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Give the RFC number for ARP. 

When checking for a gratuitous ARP, compare the raw bytes of the
protocol addresses, not the strings for those addresses.

Do the stuff we do even if we *aren't* constructing a protocol tree or
setting the Info column first, and then quit if we're doing neither.
That obviates the need to set "is_gratuitous" if we're doing neither.

Construct the strings for addresses when we need them, rather than
constructing them in advance even if we don't need them.

Capitalize "ARP" in "Gratuitous ARP".

svn path=/trunk/; revision=11168
This commit is contained in:
Guy Harris 2004-06-17 20:04:53 +00:00
parent dc1a5f5a60
commit e08deab6f5
1 changed files with 71 additions and 58 deletions
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129
packet-arp.c
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@ -1,7 +1,7 @@
/* packet-arp.c
* Routines for ARP packet disassembly
* Routines for ARP packet disassembly (RFC 826)
*
* $Id: packet-arp.c,v 1.59 2004/06/17 08:32:59 jmayer Exp $
* $Id: packet-arp.c,v 1.60 2004/06/17 20:04:53 guy Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@ethereal.com>
@ -669,7 +669,6 @@ dissect_arp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
gchar *op_str;
int sha_offset, spa_offset, tha_offset, tpa_offset;
const guint8 *sha_val, *spa_val, *tha_val, *tpa_val;
gchar *sha_str, *spa_str, *tha_str, *tpa_str;
gboolean is_gratuitous;
/* Call it ARP, for now, so that if we throw an exception before
@ -705,16 +704,6 @@ dissect_arp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
was padding. */
tvb_set_reported_length(tvb, tot_len);
/* Get the offsets of the addresses. */
/* Source Hardware Address */
sha_offset = MIN_ARP_HEADER_SIZE;
/* Source Protocol Address */
spa_offset = sha_offset + ar_hln;
/* Target Hardware Address */
tha_offset = spa_offset + ar_pln;
/* Target Protocol Address */
tpa_offset = tha_offset + ar_hln;
if (check_col(pinfo->cinfo, COL_PROTOCOL)) {
switch (ar_op) {
@ -736,50 +725,15 @@ dissect_arp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
}
}
if (tree || check_col(pinfo->cinfo, COL_INFO)) {
sha_val = tvb_get_ptr(tvb, sha_offset, ar_hln);
sha_str = arphrdaddr_to_str(sha_val, ar_hln, ar_hrd);
spa_val = tvb_get_ptr(tvb, spa_offset, ar_pln);
spa_str = arpproaddr_to_str(spa_val, ar_pln, ar_pro);
tha_val = tvb_get_ptr(tvb, tha_offset, ar_hln);
tha_str = arphrdaddr_to_str(tha_val, ar_hln, ar_hrd);
tpa_val = tvb_get_ptr(tvb, tpa_offset, ar_pln);
tpa_str = arpproaddr_to_str(tpa_val, ar_pln, ar_pro);
if ((ar_op == ARPOP_REQUEST) && !strcmp(tpa_str, spa_str))
is_gratuitous = TRUE;
else
is_gratuitous = FALSE;
}
if (check_col(pinfo->cinfo, COL_INFO)) {
switch (ar_op) {
case ARPOP_REQUEST:
if (is_gratuitous)
col_add_fstr(pinfo->cinfo, COL_INFO, "Who has %s? Gratuitous arp", tpa_str);
else
col_add_fstr(pinfo->cinfo, COL_INFO, "Who has %s? Tell %s", tpa_str, spa_str);
break;
case ARPOP_REPLY:
col_add_fstr(pinfo->cinfo, COL_INFO, "%s is at %s", spa_str, sha_str);
break;
case ARPOP_RREQUEST:
case ARPOP_IREQUEST:
