Useful for parsing things when you don't know what tag to expect (e.g. a
CHOICE). Also allow its operands to be NULL, so that it can be used to skip
arbitrary elements.

Delete CBS_ASN1_ANY which wasn't doing anything.

Change-Id: I56413e68b4f2e13860ea3e55373d5830713d7e5c
Reviewed-on: https://boringssl-review.googlesource.com/1661
Reviewed-by: Adam Langley <agl@google.com>

Previously, the ASN.1 functions in bytestring were capable of processing
indefinite length elements when the _ber functions were used. That works
well enough for PKCS#3, but NSS goes a bit crazy with BER encoding and
PKCS#12. Rather than complicate the core bytestring functions further,
the BER support is removed from them and moved to a separate function
that converts from BER to DER (if needed).

Change-Id: I2212b28e99bab9fab8c61f80d2012d3e5a3cc2f0
Reviewed-on: https://boringssl-review.googlesource.com/1591
Reviewed-by: Adam Langley <agl@google.com>

Equivalent of e532f823d6 for CBS.

Change-Id: I5c31f589db119115c78da3f0d592d71254836f89
Reviewed-on: https://boringssl-review.googlesource.com/1508
Reviewed-by: Adam Langley <agl@google.com>

Also fix some DTLS cookie bugs. rcvd_cookie is never referenced after being
saved (and the length isn't saved, so it couldn't be used anyway), and the
cookie verification failed to check the length.

For convenience, add a CBS_mem_equal helper function. Saves a bit of
repetition.

Change-Id: I187137733b069f0ac8d8b1bf151eeb80d388b971
Reviewed-on: https://boringssl-review.googlesource.com/1174
Reviewed-by: Adam Langley <agl@google.com>

Also tidy up some variable names and update RSA_verify call for it no longer
returning -1. Add CBS helper functions for dealing with C strings.

Change-Id: Ibc398d27714744f5d99d4f94ae38210cbc89471a
Reviewed-on: https://boringssl-review.googlesource.com/1164
Reviewed-by: Adam Langley <agl@google.com>

This gives us systematic bounds-checking on all the parses. Also adds a
convenience function, CBS_memdup, for saving the current contents of a CBS.

Change-Id: I17dad74575f03121aee3f771037b8806ff99d0c3
Reviewed-on: https://boringssl-review.googlesource.com/1031
Reviewed-by: Adam Langley <agl@google.com>

Initial fork from f2d678e6e8 (1.0.2 beta).

(This change contains substantial changes from the original and
effectively starts a new history.)