Some EMC targets will fail if we advertise that we can authenticate with
CHAP, but the target is configured to allow unauthenticated access to that
target.  We advertise AuthMethod=CHAP,None; the target should (I think)
select AuthMethod=None for unprotected targets.  IETD does this, but an
EMC Celerra NS83 doesn't.

Fix by offering only AuthMethod=None if the user hasn't supplied a
username and password; this means that we won't be offering CHAP
authentication unless the user is expecting to use it (in which case the
target is presumably configured appropriately).

Many thanks to Alessandro Iurlano <alessandro.iurlano@gmail.com> for
reporting and helping to diagnose this problem.

gPXE is not compliant with the HTTP/1.1 specification (RFC 2616),
since it lacks support for "Transfer-Encoding: chunked".  gPXE is,
however, compliant with the HTTP/1.0 specification (RFC 1945), which
does not require "Transfer-Encoding: chunked" to be supported.

The only HTTP/1.1 feature that gPXE uses is the "Host:" header, but
servers universally accept that one from HTTP/1.0 clients as an
optional extension (it is obligatory for HTTP/1.1).  gPXE does not,
for example, appear to support connection caching.  Advertising as a
HTTP/1.0 client will typically make the server close the connection
immediately upon sending the last data, which is actually beneficial
if we aren't going to keep the connection alive anyway.

Allow for settings to be described by something other than a DHCP option
tag if desirable.  Currently used only for the MAC address setting.

Separate out fake DHCP packet creation code from dhcp.c to fakedhcp.c.

Remove notion of settings from dhcppkt.c.

Rationalise dhcp.c to use settings API only for final registration of the
DHCP options, rather than using {store,fetch}_setting throughout.

Convert DHCP option applicators in dns.c and iscsi.c to settings
applicators.

Kill off DHCP option applicators.

  Allow port numbers in iSCSI redirection.

  Wait for SCSI status, not just the final data-in (which may be followed
  by an explicit SCSI Response PDU if the S bit is not set).

separate xfer method.

Add missing .alloc_iob entries to several xfer_interface_operations
structures.

We didn't specify values for MaxRecvDataSegmentLength and
MaxBurstLength (to save space, since we were happy with the
RFC-defined default values of 8kB and 256kB respectively).  However,
the OpenSolaris target (incorrectly) assumes default values of zero
for these parameters.

The upshot was that the OpenSolaris target would get stuck in an
endless loop trying to send us the first 512-byte sector, zero bytes
at a time, and would eventually run out of memory and core-dump.

Fixed by explicitly specifying the default values for these two
parameters.

list.

Added FEATURE() macros to most relevant (non-driver) files.

and generate DHCP options to indicate features to DHCP server (and to
PXE NBPs).

really ugly hack at present, but that doesn't hugely matter since I'm
aiming to change the interface to iSCSI devices anyway within the next
week.

SCSI interface not yet implemented.

xfer_window() function, which can return a scalar rather than a
boolean.

implement sendto()/recvfrom() equivalents.

elsewhere as well.

download

this saves around 70us per received packet (which is around 50% of the
overall packet processing time).

other protocol won't work at the moment.

exception rather than the rule; we may as well keep things clean for other
protocols.