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sdp, engine, imsd: SendDtmf sends the tones as RFC 4733 events over the media leg

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SendDtmf was a stub: GNOME Calls' SendTones and Plasma Dialer's sendDtmf
reached imsd and went nowhere. The SDP parser reads the telephone-event
payload type at the chosen codec's clock into the answer, among the
m-line's formats only — an rtpmap the line does not list is not
negotiated, and nothing is sent with a format the answer does not carry
(RFC 3264 §8.3.2); an event's rate is its rtpmap clock (RFC 4733
§2.4.1), an offer with two codec clocks lists telephone-event at each,
and the name is matched as every encoding name is, case-insensitively,
with the clock whole. The media leg carries it, and imsd-media gets it
as DTMF_PT with its stdin on a pipe from imsd, the control pipe. The
SDP answer imsd sends to an inbound offer carries telephone-event by the
same rule, where it echoed any telephone-event rtpmap with a lower-case
name and a clock prefix before: an rtpmap off the offer's m-line is no
longer echoed, an upper-case name now is. The decision is the engine's:
OnDtmf lets the tones through on an active call that negotiated
telephone-event (the answer's number on a call we placed, the offer's on
one we answered) and drops them otherwise with a line that says why:
before the answer, after the call, no telephone-event at the codec's
clock in the SDP, a character that is no tone or more than 128 tones
(then the whole string, never part of what was pressed); letters are
upper-cased. The shell writes one `dtmf <tones>` line per SendDtmf,
whole or not at all: the bound keeps the line within one atomic pipe
write, the write end is non-blocking so that a leg that stopped reading
fails the write instead of holding the engine thread, and a longer line
is refused; SIGPIPE is ignored so that a write after the leg died fails
with EPIPE instead of ending the daemon. The command queue's one
argument is `arg` now — the number to dial, or the tones. The `media …`
start line gains the telephone-event pt at its end.

Tested: tests/Sdp and tests/Engine (the eight suites pass); the dev
phone's dtmf benches ran in builds of this series
(journal/ims/captures/2026-10-14-dtmf-bench-1/ onward).
This commit is contained in:
Jorijn van der Graaf 2026-10-14 15:05:24 +02:00
commit 92fba40da0
Signed by: jorijnvdgraaf
GPG key ID: 2937E59CDCC1BCFB
6 changed files with 365 additions and 73 deletions
Download patch file Download diff file Expand all files Collapse all files

