IXFR-in fails with error "a patchset did not change the SOA record"

[ximon18]

Note: I believe this issue does NOT affect the alpha-5 release as it is caused by code changes since alpha-5 in the Git main branch, specifically the new zone loader.

---

Given the following IXFR served by NSD:

example.test.		5	IN	SOA	ns1.example.test. mail.example.test. 2 60 60 3600 5 <- Start of IXFR for serial 2
example.test.		5	IN	SOA	ns1.example.test. mail.example.test. 1 60 60 3600 5 <- Start of deletions from serial 1
www         A   169.254.1.1
example.test.		5	IN	SOA	ns1.example.test. mail.example.test. 2 60 60 3600 5 <- Start of addiitions in serial 2
www         A   192.168.0.1
example.test.		5	IN	SOA	ns1.example.test. mail.example.test. 2 60 60 3600 5 <- End of IXFR for serial 2

Cascade incorrectly rejects the IXFR with:

| 2026-03-02T14:35:07.112263Z  INFO refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}: cascaded::loader: Refreshing Name(example.test.)
| 2026-03-02T14:35:07.112284Z DEBUG refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}:refresh{zone=example.test addr=127.0.0.1:1055}: cascaded::loader::server: Refreshing Name(example.test.) from server 127.0.0.1:1055
| 2026-03-02T14:35:07.112298Z TRACE refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}:refresh{zone=example.test addr=127.0.0.1:1055}: cascaded::loader::server: Attempting an IXFR against 127.0.0.1:1055 for Name(example.test.)
| 2026-03-02T14:35:07.112335Z DEBUG refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}:refresh{zone=example.test addr=127.0.0.1:1055}:ixfr{zone=example.test addr=127.0.0.1:1055}: cascaded::loader::server: Attempting an IXFR against 127.0.0.1:1055 for Name(example.test.)
| 2026-03-02T14:35:07.112634Z TRACE refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}:refresh{zone=example.test addr=127.0.0.1:1055}:ixfr{zone=example.test addr=127.0.0.1:1055}: domain::net::client::dgram: Received 230 bytes of message
| 2026-03-02T14:35:07.112654Z TRACE refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}:refresh{zone=example.test addr=127.0.0.1:1055}:ixfr{zone=example.test addr=127.0.0.1:1055}: domain::net::client::dgram: Received message is accepted
| 2026-03-02T14:35:07.112686Z TRACE refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}:refresh{zone=example.test addr=127.0.0.1:1055}:ixfr{zone=example.test addr=127.0.0.1:1055}: domain::net::xfr::protocol::iterator: XFR record 0: Record { owner: ParsedName(example.test.), class: Class::IN, ttl: Ttl(5), data: ZoneRecordData::Soa(Soa { mname: ParsedName(ns1.example.test.), rname: ParsedName(mail.example.test.), serial: Serial(2), refresh: Ttl(60), retry: Ttl(60), expire: Ttl(3600), minimum: Ttl(5) }) }
| 2026-03-02T14:35:07.112710Z TRACE refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}:refresh{zone=example.test addr=127.0.0.1:1055}:ixfr{zone=example.test addr=127.0.0.1:1055}: domain::net::xfr::protocol::iterator: XFR record 1: Record { owner: ParsedName(example.test.), class: Class::IN, ttl: Ttl(5), data: ZoneRecordData::Soa(Soa { mname: ParsedName(ns1.example.test.), rname: ParsedName(mail.example.test.), serial: Serial(1), refresh: Ttl(60), retry: Ttl(60), expire: Ttl(3600), minimum: Ttl(5) }) }
| 2026-03-02T14:35:07.112728Z TRACE refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}:refresh{zone=example.test addr=127.0.0.1:1055}:ixfr{zone=example.test addr=127.0.0.1:1055}: domain::net::xfr::protocol::iterator: XFR record 2: Record { owner: ParsedName(www.example.test.), class: Class::IN, ttl: Ttl(5), data: ZoneRecordData::A(A { addr: 169.254.1.1 }) }
| 2026-03-02T14:35:07.112752Z TRACE refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}:refresh{zone=example.test addr=127.0.0.1:1055}:ixfr{zone=example.test addr=127.0.0.1:1055}: domain::net::xfr::protocol::iterator: XFR record 3: Record { owner: ParsedName(example.test.), class: Class::IN, ttl: Ttl(5), data: ZoneRecordData::Soa(Soa { mname: ParsedName(ns1.example.test.), rname: ParsedName(mail.example.test.), serial: Serial(2), refresh: Ttl(60), retry: Ttl(60), expire: Ttl(3600), minimum: Ttl(5) }) }
| 2026-03-02T14:35:07.112773Z TRACE refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}:refresh{zone=example.test addr=127.0.0.1:1055}:ixfr{zone=example.test addr=127.0.0.1:1055}: domain::net::xfr::protocol::iterator: XFR record 4: Record { owner: ParsedName(www.example.test.), class: Class::IN, ttl: Ttl(5), data: ZoneRecordData::A(A { addr: 192.168.0.1 }) }
| 2026-03-02T14:35:07.112784Z TRACE refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}:refresh{zone=example.test addr=127.0.0.1:1055}:ixfr{zone=example.test addr=127.0.0.1:1055}: domain::net::xfr::protocol::iterator: XFR record 5: Record { owner: ParsedName(example.test.), class: Class::IN, ttl: Ttl(5), data: ZoneRecordData::Soa(Soa { mname: ParsedName(ns1.example.test.), rname: ParsedName(mail.example.test.), serial: Serial(2), refresh: Ttl(60), retry: Ttl(60), expire: Ttl(3600), minimum: Ttl(5) }) }
| 2026-03-02T14:35:07.112821Z DEBUG refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}: cascaded::loader::refresh: Updating the scheduling of 'Name(example.test.)' from Some(Instant { tv_sec: 4148565, tv_nsec: 80942976 }) to Some(Instant { tv_sec: 4148565, tv_nsec: 382927134 })
| 2026-03-02T14:35:07.112859Z ERROR refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}: cascaded::loader: Could not load the zone: the IXFR failed: could not write the zone data: a patchset did not change the SOA record zone=example.test
| 2026-03-02T14:35:07.112869Z TRACE refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}: cascaded::zone::storage: Giving up on the ongoing load zone=example.test

