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Allocate IPv4 addresses and keep them, as signed state

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Derived IPv4 addresses could not survive anything: they changed with the
range, and there was no way for a member to come back to the one it had.
Addresses are now allocated and recorded as signed facts, which is the
first slice of the model in docs/sync-model.md.

src/state/ holds one record per author per network, carrying that author's
complete current statement, signed with its persistent device key over a
length-prefixed canonical encoding. Merging follows the model's rules: a
higher version wins, an older one never rolls back a newer, duplicates are
idempotent, absence from a snapshot is not deletion, and a same-version
conflict is resolved identically on every replica and reported rather than
letting replicas diverge. Records are persisted in state.sqlite, with the
record and the author's version counter committed in one transaction
before anything is announced, and distributed as a State control message
that is merged into what the receiver already holds.

No vote, deliberately, despite the request. A majority is not a trust root
here — anyone with the secret can mint identities — and a quorum would
stall with one peer online and diverge across a partition. Signatures plus
a deterministic merge converge without either failure mode: two members
claiming one address at once are resolved by the lower endpoint id, and
the loser allocates again with a higher version.

The range moved from the plugin to the agent, defaults to 10.13.37.0/24,
and is now agreed rather than configured per member: a joining agent
adopts what the network already uses, so --ipv4-range only matters for
whoever starts it. The announcement went back to identity only (version 3)
since the range travels in signed records now.

A release tombstone exists and merges correctly, but nothing emits one
yet.

116 tests. The headline ones: an address survives restarting both agents,
three members get three distinct addresses, and a member started with a
different range adopts the one in use. Confirmed by hand with two CLI
agents restarted end to end.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
This commit is contained in:
tsunagiandClaude Opus 5 committed 2026-09-21 13:43:01 +01:00
1 parent ce64264027
commit 84c06c6cac
25 files changed
+1967 -365
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src/dataplane/wireguard/overlay.rs
+3 -75
View File
@@ -22,10 +22,9 @@
use std::net::{Ipv4Addr, Ipv6Addr};
use serde::{Deserialize, Serialize};
use sha2::{Digest, Sha256};
use crate::dataplane::PluginError;
use crate::state::Ipv4Range;
use crate::identity::NetworkId;
@@ -40,77 +39,6 @@ pub const OVERLAY_PREFIX_LEN: u8 = 64;
/// Prefix length of one member's address inside the overlay.
pub const OVERLAY_HOST_PREFIX_LEN: u8 = 128;
/// An IPv4 range the overlay can be derived into.
///
/// Every member of a network must be configured with the same one, because
/// addresses are derived from it. See [`crate::dataplane::wireguard::plugin::WireguardConfig::ipv4_range`].
#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
pub struct Ipv4Range {
/// Base address of the range.
pub base: Ipv4Addr,
/// Prefix length, at most 30 so there is room for hosts.
pub prefix_len: u8,
}
impl Ipv4Range {
/// Builds a range, rejecting one with no room for hosts.
pub fn new(base: Ipv4Addr, prefix_len: u8) -> Result<Self, PluginError> {
if prefix_len > 30 {
return Err(PluginError::Rejected(format!(
"a /{prefix_len} has no room for hosts; use /30 or larger"
)));
}
Ok(Self { base, prefix_len })
}
/// Whether an address falls inside the range.
pub fn contains(&self, address: Ipv4Addr) -> bool {
let host_bits = 32 - u32::from(self.prefix_len);
let mask = if host_bits >= 32 {
0
} else {
u32::MAX << host_bits
};
u32::from(address) & mask == u32::from(self.base) & mask
}
}
impl std::fmt::Display for Ipv4Range {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
write!(f, "{}/{}", self.base, self.prefix_len)
}
}
impl std::str::FromStr for Ipv4Range {
type Err = PluginError;
fn from_str(text: &str) -> Result<Self, Self::Err> {
let (base, prefix) = text.split_once('/').ok_or_else(|| {
PluginError::Rejected(format!(
"`{text}` is not an address with a prefix, for example 10.77.0.0/16"
))
})?;
let base = base.parse().map_err(|err| {
PluginError::Rejected(format!("`{base}` is not an IPv4 address: {err}"))
})?;
let prefix_len = prefix.parse().map_err(|err| {
PluginError::Rejected(format!("`{prefix}` is not a prefix length: {err}"))
})?;
Self::new(base, prefix_len)
}
}
/// RFC 6598 shared address space, offered only as a reference point.
///
/// **Not a default, and usually a bad choice.** Tailscale uses exactly this
/// range, and so does carrier-grade NAT, so a machine running either will
/// collide with it. There is no IPv4 range that is free on every host, which
/// is why the IPv4 overlay has no default at all and must be configured.
pub const RFC6598_SHARED_RANGE: Ipv4Range = Ipv4Range {
base: Ipv4Addr::new(100, 64, 0, 0),
prefix_len: 10,
};
fn push_lp(out: &mut Vec<u8>, bytes: &[u8]) {
let len = u32::try_from(bytes.len()).unwrap_or(u32::MAX);
out.extend_from_slice(&len.to_be_bytes());
@@ -252,7 +180,7 @@ mod tests {
#[test]
fn ipv4_addresses_land_inside_the_range_and_avoid_its_edges() {
let id = network("v4");
let range = RFC6598_SHARED_RANGE;
let range: Ipv4Range = "100.64.0.0/10".parse().unwrap();
for byte in 0..64u8 {
let key = WgPublicKey::from_bytes([byte; 32]);
let addr = overlay_address_v4(id, &key, range).unwrap();
@@ -286,7 +214,7 @@ mod tests {
let key = WgPublicKey::from_bytes([9u8; 32]);
let first = network("one");
let second = network("two");
let range = RFC6598_SHARED_RANGE;
let range: Ipv4Range = "100.64.0.0/10".parse().unwrap();
assert_eq!(
overlay_address_v4(first, &key, range),