69
tests/Engine/main.cpp
View file

@ -11,7 +11,10 @@
// reject -> 486, remote CANCEL -> 200+487, unusable offer -> 488 (naming
// what was offered), a landline gateway's G.711-only and AMR-NB offers
// ring and are answered at the offer's own payload types, ring timeout ->
// 480, BYE both ways. Then RegRecovery, the registration recovery policy:
// 480, BYE both ways. DTMF: the tones reach the media leg on an active
// call that negotiated telephone-event, and are dropped — with the reason
// — before the answer, after the call, without the negotiation or with a
// character that is no tone. Then RegRecovery, the registration recovery policy:
// the refusal and silence thresholds, local refusals, the reconnect and
// fresh backoffs, the throttle schedule, Retry-After, which waits a Dial
// may cut short, when the old registration counts as gone, the holds a
@ -90,6 +93,21 @@ namespace {
"v=0\r\no=- 1 1 IN IP6 2001:db8::9\r\ns=-\r\nc=IN IP6 2001:db8::9\r\n"
"t=0 0\r\nm=audio 6004 RTP/AVP 97\r\na=rtpmap:97 AMR-WB/16000/1\r\n", callid);
}
// A 200 OK around an arbitrary SDP answer, Content-Length from it — a
// message the shell's framing would deliver whole.
std::string R200Sdp(std::string_view callid, std::string_view sdp) {
return std::format(
"SIP/2.0 200 OK\r\n"
"Via: SIP/2.0/TCP [2001:db8::db43]:45061;branch=z9hG4bKx\r\n"
"From: <sip:001010123456789@ims.mnc001.mcc001.3gppnetwork.org>;tag=it\r\n"
"To: <sip:1233@ims>;tag=remote7\r\n"
"Call-ID: {}\r\n"
"CSeq: 1 INVITE\r\n"
"Contact: <sip:termgw@[2001:db8::9]:5060>\r\n"
"Content-Type: application/sdp\r\n"
"Content-Length: {}\r\n\r\n{}", callid, sdp.size(), sdp);
}
constexpr std::string_view SdpHead = "v=0\r\no=- 1 1 IN IP6 2001:db8::9\r\ns=-\r\nc=IN IP6 2001:db8::9\r\nt=0 0\r\n";
std::string Final(std::string_view callid, int code, std::string_view text) {
return std::format(
"SIP/2.0 {} {}\r\n"
@ -209,6 +227,7 @@ int main() {
Check(media && media->media.remotePort == 6004, "media remote port");
Check(media && media->media.payloadType == 97, "media pt");
Check(media && media->media.codec == "AMR-WB", "media codec");
Check(media && !media->media.dtmfPt, "an answer without telephone-event: the leg has no DTMF pt");
const Action* active = Find(a200, Action::Type::State);
Check(active && active->state == "active" && active->reason == "accepted", "200 emits active/accepted");
Check(m.State() == CallState::Active, "state active");
@ -220,6 +239,12 @@ int main() {
Check(!Has(a200b, Action::Type::StartMedia) && !Has(a200b, Action::Type::State), "retransmitted 200: no second media start, no state action");
Check(m.State() == CallState::Active, "state still active after the retransmit");
// DTMF on a call whose answer negotiated no telephone-event: dropped, said why
auto adt = m.OnDtmf("1");
Check(!Has(adt, Action::Type::SendDtmf), "no telephone-event negotiated: no SendDtmf");
const Action* dtLog = Find(adt, Action::Type::Log);
Check(dtLog && dtLog->text == "call ims-call-1: DTMF '1' dropped: no telephone-event negotiated for this call", "...and the line says so");
// media leg exits code 3 (downlink dried up) -> BYE + terminated
auto amx = m.OnMediaExit(3);
Check(Sent(amx, "BYE ") != nullptr, "media far-end hangup sends BYE");
@ -230,6 +255,43 @@ int main() {
Check(m.Terminated(), "terminated");
}
// ---- DTMF, outgoing: the answer echoes our telephone-event/16000 at pt
// 98; the tones go to the leg once active, in upper case, and are
// dropped before the answer, with a character that is no tone,
// and after the call
{
imsd::util::Rng rng(43);
CallMachine m(c, rng, "ims-call-1d", "1233", 50004, false);
m.Start();
auto early = m.OnDtmf("1");
Check(!Has(early, Action::Type::SendDtmf), "DTMF while dialing: not sent");
const Action* earlyLog = Find(early, Action::Type::Log);
Check(earlyLog && earlyLog->text == "call ims-call-1d: DTMF '1' dropped: the call is dialing", "...the line names the state");
auto a200 = m.OnInviteResponse(R200Sdp(m.CallId(), std::format("{}m=audio 6004 RTP/AVP 97 98 100\r\na=rtpmap:97 AMR-WB/16000/1\r\na=rtpmap:98 telephone-event/16000\r\na=rtpmap:100 telephone-event/8000\r\n", SdpHead)));
const Action* media = Find(a200, Action::Type::StartMedia);
Check(media && media->media.dtmfPt == 98, "the leg carries the answer's telephone-event pt at the codec's clock (98, not the narrowband 100)");
Check(m.State() == CallState::Active, "active");
auto sent = m.OnDtmf("12#*a");
const Action* dt = Find(sent, Action::Type::SendDtmf);
Check(dt && dt->text == "12#*A", "active + negotiated: SendDtmf with the tones, letters upper-cased");
const Action* dtLog = Find(sent, Action::Type::Log);
Check(dtLog && dtLog->text == "call ims-call-1d: DTMF '12#*A' -> media leg (telephone-event pt 98)", "...and the line names the pt");
auto bad = m.OnDtmf("1x");
Check(!Has(bad, Action::Type::SendDtmf), "a character that is no tone: nothing sent, not even the '1'");
const Action* badLog = Find(bad, Action::Type::Log);
Check(badLog && badLog->text == "call ims-call-1d: DTMF '1x' dropped: 'x' is not a tone", "...the line names the character");
Check(m.OnDtmf("").empty(), "an empty string: nothing, silently");
const std::string atMost(DtmfMaxTones, '1');
auto most = m.OnDtmf(atMost);
const Action* maxDt = Find(most, Action::Type::SendDtmf);
Check(maxDt && maxDt->text == atMost, "a string of DtmfMaxTones tones goes");
auto tooMany = m.OnDtmf(std::format("{}1", atMost));
Check(!Has(tooMany, Action::Type::SendDtmf) && Find(tooMany, Action::Type::Log) && Find(tooMany, Action::Type::Log)->text == std::format("call ims-call-1d: DTMF of {} tones dropped: more than {}", DtmfMaxTones + 1, DtmfMaxTones), "one more: dropped, the line names the bound");
m.OnHangup();
auto late = m.OnDtmf("5");
Check(!Has(late, Action::Type::SendDtmf) && Find(late, Action::Type::Log) && Find(late, Action::Type::Log)->text.ends_with("the call is terminated"), "DTMF after the call: dropped, the line names the state");
}
// ---- remote BYE mid-call
{
imsd::util::Rng rng(7);
@ -368,6 +430,11 @@ int main() {
Check(ok && ok->text.contains("a=rtpmap:104 AMR-WB/16000/1\r\n"), "answer keeps AMR-WB at the offer's pt");
Check(ok && ok->text.contains("a=fmtp:104 octet-align=1\r\n"), "answer mirrors octet-align");
Check(ok && ok->text.contains("a=rtpmap:105 telephone-event/16000\r\n"), "answer keeps telephone-event");
const Action* mtMedia = Find(aa, Action::Type::StartMedia);
Check(mtMedia && mtMedia->media.dtmfPt == 105, "incoming: the leg carries the offer's telephone-event pt");
auto mtDtmf = m.OnDtmf("9");
const Action* mtDt = Find(mtDtmf, Action::Type::SendDtmf);
Check(mtDt && mtDt->text == "9", "incoming, accepted: the tones go to the leg");
Check(ok && ok->text.contains("Session-Expires: 1800;refresher=uac\r\n"), "200 echoes Session-Expires, caller refreshes");
Check(ok && ok->text.contains("Contact: <sip:001010123456789@"), "200 carries our Contact");
// the 180 and 200 carry the SAME To tag (one dialog)

