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, 147 insertions, 0 deletions

diff --git a/src/resolve/resolved-dns-scope.c b/src/resolve/resolved-dns-scope.c
new file mode 100644
index 0000000000..4e0a742768
--- /dev/null
+++ b/src/resolve/resolved-dns-scope.c
@@ -0,0 +1,147 @@
+/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
+
+/***
+  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 "strv.h"
+#include "resolved-dns-domain.h"
+#include "resolved-dns-scope.h"
+
+#define SEND_TIMEOUT_USEC (2*USEC_PER_SEC)
+
+int dns_scope_new(Manager *m, DnsScope **ret, DnsScopeType t) {
+        DnsScope *s;
+
+        assert(m);
+        assert(ret);
+
+        s = new0(DnsScope, 1);
+        if (!s)
+                return -ENOMEM;
+
+        s->manager = m;
+        s->type = t;
+
+        LIST_PREPEND(scopes, m->dns_scopes, s);
+
+        *ret = s;
+        return 0;
+}
+
+DnsScope* dns_scope_free(DnsScope *s) {
+        if (!s)
+                return NULL;
+
+        while (s->transactions) {
+                DnsQuery *q;
+
+                q = s->transactions->query;
+                dns_query_transaction_free(s->transactions);
+
+                dns_query_finish(q);
+        }
+
+        LIST_REMOVE(scopes, s->manager->dns_scopes, s);
+        strv_free(s->domains);
+        free(s);
+
+        return NULL;
+}
+
+DnsServer *dns_scope_get_server(DnsScope *s) {
+        assert(s);
+
+        if (s->link)
+                return link_get_dns_server(s->link);
+        else
+                return manager_get_dns_server(s->manager);
+}
+
+void dns_scope_next_dns_server(DnsScope *s) {
+        assert(s);
+
+        if (s->link)
+                link_next_dns_server(s->link);
+        else
+                manager_next_dns_server(s->manager);
+}
+
+int dns_scope_send(DnsScope *s, DnsPacket *p) {
+        int ifindex = 0;
+        DnsServer *srv;
+        int r;
+
+        assert(s);
+        assert(p);
+
+        srv = dns_scope_get_server(s);
+        if (!srv)
+                return 0;
+
+        if (s->link)
+                ifindex = s->link->ifindex;
+
+        if (srv->family == AF_INET)
+                r = manager_dns_ipv4_send(s->manager, srv, ifindex, p);
+        else if (srv->family == AF_INET6)
+                r = manager_dns_ipv6_send(s->manager, srv, ifindex, p);
+        else
+                return -EAFNOSUPPORT;
+
+        if (r < 0)
+                return r;
+
+        return 1;
+}
+
+DnsScopeMatch dns_scope_test(DnsScope *s, const char *domain) {
+        char **i;
+
+        assert(s);
+        assert(domain);
+
+        STRV_FOREACH(i, s->domains)
+                if (dns_name_endswith(domain, *i))
+                        return DNS_SCOPE_YES;
+
+        if (dns_name_root(domain))
+                return DNS_SCOPE_NO;
+
+        if (s->type == DNS_SCOPE_MDNS) {
+                if (dns_name_endswith(domain, "254.169.in-addr.arpa") ||
+                    dns_name_endswith(domain, "0.8.e.f.ip6.arpa"))
+                        return DNS_SCOPE_YES;
+                else if (dns_name_endswith(domain, "local") ||
+                         !dns_name_single_label(domain))
+                        return DNS_SCOPE_MAYBE;
+
+                return DNS_SCOPE_NO;
+        }
+
+        if (s->type == DNS_SCOPE_DNS) {
+                if (dns_name_endswith(domain, "254.169.in-addr.arpa") ||
+                    dns_name_endswith(domain, "0.8.e.f.ip6.arpa") ||
+                    dns_name_single_label(domain))
+                        return DNS_SCOPE_NO;
+
+                return DNS_SCOPE_MAYBE;
+        }
+
+        assert_not_reached("Unknown scope type");
+}