Adding upstream version 241.upstream/241upstream

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

1 files changed, 377 insertions, 0 deletions

diff --git a/src/resolve/resolved-etc-hosts.c b/src/resolve/resolved-etc-hosts.c
new file mode 100644
index 0000000..ee21222
--- /dev/null
+++ b/src/resolve/resolved-etc-hosts.c
@@ -0,0 +1,377 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include "fd-util.h"
+#include "fileio.h"
+#include "hostname-util.h"
+#include "resolved-dns-synthesize.h"
+#include "resolved-etc-hosts.h"
+#include "string-util.h"
+#include "strv.h"
+#include "time-util.h"
+
+/* Recheck /etc/hosts at most once every 2s */
+#define ETC_HOSTS_RECHECK_USEC (2*USEC_PER_SEC)
+
+static void etc_hosts_item_free(EtcHostsItem *item) {
+        strv_free(item->names);
+        free(item);
+}
+
+static void etc_hosts_item_by_name_free(EtcHostsItemByName *item) {
+        free(item->name);
+        free(item->addresses);
+        free(item);
+}
+
+void etc_hosts_free(EtcHosts *hosts) {
+        hosts->by_address = hashmap_free_with_destructor(hosts->by_address, etc_hosts_item_free);
+        hosts->by_name = hashmap_free_with_destructor(hosts->by_name, etc_hosts_item_by_name_free);
+        hosts->no_address = set_free_free(hosts->no_address);
+}
+
+void manager_etc_hosts_flush(Manager *m) {
+        etc_hosts_free(&m->etc_hosts);
+        m->etc_hosts_mtime = USEC_INFINITY;
+}
+
+static int parse_line(EtcHosts *hosts, unsigned nr, const char *line) {
+        _cleanup_free_ char *address_str = NULL;
+        struct in_addr_data address = {};
+        bool found = false;
+        EtcHostsItem *item;
+        int r;
+
+        assert(hosts);
+        assert(line);
+
+        r = extract_first_word(&line, &address_str, NULL, EXTRACT_RELAX);
+        if (r < 0)
+                return log_error_errno(r, "/etc/hosts:%u: failed to extract address: %m", nr);
+        assert(r > 0); /* We already checked that the line is not empty, so it should contain *something* */
+
+        r = in_addr_ifindex_from_string_auto(address_str, &address.family, &address.address, NULL);
+        if (r < 0) {
+                log_warning_errno(r, "/etc/hosts:%u: address '%s' is invalid, ignoring: %m", nr, address_str);
+                return 0;
+        }
+
+        r = in_addr_is_null(address.family, &address.address);
+        if (r < 0) {
+                log_warning_errno(r, "/etc/hosts:%u: address '%s' is invalid, ignoring: %m", nr, address_str);
+                return 0;
+        }
+        if (r > 0)
+                /* This is an 0.0.0.0 or :: item, which we assume means that we shall map the specified hostname to
+                 * nothing. */
+                item = NULL;
+        else {
+                /* If this is a normal address, then simply add entry mapping it to the specified names */
+
+                item = hashmap_get(hosts->by_address, &address);
+                if (!item) {
+                        r = hashmap_ensure_allocated(&hosts->by_address, &in_addr_data_hash_ops);
+                        if (r < 0)
+                                return log_oom();
+
+                        item = new0(EtcHostsItem, 1);
+                        if (!item)
+                                return log_oom();
+
+                        item->address = address;
+
+                        r = hashmap_put(hosts->by_address, &item->address, item);
+                        if (r < 0) {
+                                free(item);
+                                return log_oom();
+                        }
+                }
+        }
+
+        for (;;) {
+                _cleanup_free_ char *name = NULL;
+                EtcHostsItemByName *bn;
+
+                r = extract_first_word(&line, &name, NULL, EXTRACT_RELAX);
+                if (r < 0)
+                        return log_error_errno(r, "/etc/hosts:%u: couldn't extract host name: %m", nr);
+                if (r == 0)
+                        break;
+
+                found = true;
+
+                r = dns_name_is_valid_ldh(name);
+                if (r <= 0) {
+                        log_warning_errno(r, "/etc/hosts:%u: hostname \"%s\" is not valid, ignoring.", nr, name);
+                        continue;
+                }
+
+                if (is_localhost(name))
+                        /* Suppress the "localhost" line that is often seen */
+                        continue;
+
