[client, management] offload client config generation to the client (#6711)

Signed-off-by: Dmitri Dolguikh <dmitri.external@netbird.io>
Co-authored-by: crn4 <vladimir@netbird.io>
Co-authored-by: pascal <pascal@netbird.io>

shared/management/networkmap/envelope.go

@@ -0,0 +1,189 @@
+package networkmap
+
+import (
+	"context"
+	"encoding/base64"
+	"fmt"
+
+	"github.com/netbirdio/netbird/shared/management/proto"
+	"github.com/netbirdio/netbird/shared/management/types"
+)
+
+// EnvelopeResult is what the client engine consumes after receiving a
+// component-format NetworkMap. Both fields are populated:
+//
+//   - NetworkMap is the *proto.NetworkMap shape the engine reads today via
+//     update.GetNetworkMap() — built from the envelope's components by
+//     running Calculate() locally + converting back through the shared
+//     proto helpers + merging the optional ProxyPatch.
+//   - Components is the *types.NetworkMapComponents the engine retains so
+//     future incremental delta updates have a base to apply changes
+//     against. The client keeps it under its sync lock.
+type EnvelopeResult struct {
+	NetworkMap *proto.NetworkMap
+	Components *types.NetworkMapComponents
+}
+
+// EnvelopeToNetworkMap is the full client-side pipeline: decode the
+// component envelope back to a typed NetworkMapComponents, run Calculate()
+// locally to produce the typed NetworkMap, convert it to the wire form the
+// engine consumes, and fold in any ProxyPatch the server attached.
+//
+// localPeerKey is the receiving peer's WG pub key (used to derive
+// includeIPv6 / useSourcePrefixes from the receiving peer's own record in
+// the components struct, mirroring legacy ToSyncResponse behaviour).
+//
+// dnsName is the account's DNS domain ("netbird.cloud" etc.); used when
+// rebuilding the per-peer FQDNs that proto.RemotePeerConfig carries.
+func EnvelopeToNetworkMap(ctx context.Context, env *proto.NetworkMapEnvelope, localPeerKey, dnsName string) (*EnvelopeResult, error) {
+	components, err := DecodeEnvelope(env)
+	if err != nil {
+		return nil, fmt.Errorf("decode envelope: %w", err)
+	}
+
+	// Find the receiving peer in the decoded components by WG key.
+	// c.Peers is keyed by canonical base64 of the raw 32-byte pub key
+	// (decoder re-encodes the bytes off the wire). The caller may pass a
+	// non-canonical encoding (some persisted production keys carry
+	// non-zero trailing padding bits that survived a legacy import), so
+	// round-trip through raw bytes once to canonicalize before lookup.
+	canonicalKey := canonicalizeWgKey(localPeerKey)
+	localPeer := components.Peers[canonicalKey]
+	if localPeer == nil {
+		return nil, fmt.Errorf("receiving peer (wg_key prefix %q) not found among %d decoded peers — components have no PeerID, Calculate would return empty", trimKey(localPeerKey), len(components.Peers))
+	}
+	components.PeerID = canonicalKey
+
+	includeIPv6 := localPeer.SupportsIPv6() && localPeer.IPv6.IsValid()
+	useSourcePrefixes := localPeer.SupportsSourcePrefixes()
+
+	typedNM := components.Calculate(ctx)
+
+	full := env.GetFull()
+	dnsFwdPort := int64(0)
+	if full != nil {
+		dnsFwdPort = full.DnsForwarderPort
+	}
+
+	protoNM := &proto.NetworkMap{
+		Serial: typedNM.Network.CurrentSerial(),
+	}
+	if full != nil {
+		protoNM.PeerConfig = full.PeerConfig
+	}
+	protoNM.Routes = ToProtocolRoutes(typedNM.Routes)
+	protoNM.DNSConfig = ToProtocolDNSConfig(typedNM.DNSConfig, nil, dnsFwdPort)
+
+	remotePeers := AppendRemotePeerConfig(nil, typedNM.Peers, dnsName, includeIPv6)
+	protoNM.RemotePeers = remotePeers
+	protoNM.RemotePeersIsEmpty = len(remotePeers) == 0
+
