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imsd: P-CSCF candidates from PCSCF_DISCOVERED when PCSCF= is not set

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imsd reads PCSCF_DISCOVERED= — a comma-separated IPv6 list — from its
environment; nothing in this tree writes it yet. FreshPcscfFromEnv picks
the fresh target: PCSCF= when set — one address, it wins — else the first
entry of the list CanonicalIp6 accepts; the journal says which, and names
the entries it refused. imsd routes the P-CSCF it uses itself — the fresh
target before a fresh registration (BringUp, FreshRecover), the resumed SA
peer once its SAs are confirmed — with the same idempotent `ip -6 route
replace` as a call's media peer: the bring-up script routes only the configured
PCSCF=, so a target taken from PCSCF_DISCOVERED= (set by hand in this tree),
or a route lost with the PDN, had no route. The start line prints that target; a resume still follows the
kernel's SA peer and now says whether that peer is in today's list. With
neither variable and nothing to resume, the fatal names both.

Tested: crafter-build test, 8 passed; the configured, discovered, differing (the
discovered list's order flipped: the resume stays on the SA peer, the next
fresh registration's target is the other address) and empty arms in builds
of this series on the dev phone (KPN).
This commit is contained in:
Jorijn van der Graaf 2026-10-11 16:09:45 +02:00
commit bd52afd931
Signed by: jorijnvdgraaf
GPG key ID: 2937E59CDCC1BCFB
3 changed files with 105 additions and 43 deletions
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66
implementations/main.cpp
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@ -295,6 +295,20 @@ void LogAudioSession() {
Log(AudioSessionLine(s) + (s.name.empty() ? "; looked up again at each call, set AUDIO_USER to pin one" : ""));
}
// The P-CSCF a fresh registration goes to, from the environment: PCSCF=
// when set (one address, any spelling — a list is left as it came and
// refused at bring-up), else the first address of PCSCF_DISCOVERED=, the
// list the bring-up read from the PDN's PCO (comma-separated IPv6, PCO
// order). `discovered` and `rejected` get the list and what was not an
// IPv6 literal, for the caller's log lines.
std::string FreshPcscfFromEnv(std::vector<std::string>* discovered = nullptr, std::vector<std::string>* rejected = nullptr) {
std::string configured = imsd::util::CanonicalAddr(EnvOr("PCSCF", ""));
std::vector<std::string> list = imsd::util::ParseAddressList(EnvOr("PCSCF_DISCOVERED", ""), rejected);
if (discovered) *discovered = list;
if (!configured.empty()) return configured;
return list.empty() ? std::string() : list.front();
}
// ---- sockaddr helper ------------------------------------------------------
socklen_t MakeAddr(std::string_view ip, int port, sockaddr_storage& ss) {
std::memset(&ss, 0, sizeof ss);
@ -942,11 +956,25 @@ void PostEvent(std::unique_ptr<Event> ev) {
class Engine {
public:
Engine() {
// The P-CSCF a fresh registration goes to: PCSCF= (no baked-in
// default — carrier infrastructure). A resume follows the kernel's
// SAs instead (TryResume), whatever this says today.
pcscfTarget_ = imsd::util::CanonicalAddr(EnvOr("PCSCF", ""));
pcscf_ = pcscfTarget_;
// The P-CSCF a fresh registration goes to: PCSCF= when set, else the
// first address the bring-up read from the PDN's PCO
// (PCSCF_DISCOVERED=); no baked-in default — carrier infrastructure.
// A resume follows the kernel's SAs instead (TryResume), whatever
// this says today.
{
std::vector<std::string> rejected;
pcscfTarget_ = FreshPcscfFromEnv(&pcscfCandidates_, &rejected);
pcscf_ = pcscfTarget_;
std::string configured = imsd::util::CanonicalAddr(EnvOr("PCSCF", ""));
std::string list;
for (const std::string& c : pcscfCandidates_) list += (list.empty() ? "" : ", ") + c;
if (!configured.empty())
Log(pcscfCandidates_.empty() ? std::format("pcscf: configured {}", configured)
: std::format("pcscf: configured {}; discovery gave {} (ignored: PCSCF= wins)", configured, list));
else if (!pcscfCandidates_.empty())
Log(std::format("pcscf: discovered {} (using {})", list, pcscfTarget_));
for (const std::string& r : rejected) Log(std::format("pcscf: PCSCF_DISCOVERED entry '{}' is not an IPv6 address; ignored", r));
}
pcscfPort_ = std::atoi(EnvOr("PCSCF_PORT", "5060").c_str());
dev_ = EnvOr("DEV", "qmapmux0.0");
outDir_ = EnvOr("OUT_DIR", StateDir());
@ -1156,13 +1184,15 @@ private:
// config
std::string pcscf_, dev_, outDir_, local_, ealgOffer_, mediaBin_;
// The P-CSCF a fresh registration goes to (PCSCF=). pcscf_ is the one in
// The P-CSCF a fresh registration goes to (PCSCF=, else the first of
// PCSCF_DISCOVERED=) and the whole discovered list. pcscf_ is the one in
// use: the same, or the kernel's SA peer while a resumed registration
// made to another one lives (TryResume) — the next fresh registration
// moves to the target, and back when it fails before the SA setup
// (FreshRecover), as local_ does against pdnLocal_.
