[PATCH proxmox-perl-rs v2 03/16] pve-rs: sdn: add dhcp responder bindings

[Hannes Laimer <h.laimer@proxmox.com>]

The SDN side hands the responder subsystem of proxmox-ebpf its desired
state, a single interface on every change and the complete set on a full
pass. Every record write carries a generation drawn after its input was
written, a plug's before it read the cache. So the subsystem can drop a
change that arrives out of order. Every interface names the vnet it sits
on, so a pass whose configs trail a hotplug leaves the plug's entry
alone. An unplug says whether the interface is gone or was plugged onto
a bridge the responder does not serve. The latter trades its entry for a
marker naming that place.

Signed-off-by: Hannes Laimer <h.laimer@proxmox.com>
---
 pve-rs/Cargo.toml               |   2 +
 pve-rs/Makefile                 |   1 +
 pve-rs/debian/control           |   2 +
 pve-rs/src/bindings/sdn/dhcp.rs | 162 ++++++++++++++++++++++++++++++++
 pve-rs/src/bindings/sdn/mod.rs  |   1 +
 5 files changed, 168 insertions(+)
 create mode 100644 pve-rs/src/bindings/sdn/dhcp.rs

diff --git a/pve-rs/Cargo.toml b/pve-rs/Cargo.toml
index 5ae9082..0adf00b 100644
--- a/pve-rs/Cargo.toml
+++ b/pve-rs/Cargo.toml
@@ -34,6 +34,7 @@ proxmox-apt = { version = "1.0.1", features = ["cache"] }
 proxmox-apt-api-types = "3"
 proxmox-base64 = "1"
 proxmox-config-digest = "1"
+proxmox-ebpf = { version = "0.1", features = ["dhcp"] }
 proxmox-frr = { version = "0.5.1" }
 proxmox-http = { version = "1.0.2", features = ["client-sync", "client-trait"] }
 proxmox-http-error = "1"
@@ -70,6 +71,7 @@ proxmox-wireguard = { version = "0.1.2" }
 # proxmox-config-digest = { path = "../../proxmox/proxmox-config-digest" }
 # proxmox-daemon = { path = "../../proxmox/proxmox-daemon" }
 # proxmox-dns-api = { path = "../../proxmox/proxmox-dns-api" }
+# proxmox-ebpf = { path = "../../proxmox-ebpf" }
 # proxmox-http-error = { path = "../../proxmox/proxmox-http-error" }
 # proxmox-http = { path = "../../proxmox/proxmox-http" }
 # proxmox-human-byte = { path = "../../proxmox/proxmox-human-byte" }
diff --git a/pve-rs/Makefile b/pve-rs/Makefile
index bb1cd2d..7609a1e 100644
--- a/pve-rs/Makefile
+++ b/pve-rs/Makefile
@@ -32,6 +32,7 @@ PERLMOD_PACKAGES := \
 	  PVE::RS::OpenId \
 	  PVE::RS::ResourceScheduling::Static \
 	  PVE::RS::ResourceScheduling::Dynamic \
+	  PVE::RS::SDN::Dhcp \
 	  PVE::RS::SDN::Fabrics \
 	  PVE::RS::SDN::PrefixLists \
 	  PVE::RS::SDN::RouteMaps \
diff --git a/pve-rs/debian/control b/pve-rs/debian/control
index 70367dc..521d966 100644
--- a/pve-rs/debian/control
+++ b/pve-rs/debian/control
@@ -20,6 +20,8 @@ Build-Depends: debhelper-compat (= 13),
                librust-proxmox-apt-api-types-3+default-dev (>= 3.0.0-~~),
                librust-proxmox-base64-1+default-dev,
                librust-proxmox-config-digest-1+default-dev,
+               librust-proxmox-ebpf-0.1+default-dev,
+               librust-proxmox-ebpf-0.1+dhcp-dev,
                librust-proxmox-frr-0.5+default-dev (>= 0.5.1-~~),
                librust-proxmox-http-1+client-sync-dev (>= 1.0.2-~~),
                librust-proxmox-http-1+client-trait-dev (>= 1.0.2-~~),
diff --git a/pve-rs/src/bindings/sdn/dhcp.rs b/pve-rs/src/bindings/sdn/dhcp.rs
new file mode 100644
index 0000000..2f193d4
--- /dev/null
+++ b/pve-rs/src/bindings/sdn/dhcp.rs
@@ -0,0 +1,162 @@
+#[perlmod::package(name = "PVE::RS::SDN::Dhcp", lib = "pve_rs")]
+pub mod pve_rs_sdn_dhcp {
+    //! The `PVE::RS::SDN::Dhcp` package.
+    //!
+    //! Bindings for the per-tap eBPF DHCP responder. Interfaces and the records they answer with
+    //! are handed in here and served directly from the kernel.
+
+    use std::net::Ipv4Addr;
+
+    use anyhow::Error;
+    use serde::{Deserialize, Deserializer};
+
+    use proxmox_ebpf::dhcp::{DhcpSubsystem, Iface, Outcome, Record, Unplugged};
+
+    /// One interface's DHCP answer, the address and every option the reply carries.
+    #[derive(Deserialize)]
+    pub struct DhcpRecord {
+        ip: Ipv4Addr,
+        prefixlen: u8,
+        server_id: Ipv4Addr,
+        lease: u32,
+        #[serde(default)]
+        router: Option<Ipv4Addr>,
+        #[serde(default)]
+        dns: Option<Ipv4Addr>,
+        #[serde(default)]
+        mtu: Option<u16>,
+        #[serde(deserialize_with = "mac_from_str")]
+        mac: [u8; 6],
+    }
+
+    // a MAC as six hex pairs
+    fn mac_from_str<'de, D: Deserializer<'de>>(d: D) -> Result<[u8; 6], D::Error> {
+        let text = String::deserialize(d)?;
+        let mut mac = [0u8; 6];
+        let mut parts = text.split(':');
+        for byte in &mut mac {
+            let part = parts
+                .next()
+                .ok_or_else(|| serde::de::Error::custom(format!("MAC {text} is too short")))?;
