with at the time. Using fseeko/ftello may in fact be better because it involves fewer code changes.) The attached patch also has a diff for gwtm2secs.c to fix the Y2K problem in #3. I realize this doesn't stand much of a chance of happening in the middle of the 4.0 code freeze, but I wanted to write this up while it's still fresh in my mind. (Vern: I sent you a CC on this in case you're still doing work on tcpslice. You can get some of the background info leading up to this discussion at: http://www.freebsd.org/cgi/query-pr-summary.cgi ) (David: I don't mean to hassle you over bin/10633, but I thought you'd probably be interested.) Thanks all! Bruce. diff -c -r tcpslice-1.1a3-dist/gwtm2secs.c tcpslice-1.1a3/gwtm2secs.c *** tcpslice-1.1a3-dist/gwtm2secs.c Sat Dec 21 19:56:52 1996 --- tcpslice-1.1a3/gwtm2secs.c Fri Feb 11 08:17:02 2000 *************** *** 62,67 **** --- 62,74 ---- else year += 2000; + /* Make sure our year is still >= 1970. We fix 3-digit years + * this way, because localtime(3) can return tm_year >= 100, + * starting in year 2000. + */ + if ( year < 1970 ) + year += 1900; + days = 0; for ( i = 1970; i < year; ++i ) { diff -c -r tcpslice-1.1a3-dist/search.c tcpslice-1.1a3/search.c *** tcpslice-1.1a3-dist/search.c Sat Dec 21 19:56:37 1996 --- tcpslice-1.1a3/search.c Wed Apr 21 08:00:42 1999 *************** *** 295,301 **** * end of the file. */ num_bytes = MAX_BYTES_FOR_DEFINITE_HEADER; ! if ( fseek( pcap_file( p ), (off_t) -num_bytes, 2 ) < 0 ) return 0; buf = (u_char *)malloc((u_int) num_bytes); --- 295,301 ---- * end of the file. */ num_bytes = MAX_BYTES_FOR_DEFINITE_HEADER; ! if ( fseek( pcap_file( p ), (off_t) -num_bytes, SEEK_END ) < 0 ) return 0; buf = (u_char *)malloc((u_int) num_bytes); *************** *** 360,366 **** status = 1; /* Seek so that the next read will start at last valid packet. */ ! if ( fseek( pcap_file( p ), (off_t) -(bufend - hdrpos), 2 ) < 0 ) error( "final fseek() failed in sf_find_end()" ); done: --- 360,366 ---- status = 1; /* Seek so that the next read will start at last valid packet. */ ! if ( fseek( pcap_file( p ), (off_t) -(bufend - hdrpos), SEEK_END ) < 0 ) error( "final fseek() failed in sf_find_end()" ); done: *************** *** 433,439 **** { struct timeval *timestamp; ! pos = ftell( pcap_file( p ) ); buf = pcap_next( p, &hdr ); if ( buf == 0 ) --- 433,439 ---- { struct timeval *timestamp; ! fgetpos( pcap_file( p ), &pos ); buf = pcap_next( p, &hdr ); if ( buf == 0 ) *************** *** 457,464 **** } } ! if ( fseek( pcap_file( p ), pos, 0 ) < 0 ) ! error( "fseek() failed in read_up_to()" ); return (status); } --- 457,464 ---- } } ! if ( fsetpos( pcap_file( p ), &pos ) < 0 ) ! error( "fsetpos() failed in read_up_to()" ); return (status); } *************** *** 515,521 **** break; } ! present_pos = ftell( pcap_file( p ) ); if ( present_pos <= desired_pos && desired_pos - present_pos < STRAIGHT_SCAN_THRESHOLD ) --- 515,521 ---- break; } ! fgetpos( pcap_file( p ), &present_pos ); if ( present_pos <= desired_pos && desired_pos - present_pos < STRAIGHT_SCAN_THRESHOLD ) *************** *** 531,538 **** if ( desired_pos < min_pos ) desired_pos = min_pos; ! if ( fseek( pcap_file( p ), desired_pos, 0 ) < 0 ) ! error( "fseek() failed in sf_find_packet()" ); num_bytes_read = fread( (char *) buf, 1, num_bytes, pcap_file( p ) ); --- 531,538 ---- if ( desired_pos < min_pos ) desired_pos = min_pos; ! if ( fsetpos( pcap_file( p ), &desired_pos ) < 0 ) ! error( "fsetpos() failed in sf_find_packet()" ); num_bytes_read = fread( (char *) buf, 1, num_bytes, pcap_file( p ) ); *************** *** 554,561 **** desired_pos += (hdrpos - buf); /* Seek to the beginning of the header. */ ! if ( fseek( pcap_file( p ), desired_pos, 0 ) < 0 ) ! error( "fseek() failed in sf_find_packet()" ); if ( sf_timestamp_less_than( &hdr.ts, desired_time ) ) { /* too early in the file */ --- 554,561 ---- desired_pos += (hdrpos - buf); /* Seek to the beginning of the header. */ ! if ( fsetpos( pcap_file( p ), &desired_pos ) < 0 ) ! error( "fsetpos() failed in sf_find_packet()" ); if ( sf_timestamp_less_than( &hdr.ts, desired_time ) ) { /* too early in the file */ diff -c -r tcpslice-1.1a3-dist/tcpslice.c tcpslice-1.1a3/tcpslice.c *** tcpslice-1.1a3-dist/tcpslice.c Fri Jan 24 13:36:09 1997 --- tcpslice-1.1a3/tcpslice.c Wed Apr 21 08:01:01 1999 *************** *** 470,476 **** error( "bad tcpdump file %s: %s", filename, errbuf ); snaplen = pcap_snapshot( p ); ! start_pos = ftell( pcap_file( p ) ); if ( ! dumper ) { --- 470,476 ---- error( "bad tcpdump file %s: %s", filename, errbuf ); snaplen = pcap_snapshot( p ); ! fgetpos( pcap_file( p ), &start_pos ); if ( ! dumper ) { *************** *** 491,497 **** error( "problems finding end packet of file %s", filename ); ! stop_pos = ftell( pcap_file( p ) ); /* sf_find_packet() requires that the time it's passed as its last --- 491,497 ---- error( "problems finding end packet of file %s", filename ); ! fgetpos( pcap_file( p ), &stop_pos ); /* sf_find_packet() requires that the time it's passed as its last To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-bugs" in the body of the message
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