From b95d1f1878b8facde47c46a8a9a2e5b610810442 Mon Sep 17 00:00:00 2001
From: Alejandro Mery <amery@jpi.io>
Date: Sat, 26 Aug 2023 16:37:06 +0000
Subject: [PATCH] zones: introduce Wireguard Ring Config factory

Signed-off-by: Alejandro Mery <amery@jpi.io>
---
 pkg/zones/rings.go | 166 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 166 insertions(+)

diff --git a/pkg/zones/rings.go b/pkg/zones/rings.go
index 6ca0593..1cbdd06 100644
--- a/pkg/zones/rings.go
+++ b/pkg/zones/rings.go
@@ -2,6 +2,7 @@ package zones
 
 import (
 	"fmt"
+	"io/fs"
 	"net/netip"
 
 	"git.jpi.io/amery/jpictl/pkg/wireguard"
@@ -179,3 +180,168 @@ func RingOneAddress(zoneID, nodeID int) (netip.Addr, bool) {
 		return netip.AddrFrom4(a4), true
 	}
 }
+
+var (
+	_ MachineIterator = (*Ring)(nil)
+	_ ZoneIterator    = (*Ring)(nil)
+)
+
+// A Ring describes all peers on a ring
+type Ring struct {
+	RingAddressEncoder
+	ZoneIterator
+
+	Peers []*RingPeer
+}
+
+// AddPeer adds a [Machine] to the ring
+func (r *Ring) AddPeer(p *Machine) bool {
+	ri, ok := p.getRingInfo(r.ID)
+	if !ok {
+		return false
+	}
+
+	nodeID := p.ID
+	zoneID := p.Zone()
+	addr, _ := r.Encode(zoneID, nodeID)
+
+	rp := &RingPeer{
+		Node:       p,
+		Address:    addr,
+		PrivateKey: ri.Keys.PrivateKey,
+		PeerConfig: wireguard.PeerConfig{
+			PublicKey: ri.Keys.PublicKey,
+			Endpoint: wireguard.EndpointAddress{
+				Host: p.FullName(),
+				Port: r.Port,
+			},
+		},
+	}
+
+	switch {
+	case r.ID == 0:
+		r.setRingZeroAllowedIPs(rp)
+	case p.IsGateway():
+		r.setRingOneGatewayAllowedIPs(rp)
+	default:
+		r.setRingOneNodeAllowedIPs(rp)
+	}
+
+	r.Peers = append(r.Peers, rp)
+	return true
+}
+
+func (r *Ring) setRingZeroAllowedIPs(rp *RingPeer) {
+	zoneID, _, _ := r.Decode(rp.Address)
+
+	// everyone on ring0 is a gateway to ring1
+	addr, _ := RingOneAddress(zoneID, 0)
+	rp.AllowCIDR(addr, 12)
+
+	// peer
+	rp.AllowCIDR(rp.Address, 32)
+}
+
+func (r *Ring) setRingOneGatewayAllowedIPs(rp *RingPeer) {
+	zoneID, _, _ := r.Decode(rp.Address)
+
+	// peer
+	rp.AllowCIDR(rp.Address, 32)
+
+	// ring1 gateways connect to all other ring1 networks
+	r.ForEachZone(func(z *Zone) bool {
+		if z.ID != zoneID {
+			addr, _ := r.Encode(z.ID, 0)
+			rp.AllowCIDR(addr, 12)
+		}
+		return false
+	})
+
+	// ring1 gateways also connect to all ring0 addresses
+	r.ForEachZone(func(z *Zone) bool {
+		z.ForEachMachine(func(p *Machine) bool {
+			if p.IsGateway() {
+				addr, _ := RingZeroAddress(z.ID, p.ID)
+				rp.AllowCIDR(addr, 32)
+			}
+			return false
+		})
+		return false
+	})
+}
+
+func (*Ring) setRingOneNodeAllowedIPs(rp *RingPeer) {
+	// only to the peer itself
+	rp.AllowCIDR(rp.Address, 32)
+}
+
+// ForEachMachine calls a function for each Machine in the ring
+// until instructed to terminate the loop
+func (r *Ring) ForEachMachine(fn func(*Machine) bool) {
+	for _, pp := range r.Peers {
+		if fn(pp.Node) {
+			return
+		}
+	}
+}
+
+// ExportConfig builds a wgN.conf for the specified machine on the ring
+func (r *Ring) ExportConfig(p *Machine) (*wireguard.Config, error) {
+	var found bool
+
+	out := &wireguard.Config{
+		Interface: wireguard.InterfaceConfig{
+			ListenPort: r.Port,
+		},
+	}
+
+	for _, pp := range r.Peers {
+		switch {
+		case pp.Node == p:
+			// current
+			found = true
+			out.Interface.Address = pp.Address
+			out.Interface.PrivateKey = pp.PrivateKey
+		default:
+			// peer
+			pc := pp.PeerConfig
+			out.Peer = append(out.Peer, pc)
+		}
+	}
+
+	if !found {
+		return nil, fs.ErrNotExist
+	}
+
+	return out, nil
+}
+
+// A RingPeer is a node on a [Ring]
+type RingPeer struct {
+	Node *Machine
+
+	Address    netip.Addr
+	PrivateKey wireguard.PrivateKey
+	PeerConfig wireguard.PeerConfig
+}
+
+// AllowCIDR allows an IP range via this peer
+func (rp *RingPeer) AllowCIDR(addr netip.Addr, bits int) {
+	cidr := netip.PrefixFrom(addr, bits)
+	rp.PeerConfig.AllowedIPs = append(rp.PeerConfig.AllowedIPs, cidr)
+}
+
+// NewRing composes a new Ring for Wireguard setup
+func NewRing(z ZoneIterator, m MachineIterator, ring int) (*Ring, error) {
+	r := &Ring{
+		RingAddressEncoder: Rings[ring],
+		ZoneIterator:       z,
+	}
+
+	m.ForEachMachine(func(p *Machine) bool {
+		r.AddPeer(p)
+		return false
+	})
+
+	return r, nil
+}