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improve BGP path attribute decoding tree. 

show detail of path attribute to outside of the tree, to help users
browse the structure.  BGP protocol header structure is very complex
and the previous code required users to click through the tree to check,
say, AS path.

svn path=/trunk/; revision=951
This commit is contained in:
Jun-ichiro itojun Hagino 1999-10-31 00:20:44 +00:00
parent b99cfa28c8
commit 10fdc90bb0
1 changed files with 101 additions and 18 deletions
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119
packet-bgp.c
View File

@ -2,7 +2,7 @@
* Routines for BGP packet dissection
* Copyright 1999, Jun-ichiro itojun Hagino <itojun@itojun.org>
*
* $Id: packet-bgp.c,v 1.3 1999/10/16 15:35:27 itojun Exp $
* $Id: packet-bgp.c,v 1.4 1999/10/31 00:20:44 itojun Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@unicom.net>
@ -303,6 +303,33 @@ dissect_bgp_open(const u_char *pd, int offset, frame_data *fd, proto_tree *tree)
}
}
/* NOTE: caller needs to free() the returned value. */
static char *
dissect_bgp_aspath(const u_char *pd, int len)
{
char *msg;
int j, n;
char *q;
if (len % 2)
return NULL;
msg = malloc(len / 2 * 6 + 10);
if (!msg)
return NULL;
q = msg;
for (j = 0; j < len; j += 2) {
n = sprintf(q, "%u ", ntohs(*(guint16 *)&pd[j]));
q += n;
}
/* remove the last blank */
q--;
*q = '\0';
return msg;
}
static void
dissect_bgp_update(const u_char *pd, int offset, frame_data *fd,
proto_tree *tree)
@ -349,11 +376,75 @@ dissect_bgp_update(const u_char *pd, int offset, frame_data *fd,
alen = p[i + sizeof(bgpa)];
aoff = sizeof(bgpa) + 1;
}
ti = proto_tree_add_text(subtree, p - pd + i, alen + aoff,
"Attribute: %s (%u bytes)",
val_to_str(bgpa.bgpa_type, bgpattr_type, "Unknown"),
alen + aoff);
/*
* This is kind of ugly - similar code appears twice,
* but it helps browsing attrs.
*/
switch (bgpa.bgpa_type) {
case BGPTYPE_ORIGIN:
if (alen != 1)
goto default_attribute_top;
msg = val_to_str(p[i + aoff], bgpattr_origin, "Unknown");
ti = proto_tree_add_text(subtree, p - pd + i, alen + aoff,
"Attribute: %s: %s (%u bytes)",
val_to_str(bgpa.bgpa_type, bgpattr_type, "Unknown"),
msg, alen + aoff);
break;
case BGPTYPE_AS_PATH:
if (alen % 2)
goto default_attribute_top;
msg = dissect_bgp_aspath(p + i + aoff, alen);
if (msg == NULL)
goto default_attribute_top;
ti = proto_tree_add_text(subtree, p - pd + i, alen + aoff,
"Attribute: %s: %s (%u bytes)",
val_to_str(bgpa.bgpa_type, bgpattr_type, "Unknown"),
msg, alen + aoff);
free(msg);
break;
case BGPTYPE_NEXT_HOP:
if (alen != 4)
goto default_attribute_top;
ti = proto_tree_add_text(subtree, p - pd + i, alen + aoff,
"Attribute: %s: %s (%u bytes)",
val_to_str(bgpa.bgpa_type, bgpattr_type, "Unknown"),
ip_to_str(&p[i + aoff]), alen + aoff);
break;
case BGPTYPE_MULTI_EXIT_DISC:
if (alen != 4)
goto default_attribute_top;
ti = proto_tree_add_text(subtree, p - pd + i, alen + aoff,
"Attribute: %s: %u (%u bytes)",
val_to_str(bgpa.bgpa_type, bgpattr_type, "Unknown"),
ntohl(*(guint32 *)&p[i + aoff]),
alen + aoff);
break;
case BGPTYPE_LOCAL_PREF:
if (alen != 4)
goto default_attribute_top;
ti = proto_tree_add_text(subtree, p - pd + i, alen + aoff,
"Attribute: %s: %u (%u bytes)",
val_to_str(bgpa.bgpa_type, bgpattr_type, "Unknown"),
ntohl(*(guint32 *)&p[i + aoff]),
alen + aoff);
break;
case BGPTYPE_AGGREGATOR:
if (alen != 6)
goto default_attribute_top;
ti = proto_tree_add_text(subtree, p - pd + i, alen + aoff,
"Attribute: %s: AS %u, origin %s (%u bytes)",
val_to_str(bgpa.bgpa_type, bgpattr_type, "Unknown"),
ntohs(*(guint16 *)&p[i + aoff]),
ip_to_str(&p[i + aoff + 2]), alen + aoff);
break;
default:
default_attribute_top:
ti = proto_tree_add_text(subtree, p - pd + i, alen + aoff,
"Attribute: %s (%u bytes)",
val_to_str(bgpa.bgpa_type, bgpattr_type, "Unknown"),
alen + aoff);
}
subtree2 = proto_item_add_subtree(ti, ETT_BGP);
ti = proto_tree_add_text(subtree2,
@ -409,26 +500,18 @@ dissect_bgp_update(const u_char *pd, int offset, frame_data *fd,
proto_tree_add_text(subtree2, p - pd + i + aoff, alen,
"AS path: Invalid (%d bytes)", alen);
} else {
int j, n;
char *q;
msg = malloc(alen / 2 * 6 + 10);
if (!msg) {
msg = dissect_bgp_aspath(p + i + aoff, alen);
if (msg == NULL) {
proto_tree_add_text(subtree2, p - pd + i + aoff, alen,
"AS path (%d bytes)", alen);
} else {
q = msg;
for (j = 0; j < alen; j += 2) {
n = sprintf(q, "%d ",
ntohs(*(guint16 *)&p[i + aoff + j]));
q += n;
}
proto_tree_add_text(subtree2, p - pd + i + aoff, alen,
"AS path: %s(%d ASes, %d bytes)",
"AS path: %s (%d ASes, %d bytes)",
msg, alen / 2, alen);
free(msg);
}
break;
}
break;
case BGPTYPE_NEXT_HOP:
if (alen != 4) {
proto_tree_add_text(subtree2, p - pd + i + aoff, alen,