Add a check for NULL return in t1_lib.c.
    Since return type of ssl_cert_lookup_by_idx is pointer and unify coding
    style, I changed from zero to NULL in ssl_cert.c.

Remove unnecessary space for ++.

Fix incorrect condition
    Expression is always false because 'else if' condition matches previous
    condition.  SInce the next line of 'else if' condition has substituted
    TLSEXT_ECPOINTFORMAT_ansiX962_compressed_char2, the 'else if'
    condition should compare with NID_X9_62_characteristic_two_field.
Reviewed-by: NAndy Polyakov <appro@openssl.org>
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4562)

The function tls_check_curve is only called on clients and contains
almost identical functionaity to tls1_check_group_id when called from
a client. Merge the two.
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4475)

Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4475)

Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4475)

[extended tests]
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/=4412)

Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/=4412)

Rename tls1_get_curvelist to tls1_get_grouplist, change to void as
it can never fail and remove unnecessary return value checks. Clean
up the code.
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/=4412)

Replace existing compression and groups check with two functions.

tls1_check_pkey_comp() checks a keys compression algorithms is consistent
with extensions.

tls1_check_group_id() checks is a group is consistent with extensions
and preferences.

Rename tls1_ec_nid2curve_id() to tls1_nid2group_id() and make it static.
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/=4412)

Replace tls1_ec_curve_id2nid() with tls_group_id_lookup() which returns
the TLS_GROUP_INFO for the group.
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/=4412)

Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/=4412)

Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/=4412)

Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/=4412)

Found by OSS-Fuzz and the tests
Reviewed-by: NAndy Polyakov <appro@openssl.org>
GH: #4410

Instead of storing supported groups in on-the-wire format store
them as parsed uint16_t values. This simplifies handling of groups
as the values can be directly used instead of being converted.
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4406)

Compilation failed due to -Werror=misleading-indentation.
Signed-off-by: NPatrick Steuer <patrick.steuer@de.ibm.com>
Reviewed-by: NRich Salz <rsalz@openssl.org>
Reviewed-by: NPaul Dale <paul.dale@oracle.com>
Reviewed-by: NBen Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/4395)

Allo RSA certificate to be used for RSA-PSS signatures: this needs
to be explicit because RSA and RSA-PSS certificates are now distinct
types.
Reviewed-by: NBen Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/4368)

Recognise RSA-PSS certificate algorithm and add a new certificate
type.
Reviewed-by: NBen Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/4368)

Removed e_os.h from all bar three headers (apps/apps.h crypto/bio/bio_lcl.h and
ssl/ssl_locl.h).

Added e_os.h into the files that need it now.

Directly reference internal/nelem.h when required.
Reviewed-by: NAndy Polyakov <appro@openssl.org>
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/4188)

Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3858)

Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3858)

Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3858)

The functiontls12_get_pkey_idx is only used to see if a certificate index is
enabled: call ssl_cert_is_disabled instead.
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3858)

Fixes #3680
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3782)

In draft-ietf-tls-tls13-20 Appendix B we find that:

   This section describes protocol types and constants.  Values listed
   as _RESERVED were used in previous versions of TLS and are listed
   here for completeness.  TLS 1.3 implementations MUST NOT send them
   but might receive them from older TLS implementations.

Similarly, in section 4.2.3 we see:

   Legacy algorithms  Indicates algorithms which are being deprecated
      because they use algorithms with known weaknesses, specifically
      SHA-1 which is used in this context with either with RSA using
      RSASSA-PKCS1-v1_5 or ECDSA.  These values refer solely to
      signatures which appear in certificates (see Section 4.4.2.2) and
      are not defined for use in signed TLS handshake messages.
      Endpoints SHOULD NOT negotiate these algorithms but are permitted
      to do so solely for backward compatibility.  Clients offering
      these values MUST list them as the lowest priority (listed after
      all other algorithms in SignatureSchemeList).  TLS 1.3 servers
      MUST NOT offer a SHA-1 signed certificate unless no valid
      certificate chain can be produced without it (see
      Section 4.4.2.2).

However, we are currently sending the SHA2-based DSA signature schemes
and many SHA1-based schemes, which is in contradiction with the specification.

Because TLS 1.3 support will appear in OpenSSL 1.1, we are bound by
stability requirements to continue to offer the DSA signature schemes
and the deprecated hash algorithms.  at least until OpenSSL 1.2.
However, for pure TLS 1.3 clients that do not offer lower TLS versions,
we can be compliant.  Do so, and leave a note to revisit the issue when
we are permitted to break with sacred historical tradition.
Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3326)

Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3585)

Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3585)

Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3585)

Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3585)

Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3585)

Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3585)

Reviewed-by: NMatt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3585)

Also remove nested OPENSSL_NO_EC conditional; it was properly indented,
but a no-op.
Reviewed-by: NRich Salz <rsalz@openssl.org>
Reviewed-by: NBenjamin Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/3693)

This used to work but was inadvertently removed as part of the TLSv1.3
work. This adds it back.

Fixes #3633
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3639)

Provides consistent output and approach.
Reviewed-by: NTim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3496)

We are quite inconsistent about which alerts get sent. Specifically, these
alerts should be used (normally) in the following circumstances:

SSL_AD_DECODE_ERROR = The peer sent a syntactically incorrect message
SSL_AD_ILLEGAL_PARAMETER = The peer sent a message which was syntactically
correct, but a parameter given is invalid for the context
SSL_AD_HANDSHAKE_FAILURE = The peer's messages were syntactically and
semantically correct, but the parameters provided were unacceptable to us
(e.g. because we do not support the requested parameters)
SSL_AD_INTERNAL_ERROR = We messed up (e.g. malloc failure)

The standards themselves aren't always consistent but I think the above
represents the best interpretation.
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3480)

Ensure that there are ciphersuites enabled for the maximum supported
version we will accept in a ClientHello.
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3316)

ECDHE is not properly defined for SSLv3. Commit fe55c4a2 prevented ECDHE
from being selected in that protocol. However, historically, servers do
still select ECDHE anyway so that commit causes interoperability problems.
Clients that previously worked when talking to an SSLv3 server could now
fail.

This commit introduces an exception which enables a client to continue in
SSLv3 if the server selected ECDHE.

[extended tests]
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3204)

Add functions to add/retrieve the certificate_authorities. The older
client_CA functions mainly just call the new versions now.

Rename fields sice new extension can be generated by client and server.
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3015)

Fix some comments too
[skip ci]
Reviewed-by: NTim Hudson <tjh@openssl.org>
Reviewed-by: NRichard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3069)

that refers to space
deallocated by a call to the free function in tls_decrypt_ticket.
Reviewed-by: NMatt Caswell <matt@openssl.org>
Reviewed-by: NRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2897)
(cherry picked from commit 13ed1afa923f4ffb553e389de08f26e9ce84e8a2)