std::string pcscfTarget_;
static constexpr std::string_view NoFreshPcscf = "no P-CSCF for a fresh registration: none configured (PCSCF=)";
std::vector<std::string> pcscfCandidates_;
static constexpr std::string_view NoFreshPcscf = "no P-CSCF for a fresh registration: none configured (PCSCF=) and none discovered (PCSCF_DISCOVERED empty)";
// The PDN's own address (LOCAL, else DetectLocal) — every fresh
// registration's. local_ differs from it only while a resume runs on the
// address an older registration was made on (TryResume).
@ -1352,6 +1382,11 @@ private:
local_ = pdnLocal_; ctx_.local = local_;
KeepHolds();
pcscf_ = pcscfTarget_;
// the target's host route is imsd's own: the bring-up script routes only
// the configured address (§7.2 step 3), not a target set in /etc/imsd.env
// as PCSCF_DISCOVERED= nor a route lost with the PDN — the same idempotent
// replace as a media peer's
RunCmd({"ip", Is6(pcscf_) ? "-6" : "-4", "route", "replace", pcscf_, "dev", dev_});
if (recovery_.Next(Boot()).at > Boot()) Log(std::format("the network's hold stands; {}", NextStep()));
if (!WaitForPolicy()) throw Stopping{};
FreshRegister();
@ -1373,13 +1408,12 @@ private:
// the replace covers a target that changed under a running phone.
auto peer = imsd::ipsec::SaPeer(policy.out);
if (!peer) return ResumeOutcome::None;
bool routePeer = false;
if (*peer != pcscf_) {
bool listed = *peer == pcscfTarget_ || std::ranges::find(pcscfCandidates_, *peer) != pcscfCandidates_.end();
Log(pcscfTarget_.empty()
? std::format("pcscf: resuming on {}, the registration's SA peer (no P-CSCF configured)", *peer)
: std::format("pcscf: resuming on {}, the registration's SA peer; the configured P-CSCF is {} — the next fresh registration moves there", *peer, pcscfTarget_));
? std::format("pcscf: resuming on {}, the registration's SA peer (no P-CSCF configured or discovered)", *peer)
: std::format("pcscf: resuming on {}, the registration's SA peer; the next fresh registration goes to {}{}", *peer, pcscfTarget_, listed ? "" : " (the peer is not in today's list)"));
pcscf_ = *peer;
routePeer = true; // routed below, once the SAs are confirmed: a peer named by a pair that is not ours gets no route into the PDN
}
auto sa = imsd::ipsec::ParseExistingSa(state.out, policy.out, pcscf_, local_);
// The registration may sit on another address of the link: before
@ -1403,7 +1437,10 @@ private:
}
}
if (!sa) { Log(std::format("the SA pair to {} has no SA on an address of {}: nothing to resume", pcscf_, dev_)); return ResumeOutcome::Dead; }
if (routePeer) RunCmd({"ip", Is6(pcscf_) ? "-6" : "-4", "route", "replace", pcscf_, "dev", dev_});
// the peer's host route is imsd's own once the SAs are confirmed (a peer
// named by a pair that is not ours gets no route into the PDN), whether
// or not the bring-up script routed the same address — idempotent
RunCmd({"ip", Is6(pcscf_) ? "-6" : "-4", "route", "replace", pcscf_, "dev", dev_});
auto ps = LoadState();
if (!ps || !ps->callid) { Log(std::format("no reg state file; {}", ResumeDeadNext())); return ResumeOutcome::Dead; }
// A file another attempt left behind — one that got through the SA
@ -2046,6 +2083,8 @@ private:
Log(std::format("the fresh registration moves from {} to the PDN's own address {}", local_, pdnLocal_));
MoveTo(pdnLocal_);
}
// the fresh target's host route, imsd's own (BringUp's fresh path does the same)
RunCmd({"ip", Is6(pcscf_) ? "-6" : "-4", "route", "replace", pcscf_, "dev", dev_});
bool ok = false;
try {
RefreshPani();
@ -2680,7 +2719,8 @@ int main(int argc, char** argv) {
return 1;
}
local = imsd::util::CanonicalAddr(local);
Log(std::format("LOCAL={} P-CSCF=[{}]:{}", local, imsd::util::CanonicalAddr(EnvOr("PCSCF", "(unset)")), EnvOr("PCSCF_PORT", "5060")));
std::string freshPcscf = FreshPcscfFromEnv();
Log(std::format("LOCAL={} P-CSCF=[{}]:{}", local, freshPcscf.empty() ? "(none)" : freshPcscf, EnvOr("PCSCF_PORT", "5060")));
if (!session) LogAudioSession();
imsd::bus::AuthorizeCalls = !session;