Add 'hostname' param to wrapConnectedSocket

lib/pure/asyncnet.nim

@@ -647,9 +647,12 @@ when defineSsl:
     sslSetBio(socket.sslHandle, socket.bioIn, socket.bioOut)
 
   proc wrapConnectedSocket*(ctx: SslContext, socket: AsyncSocket,
-                            handshake: SslHandshakeType) =
+                            handshake: SslHandshakeType,
+                            hostname: string = nil) =
     ## Wraps a connected socket in an SSL context. This function effectively
     ## turns ``socket`` into an SSL socket.
+    ## ``hostname`` should be specified so that the client knows which hostname
+    ## the server certificate should be validated against.
     ##
     ## This should be called on a connected socket, and will perform
     ## an SSL handshake immediately.
@@ -660,6 +663,10 @@ when defineSsl:
 
     case handshake
     of handshakeAsClient:
+      if not hostname.isNil and not isIpAddress(hostname):
+        # Set the SNI address for this connection. This call can fail if
+        # we're not using TLSv1+.
+        discard SSL_set_tlsext_host_name(socket.sslHandle, hostname)
       sslSetConnectState(socket.sslHandle)
     of handshakeAsServer:
       sslSetAcceptState(socket.sslHandle)