ERL-855: prf for DTLS missing

[OTP-Maintainer]

Original reporter: benbro
Affected version: OTP-21.2.4
Component: ssl
Migrated from: https://bugs.erlang.org/browse/ERL-855

---

ssl_handshake:prf/6 is missing DTLS:
https://github.com/erlang/otp/blob/master/lib/ssl/src/ssl_handshake.erl#L917

I'm not sure if it's correct but maybe it should like something like:


{code:java}
prf({3,0}, _, _, _, _, _) ->
    {error, undefined};
prf({3,_N}, PRFAlgo, Secret, Label, Seed, WantedLength) ->
+    {ok, tls_v1:prf(PRFAlgo, Secret, Label, Seed, WantedLength)};
+prf({254, 255}, PRFAlgo, Secret, Label, Seed, WantedLength) ->
+    {ok, tls_v1:prf(PRFAlgo, Secret, Label, Seed, WantedLength)};
+prf({254, _}, PRFAlgo, Secret, Label, Seed, WantedLength) ->
+    {ok, tls_v1:prf(PRFAlgo, Secret, Label, Seed, WantedLength)}.
{code}

[OTP-Maintainer]

ingela said:

DTLS versions correspond to TLS versions, and when this code is called from DTLS the version
will be converted to the corresponding TLS version. DTLS is a diff agianst TLS and common code will
not be DTLS aware.