+	protoNM.OfflinePeers = AppendRemotePeerConfig(nil, typedNM.OfflinePeers, dnsName, includeIPv6)
+
+	firewallRules := ToProtocolFirewallRules(typedNM.FirewallRules, includeIPv6, useSourcePrefixes)
+	protoNM.FirewallRules = firewallRules
+	protoNM.FirewallRulesIsEmpty = len(firewallRules) == 0
+
+	routesFirewallRules := ToProtocolRoutesFirewallRules(typedNM.RoutesFirewallRules)
+	protoNM.RoutesFirewallRules = routesFirewallRules
+	protoNM.RoutesFirewallRulesIsEmpty = len(routesFirewallRules) == 0
+
+	if typedNM.AuthorizedUsers != nil {
+		hashedUsers, machineUsers := BuildAuthorizedUsersProto(ctx, typedNM.AuthorizedUsers)
+		userIDClaim := ""
+		if full != nil {
+			userIDClaim = full.UserIdClaim
+		}
+		protoNM.SshAuth = &proto.SSHAuth{
+			AuthorizedUsers: hashedUsers,
+			MachineUsers:    machineUsers,
+			UserIDClaim:     userIDClaim,
+		}
+	}
+
+	if typedNM.ForwardingRules != nil {
+		forwardingRules := make([]*proto.ForwardingRule, 0, len(typedNM.ForwardingRules))
+		for _, rule := range typedNM.ForwardingRules {
+			forwardingRules = append(forwardingRules, rule.ToProto())
+		}
+		protoNM.ForwardingRules = forwardingRules
+	}
+
+	// Merge the proxy patch the server attached. Mirrors the legacy
+	// NetworkMap.Merge step that the server runs after Calculate().
+	if full != nil && full.ProxyPatch != nil {
+		mergeProxyPatch(protoNM, full.ProxyPatch)
+	}
+
+	return &EnvelopeResult{
+		NetworkMap: protoNM,
+		Components: components,
+	}, nil
+}
+
+// mergeProxyPatch folds a ProxyPatch's pre-expanded fragments into the
+// proto.NetworkMap that Calculate() produced. Mirrors types.NetworkMap.Merge
+// — same six collections, deduplicated where the legacy merge dedupes.
+func mergeProxyPatch(nm *proto.NetworkMap, patch *proto.ProxyPatch) {
+	nm.RemotePeers = appendUniquePeers(nm.RemotePeers, patch.Peers)
+	nm.OfflinePeers = appendUniquePeers(nm.OfflinePeers, patch.OfflinePeers)
+	nm.FirewallRules = append(nm.FirewallRules, patch.FirewallRules...)
+	nm.Routes = append(nm.Routes, patch.Routes...)
+	nm.RoutesFirewallRules = append(nm.RoutesFirewallRules, patch.RouteFirewallRules...)
+	nm.ForwardingRules = append(nm.ForwardingRules, patch.ForwardingRules...)
+	if len(nm.RemotePeers) > 0 {
+		nm.RemotePeersIsEmpty = false
+	}
+	if len(nm.FirewallRules) > 0 {
+		nm.FirewallRulesIsEmpty = false
+	}
+	if len(nm.RoutesFirewallRules) > 0 {
+		nm.RoutesFirewallRulesIsEmpty = false
+	}
+}
+
+// appendUniquePeers dedupes by WgPubKey — mirrors legacy
+// mergeUniquePeersByID's intent (legacy keyed off Peer.ID; in proto form the
+// closest stable identifier is WgPubKey).
+func appendUniquePeers(dst, extra []*proto.RemotePeerConfig) []*proto.RemotePeerConfig {
+	if len(extra) == 0 {
+		return dst
+	}
+	seen := make(map[string]struct{}, len(dst))
+	for _, p := range dst {
+		if p == nil {
+			continue
+		}
+		seen[p.WgPubKey] = struct{}{}
+	}
+	for _, p := range extra {
+		if p == nil {
+			continue
+		}
+		if _, ok := seen[p.WgPubKey]; ok {
+			continue
+		}
+		seen[p.WgPubKey] = struct{}{}
+		dst = append(dst, p)
+	}
+	return dst
+}
+
+func trimKey(s string) string {
+	if len(s) > 12 {
+		return s[:12]
+	}
+	return s
+}
+
+// canonicalizeWgKey normalises a base64-encoded WireGuard public key so it
+// matches the canonical encoding emitted by the envelope decoder. Returns
+// the input unchanged when it does not decode to 32 raw bytes (caller will
+// hit a miss in the peer map and surface the error).
+func canonicalizeWgKey(s string) string {
+	raw, err := base64.StdEncoding.DecodeString(s)
+	if err != nil || len(raw) != 32 {
+		return s
+	}
+	return base64.StdEncoding.EncodeToString(raw)
+}