This appears to be because of this code (from

cascade/src/loader/server.rs

Line 189 in 6a92108

Some(Ok(ZoneUpdate::BeginBatchDelete(_))) => {

):

        Some(Ok(ZoneUpdate::BeginBatchDelete(_))) => {
            // This is an IXFR.
            let mut writer = builder.patch().unwrap();
            process_ixfr(&mut writer, updates, metrics)?;
            if !interpreter.is_finished() {
                // Fail: UDP-based IXFR returned a partial IXFR
                return Err(IxfrError::IncompleteResponse);
            }

The issue is that process_ixfr() expects to receive the initial SOA that begins the batch delete, but that was already consumed. Note that the consumed SOA is still available as the unnamed _ value of BeginBatchDelete(_), but is no longer available via updates.next().

[ximon18]

Note that the new ixfr-in system test in branch add-ixfr-system-test reproduces this problem when run locally with nektos/act, specifically the output says:

[System/Integration tests/Receive a zone via IXFR from the NSD primary.] ⭐ Run Main Query changed SOA at Cascade unsigned review server
[System/Integration tests/Receive a zone via IXFR from the NSD primary.]   🐳  docker exec cmd=[bash -e /var/run/act/workflow/1-composite-9] user= workdir=
[System/Integration tests/Receive a zone via IXFR from the NSD primary.]   ❗  ::error:: Expected SOA serial '2' but dig reports 'ns1.example.test. mail.example.test. 1 60 60 3600 5'
[System/Integration tests/Receive a zone via IXFR from the NSD primary.]   ❌  Failure - Main Query changed SOA at Cascade unsigned review server [65.909866ms]
[System/Integration tests/Receive a zone via IXFR from the NSD primary.] exitcode '1': failure

And further down in the output where it shows the Cascade log one can see:

| 2026-03-03T09:37:25.241903Z ERROR refresh{zone=example.test source=Server { addr: 127.0.0.1:1055, tsig_key: None }}: cascaded::loader: Could not load the zone: the IXFR failed: could not write the zone data: a patchset did not change the SOA record zone=example.test