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Make off_linktype, off_nl, and off_nl_nosnap *not* include off_ll. 

Make gen_load_llrel() add in off_ll if there isn't a variable-length
radio header, so the offset passed to it is always relative to the
beginning of the link-layer header, not the beginning of the packet.
Don't add in off_ll when calling it.

Those changes centralize the addition of off_ll, so it's only done in
one place (rather than twice, where it was done before, meaning that the
offsets were wrong for the Prism and AVS headers as they had 2*off_ll
rather than just off_ll, as off_ll was added twice).
This commit is contained in:
guy 2006-09-13 06:57:07 +00:00
parent 1bc7157652
commit bc022c53df
1 changed files with 35 additions and 13 deletions
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48
gencode.c
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@ -21,7 +21,7 @@
*/
#ifndef lint
static const char rcsid[] _U_ =
"@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.221.2.39 2006-05-28 20:13:42 guy Exp $ (LBL)";
"@(#) $Header: /tcpdump/master/libpcap/gencode.c,v 1.221.2.40 2006-09-13 06:57:07 guy Exp $ (LBL)";
#endif
#ifdef HAVE_CONFIG_H
@ -668,20 +668,26 @@ gen_ncmp(offrel, offset, size, mask, jtype, reverse, v)
static int reg_ll_size;
/*
* This is the offset of the beginning of the link-layer header.
* This is the offset of the beginning of the link-layer header from
* the beginning of the raw packet data.
*
* It's usually 0, except for 802.11 with a fixed-length radio header.
* (For 802.11 with a variable-length radio header, we have to generate
* code to compute that offset; off_ll is 0 in that case.)
*/
static u_int off_ll;
/*
* This is the offset of the beginning of the MAC-layer header.
* It's usually 0, except for ATM LANE.
* It's usually 0, except for ATM LANE, where it's the offset, relative
* to the beginning of the raw packet data, of the Ethernet header.
*/
static u_int off_mac;
/*
* "off_linktype" is the offset to information in the link-layer header
* giving the packet type.
* giving the packet type. This offset is relative to the beginning
* of the link-layer header (i.e., it doesn't include off_ll).
*
* For Ethernet, it's the offset of the Ethernet type field.
*
@ -734,6 +740,8 @@ static u_int off_payload;
/*
* These are offsets to the beginning of the network-layer header.
* They are relative to the beginning of the link-layer header (i.e.,
* they don't include off_ll).
*
* If the link layer never uses 802.2 LLC:
*
@ -956,9 +964,9 @@ init_linktype(p)
* the Prism header is fixed-length.
*/
off_ll = 144;
off_linktype = 144+24;
off_nl = 144+32; /* Prism+802.11+802.2+SNAP */
off_nl_nosnap = 144+27; /* Prism+802.11+802.2 */
off_linktype = 24;
off_nl = 32; /* Prism+802.11+802.2+SNAP */
off_nl_nosnap = 27; /* Prism+802.11+802.2 */
return;
case DLT_IEEE802_11_RADIO_AVS:
@ -974,12 +982,23 @@ init_linktype(p)
* more so; this header is also variable-length,
* with the length being the 32-bit big-endian
* number at an offset of 4 from the beginning
* of the radio header.
* of the radio header. We should handle that the
* same way we handle the length at the beginning
* of the radiotap header.
*
* XXX - in Linux, do any drivers that supply an AVS
* header supply a link-layer type other than
* ARPHRD_IEEE80211_PRISM? If so, we should map that
* to DLT_IEEE802_11_RADIO_AVS; if not, or if there are
* any drivers that supply an AVS header but supply
* an ARPHRD value of ARPHRD_IEEE80211_PRISM, we'll
* have to check the header in the generated code to
* determine whether it's Prism or AVS.
*/
off_ll = 64;
off_linktype = 64+24;
off_nl = 64+32; /* Radio+802.11+802.2+SNAP */
off_nl_nosnap = 64+27; /* Radio+802.11+802.2 */
off_linktype = 24;
off_nl = 32; /* Radio+802.11+802.2+SNAP */
off_nl_nosnap = 27; /* Radio+802.11+802.2 */
return;
case DLT_IEEE802_11_RADIO:
@ -1240,6 +1259,9 @@ gen_load_llrel(offset, size)
* If "s" is non-null, it has code to arrange that the X register
* contains the length of the prefix preceding the link-layer
* header.
*
* Otherwise, the length of the prefix preceding the link-layer
* header is "off_ll".
*/
if (s != NULL) {
s2 = new_stmt(BPF_LD|BPF_IND|size);
@ -1247,7 +1269,7 @@ gen_load_llrel(offset, size)
sappend(s, s2);
} else {
s = new_stmt(BPF_LD|BPF_ABS|size);
s->s.k = offset;
s->s.k = offset + off_ll;
}
return s;
}
@ -1269,7 +1291,7 @@ gen_load_a(offrel, offset, size)
break;
case OR_LINK:
s = gen_load_llrel(off_ll + offset, size);
s = gen_load_llrel(offset, size);
break;
case OR_NET: