Throw error when using sni and setting server_hostname manually i…

…n `remote`

Prevents silently replacing the `server_hostname` that was provided in `ssl_args`.

Fixes #2425

pwnlib/tubes/remote.py

@@ -89,6 +89,8 @@ def __init__(self, host, port,
                 import ssl as _ssl
 
                 ssl_args = ssl_args or {}
+                if "server_hostname" in ssl_args and sni:
+                    log.error("sni and server_hostname cannot be set at the same time")
                 ssl_context = ssl_context or _ssl.SSLContext(_ssl.PROTOCOL_TLSv1_2)
                 if isinstance(sni, str):
                     ssl_args["server_hostname"] = sni