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

At some point in the past few years, binutils became more aggressive
at removing unused symbols.  To function as a symbol requirement, a
relocation record must now be in a section marked with @progbits and
must not be in a section which gets discarded during the link (either
via --gc-sections or via /DISCARD/).

Update REQUIRE_SYMBOL() to generate relocation records meeting these
criteria.  To minimise the impact upon the final binary size, we use
existing symbols (specified via the REQUIRING_SYMBOL() macro) as the
relocation targets where possible.  We use R_386_NONE or R_X86_64_NONE
relocation types to prevent any actual unwanted relocation taking
place.  Where no suitable symbol exists for REQUIRING_SYMBOL() (such
as in config.c), the macro PROVIDE_REQUIRING_SYMBOL() can be used to
generate a one-byte-long symbol to act as the relocation target.

If there are versions of binutils for which this approach fails, then
the fallback will probably involve killing off REQUEST_SYMBOL(),
redefining REQUIRE_SYMBOL() to use the current definition of
REQUEST_SYMBOL(), and postprocessing the linked ELF file with
something along the lines of "nm -u | wc -l" to check that there are
no undefined symbols remaining.

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

Relicense files for which I am the sole author (as identified by
util/relicense.pl).

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

We currently compare the entirety of the KeyHash object (including the
ASN.1 tag and length byte) against the raw SHA-1 hash of the
certificate's public key.  This causes OCSP validation to fail for any
responses which identify the responder by key hash rather than by
name, and hence prevents the use of X.509 certificates where any
certificate in the chain has an OCSP responder which chooses to
identify itself via its key hash.

Fix by adding the missing asn1_enter() required to enter the ASN.1
octet string containing the key hash.

Also add a corresponding test case including an OCSP response where
the responder is identified by key hash, to ensure that this
functionality cannot be broken in future.

Debugged-by: Brian Rak <brak@gameservers.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>

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

Add self-tests for OCSP using test vectors generated with the openssl
tools.

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