16
tests/Sdp/main.cpp
View file

@ -207,7 +207,21 @@ int main() {
"a=rtpmap:105 telephone-event/16000\r\n"
"a=rtpmap:106 telephone-event/8000\r\n";
Check(TelephoneEventPt(offer, 16000) == 105, "telephone-event pt by clock rate");
Check(TelephoneEventPt(offer, 8000) == 106, "narrowband telephone-event pt");
Check(!TelephoneEventPt(offer, 8000), "an rtpmap the m-line does not list (106 among 104 105) is not negotiated");
Check(ParseAnswer(offer).dtmfPt == 105, "the answer's dtmfPt is the one at the chosen codec's clock (AMR-WB: 16000)");
std::string both = std::format("{}a=rtpmap:99 AMR/8000/1\r\n", offer);
both.replace(both.find("RTP/AVP 104 105"), 15, "RTP/AVP 104 99 105 106");
std::array<std::string, 1> nb = {"AMR"};
Check(ParseAnswer(both, nb).dtmfPt == 106, "...and the narrowband one when AMR is chosen");
Check(TelephoneEventPt(both, 8000) == 106, "listed on the m-line, the narrowband telephone-event pt is found");
Check(!ParseAnswer(offer, nb).dtmfPt, "no codec we play chosen: no dtmfPt either");
Check(!ParseAnswer("c=IN IP4 192.0.2.1\r\n" "m=audio 5000 RTP/AVP 8\r\n" "a=rtpmap:8 PCMA/8000\r\n").dtmfPt, "no telephone-event in the answer: dtmfPt empty");
Check(!ParseAnswer("c=IN IP4 192.0.2.1\r\n" "m=audio 5000 RTP/AVP 8\r\n" "a=rtpmap:8 PCMA/8000\r\n" "a=rtpmap:101 telephone-event/8000\r\n").dtmfPt, "the answer dropped telephone-event from its m-line and kept the rtpmap: not negotiated (RFC 3264 §8.3.2: nothing is sent with a format the answer does not list)");
Check(ParseAnswer("c=IN IP4 192.0.2.1\r\n" "m=audio 5000 RTP/AVP 8 101\r\n" "a=rtpmap:101 telephone-event/8000\r\n").dtmfPt == 101, "G.711 answer with telephone-event/8000: dtmfPt 101");
Check(!ParseAnswer("c=IN IP4 192.0.2.1\r\n" "m=audio 5000 RTP/AVP 8 101\r\n" "a=rtpmap:101 telephone-event/16000\r\n").dtmfPt, "telephone-event at the wrong clock for the codec is not the call's");
Check(ParseAnswer("c=IN IP4 192.0.2.1\r\n" "m=audio 5000 RTP/AVP 8 101\r\n" "a=rtpmap:101 TELEPHONE-EVENT/8000\r\n").dtmfPt == 101, "the name in another case (RFC 4566: case-insensitive)");
Check(TelephoneEventPt("m=audio 1 RTP/AVP 98\r\na=rtpmap:98 Telephone-Event/16000/1\r\n", 16000) == 98, "mixed case, with a channel count");
Check(!TelephoneEventPt("m=audio 1 RTP/AVP 98\r\na=rtpmap:98 telephone-event/80000\r\n", 8000), "the clock is matched whole: /80000 is not /8000");
Check(!TelephoneEventPt(offer, 48000).has_value(), "absent clock rate -> nullopt");
Check(!TelephoneEventPt("m=audio 1 RTP/AVP 0\r\n", 16000).has_value(), "no rtpmap -> nullopt");
}