feat(thoth): cached ip to asn checker

Signed-off-by: Xe Iaso <me@xeiaso.net>

internal/thoth/cachediptoasn.go

@@ -0,0 +1,58 @@
+package thoth
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"log/slog"
+	"net/netip"
+
+	iptoasnv1 "github.com/TecharoHQ/thoth-proto/gen/techaro/thoth/iptoasn/v1"
+	"github.com/gaissmai/bart"
+	"google.golang.org/grpc"
+)
+
+type IPToASNWithCache struct {
+	next  iptoasnv1.IpToASNServiceClient
+	table *bart.Table[*iptoasnv1.LookupResponse]
+}
+
+func NewIpToASNWithCache(next iptoasnv1.IpToASNServiceClient) *IPToASNWithCache {
+	return &IPToASNWithCache{
+		next:  next,
+		table: &bart.Table[*iptoasnv1.LookupResponse]{},
+	}
+}
+
+func (ip2asn *IPToASNWithCache) Lookup(ctx context.Context, lr *iptoasnv1.LookupRequest, opts ...grpc.CallOption) (*iptoasnv1.LookupResponse, error) {
+	addr, err := netip.ParseAddr(lr.GetIpAddress())
+	if err != nil {
+		return nil, fmt.Errorf("input is not an IP address: %w", err)
+	}
+
+	cachedResponse, ok := ip2asn.table.Lookup(addr)
+	if ok {
+		return cachedResponse, nil
+	}
+
+	resp, err := ip2asn.next.Lookup(ctx, lr, opts...)
+	if err != nil {
+		return nil, err
+	}
+
+	var errs []error
+	for _, cidr := range resp.GetCidr() {
+		pfx, err := netip.ParsePrefix(cidr)
+		if err != nil {
+			errs = append(errs, err)
+			continue
+		}
+		ip2asn.table.Insert(pfx, resp)
+	}
+
+	if len(errs) != 0 {
+		slog.Error("errors parsing IP prefixes", "err", errors.Join(errs...))
+	}
+
+	return resp, nil
+}