diff options
Diffstat (limited to 'packet-ppp.c')
| -rw-r--r-- | packet-ppp.c | 182 |
1 files changed, 139 insertions, 43 deletions
diff --git a/packet-ppp.c b/packet-ppp.c index 59c7a721b3..9d1f72f721 100644 --- a/packet-ppp.c +++ b/packet-ppp.c @@ -1,7 +1,7 @@ /* packet-ppp.c * Routines for ppp packet disassembly * - * $Id: packet-ppp.c,v 1.91 2002/04/24 06:03:34 guy Exp $ + * $Id: packet-ppp.c,v 1.92 2002/05/20 00:56:30 guy Exp $ * * Ethereal - Network traffic analyzer * By Gerald Combs <gerald@ethereal.com> @@ -1292,11 +1292,10 @@ static const unsigned short fcstab_16[256] = { ******************************************************************************* */ static guint16 -fcs16(register guint16 fcs, - tvbuff_t * tvbuff, - guint32 offset, - guint32 len) +fcs16(register guint16 fcs, tvbuff_t * tvbuff) { + int offset = 0; + guint len = tvb_length(tvbuff); guint8 val; /* Check for Invalid Length */ @@ -1317,11 +1316,10 @@ fcs16(register guint16 fcs, ******************************************************************************* */ static guint32 -fcs32(guint32 fcs, - tvbuff_t * tvbuff, - guint32 offset, - guint32 len) +fcs32(guint32 fcs, tvbuff_t * tvbuff) { + int offset = 0; + guint len = tvb_length(tvbuff); guint8 val; /* Check for invalid Length */ @@ -2132,7 +2130,9 @@ dissect_bap_call_status_opt(const ip_tcp_opt *optp, tvbuff_t *tvb, static void dissect_cp( tvbuff_t *tvb, int proto_id, int proto_subtree_index, const value_string *proto_vals, int options_subtree_index, - const ip_tcp_opt *opts, int nopts, packet_info *pinfo, proto_tree *tree ) { + const ip_tcp_opt *opts, int nopts, packet_info *pinfo, + proto_tree *tree ) +{ proto_item *ti; proto_tree *fh_tree = NULL; proto_item *tf; @@ -2256,37 +2256,34 @@ dissect_cp( tvbuff_t *tvb, int proto_id, int proto_subtree_index, #define PFC_BIT 0x01 static void -dissect_ppp_common( tvbuff_t *tvb, int offset, packet_info *pinfo, - proto_tree *tree, proto_tree *fh_tree, - proto_item *ti ) { +dissect_ppp_common( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, + proto_tree *fh_tree, proto_item *ti ) +{ guint16 ppp_prot; int proto_len; tvbuff_t *next_tvb; - ppp_prot = tvb_get_guint8(tvb, offset); + ppp_prot = tvb_get_guint8(tvb, 0); if (ppp_prot & PFC_BIT) { /* Compressed protocol field - just the byte we fetched. */ proto_len = 1; } else { /* Uncompressed protocol field - fetch all of it. */ - ppp_prot = tvb_get_ntohs(tvb, offset); + ppp_prot = tvb_get_ntohs(tvb, 0); proto_len = 2; } /* If "ti" is not null, it refers to the top-level "proto_ppp" item for PPP, and was given a length equal to the length of any stuff in the header preceding the protocol type, e.g. an HDLC - header, which is just "offset"; add the length of the protocol - type field to it. */ + header; add the length of the protocol type field to it. */ if (ti != NULL) - proto_item_set_len(ti, offset + proto_len); + proto_item_set_len(ti, proto_item_get_len(ti) + proto_len); - if (tree) { - proto_tree_add_uint(fh_tree, hf_ppp_protocol, tvb, offset, proto_len, - ppp_prot); - } + if (tree) + proto_tree_add_uint(fh_tree, hf_ppp_protocol, tvb, 0, proto_len, ppp_prot); - next_tvb = tvb_new_subset(tvb, offset + proto_len, -1, -1); + next_tvb = tvb_new_subset(tvb, proto_len, -1, -1); /* do lookup with the subdissector table */ if (!dissector_try_port(subdissector_table, ppp_prot, next_tvb, pinfo, tree)) { @@ -2603,7 +2600,7 @@ dissect_ppp( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree ) { fh_tree = proto_item_add_subtree(ti, ett_ppp); } - dissect_ppp_common(tvb, 0, pinfo, tree, fh_tree, ti); + dissect_ppp_common(tvb, pinfo, tree, fh_tree, ti); } /* @@ -2611,11 +2608,14 @@ dissect_ppp( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree ) { * a PPP in HDLC-like Framing frame (RFC 1662) or a Cisco HDLC frame. */ static void -dissect_ppp_hdlc( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree ) { +dissect_ppp_hdlc( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree ) +{ proto_item *ti = NULL; proto_tree *fh_tree = NULL; guint8 byte0; int proto_offset; + gint len, reported_len; + tvbuff_t *next_tvb; int rx_fcs_offset; guint32 rx_fcs_exp; guint32 rx_fcs_got; @@ -2658,29 +2658,126 @@ dissect_ppp_hdlc( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree ) { } } - dissect_ppp_common(tvb, proto_offset, pinfo, tree, fh_tree, ti); + /* + * Remove the FCS, if any, from the packet data. + */ + switch (ppp_fcs_decode) { + + case NO_FCS: + next_tvb = tvb_new_subset(tvb, proto_offset, -1, -1); + break; - /* Calculate