resolved: add a DNS client stub resolver

Let's turn resolved into a something truly useful: a fully asynchronous
DNS stub resolver that subscribes to network changes.

(More to come: caching, LLMNR, mDNS/DNS-SD, DNSSEC, IDN, NSS module)

1 files changed, 114 insertions, 0 deletions

diff --git a/src/resolve/resolved-dns-rr.h b/src/resolve/resolved-dns-rr.h
new file mode 100644
index 0000000000..144fffa3e0
--- /dev/null
+++ b/src/resolve/resolved-dns-rr.h
@@ -0,0 +1,114 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+#pragma once
+
+/***
+  This file is part of systemd.
+
+  Copyright 2014 Lennart Poettering
+
+  systemd is free software; you can redistribute it and/or modify it
+  under the terms of the GNU Lesser General Public License as published by
+  the Free Software Foundation; either version 2.1 of the License, or
+  (at your option) any later version.
+
+  systemd is distributed in the hope that it will be useful, but
+  WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+  Lesser General Public License for more details.
+
+  You should have received a copy of the GNU Lesser General Public License
+  along with systemd; If not, see <http://www.gnu.org/licenses/>.
+ ***/
+
+#include <inttypes.h>
+#include <netinet/in.h>
+
+#include "util.h"
+
+typedef struct DnsResourceKey DnsResourceKey;
+typedef struct DnsResourceRecord DnsResourceRecord;
+
+/* DNS record classes, see RFC 1035 */
+enum {
+        DNS_CLASS_IN   = 0x01,
+};
+
+/* DNS record types, see RFC 1035 */
+enum {
+        /* Normal records */
+        DNS_TYPE_A     = 0x01,
+        DNS_TYPE_NS    = 0x02,
+        DNS_TYPE_CNAME = 0x05,
+        DNS_TYPE_SOA   = 0x06,
+        DNS_TYPE_PTR   = 0x0C,
+        DNS_TYPE_HINFO = 0x0D,
+        DNS_TYPE_MX    = 0x0F,
+        DNS_TYPE_TXT   = 0x10,
+        DNS_TYPE_AAAA  = 0x1C,
+        DNS_TYPE_SRV   = 0x21,
+
+        /* Special records */
+        DNS_TYPE_ANY   = 0xFF,
+        DNS_TYPE_OPT   = 0x29,      /* EDNS0 option */
+        DNS_TYPE_TKEY  = 0xF9,
+        DNS_TYPE_TSIG  = 0xFA,
+        DNS_TYPE_IXFR  = 0xFB,
+        DNS_TYPE_AXFR  = 0xFC,
+};
+
+struct DnsResourceKey {
+        uint16_t class;
+        uint16_t type;
+        char *name;
+};
+
+struct DnsResourceRecord {
+        unsigned n_ref;
+
+        DnsResourceKey key;
+        uint32_t ttl;
+
+        union {
+                struct {
+                        void *data;
+                        uint16_t size;
+                } generic;
+
+                /* struct { */
+                /*         uint16_t priority; */
+                /*         uint16_t weight; */
+                /*         uint16_t port; */
+                /*         char *name; */
+                /* } srv; */
+
+                struct {
+                        char *name;
+                } ptr, ns, cname;
+
+                struct {
+                        char *cpu;
+                        char *os;
+                } hinfo;
+
+                /* struct { */
+                /*         char **list; */
+                /* } txt; */
+
+                struct {
+                        struct in_addr in_addr;
+                } a;
+
+                struct {
+                        struct in6_addr in6_addr;
+                } aaaa;
+        };
+};
+
+void dns_resource_key_free(DnsResourceKey *key);
+
+DnsResourceRecord* dns_resource_record_new(void);
+DnsResourceRecord* dns_resource_record_ref(DnsResourceRecord *rr);
+DnsResourceRecord* dns_resource_record_unref(DnsResourceRecord *rr);
+
+DEFINE_TRIVIAL_CLEANUP_FUNC(DnsResourceRecord*, dns_resource_record_unref);