Add core modules (SSH args parser, cache, resolver, NetBox client) with tests

internal/resolver/interface_name.go

@@ -0,0 +1,38 @@
+package resolver
+
+import (
+	"context"
+	"fmt"
+	"net/url"
+
+	"git.zb-server.de/Sebi/ssh-netbox-wrapper/internal/netbox"
+)
+
+// InterfaceNameStrategy finds the first IP assigned to a named interface (e.g. "mgmt0", "eth0").
+type InterfaceNameStrategy struct {
+	name string
+}
+
+func (s *InterfaceNameStrategy) Name() string { return "interface_name" }
+
+func (s *InterfaceNameStrategy) Resolve(ctx context.Context, entry *netbox.HostEntry, client *netbox.Client) (string, error) {
+	// Build filter parameters for IP addresses attached to the named interface.
+	var filterParam string
+	switch entry.Kind {
+	case "device":
+		filterParam = fmt.Sprintf("device_id=%d&interface_name=%s", entry.ID, url.QueryEscape(s.name))
+	case "vm":
+		filterParam = fmt.Sprintf("virtual_machine_id=%d&vminterface_name=%s", entry.ID, url.QueryEscape(s.name))
+	default:
+		return "", fmt.Errorf("unknown kind %q", entry.Kind)
+	}
+
+	ips, err := client.GetIPsWithFilter(ctx, filterParam)
+	if err != nil {
+		return "", fmt.Errorf("fetching IPs for interface %q: %w", s.name, err)
+	}
+	if len(ips) == 0 {
+		return "", ErrNoIP
+	}
+	return ips[0], nil
+}