resolved: move DNS RR/key/answer/question/packet tools to shared/

We want to reuse these generic DNS concepts in resolved hook
implementations, hence move them to shared code.

(This also enables us to immediately remove som SVCB record handling
duplicate definitions.)

No real code changes, just some moving around of things.

src/shared/resolved-def.h

@@ -0,0 +1,89 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include "shared-forward.h"
+#include "time-util.h"
+
+/* Input + Output: The various protocols we can use */
+#define SD_RESOLVED_DNS             (UINT64_C(1) << 0)
+#define SD_RESOLVED_LLMNR_IPV4      (UINT64_C(1) << 1)
+#define SD_RESOLVED_LLMNR_IPV6      (UINT64_C(1) << 2)
+#define SD_RESOLVED_MDNS_IPV4       (UINT64_C(1) << 3)
+#define SD_RESOLVED_MDNS_IPV6       (UINT64_C(1) << 4)
+
+/* Input: Don't follow CNAMEs/DNAMEs */
+#define SD_RESOLVED_NO_CNAME        (UINT64_C(1) << 5)
+
+/* Input: When doing service (SRV) resolving, don't resolve associated mDNS-style TXT records */
+#define SD_RESOLVED_NO_TXT          (UINT64_C(1) << 6)
+
+/* Input: When doing service (SRV) resolving, don't resolve A/AAA RR for included hostname */
+#define SD_RESOLVED_NO_ADDRESS      (UINT64_C(1) << 7)
+
+/* Input: Don't apply search domain logic to request */
+#define SD_RESOLVED_NO_SEARCH       (UINT64_C(1) << 8)
+
+/* Output: Result is authenticated */
+#define SD_RESOLVED_AUTHENTICATED   (UINT64_C(1) << 9)
+
+/* Input: Don't DNSSEC validate request */
+#define SD_RESOLVED_NO_VALIDATE     (UINT64_C(1) << 10)
+
+/* Input: Don't answer request from locally synthesized records (which includes /etc/hosts) */
+#define SD_RESOLVED_NO_SYNTHESIZE   (UINT64_C(1) << 11)
+
+/* Input: Don't answer request from cache */
+#define SD_RESOLVED_NO_CACHE        (UINT64_C(1) << 12)
+
+/* Input: Don't answer request from locally registered public LLMNR/mDNS RRs */
+#define SD_RESOLVED_NO_ZONE         (UINT64_C(1) << 13)
+
+/* Input: Don't answer request from locally configured trust anchors. */
+#define SD_RESOLVED_NO_TRUST_ANCHOR (UINT64_C(1) << 14)
+
+/* Input: Don't go to network for this request */
+#define SD_RESOLVED_NO_NETWORK      (UINT64_C(1) << 15)
+
+/* Input: Require that request is answered from a "primary" answer, i.e. not from RRs acquired as
+ * side-effect of a previous transaction */
+#define SD_RESOLVED_REQUIRE_PRIMARY (UINT64_C(1) << 16)
+
+/* Input: If reply is answered from cache, the TTLs will be adjusted by age of cache entry */
+#define SD_RESOLVED_CLAMP_TTL       (UINT64_C(1) << 17)
+
+/* Output: Result was only sent via encrypted channels, or never left this system */
+#define SD_RESOLVED_CONFIDENTIAL    (UINT64_C(1) << 18)
+
+/* Output: Result was (at least partially) synthesized locally */
+#define SD_RESOLVED_SYNTHETIC       (UINT64_C(1) << 19)
+
+/* Output: Result was (at least partially) answered from cache */
+#define SD_RESOLVED_FROM_CACHE      (UINT64_C(1) << 20)
+
+/* Output: Result was (at least partially) answered from local zone */
+#define SD_RESOLVED_FROM_ZONE       (UINT64_C(1) << 21)
+
+/* Output: Result was (at least partially) answered from trust anchor */
+#define SD_RESOLVED_FROM_TRUST_ANCHOR (UINT64_C(1) << 22)
+
+/* Output: Result was (at least partially) answered from network */
+#define SD_RESOLVED_FROM_NETWORK    (UINT64_C(1) << 23)
+
+/* Input: Don't answer request with stale data */
+#define SD_RESOLVED_NO_STALE        (UINT64_C(1) << 24)
+
+/* Input: Allow single-label lookups to Internet DNS servers */
+#define SD_RESOLVED_RELAX_SINGLE_LABEL          \
+                                    (UINT64_C(1) << 25)
+
+/* Input: To differentiate between a probe and a continuous query. */
+#define SD_RESOLVED_QUERY_CONTINUOUS            \
+                                    (UINT64_C(1) << 26)
+
+#define SD_RESOLVED_LLMNR           (SD_RESOLVED_LLMNR_IPV4|SD_RESOLVED_LLMNR_IPV6)
+#define SD_RESOLVED_MDNS            (SD_RESOLVED_MDNS_IPV4|SD_RESOLVED_MDNS_IPV6)
+#define SD_RESOLVED_PROTOCOLS_ALL   (SD_RESOLVED_MDNS|SD_RESOLVED_LLMNR|SD_RESOLVED_DNS)
+
+#define SD_RESOLVED_FROM_MASK       (SD_RESOLVED_FROM_CACHE|SD_RESOLVED_FROM_ZONE|SD_RESOLVED_FROM_TRUST_ANCHOR|SD_RESOLVED_FROM_NETWORK)
+
+#define SD_RESOLVED_QUERY_TIMEOUT_USEC (120 * USEC_PER_SEC)