Made tls_do_handshake take an extension argument

- Allows to perform fast handshakes while controlling extensions
- Added a do_round_trip method, to performing send/recv whilst
  wrapping errors

scapy_ssl_tls/ssl_tls.py

@@ -989,6 +989,12 @@ def __enter__(self):
     def __exit__(self, exc_type, exc_val, exc_tb):
         self.close()
 
+    def do_handshake(self, version, ciphers, extensions=[]):
+        return tls_do_handshake(self, version, ciphers, extensions)
+
+    def do_round_trip(self, pkt, recv=True):
+        return tls_do_round_trip(self, pkt, recv)
+
 
 # entry class
 class SSL(Packet):
@@ -1149,23 +1155,44 @@ class TLSProtocolError(Exception):
 
     def __init__(self, *args, **kwargs):
         try:
-            self.pkt = kwargs["pkt"]
-        except KeyError:
-            self.pkt = None
-        Exception.__init__(self, *args, **kwargs)
+            self.response = args[2]
+        except IndexError:
+            self.response = kwargs.get("response", TLS())
+
+        try:
+            self.request = args[1]
+        except IndexError:
+            self.request = kwargs.get("request", TLS())
 
+        Exception.__init__(self, args[0], **kwargs)
+
+
+def tls_do_round_trip(tls_socket, pkt, recv=True):
+    resp = TLS()
+    try:
+        tls_socket.sendall(pkt)
+        if recv:
+            resp = tls_socket.recvall()
+            if resp.haslayer(TLSAlert):
+                alert = resp[TLSAlert]
+                level = TLS_ALERT_LEVELS.get(alert.level, "unknown")
+                description = TLS_ALERT_DESCRIPTIONS.get(alert.description, "unknown description")
+                raise TLSProtocolError("%s alert returned by server: %s" % (level.upper(), description.upper()), pkt, resp)
+    except socket.error as se:
+        raise TLSProtocolError(se, pkt, resp)
+    return resp
+
+
+def tls_do_handshake(tls_socket, version, ciphers, extensions=[]):
+    client_hello = TLSRecord(version=version) / TLSHandshake() / TLSClientHello(version=version, cipher_suites=ciphers, extensions=extensions)
+    resp1 = tls_do_round_trip(tls_socket, client_hello)
 
-def tls_do_handshake(tls_socket, version, ciphers):
-    client_hello = TLSRecord(version=version) / TLSHandshake() / TLSClientHello(version=version, cipher_suites=ciphers)
-    tls_socket.sendall(client_hello)
-    r = tls_socket.recvall()
-    if r.haslayer(TLSAlert):
-        raise TLSProtocolError("Alert returned by server", r)
     client_key_exchange = TLSRecord(version=version) / TLSHandshake() / tls_socket.tls_ctx.get_client_kex_data()
     client_ccs = TLSRecord(version=version) / TLSChangeCipherSpec()
-    tls_socket.sendall(TLS.from_records([client_key_exchange, client_ccs]))
-    tls_socket.sendall(to_raw(TLSFinished(), tls_socket.tls_ctx))
-    tls_socket.recvall()
+    tls_do_round_trip(tls_socket, TLS.from_records([client_key_exchange, client_ccs]), False)
+
+    resp2 = tls_do_round_trip(tls_socket, to_raw(TLSFinished(), tls_socket.tls_ctx))
+    return resp1, resp2
 
 
 def tls_fragment_payload(pkt, record=None, size=2**14):