+                if (!item) {
+                        /* Optimize the case where we don't need to store any addresses, by storing
+                         * only the name in a dedicated Set instead of the hashmap */
+
+                        r = set_ensure_allocated(&hosts->no_address, &dns_name_hash_ops);
+                        if (r < 0)
+                                return log_oom();
+
+                        r = set_put(hosts->no_address, name);
+                        if (r < 0)
+                                return r;
+
+                        TAKE_PTR(name);
+                        continue;
+                }
+
+                r = strv_extend(&item->names, name);
+                if (r < 0)
+                        return log_oom();
+
+                bn = hashmap_get(hosts->by_name, name);
+                if (!bn) {
+                        r = hashmap_ensure_allocated(&hosts->by_name, &dns_name_hash_ops);
+                        if (r < 0)
+                                return log_oom();
+
+                        bn = new0(EtcHostsItemByName, 1);
+                        if (!bn)
+                                return log_oom();
+
+                        r = hashmap_put(hosts->by_name, name, bn);
+                        if (r < 0) {
+                                free(bn);
+                                return log_oom();
+                        }
+
+                        bn->name = TAKE_PTR(name);
+                }
+
+                if (!GREEDY_REALLOC(bn->addresses, bn->n_allocated, bn->n_addresses + 1))
+                        return log_oom();
+
+                bn->addresses[bn->n_addresses++] = &item->address;
+        }
+
+        if (!found)
+                log_warning("/etc/hosts:%u: line is missing any host names", nr);
+
+        return 0;
+}
+
+int etc_hosts_parse(EtcHosts *hosts, FILE *f) {
+        _cleanup_(etc_hosts_free) EtcHosts t = {};
+        unsigned nr = 0;
+        int r;
+
+        for (;;) {
+                _cleanup_free_ char *line = NULL;
+                char *l;
+
+                r = read_line(f, LONG_LINE_MAX, &line);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to read /etc/hosts: %m");
+                if (r == 0)
+                        break;
+
+                nr++;
+
+                l = strchr(line, '#');
+                if (l)
+                        *l = '\0';
+
+                l = strstrip(line);
+                if (isempty(l))
+                        continue;
+
+                r = parse_line(&t, nr, l);
+                if (r < 0)
+                        return r;
+        }
+
+        etc_hosts_free(hosts);
+        *hosts = t;
+        t = (EtcHosts) {}; /* prevent cleanup */
+        return 0;
+}
+
+static int manager_etc_hosts_read(Manager *m) {
+        _cleanup_fclose_ FILE *f = NULL;
+        struct stat st;
+        usec_t ts;
+        int r;
+
+        assert_se(sd_event_now(m->event, clock_boottime_or_monotonic(), &ts) >= 0);
+
+        /* See if we checked /etc/hosts recently already */
+        if (m->etc_hosts_last != USEC_INFINITY && m->etc_hosts_last + ETC_HOSTS_RECHECK_USEC > ts)
+                return 0;
+
+        m->etc_hosts_last = ts;
+
+        if (m->etc_hosts_mtime != USEC_INFINITY) {
+                if (stat("/etc/hosts", &st) < 0) {
+                        if (errno != ENOENT)
+                                return log_error_errno(errno, "Failed to stat /etc/hosts: %m");
+
+                        manager_etc_hosts_flush(m);
+                        return 0;
+                }
+
+                /* Did the mtime change? If not, there's no point in re-reading the file. */
+                if (timespec_load(&st.st_mtim) == m->etc_hosts_mtime)
+                        return 0;
+        }
+
+        f = fopen("/etc/hosts", "re");
+        if (!f) {
+                if (errno != ENOENT)
+                        return log_error_errno(errno, "Failed to open /etc/hosts: %m");
+
+                manager_etc_hosts_flush(m);
+                return 0;
+        }
+
+        /* Take the timestamp at the beginning of processing, so that any changes made later are read on the next
+         * invocation */
+        r = fstat(fileno(f), &st);
+        if (r < 0)
+                return log_error_errno(errno, "Failed to fstat() /etc/hosts: %m");
+
+        r = etc_hosts_parse(&m->etc_hosts, f);
+        if (r < 0)
+                return r;
+
