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Extend the interface to ether_input(): a NULL eh pointer means that

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the mbuf contains the ethernet header (eh) as well, which ether_input()
will strip off as needed.

This permits the removal (in a backward compatible way) of the
header removal code which right now is replicated in all drivers,
sometimes in an inconsistent way. Also, because many functions
called after ether_input() require the eh in the mbuf, eventually
we can propagate the interface and handle outdated drivers just
in ether_input().

Individual driver changes to use the new interface will follow as
we have a chance to touch them.

NOTE THAT THIS CHANGE IS FULLY BACKWARD COMPATIBLE AND DOES NOT BREAK
BINARY COMPATIBILITY FOR DRIVERS.

MFC after: 3 days
This commit is contained in:
Luigi Rizzo 2002-08-04 23:55:06 +00:00
parent 2b5989e943
commit c939f1aee7
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=101345
1 changed files with 26 additions and 12 deletions
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38
sys/net/if_ethersubr.c
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@ -535,30 +535,44 @@ ether_ipfw_chk(struct mbuf **m0, struct ifnet *dst,
} }
/* /*
* Process a received Ethernet packet; * Process a received Ethernet packet. We have two different interfaces:
* the packet is in the mbuf chain m without * one (conventional) assumes the packet in the mbuf, with the ethernet
* the ether header, which is provided separately. * header provided separately in *eh. The second one (new) has everything
* in the mbuf, and we can tell it because eh == NULL.
* The caller MUST MAKE SURE that there are at least
* sizeof(struct ether_header) bytes in the first mbuf.
*
* This allows us to concentrate in one place a bunch of code which
* is replicated in all device drivers. Also, many functions called
* from ether_input() try to put the eh back into the mbuf, so we
* can later propagate the 'contiguous packet' interface to them,
* and handle the old interface just here.
* *
* NOTA BENE: for many drivers "eh" is a pointer into the first mbuf or * NOTA BENE: for many drivers "eh" is a pointer into the first mbuf or
* cluster, right before m_data. So be very careful when working on m, * cluster, right before m_data. So be very careful when working on m,
* as you could destroy *eh !! * as you could destroy *eh !!
* A (probably) more convenient and efficient interface to ether_input
* is to have the whole packet (with the ethernet header) into the mbuf:
* modules which do not need the ethernet header can easily drop it, while
* others (most noticeably bridge and ng_ether) do not need to do additional
* work to put the ethernet header back into the mbuf.
* *
* First we perform any link layer operations, then continue * First we perform any link layer operations, then continue
* to the upper layers with ether_demux(). * to the upper layers with ether_demux().
*/ */
void void
ether_input(ifp, eh, m) ether_input(struct ifnet *ifp, struct ether_header *eh, struct mbuf *m)
struct ifnet *ifp;
struct ether_header *eh;
struct mbuf *m;
{ {
struct ether_header save_eh; struct ether_header save_eh;
if (eh == NULL) {
if (m->m_len < sizeof(struct ether_header)) {
/* XXX error in the caller. */
m_freem(m);
return;
}
m->m_pkthdr.rcvif = ifp;
eh = mtod(m, struct ether_header *);
m->m_data += sizeof(struct ether_header);
m->m_len -= sizeof(struct ether_header);
m->m_pkthdr.len = m->m_len;
}
#ifdef MAC #ifdef MAC
mac_create_mbuf_from_ifnet(ifp, m); mac_create_mbuf_from_ifnet(ifp, m);
#endif #endif