doc,test: mention Duplex support for TLS

Document and test the existing support for generic Duplex streams
in the TLS module.

PR-URL: https://github.com/nodejs/node/pull/17599
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

1 files changed, 10 insertions, 5 deletions

diff --git a/doc/api/tls.md b/doc/api/tls.md
index 38e35fb5d2..13af0b2aa2 100644
--- a/doc/api/tls.md
+++ b/doc/api/tls.md
@@ -455,7 +455,10 @@ changes:
     description: ALPN options are supported now.
 -->
 
-* `socket` {net.Socket} An instance of [`net.Socket`][]
+* `socket` {net.Socket|stream.Duplex}
+  On the server side, any `Duplex` stream. On the client side, any
+  instance of [`net.Socket`][] (for generic `Duplex` stream support
+  on the client side, [`tls.connect()`][] must be used).
 * `options` {Object}
   * `isServer`: The SSL/TLS protocol is asymmetrical, TLSSockets must know if
     they are to behave as a server or a client. If `true` the TLS socket will be
@@ -815,10 +818,12 @@ changes:
   * `port` {number} Port the client should connect to.
   * `path` {string} Creates unix socket connection to path. If this option is
     specified, `host` and `port` are ignored.
-  * `socket` {net.Socket} Establish secure connection on a given socket rather
-    than creating a new socket. If this option is specified, `path`, `host` and
-    `port` are ignored.  Usually, a socket is already connected when passed to
-    `tls.connect()`, but it can be connected later. Note that
+  * `socket` {stream.Duplex} Establish secure connection on a given socket
+    rather than creating a new socket. Typically, this is an instance of
+    [`net.Socket`][], but any `Duplex` stream is allowed.
+    If this option is specified, `path`, `host` and `port` are ignored,
+    except for certificate validation.  Usually, a socket is already connected
+    when passed to `tls.connect()`, but it can be connected later. Note that
     connection/disconnection/destruction of `socket` is the user's
     responsibility, calling `tls.connect()` will not cause `net.connect()` to be
     called.