diff options
| -rw-r--r-- | packet-clnp.c | 39 | ||||
| -rw-r--r-- | packet-esis.c | 32 | ||||
| -rw-r--r-- | packet-osi.c | 56 | ||||
| -rw-r--r-- | packet-osi.h | 14 |
4 files changed, 112 insertions, 29 deletions
diff --git a/packet-clnp.c b/packet-clnp.c index d1cd4c8abb..78ec69e43d 100644 --- a/packet-clnp.c +++ b/packet-clnp.c @@ -1,14 +1,13 @@ /* packet-clnp.c * Routines for ISO/OSI network and transport protocol packet disassembly * - * $Id: packet-clnp.c,v 1.28 2001/05/27 04:14:52 guy Exp $ + * $Id: packet-clnp.c,v 1.29 2001/06/05 09:06:19 guy Exp $ * Laurent Deniel <deniel@worldnet.fr> * Ralf Schneider <Ralf.Schneider@t-online.de> * * Ethereal - Network traffic analyzer - * By Gerald Combs <gerald@zing.org> + * By Gerald Combs <gerald@ethereal.com> * Copyright 1998 Gerald Combs - * * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License @@ -1675,10 +1674,42 @@ static void dissect_clnp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) proto_tree_add_uint(clnp_tree, hf_clnp_pdu_length, tvb, P_CLNP_SEGLEN, 2, segment_length); cnf_cksum = tvb_get_ntohs(tvb, P_CLNP_CKSUM); - proto_tree_add_uint_format(clnp_tree, hf_clnp_checksum, tvb, P_CLNP_CKSUM, 2, + switch (calc_checksum(tvb, 0, cnf_hdr_len, cnf_cksum)) { + + default: + /* + * No checksum present, or not enough of the header present to + * checksum it. + */ + proto_tree_add_uint_format(clnp_tree, hf_clnp_checksum, tvb, + P_CLNP_CKSUM, 2, cnf_cksum, "Checksum : 0x%04x", cnf_cksum); + break; + + case CKSUM_OK: + /* + * Checksum is correct. + */ + proto_tree_add_uint_format(clnp_tree, hf_clnp_checksum, tvb, + P_CLNP_CKSUM, 2, + cnf_cksum, + "Checksum : 0x%04x (correct)", + cnf_cksum); + break; + + case CKSUM_NOT_OK: + /* + * Checksum is not correct. + */ + proto_tree_add_uint_format(clnp_tree, hf_clnp_checksum, tvb, + P_CLNP_CKSUM, 2, + cnf_cksum, + "Checksum : 0x%04x (incorrect)", + cnf_cksum); + break; + } opt_len -= 9; /* Fixed part of Hesder */ } /* tree */ diff --git a/packet-esis.c b/packet-esis.c index 906b1987ed..51b78a0183 100644 --- a/packet-esis.c +++ b/packet-esis.c @@ -2,13 +2,12 @@ * Routines for ISO/OSI End System to Intermediate System * Routeing Exchange Protocol ISO 9542. * - * $Id: packet-esis.c,v 1.14 2001/03/30 10:51:50 guy Exp $ + * $Id: packet-esis.c,v 1.15 2001/06/05 09:06:19 guy Exp $ * Ralf Schneider <Ralf.Schneider@t-online.de> * * Ethereal - Network traffic analyzer - * By Gerald Combs <gerald@zing.org> + * By Gerald Combs <gerald@ethereal.com> * Copyright 1998 Gerald Combs - * * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License @@ -292,6 +291,7 @@ dissect_esis(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) { proto_tree *esis_tree = NULL; int variable_len = 0; u_int tmp_uint = 0; + char *cksum_status; if (check_col(pinfo->fd, COL_PROTOCOL)) col_set_str(pinfo->fd, COL_PROTOCOL, "ESIS"); @@ -337,11 +337,31 @@ dissect_esis(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree) { tmp_uint = pntohs( ehdr.esis_checksum ); + switch (calc_checksum( tvb, 0, ehdr.esis_length, tmp_uint )) { + + case NO_CKSUM: + cksum_status = "Not Used"; + break; + + case DATA_MISSING: + cksum_status = "Not checkable - not all of packet was captured"; + break; + + case CKSUM_OK: + cksum_status = "Is good"; + break; + + case CKSUM_NOT_OK: + cksum_status = "Is wrong"; + break; + + default: + cksum_status = NULL; + g_assert_not_reached(); + } proto_tree_add_uint_format( esis_tree, hf_esis_checksum, tvb, 7, 