col_add_fstr(pinfo->cinfo, COL_INFO, "Who is %s? Tell %s", tha_str, sha_str);
break;
case ARPOP_RREPLY:
col_add_fstr(pinfo->cinfo, COL_INFO, "%s is at %s", tha_str, tpa_str);
break;
case ARPOP_IREPLY:
col_add_fstr(pinfo->cinfo, COL_INFO, "%s is at %s", sha_str, spa_str);
break;
default:
col_add_fstr(pinfo->cinfo, COL_INFO, "Unknown ARP opcode 0x%04x", ar_op);
break;
}
}
/* Get the offsets of the addresses. */
/* Source Hardware Address */
sha_offset = MIN_ARP_HEADER_SIZE;
/* Source Protocol Address */
spa_offset = sha_offset + ar_hln;
/* Target Hardware Address */
tha_offset = spa_offset + ar_pln;
/* Target Protocol Address */
tpa_offset = tha_offset + ar_hln;
if ((ar_op == ARPOP_REPLY || ar_op == ARPOP_REQUEST) &&
ARP_HW_IS_ETHER(ar_hrd, ar_hln) &&
@ -807,10 +761,69 @@ dissect_arp(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
add_ether_byip(ip, mac);
}
if (!tree && !check_col(pinfo->cinfo, COL_INFO)) {
/* We're not building a protocol tree and we're not setting the Info
column, so we don't have any more work to do. */
return;
}
sha_val = tvb_get_ptr(tvb, sha_offset, ar_hln);
spa_val = tvb_get_ptr(tvb, spa_offset, ar_pln);
tha_val = tvb_get_ptr(tvb, tha_offset, ar_hln);
tpa_val = tvb_get_ptr(tvb, tpa_offset, ar_pln);
/* ARP requests with the same sender and target protocol address
are flagged as "gratuitous ARPs", i.e. ARPs sent out as, in
effect, an announcement that the machine has MAC address
XX:XX:XX:XX:XX:XX and IPv4 address YY.YY.YY.YY, to provoke
complaints if some other machine has the same IPv4 address. */
if ((ar_op == ARPOP_REQUEST) && (memcmp(spa_val, tpa_val, ar_pln) == 0))
is_gratuitous = TRUE;
else
is_gratuitous = FALSE;
if (check_col(pinfo->cinfo, COL_INFO)) {
switch (ar_op) {
case ARPOP_REQUEST:
if (is_gratuitous)
col_add_fstr(pinfo->cinfo, COL_INFO, "Who has %s? Gratuitous ARP",
arpproaddr_to_str(tpa_val, ar_pln, ar_pro));
else
col_add_fstr(pinfo->cinfo, COL_INFO, "Who has %s? Tell %s",
arpproaddr_to_str(tpa_val, ar_pln, ar_pro),
arpproaddr_to_str(spa_val, ar_pln, ar_pro));
break;
case ARPOP_REPLY:
col_add_fstr(pinfo->cinfo, COL_INFO, "%s is at %s",
arpproaddr_to_str(spa_val, ar_pln, ar_pro),
arphrdaddr_to_str(sha_val, ar_hln, ar_hrd));
break;
case ARPOP_RREQUEST:
case ARPOP_IREQUEST:
col_add_fstr(pinfo->cinfo, COL_INFO, "Who is %s? Tell %s",
arphrdaddr_to_str(tha_val, ar_hln, ar_hrd),
arphrdaddr_to_str(sha_val, ar_hln, ar_hrd));
break;
case ARPOP_RREPLY:
col_add_fstr(pinfo->cinfo, COL_INFO, "%s is at %s",
arphrdaddr_to_str(tha_val, ar_hln, ar_hrd),
arpproaddr_to_str(tpa_val, ar_pln, ar_pro));
break;
case ARPOP_IREPLY:
col_add_fstr(pinfo->cinfo, COL_INFO, "%s is at %s",
arphrdaddr_to_str(sha_val, ar_hln, ar_hrd),
arpproaddr_to_str(spa_val, ar_pln, ar_pro));
break;
default:
col_add_fstr(pinfo->cinfo, COL_INFO, "Unknown ARP opcode 0x%04x", ar_op);
break;
}
}
if (tree) {
if ((op_str = match_strval(ar_op, op_vals))) {
if (is_gratuitous)
op_str = "request/gratuitous arp";
op_str = "request/gratuitous ARP";
ti = proto_tree_add_protocol_format(tree, proto_arp, tvb, 0, tot_len,
"Address Resolution Protocol (%s)", op_str);
} else