forked from osmocom/wireshark
Decode DHCP option 52 (Option Overload). Decode the options embedded
in the sname and file options as needed. Thanks to Tedd Frechette for the sample capture. svn path=/trunk/; revision=6345
This commit is contained in:
Gerald Combs
parent
c2bb2c8d52
commit
7928808681
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@ -2,7 +2,7 @@
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* Routines for BOOTP/DHCP packet disassembly
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* Gilbert Ramirez <gram@alumni.rice.edu>
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*
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* $Id: packet-bootp.c,v 1.70 2002/08/28 21:00:08 jmayer Exp $
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* $Id: packet-bootp.c,v 1.71 2002/09/28 04:12:38 gerald Exp $
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*
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* The information used comes from:
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* RFC 951: Bootstrap Protocol
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@ -134,6 +134,18 @@ get_dhcp_type(guint8 byte)
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/* DHCP Authentication Replay Detection Methods */
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#define AUTHEN_RDM_MONOTONIC_COUNTER 0x00
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/* DHCP Option Overload (option code 52) */
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#define OPT_OVERLOAD_FILE 1
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#define OPT_OVERLOAD_SNAME 2
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#define OPT_OVERLOAD_BOTH 3
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/* Server name and boot file offsets and lengths */
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#define SERVER_NAME_OFFSET 44
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#define SERVER_NAME_LEN 64
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#define FILE_NAME_OFFSET 108
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#define FILE_NAME_LEN 128
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#define VENDOR_INFO_OFFSET 236
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/* Returns the number of bytes consumed by this option. */
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static int
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bootp_option(tvbuff_t *tvb, proto_tree *bp_tree, int voff, int eoff,
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@ -147,11 +159,13 @@ bootp_option(tvbuff_t *tvb, proto_tree *bp_tree, int voff, int eoff,
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guchar byte;
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int i,optp, consumed;
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gulong time_secs;
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proto_tree *v_tree;
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proto_tree *v_tree, *o52tree;
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proto_item *vti;
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guint8 protocol;
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guint8 algorithm;
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guint8 rdm;
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int o52voff, o52eoff;
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gboolean o52at_end;
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static const value_string nbnt_vals[] = {
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{0x1, "B-node" },
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@ -173,6 +187,12 @@ bootp_option(tvbuff_t *tvb, proto_tree *bp_tree, int voff, int eoff,
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{AUTHEN_RDM_MONOTONIC_COUNTER, "Monotonically-increasing counter" },
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{0, NULL } };
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static const value_string opt_overload_vals[] = {
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{ OPT_OVERLOAD_FILE, "Boot file name holds options", },
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{ OPT_OVERLOAD_SNAME, "Server host name holds options", },
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{ OPT_OVERLOAD_BOTH, "Boot file and server host names hold options" },
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{ 0, NULL } };
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static struct opt_info opt[] = {
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/* 0 */ { "Padding", none },
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/* 1 */ { "Subnet Mask", ipv4 },
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@ -562,6 +582,51 @@ bootp_option(tvbuff_t *tvb, proto_tree *bp_tree, int voff, int eoff,
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"Unknown (0x%02x)"));
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break;
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case 52: /* Option Overload */
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byte = tvb_get_guint8(tvb, voff+2);
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vti = proto_tree_add_text(bp_tree, tvb, voff, consumed,
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"Option %d: %s = %s", code, text,
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val_to_str(byte, opt_overload_vals,
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"Unknown (0x%02x)"));
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/* Just in case we find an option 52 in sname or file */
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if (voff > VENDOR_INFO_OFFSET && byte >= 1 && byte <= 3) {
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o52tree = proto_item_add_subtree(vti, ett_bootp_option);
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if (byte == 1 || byte == 3) { /* 'file' */
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vti = proto_tree_add_text (o52tree, tvb,
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FILE_NAME_OFFSET, FILE_NAME_LEN,
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"Boot file name option overload");
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v_tree = proto_item_add_subtree(vti, ett_bootp_option);
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o52voff = FILE_NAME_OFFSET;
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o52eoff = FILE_NAME_OFFSET + FILE_NAME_LEN;
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o52at_end = FALSE;
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while (o52voff < o52eoff && !o52at_end) {
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o52voff += bootp_option(tvb, v_tree, o52voff,
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o52eoff, FALSE, &o52at_end,
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dhcp_type_p, vendor_class_id_p);
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}
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}
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if (byte == 2 || byte == 3) { /* 'sname' */
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vti = proto_tree_add_text (o52tree, tvb,
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SERVER_NAME_OFFSET, SERVER_NAME_LEN,
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"Server host name option overload");
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v_tree = proto_item_add_subtree(vti, ett_bootp_option);
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o52voff = SERVER_NAME_OFFSET;
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o52eoff = SERVER_NAME_OFFSET + SERVER_NAME_LEN;
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o52at_end = FALSE;
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while (o52voff < o52eoff && !o52at_end) {
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o52voff += bootp_option(tvb, v_tree, o52voff,
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o52eoff, FALSE, &o52at_end,
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dhcp_type_p, vendor_class_id_p);
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}
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}
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}
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/* protocol = tvb_get_guint8(tvb, voff+2);
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proto_tree_add_text(v_tree, tvb, voff+2, 1, "Protocol: %s (%u)",
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val_to_str(protocol, authen_protocol_vals, "Unknown"),
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protocol); */
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break;
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case 53: /* DHCP Message Type */
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proto_tree_add_text(bp_tree, tvb, voff, 3, "Option %d: %s = DHCP %s",
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code, text, get_dhcp_type(tvb_get_guint8(tvb, voff+2)));
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@ -1196,29 +1261,33 @@ dissect_bootp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
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/* The server host name is optional */
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if (tvb_get_guint8(tvb, 44) != '\0') {
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proto_tree_add_item(bp_tree, hf_bootp_server, tvb,
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44, 64, FALSE);
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SERVER_NAME_OFFSET,
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SERVER_NAME_LEN, FALSE);
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}
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else {
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proto_tree_add_string_format(bp_tree, hf_bootp_server, tvb,
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44, 64,
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tvb_get_ptr(tvb, 44, 1),
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SERVER_NAME_OFFSET,
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SERVER_NAME_LEN,
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tvb_get_ptr(tvb, SERVER_NAME_OFFSET, 1),
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"Server host name not given");
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}
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/* Boot file */
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if (tvb_get_guint8(tvb, 108) != '\0') {
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proto_tree_add_item(bp_tree, hf_bootp_file, tvb,
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108, 128, FALSE);
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FILE_NAME_OFFSET,
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FILE_NAME_LEN, FALSE);
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}
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else {
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proto_tree_add_string_format(bp_tree, hf_bootp_file, tvb,
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108, 128,
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tvb_get_ptr(tvb, 108, 1),
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FILE_NAME_OFFSET,
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FILE_NAME_LEN,
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tvb_get_ptr(tvb, FILE_NAME_OFFSET, 1),
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"Boot file name not given");
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}
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}
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voff = 236;
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voff = VENDOR_INFO_OFFSET;
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/* rfc2132 says it SHOULD exist, not that it MUST exist */
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if (tvb_bytes_exist(tvb, voff, 4)) {
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