2, tmp_uint, "Checksum : 0x%x ( %s )", - tmp_uint, calc_checksum( tvb, 0, - ehdr.esis_length , - tmp_uint ) ); + tmp_uint, cksum_status ); } diff --git a/packet-osi.c b/packet-osi.c index b165677243..4b5c8900a8 100644 --- a/packet-osi.c +++ b/packet-osi.c @@ -2,14 +2,13 @@ * Routines for ISO/OSI network and transport protocol packet disassembly * Main entrance point and common functions * - * $Id: packet-osi.c,v 1.44 2001/04/16 10:04:30 guy Exp $ + * $Id: packet-osi.c,v 1.45 2001/06/05 09:06:19 guy Exp $ * Laurent Deniel <deniel@worldnet.fr> * Ralf Schneider <Ralf.Schneider@t-online.de> * * Ethereal - Network traffic analyzer - * By Gerald Combs <gerald@zing.org> + * By Gerald Combs <gerald@ethereal.com> * Copyright 1998 Gerald Combs - * * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License @@ -49,29 +48,56 @@ #include "packet-esis.h" -gchar *calc_checksum( tvbuff_t *tvb, int offset, u_int len, u_int checksum) { - u_int calc_sum = 0; - u_int count = 0; +cksum_status_t +calc_checksum( tvbuff_t *tvb, int offset, u_int len, u_int checksum) { const gchar *buffer; guint available_len; + const guint8 *p; + guint32 c0, c1; + u_int seglen; + int i; if ( 0 == checksum ) - return( "Not Used" ); + return( NO_CKSUM ); available_len = tvb_length_remaining( tvb, offset ); if ( available_len < len ) - return( "Not checkable - not all of packet was captured" ); + return( DATA_MISSING ); buffer = tvb_get_ptr( tvb, offset, len ); - for ( count = 0; count < len; count++ ) { - calc_sum += (u_int) buffer[count]; + + /* + * The maximum values of c0 and c1 will occur if all bytes have the + * value 255; if so, then c0 will be len*255 and c1 will be + * (len*255 + (len-1)*255 + ... + 255), which is + * (len + (len - 1) + ... + 1)*255, or 255*(len*(len + 1))/2. + * This means it can overflow if "len" is 5804 or greater. + * + * (A+B) mod 255 = ((A mod 255) + (B mod 255) mod 255, so + * we can solve this by taking c0 and c1 mod 255 every + * 5803 bytes. + */ + p = buffer; + c0 = 0; + c1 = 0; + while (len != 0) { + seglen = len; + if (seglen > 5803) + seglen = 5803; + for (i = 0; i < seglen; i++) { + c0 = c0 + *(p++); + c1 += c0; + } + + c0 = c0 % 255; + c1 = c1 % 255; + + len -= seglen; } - calc_sum %= 255; /* modulo 255 divison */ - - if ( 0 == calc_sum ) - return( "Is good" ); + if (c0 != 0 || c1 != 0) + return( CKSUM_NOT_OK ); /* XXX - what should the checksum be? */ else - return( "Is wrong" ); /* XXX - what should the checksum be? */ + return( CKSUM_OK ); } diff --git a/packet-osi.h b/packet-osi.h index 6694ef1ef5..6b2573526f 100644 --- a/packet-osi.h +++ b/packet-osi.h @@ -1,11 +1,10 @@ /* packet-osi.h * - * $Id: packet-osi.h,v 1.7 2001/04/01 05:48:14 hagbard Exp $ + * $Id: packet-osi.h,v 1.8 2001/06/05 09:06:19 guy Exp $ * * Ethereal - Network traffic analyzer - * By Gerald Combs <gerald@zing.org> + * By Gerald Combs <gerald@ethereal.com> * Copyright 1998 Gerald Combs - * * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License @@ -85,6 +84,13 @@ dissector_table_t osinl_subdissector_table; * published API functions */ -extern gchar *calc_checksum ( tvbuff_t *, int, u_int, u_int ); +typedef enum { + NO_CKSUM, /* checksum field is 0 */ + DATA_MISSING, /* not all the data covered by the checksum was captured */ + CKSUM_OK, /* checksum is OK */ + CKSUM_NOT_OK /* checksum is not OK */ +} cksum_status_t; + +extern cksum_status_t calc_checksum(tvbuff_t *, int, u_int, u_int); #endif /* _PACKET_OSI_H */ |