Adding upstream version 247.3.upstream/247.3upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 450 insertions, 0 deletions

diff --git a/src/resolve/resolved-dns-synthesize.c b/src/resolve/resolved-dns-synthesize.c
new file mode 100644
index 0000000..f08d621
--- /dev/null
+++ b/src/resolve/resolved-dns-synthesize.c
@@ -0,0 +1,450 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "alloc-util.h"
+#include "hostname-util.h"
+#include "local-addresses.h"
+#include "missing_network.h"
+#include "resolved-dns-synthesize.h"
+
+int dns_synthesize_ifindex(int ifindex) {
+
+        /* When the caller asked for resolving on a specific
+         * interface, we synthesize the answer for that
+         * interface. However, if nothing specific was claimed and we
+         * only return localhost RRs, we synthesize the answer for
+         * localhost. */
+
+        if (ifindex > 0)
+                return ifindex;
+
+        return LOOPBACK_IFINDEX;
+}
+
+int dns_synthesize_family(uint64_t flags) {
+
+        /* Picks an address family depending on set flags. This is
+         * purely for synthesized answers, where the family we return
+         * for the reply should match what was requested in the
+         * question, even though we are synthesizing the answer
+         * here. */
+
+        if (!(flags & SD_RESOLVED_DNS)) {
+                if (flags & (SD_RESOLVED_LLMNR_IPV4|SD_RESOLVED_MDNS_IPV4))
+                        return AF_INET;
+                if (flags & (SD_RESOLVED_LLMNR_IPV6|SD_RESOLVED_MDNS_IPV6))
+                        return AF_INET6;
+        }
+
+        return AF_UNSPEC;
+}
+
+DnsProtocol dns_synthesize_protocol(uint64_t flags) {
+
+        /* Similar as dns_synthesize_family() but does this for the
+         * protocol. If resolving via DNS was requested, we claim it
+         * was DNS. Similar, if nothing specific was
+         * requested. However, if only resolving via LLMNR was
+         * requested we return that. */
+
+        if (flags & SD_RESOLVED_DNS)
+                return DNS_PROTOCOL_DNS;
+        if (flags & SD_RESOLVED_LLMNR)
+                return DNS_PROTOCOL_LLMNR;
+        if (flags & SD_RESOLVED_MDNS)
+                return DNS_PROTOCOL_MDNS;
+
+        return DNS_PROTOCOL_DNS;
+}
+
+static int synthesize_localhost_rr(Manager *m, const DnsResourceKey *key, int ifindex, DnsAnswer **answer) {
+        int r;
+
+        assert(m);
+        assert(key);
+        assert(answer);
+
+        r = dns_answer_reserve(answer, 2);
+        if (r < 0)
+                return r;
+
+        if (IN_SET(key->type, DNS_TYPE_A, DNS_TYPE_ANY)) {
+                _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+
+                rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_A, dns_resource_key_name(key));
+                if (!rr)
+                        return -ENOMEM;
+
+                rr->a.in_addr.s_addr = htobe32(INADDR_LOOPBACK);
+
+                r = dns_answer_add(*answer, rr, dns_synthesize_ifindex(ifindex), DNS_ANSWER_AUTHENTICATED);
+                if (r < 0)
+                        return r;
+        }
+
+        if (IN_SET(key->type, DNS_TYPE_AAAA, DNS_TYPE_ANY)) {
+                _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+
+                rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_AAAA, dns_resource_key_name(key));
+                if (!rr)
+                        return -ENOMEM;
+
+                rr->aaaa.in6_addr = in6addr_loopback;
+
+                r = dns_answer_add(*answer, rr, dns_synthesize_ifindex(ifindex), DNS_ANSWER_AUTHENTICATED);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static int answer_add_ptr(DnsAnswer **answer, const char *from, const char *to, int ifindex, DnsAnswerFlags flags) {
+        _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+
+        rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_PTR, from);
+        if (!rr)
+                return -ENOMEM;
+
+        rr->ptr.name = strdup(to);
+        if (!rr->ptr.name)
+                return -ENOMEM;
+
+        return dns_answer_add(*answer, rr, ifindex, flags);
+}
+
+static int synthesize_localhost_ptr(Manager *m, const DnsResourceKey *key, int ifindex, DnsAnswer **answer) {
+        int r;
+
+        assert(m);
+        assert(key);
+        assert(answer);
+
+        if (IN_SET(key->type, DNS_TYPE_PTR, DNS_TYPE_ANY)) {
+                r = dns_answer_reserve(answer, 1);
+                if (r < 0)
+                        return r;
+
+                r = answer_add_ptr(answer, dns_resource_key_name(key), "localhost", dns_synthesize_ifindex(ifindex), DNS_ANSWER_AUTHENTICATED);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static int answer_add_addresses_rr(
+                DnsAnswer **answer,
+                const char *name,
+                struct local_address *addresses,
+                unsigned n_addresses) {
+
+        unsigned j;
+        int r;
+
+        assert(answer);
+        assert(name);
+
+        r = dns_answer_reserve(answer, n_addresses);
+        if (r < 0)
+                return r;
+
+        for (j = 0; j < n_addresses; j++) {
+                _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+
+                r = dns_resource_record_new_address(&rr, addresses[j].family, &addresses[j].address, name);
+                if (r < 0)
