merge: testing → main (reconcile 2-week divergence)

decnet/templates/sip/server.py

@@ -0,0 +1,148 @@
+#!/usr/bin/env python3
+"""
+SIP server (UDP + TCP port 5060).
+Parses SIP REGISTER and INVITE messages, logs credentials from the
+Authorization header and call metadata, then responds with 401 Unauthorized.
+"""
+
+import asyncio
+import os
+import re
+from syslog_bridge import (
+    classify_authorization,
+    forward_syslog,
+    syslog_line,
+    write_syslog_file,
+)
+
+NODE_NAME = os.environ.get("NODE_NAME", "pbx")
+SERVICE_NAME   = "sip"
+LOG_TARGET = os.environ.get("LOG_TARGET", "")
+
+_401 = (
+    "SIP/2.0 401 Unauthorized\r\n"
+    "Via: {via}\r\n"
+    "From: {from_}\r\n"
+    "To: {to}\r\n"
+    "Call-ID: {call_id}\r\n"
+    "CSeq: {cseq}\r\n"
+    'WWW-Authenticate: Digest realm="{host}", nonce="{nonce}", algorithm=MD5\r\n'
+    "Content-Length: 0\r\n\r\n"
+)
+
+
+
+
+def _log(event_type: str, severity: int = 6, **kwargs) -> None:
+    line = syslog_line(SERVICE_NAME, NODE_NAME, event_type, severity, **kwargs)
+    write_syslog_file(line)
+    forward_syslog(line, LOG_TARGET)
+
+
+def _parse_headers(msg: str) -> dict:
+    headers = {}
+    for line in msg.splitlines()[1:]:
+        if ":" in line:
+            k, _, v = line.partition(":")
+            headers[k.strip().lower()] = v.strip()
+    return headers
+
+
+def _handle_message(data: bytes, src_addr) -> bytes | None:
+    try:
+        msg = data.decode(errors="replace")
+    except Exception:
+        return None
+    first_line = msg.splitlines()[0] if msg else ""
+    method = first_line.split()[0] if first_line else "UNKNOWN"
+    headers = _parse_headers(msg)
+
+    auth_header = headers.get("authorization", "")
+    username = ""
+    if auth_header:
+        m = re.search(r'username="([^"]+)"', auth_header)
+        username = m.group(1) if m else ""
+
+    # SIP Digest is the same shape as HTTP Digest (RFC 7616 derived from
+    # RFC 2617). classify_authorization handles it identically — emits
+    # secret_kind="http_digest_md5", which is correct: the cred is the
+    # MD5 hash response, regardless of whether it rode in over SIP or
+    # HTTP. Reuse-analytics correlates across both.
+    cred = classify_authorization(auth_header)
+
+    _log(
+        "request",
+        src=src_addr[0],
+        src_port=src_addr[1],
+        method=method,
+        from_=headers.get("from", ""),
+        to=headers.get("to", ""),
+        username=username,
+        auth=auth_header[:256],
+        **(cred or {}),
+    )
+
+    if method in ("REGISTER", "INVITE", "OPTIONS"):
+        nonce = os.urandom(8).hex()
+        response = _401.format(
+            via=headers.get("via", ""),
+            from_=headers.get("from", ""),
+            to=headers.get("to", ""),
+            call_id=headers.get("call-id", ""),
+            cseq=headers.get("cseq", ""),
+            host=NODE_NAME,
+            nonce=nonce,
+        )
+        return response.encode()
+    return None
+
+
+class SIPUDPProtocol(asyncio.DatagramProtocol):
+    def __init__(self):
+        self._transport = None
+
+    def connection_made(self, transport):
+        self._transport = transport
+
+    def datagram_received(self, data, addr):
+        response = _handle_message(data, addr)
+        if response and self._transport:
+            self._transport.sendto(response, addr)
+
+
+class SIPTCPProtocol(asyncio.Protocol):
+    def __init__(self):
+        self._transport = None
+        self._peer = None
+        self._buf = b""
+
+    def connection_made(self, transport):
+        self._transport = transport
+        self._peer = transport.get_extra_info("peername", ("?", 0))
+
+    def data_received(self, data):
+        self._buf += data
+        if b"\r\n\r\n" in self._buf or b"\n\n" in self._buf:
+            response = _handle_message(self._buf, self._peer)
+            self._buf = b""
+            if response:
+                self._transport.write(response)
+
+    def connection_lost(self, exc):
+        pass
+
+
+async def main():
+    _log("startup", msg=f"SIP server starting as {NODE_NAME}")
+    loop = asyncio.get_running_loop()
+    udp_transport, _ = await loop.create_datagram_endpoint(
+        SIPUDPProtocol, local_addr=("0.0.0.0", 5060)  # nosec B104
+    )
+    tcp_server = await loop.create_server(SIPTCPProtocol, "0.0.0.0", 5060)  # nosec B104
+    async with tcp_server:
+        await tcp_server.serve_forever()
+    udp_transport.close()
+
+
+if __name__ == "__main__":
+    asyncio.run(main())