+            if part.len() != 2 || !part.bytes().all(|b| b.is_ascii_hexdigit()) {
+                return Err(serde::de::Error::custom(format!("MAC {text} is malformed")));
+            }
+            *byte = u8::from_str_radix(part, 16)
+                .map_err(|_| serde::de::Error::custom(format!("MAC {text} is malformed")))?;
+        }
+        if parts.next().is_some() {
+            return Err(serde::de::Error::custom(format!("MAC {text} is too long")));
+        }
+        Ok(mac)
+    }
+
+    /// One guest interface, the vnet its bridge is if any, whether the responder runs on it and
+    /// what it answers there.
+    #[derive(Deserialize)]
+    pub struct DhcpIface {
+        name: String,
+        #[serde(default)]
+        vnet: Option<String>,
+        serve: bool,
+        #[serde(default)]
+        record: Option<DhcpRecord>,
+    }
+
+    /// Where an unplugged interface went, a bridge the responder does not serve, the vnet that
+    /// bridge is if any.
+    #[derive(Deserialize)]
+    pub struct DhcpTarget {
+        #[serde(default)]
+        vnet: Option<String>,
+    }
+
+    impl From<DhcpRecord> for Record {
+        fn from(r: DhcpRecord) -> Self {
+            Record {
+                ip: r.ip,
+                prefixlen: r.prefixlen,
+                server_id: r.server_id,
+                lease: r.lease,
+                router: r.router,
+                dns: r.dns,
+                mtu: r.mtu,
+                mac: r.mac,
+            }
+        }
+    }
+
+    impl From<DhcpIface> for Iface {
+        fn from(i: DhcpIface) -> Self {
+            Iface {
+                name: i.name,
+                vnet: i.vnet,
+                serve: i.serve,
+                record: i.record.map(Record::from),
+            }
+        }
+    }
+
+    fn to_ifaces(ifaces: Vec<DhcpIface>) -> Vec<Iface> {
+        ifaces.into_iter().map(Iface::from).collect()
+    }
+
+    /// Draw the next generation. A record change draws after its input is written, a full pass
+    /// and a plug before they read theirs. So changes are ordered by the input they saw.
+    #[export]
+    pub fn next_generation() -> Result<u64, Error> {
+        DhcpSubsystem::new().next_generation()
+    }
+
+    /// The full pass over every guest interface of the cluster, those found here get their entry
+    /// and a link where served. Returns whether it applied, a pass older than one already in place
+    /// is dropped.
+    #[export]
+    pub fn apply(generation: u64, ifaces: Vec<DhcpIface>) -> Result<bool, Error> {
+        DhcpSubsystem::new().apply(generation, &to_ifaces(ifaces))
+    }
+
+    /// A record change for the listed interfaces, those not found here are skipped. Returns
+    /// false when nothing is loaded to write into, a full pass is due then.
+    #[export]
+    pub fn update(generation: u64, ifaces: Vec<DhcpIface>) -> Result<bool, Error> {
+        Ok(DhcpSubsystem::new().update(generation, &to_ifaces(ifaces))? == Outcome::Done)
+    }
+
+    /// A tap plug onto a vnet with the record it answers, none answers nothing. The generation was
+    /// drawn before the cache was read. Returns false when nothing is loaded yet, an interface gone
+    /// already counts as done.
+    #[export]
+    pub fn attach(
+        generation: u64,
+        iface: String,
+        vnet: String,
+        record: Option<DhcpRecord>,
+    ) -> Result<bool, Error> {
+        let iface = Iface {
+            name: iface,
+            vnet: Some(vnet),
+            serve: true,
+            record: record.map(Record::from),
+        };
+        Ok(DhcpSubsystem::new().attach(generation, &iface)? == Outcome::Done)
+    }
+
+    /// A tap unplug. Without a target the interface is gone or going and takes its record with
+    /// it. With one it was plugged onto a bridge the responder does not serve and keeps a marker
+    /// naming that place.
+    #[export]
+    pub fn detach(iface: &str, target: Option<DhcpTarget>) -> Result<(), Error> {
+        let unplugged = match target {
+            None => Unplugged::Gone,
+            Some(target) => Unplugged::MovedTo(target.vnet),
+        };
+        DhcpSubsystem::new().detach(iface, unplugged)
+    }
+
+    /// Detach the responder everywhere and drop its pinned state. Ordered by the generation
+    /// like a full pass, returns whether it applied.
+    #[export]
+    pub fn clear(generation: u64) -> Result<bool, Error> {
+        DhcpSubsystem::new().clear(generation)
+    }
+}
diff --git a/pve-rs/src/bindings/sdn/mod.rs b/pve-rs/src/bindings/sdn/mod.rs
index dcae046..4b99b8f 100644
--- a/pve-rs/src/bindings/sdn/mod.rs
+++ b/pve-rs/src/bindings/sdn/mod.rs
@@ -1,3 +1,4 @@
+pub(crate) mod dhcp;
 pub(crate) mod fabrics;
 pub(crate) mod prefix_lists;
 pub(crate) mod route_maps;
-- 
2.47.3