+                        return r;
+
+                r = dns_answer_add(*answer, rr, addresses[j].ifindex, DNS_ANSWER_AUTHENTICATED);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static int answer_add_addresses_ptr(
+                DnsAnswer **answer,
+                const char *name,
+                struct local_address *addresses,
+                unsigned n_addresses,
+                int af, const union in_addr_union *match) {
+
+        bool added = false;
+        unsigned j;
+        int r;
+
+        assert(answer);
+        assert(name);
+
+        for (j = 0; j < n_addresses; j++) {
+                _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+
+                if (af != AF_UNSPEC) {
+
+                        if (addresses[j].family != af)
+                                continue;
+
+                        if (match && !in_addr_equal(af, match, &addresses[j].address))
+                                continue;
+                }
+
+                r = dns_answer_reserve(answer, 1);
+                if (r < 0)
+                        return r;
+
+                r = dns_resource_record_new_reverse(&rr, addresses[j].family, &addresses[j].address, name);
+                if (r < 0)
+                        return r;
+
+                r = dns_answer_add(*answer, rr, addresses[j].ifindex, DNS_ANSWER_AUTHENTICATED);
+                if (r < 0)
+                        return r;
+
+                added = true;
+        }
+
+        return added;
+}
+
+static int synthesize_system_hostname_rr(Manager *m, const DnsResourceKey *key, int ifindex, DnsAnswer **answer) {
+        _cleanup_free_ struct local_address *addresses = NULL;
+        int n = 0, af;
+
+        assert(m);
+        assert(key);
+        assert(answer);
+
+        af = dns_type_to_af(key->type);
+        if (af >= 0) {
+                n = local_addresses(m->rtnl, ifindex, af, &addresses);
+                if (n < 0)
+                        return n;
+
+                if (n == 0) {
+                        struct local_address buffer[2];
+
+                        /* If we have no local addresses then use ::1
+                         * and 127.0.0.2 as local ones. */
+
+                        if (IN_SET(af, AF_INET, AF_UNSPEC))
+                                buffer[n++] = (struct local_address) {
+                                        .family = AF_INET,
+                                        .ifindex = dns_synthesize_ifindex(ifindex),
+                                        .address.in.s_addr = htobe32(0x7F000002),
+                                };
+
+                        if (IN_SET(af, AF_INET6, AF_UNSPEC))
+                                buffer[n++] = (struct local_address) {
+                                        .family = AF_INET6,
+                                        .ifindex = dns_synthesize_ifindex(ifindex),
+                                        .address.in6 = in6addr_loopback,
+                                };
+
+                        return answer_add_addresses_rr(answer,
+                                                       dns_resource_key_name(key),
+                                                       buffer, n);
+                }
+        }
+
+        return answer_add_addresses_rr(answer, dns_resource_key_name(key), addresses, n);
+}
+
+static int synthesize_system_hostname_ptr(Manager *m, int af, const union in_addr_union *address, int ifindex, DnsAnswer **answer) {
+        _cleanup_free_ struct local_address *addresses = NULL;
+        bool added = false;
+        int n, r;
+
+        assert(m);
+        assert(address);
+        assert(answer);
+
+        if (af == AF_INET && address->in.s_addr == htobe32(0x7F000002)) {
+
+                /* Always map the IPv4 address 127.0.0.2 to the local hostname, in addition to "localhost": */
+
+                r = dns_answer_reserve(answer, 4);
+                if (r < 0)
+                        return r;
+
+                r = answer_add_ptr(answer, "2.0.0.127.in-addr.arpa", m->full_hostname, dns_synthesize_ifindex(ifindex), DNS_ANSWER_AUTHENTICATED);
+                if (r < 0)
+                        return r;
+
+                r = answer_add_ptr(answer, "2.0.0.127.in-addr.arpa", m->llmnr_hostname, dns_synthesize_ifindex(ifindex), DNS_ANSWER_AUTHENTICATED);
+                if (r < 0)
+                        return r;
+
+                r = answer_add_ptr(answer, "2.0.0.127.in-addr.arpa", m->mdns_hostname, dns_synthesize_ifindex(ifindex), DNS_ANSWER_AUTHENTICATED);
+                if (r < 0)
+                        return r;
+
+                r = answer_add_ptr(answer, "2.0.0.127.in-addr.arpa", "localhost", dns_synthesize_ifindex(ifindex), DNS_ANSWER_AUTHENTICATED);
+                if (r < 0)
+                        return r;
+
+                return 1;
+        }
+
+        n = local_addresses(m->rtnl, ifindex, af, &addresses);
+        if (n <= 0)
+                return n;
+
+        r = answer_add_addresses_ptr(answer, m->full_hostname, addresses, n, af, address);
+        if (r < 0)
+                return r;
+        if (r > 0)
+                added = true;
+
+        r = answer_add_addresses_ptr(answer, m->llmnr_hostname, addresses, n, af, address);
+        if (r < 0)
+                return r;
+        if (r > 0)
+                added = true;
+
