初版功能完成

internal/platform/windows/route/inspector.go

@@ -0,0 +1,80 @@
+// Package route owns RemLink Remote routes and performs conflict/lookup checks.
+package route
+
+import (
+	"errors"
+	"net/netip"
+
+	"remlink/internal/platform/windows/netinfo"
+)
+
+type LookupResult string
+
+const (
+	LookupDirect          LookupResult = "DIRECT"
+	LookupRouted          LookupResult = "ROUTED"
+	LookupDefaultOnly     LookupResult = "DEFAULT_ONLY"
+	LookupNoRoute         LookupResult = "NO_ROUTE"
+	LookupOverlayConflict LookupResult = "OVERLAY_CONFLICT"
+)
+
+type Entry struct {
+	InterfaceLUID uint64
+	Destination   netip.Prefix
+	NextHop       netip.Addr
+}
+
+// ConflictsFrom applies the Engineer rule: ignore default and RemLink-owned
+// routes, reject any other prefix overlap.
+func ConflictsFrom(entries []Entry, desired netip.Prefix, remLinkLUID uint64) []Entry {
+	var conflicts []Entry
+	for _, entry := range entries {
+		if entry.InterfaceLUID == remLinkLUID || !entry.Destination.Addr().Is4() || entry.Destination.Bits() == 0 {
+			continue
+		}
+		if netinfo.PrefixesOverlap(desired, entry.Destination) {
+			conflicts = append(conflicts, entry)
+		}
+	}
+	return conflicts
+}
+
+// LookupFrom returns the most-specific Windows route classification used by Site PREPARE.
+func LookupFrom(entries []Entry, target netip.Addr, overlay netip.Prefix, remLinkLUID uint64) LookupResult {
+	if !target.Is4() {
+		return LookupNoRoute
+	}
+	if overlay.Contains(target) {
+		return LookupOverlayConflict
+	}
+	var best *Entry
+	for index := range entries {
+		entry := &entries[index]
+		if !entry.Destination.Contains(target) || entry.InterfaceLUID == remLinkLUID {
+			continue
+		}
+		if best == nil || entry.Destination.Bits() > best.Destination.Bits() {
+			best = entry
+		}
+	}
+	if best == nil {
+		return LookupNoRoute
+	}
+	if best.Destination.Bits() == 0 {
+		return LookupDefaultOnly
+	}
+	if !best.NextHop.IsValid() || best.NextHop.IsUnspecified() {
+		return LookupDirect
+	}
+	return LookupRouted
+}
+
+func validateRemote(prefix, overlay netip.Prefix) error {
+	if !prefix.Addr().Is4() || prefix != prefix.Masked() || prefix.Bits() == 0 {
+		return errors.New("Remote CIDR must be canonical IPv4 and must not be 0.0.0.0/0")
+	}
+	if netinfo.PrefixesOverlap(prefix, overlay) {
+		return errors.New("Remote CIDR overlaps Overlay CIDR")
+	}
+	return nil
+}