Debugging

When a scenario misbehaves, two flags give you visibility into what the SIP backend is doing. Both are off by default and write nowhere unless you ask.

The backend log

--log [<file>] writes the backend’s log — registration, call state, module output — to stderr, or to a file if you pass a path:

ringo-flow run scenario.rhai --log            # → stderr
ringo-flow run scenario.rhai --log run.log    # → file

SIP tracing

--sip-trace [<file>] traces every SIP request and response (sent and received), to its own destination — separate from --log, so you can keep the protocol trace clean:

ringo-flow run scenario.rhai --sip-trace            # → stderr (text)
ringo-flow run scenario.rhai --sip-trace sip.txt    # → text file

Each message is printed as a timestamped block with its direction (TX → / RX ←) and transport.

Tracing into a pcap

Give --sip-trace a path ending in .pcap and you get a libpcap capture instead of text — readable by sngrep and Wireshark, including Wireshark’s Telephony → VoIP Calls flow graph:

ringo-flow run scenario.rhai --sip-trace flow.pcap
sngrep -I flow.pcap        # or: wireshark flow.pcap

This is the only way to inspect the SIP when the transport is TLS: a live sniffer on the wire sees only the encrypted bytes, but ringo-flow taps the trace inside the stack, so the capture holds the plaintext SIP. Each message is framed as one Ethernet/IP/UDP datagram (the original transport is irrelevant for parsing), so the tools render a clean ladder regardless of UDP/TCP/TLS.