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sip: log a refused REGISTER or SUBSCRIBE with its status line and reason headers

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A refused final was logged as its bare status code ("re-REGISTER failed
503", "reg-event SUBSCRIBE -> 500") — the unprotected REGISTER's as
"expected 401", without even the code — so a field journal could not say
which node refused or what it said. O2 UK answered a phone's 30-minute
refresh with 503 twenty-one times over seventy minutes and then refused
a fresh registration's reg-event SUBSCRIBE with 500 (alyx, 2026-09-24);
the journal holds nothing but the numbers.

Log the status line with the headers that carry the reason —
Retry-After, Warning, Reason, Server — for a REGISTER's refused final
(initial, protected, refresh) and for a refused SUBSCRIBE the run loop
reads, and dump the refused message under DUMP_SIP as its own fail dump
next to the 200s.

To tell a REGISTER's final from what else arrives, the final is now
matched by Call-ID and CSeq, and a request that arrives on the client
flow while one is awaited is dispatched: a refresh no longer reads such
a request as a failed REGISTER. An INVITE among those requests is a call
like any other, announced on the bus: a Dial whose reconnect it arrived
under meets the call-in-progress rule again before it places its own,
and when a resume, a refresh or a reconnect fails the call that arrived
under it ends with the flow it came in on (486 while the flow still
carries one, and the bus told). The unprotected REGISTER's reply is
matched the same way on the init port.

Tested on the dev phone (KPN) in builds of this series; not every path
has run there.
This commit is contained in:
Jorijn van der Graaf 2026-09-24 18:51:03 +02:00
commit 46bf363915
Signed by: jorijnvdgraaf
GPG key ID: 2937E59CDCC1BCFB
4 changed files with 212 additions and 45 deletions
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33
interfaces/Imsd-Sip.cppm
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@ -121,6 +121,39 @@ export namespace imsd::sip {
return v;
}
// True for a response of the transaction (callid, cseq) — the reply a
// wait for that request may judge. A request, another transaction's
// response or anything else a socket delivers is not.
bool ResponseOf(std::string_view msg, std::string_view callid, std::string_view cseq) {
return Status(msg).has_value() && Header(msg, "Call-ID") == callid && Header(msg, "CSeq") == cseq;
}
// Retry-After of a response (RFC 3261 20.33), in seconds; nullopt when
// absent or not a number.
std::optional<long> RetryAfter(std::string_view msg) {
auto v = Header(msg, "Retry-After");
if (!v) return std::nullopt;
return LeadingDigits(*v);
}
// A refused final for the journal: its status line, then the headers
// that say who refused and for how long — Retry-After (RFC 3261 20.33),
// Warning (20.43: the node's own words), Reason (RFC 3326), Server
// (20.35). "503 Service Unavailable; Retry-After: 60; Warning: 399
// pcscf1.example \"...\"". A bare status code says neither which node
// nor why: O2 UK answered a refresh 503 twenty-one times and a
// subscription 500 (alyx, 2026-09-24) and the journal could not tell
// the P-CSCF from the S-CSCF (ims ledger F17).
std::string RefusalSummary(std::string_view msg) {
std::string_view line = msg.substr(0, msg.find_first_of("\r\n"));
if (line.starts_with("SIP/2.0 ")) line.remove_prefix(8);
std::string s(Trim(line));
for (std::string_view name : {"Retry-After", "Warning", "Reason", "Server"})
for (std::string_view v : Headers(msg, name))
s += std::format("; {}: {}", name, v);
return s;
}
// Where a UDP response to this request must go (RFC 3261 18.2.2): the
// top Via's sent-by port — unless the Via carries rport, in which case
// the caller should reply to the request's source port instead