There is no practical way to generate an underlength ARP packet since
an ARP packet is always padded up to the minimum Ethernet frame length
(or dropped by the receiving Ethernet hardware if incorrectly padded),
but the absence of an explicit check causes warnings from some
analysis tools.

Fix by adding an explicit check on the I/O buffer length.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

The only way to map an eIPoIB MAC address (REMAC) to an IPoIB MAC
address is to intercept an incoming ARP request or reply.

If we do not have an REMAC cache entry for a particular destination
MAC address, then we cannot transmit the packet.  This can arise in at
least two situations:

 - An external program (e.g. a PXE NBP using the UNDI API) may attempt
   to transmit to a destination MAC address that has been obtained by
   some method other than ARP.

 - Memory pressure may have caused REMAC cache entries to be
   discarded.  This is fairly likely on a busy network, since REMAC
   cache entries are created for all received (broadcast) ARP
   requests.  (We can't sensibly avoid creating these cache entries,
   since they are required in order to send an ARP reply, and when we
   are being used via the UNDI API we may have no knowledge of which
   IP addresses are "ours".)

Attempt to ameliorate the situation by generating a semi-spurious ARP
request whenever we find a missing REMAC cache entry.  This will
hopefully trigger an ARP reply, which would then provide us with the
information required to populate the REMAC cache.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

These files cannot be automatically relicensed by util/relicense.pl
since they either contain unusual but trivial contributions (such as
the addition of __nonnull function attributes), or contain lines
dating back to the initial git revision (and so require manual
knowledge of the code's origin).

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Split the protocol-independent portions of arp.c into a separate file
neighbour.c, to allow for sharing of functionality between IPv4+ARP
and IPv6+NDP.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Take ownership from the ARP cache at the start of arp_destroy(), to
ensure that no code path can lead to arp_destroy() being re-entered.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Suggested-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

Discarding the active ARP cache entry in the middle of a download will
substantially disrupt the TCP stream.  Try to minimise any such
disruption by treating ARP cache entries as expensive, and discarding
them only when nothing else is available to discard.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Each ARP cache entry maintains a transmission queue, which is sent out
as soon as the link-layer address is known.  If multiple packets are
queued, then it is possible for memory pressure to cause the ARP cache
discarder to be invoked during transmission of the first packet, which
may cause the ARP cache entry to be deleted before the second packet
can be sent.  This results in an invalid pointer dereference.

Avoid this problem by reference-counting ARP cache entries and
ensuring that an extra reference is held while processing the
transmission queue, and by using list_first_entry() rather than
list_for_each_entry_safe() to traverse the queue.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Allow packet transmission to be deferred pending successful ARP
resolution.  This avoids the time spent waiting for a higher-level
protocol (e.g. TCP or TFTP) to attempt retransmission.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Allow the link layer to directly report whether or not a packet is
multicast or broadcast at the time of calling pull(), rather than
relying on heuristics to determine this at a later stage.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

FCoE requires the use of fabric-provided MAC addresses, which breaks
the assumption that the net device's MAC address is implicitly the
source address for net_tx() and the (unicast) destination address for
net_rx().

Signed-off-by: Michael Brown <mcb30@ipxe.org>

Declarations without the accompanying __table_entry cause misalignment
of the table entries when using gcc 4.5.  Fix by adding the
appropriate __table_entry macro or (where possible) by removing
unnecessary forward declarations.

Signed-off-by: Piotr Jaroszyński <p.jaroszynski@gmail.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

Access to the gpxe.org and etherboot.org domains and associated
resources has been revoked by the registrant of the domain.  Work
around this problem by renaming project from gPXE to iPXE, and
updating URLs to match.

Also update README, LOG and COPYRIGHTS to remove obsolete information.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

IPoIB has a link-layer broadcast address that varies according to the
partition key.  We currently go through several contortions to pretend
that the link-layer address is a fixed constant; by making the
broadcast address a property of the network device rather than the
link-layer protocol it will be possible to simplify IPoIB's broadcast
handling.

Add FILE_LICENCE declarations to almost all files that make up the
various standard builds of gPXE.

Intel's C compiler (icc) chokes on the zero-length arrays that we
currently use as part of the mechanism for accessing linker table
entries.  Abstract away the zero-length arrays, to make a port to icc
easier.

Introduce macros such as for_each_table_entry() to simplify the common
case of iterating over all entries in a linker table.

Represent table names as #defined string constants rather than
unquoted literals; this avoids visual confusion between table names
and C variable or type names, and also allows us to force a
compilation error in the event of incorrect table names.

There are many functions that take ownership of the I/O buffer they
are passed as a parameter.  The caller should not retain a pointer to
the I/O buffer.  Use iob_disown() to automatically nullify the
caller's pointer, e.g.:

    xfer_deliver_iob ( xfer, iob_disown ( iobuf ) );

This will ensure that iobuf is set to NULL for any code after the call
to xfer_deliver_iob().

iob_disown() is currently used only in places where it simplifies the
code, by avoiding an extra line explicitly setting the I/O buffer
pointer to NULL.  It should ideally be used with each call to any
function that takes ownership of an I/O buffer.  (The SSA
optimisations will ensure that use of iob_disown() gets optimised away
in cases where the caller makes no further use of the I/O buffer
pointer anyway.)

If gcc ever introduces an __attribute__((free)), indicating that use
of a function argument after a function call should generate a
warning, then we should use this to identify all applicable function
call sites, and add iob_disown() as necessary.

Achieved via Perl using:

perl -pi -e 's/pk_buff/io_buffer/g; s/Packet buffer/I\/O buffer/ig; ' \
	-e 's/pkbuff\.h/iobuf.h/g; s/pkb_/iob_/g; s/_pkb/_iob/g; ' \
	-e 's/pkb/iobuf/g; s/PKB/IOB/g;'

names.

Add "dev" pointer in struct net_device to tie network interfaces back to a
hardware device.

Force natural alignment of data types in __table() macros.  This seems to
prevent gcc from taking the unilateral decision to occasionally increase
their alignment (which screws up the table packing).

defined in vsprintf.h.  (This may change, since vsprintf.h is a
non-standard name, but for now it's the one to use.)

There should be no need to include vsprintf.h just for DBG() statements,
since include/compiler.h forces it in for a debug build anyway.

Kill off the static single net device and move to proper dynamic
registration (which we need with the new device model).

Break the (flawed) assumption that all network-layer protocols can use
ARP; such network-layer protocols (i.e. IPv4) must now register as an ARP
protocol using ARP_NET_PROTOCOL() and provide a single method for checking
the existence of a local network-layer address.

take ownership of the packet, rather than doing so only if they return
success.  This breaks semantic compatibility with Linux's
hard_start_xmit() method, but means that we don't have to worry so much
about error cases.

Split mechanism of processing received packets (net_rx_process()) out
from policy (net_step()), preparatory to putting net_step() in a separate
object.

implementation allows for only one, and does so without compromising on
the efficiency of static allocation).

Link-layer protocols are cleanly separated from the device drivers.

Network-layer protocols are cleanly separated from individual network
devices.

Link-layer and network-layer protocols are cleanly separated from each
other.

it with metadata in the pkb structure.  This is required since UNDI will
want to be able to parse the link-layer header without destroying it.

Ethernet-and-IPv4-only ARP module.  :)