the FCS check */ - /* XXX - deal with packets cut off by the snapshot length */ - if (ppp_fcs_decode == FCS_16) { - rx_fcs_offset = tvb_length(tvb) - 2; - rx_fcs_exp = fcs16(0xFFFF, tvb, 0, rx_fcs_offset); - rx_fcs_got = tvb_get_letohs(tvb, rx_fcs_offset); - if (rx_fcs_got != rx_fcs_exp) { - proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 2, "FCS 16: 0x%04x (incorrect, should be %04x)", rx_fcs_got, rx_fcs_exp); + case FCS_16: + /* + * Do we have the entire packet, and does it include a 2-byte FCS? + */ + len = tvb_length_remaining(tvb, proto_offset); + reported_len = tvb_reported_length_remaining(tvb, proto_offset); + if (reported_len < 2 || len < 0) { + /* + * The packet is claimed not to even have enough data for a 2-byte FCS, + * or we're already past the end of the captured data. + * Don't slice anything off. + */ + next_tvb = tvb_new_subset(tvb, proto_offset, -1, -1); + } else if (len < reported_len) { + /* + * The packet is claimed to have enough data for a 2-byte FCS, but + * we didn't capture all of the packet. + * Slice off the 2-byte FCS from the reported length, and trim the + * captured length so it's no more than the reported length; that + * will slice off what of the FCS, if any, is in the captured + * length. + */ + reported_len -= 2; + if (len > reported_len) + len = reported_len; + next_tvb = tvb_new_subset(tvb, proto_offset, len, reported_len); } else { - proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 2, "FCS 16: 0x%04x (correct)", rx_fcs_got); + /* + * We have the entire packet, and it includes a 2-byte FCS. + * Slice it off. + */ + len -= 2; + reported_len -= 2; + next_tvb = tvb_new_subset(tvb, proto_offset, len, reported_len); + + /* + * Compute the FCS and put it into the tree. + */ + rx_fcs_offset = proto_offset + len; + rx_fcs_exp = fcs16(0xFFFF, next_tvb); + rx_fcs_got = tvb_get_letohs(tvb, rx_fcs_offset); + if (rx_fcs_got != rx_fcs_exp) { + proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 2, + "FCS 16: 0x%04x (incorrect, should be 0x%04x)", + rx_fcs_got, rx_fcs_exp); + } else { + proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 2, + "FCS 16: 0x%04x (correct)", + rx_fcs_got); + } } - } else if (ppp_fcs_decode == FCS_32) { - rx_fcs_offset = tvb_length(tvb) - 4; - rx_fcs_exp = fcs32(0xFFFFFFFF, tvb, 0, rx_fcs_offset); - rx_fcs_got = tvb_get_letohl(tvb, rx_fcs_offset); - if (rx_fcs_got != rx_fcs_exp) { - proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 4, "FCS 32: 0x%08x (incorrect, should be %08x) ", rx_fcs_got, rx_fcs_exp); + break; + + case FCS_32: + /* + * Do we have the entire packet, and does it include a 4-byte FCS? + */ + len = tvb_length_remaining(tvb, proto_offset); + reported_len = tvb_reported_length_remaining(tvb, proto_offset); + if (reported_len < 4) { + /* + * The packet is claimed not to even have enough data for a 4-byte FCS. + * Just pass on the tvbuff as is. + */ + next_tvb = tvb_new_subset(tvb, proto_offset, -1, -1); + } else if (len < reported_len) { + /* + * The packet is claimed to have enough data for a 4-byte FCS, but + * we didn't capture all of the packet. + * Slice off the 4-byte FCS from the reported length, and trim the + * captured length so it's no more than the reported length; that + * will slice off what of the FCS, if any, is in the captured + * length. + */ + reported_len -= 4; + if (len > reported_len) + len = reported_len; + next_tvb = tvb_new_subset(tvb, proto_offset, len, reported_len); } else { - proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 4, "FCS 32: 0x%08x (correct)", rx_fcs_got); + /* + * We have the entire packet, and it includes a 4-byte FCS. + * Slice it off. + */ + len -= 4; + reported_len -= 4; + next_tvb = tvb_new_subset(tvb, proto_offset, len, reported_len); + + /* + * Compute the FCS and put it into the tree. + */ + rx_fcs_offset = proto_offset + len; + rx_fcs_exp = fcs32(0xFFFFFFFF, next_tvb); + rx_fcs_got = tvb_get_letohl(tvb, rx_fcs_offset); + if (rx_fcs_got != rx_fcs_exp) { + proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 4, + "FCS 32: 0x%08x (incorrect, should be 0x%08x)", + rx_fcs_got, rx_fcs_exp); + } else { + proto_tree_add_text(fh_tree, tvb, rx_fcs_offset, 4, + "FCS 32: 0x%08x (correct)", + rx_fcs_got); + } } + break; + + default: + g_assert_not_reached(); + next_tvb = NULL; } + + dissect_ppp_common(next_tvb, pinfo, tree, fh_tree, ti); } /* @@ -3354,4 +3451,3 @@ proto_reg_handoff_pppmux(void) */ dissector_add("ethertype", PPP_MUX, pppmux_handle); } - |