+        r = answer_add_addresses_ptr(answer, m->mdns_hostname, addresses, n, af, address);
+        if (r < 0)
+                return r;
+        if (r > 0)
+                added = true;
+
+        return added;
+}
+
+static int synthesize_gateway_rr(Manager *m, const DnsResourceKey *key, int ifindex, DnsAnswer **answer) {
+        _cleanup_free_ struct local_address *addresses = NULL;
+        int n = 0, af, r;
+
+        assert(m);
+        assert(key);
+        assert(answer);
+
+        af = dns_type_to_af(key->type);
+        if (af >= 0) {
+                n = local_gateways(m->rtnl, ifindex, af, &addresses);
+                if (n < 0) /* < 0 means: error */
+                        return n;
+
+                if (n == 0) { /* == 0 means we have no gateway */
+                        /* See if there's a gateway on the other protocol */
+                        if (af == AF_INET)
+                                n = local_gateways(m->rtnl, ifindex, AF_INET6, NULL);
+                        else {
+                                assert(af == AF_INET6);
+                                n = local_gateways(m->rtnl, ifindex, AF_INET, NULL);
+                        }
+                        if (n <= 0) /* error (if < 0) or really no gateway at all (if == 0) */
+                                return n;
+
+                        /* We have a gateway on the other protocol. Let's return > 0 without adding any RR to
+                         * the answer, i.e. synthesize NODATA (and not NXDOMAIN!) */
+                        return 1;
+                }
+        }
+
+        r = answer_add_addresses_rr(answer, dns_resource_key_name(key), addresses, n);
+        if (r < 0)
+                return r;
+
+        return 1; /* > 0 means: we have some gateway */
+}
+
+static int synthesize_gateway_ptr(Manager *m, int af, const union in_addr_union *address, int ifindex, DnsAnswer **answer) {
+        _cleanup_free_ struct local_address *addresses = NULL;
+        int n;
+
+        assert(m);
+        assert(address);
+        assert(answer);
+
+        n = local_gateways(m->rtnl, ifindex, af, &addresses);
+        if (n <= 0)
+                return n;
+
+        return answer_add_addresses_ptr(answer, "_gateway", addresses, n, af, address);
+}
+
+int dns_synthesize_answer(
+                Manager *m,
+                DnsQuestion *q,
+                int ifindex,
+                DnsAnswer **ret) {
+
+        _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
+        DnsResourceKey *key;
+        bool found = false, nxdomain = false;
+        int r;
+
+        assert(m);
+        assert(q);
+
+        DNS_QUESTION_FOREACH(key, q) {
+                union in_addr_union address;
+                const char *name;
+                int af;
+
+                if (!IN_SET(key->class, DNS_CLASS_IN, DNS_CLASS_ANY))
+                        continue;
+
+                name = dns_resource_key_name(key);
+
+                if (is_localhost(name)) {
+
+                        r = synthesize_localhost_rr(m, key, ifindex, &answer);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to synthesize localhost RRs: %m");
+
+                } else if (manager_is_own_hostname(m, name)) {
+
+                        r = synthesize_system_hostname_rr(m, key, ifindex, &answer);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to synthesize system hostname RRs: %m");
+
+                } else if (is_gateway_hostname(name)) {
+
+                        r = synthesize_gateway_rr(m, key, ifindex, &answer);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to synthesize gateway RRs: %m");
+                        if (r == 0) { /* if we have no gateway return NXDOMAIN */
+                                nxdomain = true;
+                                continue;
+                        }
+
+                } else if ((dns_name_endswith(name, "127.in-addr.arpa") > 0 && dns_name_equal(name, "2.0.0.127.in-addr.arpa") == 0) ||
+                           dns_name_equal(name, "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa") > 0) {
+
+                        r = synthesize_localhost_ptr(m, key, ifindex, &answer);
+                        if (r < 0)
+                                return log_error_errno(r, "Failed to synthesize localhost PTR RRs: %m");
+
+                } else if (dns_name_address(name, &af, &address) > 0) {
+                        int v, w;
+
+                        v = synthesize_system_hostname_ptr(m, af, &address, ifindex, &answer);
+                        if (v < 0)
+                                return log_error_errno(v, "Failed to synthesize system hostname PTR RR: %m");
+
+                        w = synthesize_gateway_ptr(m, af, &address, ifindex, &answer);
+                        if (w < 0)
+                                return log_error_errno(w, "Failed to synthesize gateway hostname PTR RR: %m");
+
+                        if (v == 0 && w == 0) /* This IP address is neither a local one nor a gateway */
+                                continue;
+
+                } else
+                        continue;
+
+                found = true;
+        }
+
+        if (found) {
+
+                if (ret)
+                        *ret = TAKE_PTR(answer);
+
+                return 1;
+        } else if (nxdomain)
+                return -ENXIO;
+
+        return 0;
+}