+        m->etc_hosts_mtime = timespec_load(&st.st_mtim);
+        m->etc_hosts_last = ts;
+
+        return 1;
+}
+
+int manager_etc_hosts_lookup(Manager *m, DnsQuestion* q, DnsAnswer **answer) {
+        bool found_a = false, found_aaaa = false;
+        struct in_addr_data k = {};
+        EtcHostsItemByName *bn;
+        DnsResourceKey *t;
+        const char *name;
+        unsigned i;
+        int r;
+
+        assert(m);
+        assert(q);
+        assert(answer);
+
+        if (!m->read_etc_hosts)
+                return 0;
+
+        (void) manager_etc_hosts_read(m);
+
+        name = dns_question_first_name(q);
+        if (!name)
+                return 0;
+
+        r = dns_name_address(name, &k.family, &k.address);
+        if (r > 0) {
+                EtcHostsItem *item;
+                DnsResourceKey *found_ptr = NULL;
+
+                item = hashmap_get(m->etc_hosts.by_address, &k);
+                if (!item)
+                        return 0;
+
+                /* We have an address in /etc/hosts that matches the queried name. Let's return successful. Actual data
+                 * we'll only return if the request was for PTR. */
+
+                DNS_QUESTION_FOREACH(t, q) {
+                        if (!IN_SET(t->type, DNS_TYPE_PTR, DNS_TYPE_ANY))
+                                continue;
+                        if (!IN_SET(t->class, DNS_CLASS_IN, DNS_CLASS_ANY))
+                                continue;
+
+                        r = dns_name_equal(dns_resource_key_name(t), name);
+                        if (r < 0)
+                                return r;
+                        if (r > 0) {
+                                found_ptr = t;
+                                break;
+                        }
+                }
+
+                if (found_ptr) {
+                        char **n;
+
+                        r = dns_answer_reserve(answer, strv_length(item->names));
+                        if (r < 0)
+                                return r;
+
+                        STRV_FOREACH(n, item->names) {
+                                _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+
+                                rr = dns_resource_record_new(found_ptr);
+                                if (!rr)
+                                        return -ENOMEM;
+
+                                rr->ptr.name = strdup(*n);
+                                if (!rr->ptr.name)
+                                        return -ENOMEM;
+
+                                r = dns_answer_add(*answer, rr, 0, DNS_ANSWER_AUTHENTICATED);
+                                if (r < 0)
+                                        return r;
+                        }
+                }
+
+                return 1;
+        }
+
+        bn = hashmap_get(m->etc_hosts.by_name, name);
+        if (bn) {
+                r = dns_answer_reserve(answer, bn->n_addresses);
+                if (r < 0)
+                        return r;
+        } else {
+                /* Check if name was listed with no address. If yes, continue to return an answer. */
+                if (!set_contains(m->etc_hosts.no_address, name))
+                        return 0;
+        }
+
+        DNS_QUESTION_FOREACH(t, q) {
+                if (!IN_SET(t->type, DNS_TYPE_A, DNS_TYPE_AAAA, DNS_TYPE_ANY))
+                        continue;
+                if (!IN_SET(t->class, DNS_CLASS_IN, DNS_CLASS_ANY))
+                        continue;
+
+                r = dns_name_equal(dns_resource_key_name(t), name);
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        continue;
+
+                if (IN_SET(t->type, DNS_TYPE_A, DNS_TYPE_ANY))
+                        found_a = true;
+                if (IN_SET(t->type, DNS_TYPE_AAAA, DNS_TYPE_ANY))
+                        found_aaaa = true;
+
+                if (found_a && found_aaaa)
+                        break;
+        }
+
+        for (i = 0; bn && i < bn->n_addresses; i++) {
+                _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
+
+                if ((!found_a && bn->addresses[i]->family == AF_INET) ||
+                    (!found_aaaa && bn->addresses[i]->family == AF_INET6))
+                        continue;
+
+                r = dns_resource_record_new_address(&rr, bn->addresses[i]->family, &bn->addresses[i]->address, bn->name);
+                if (r < 0)
+                        return r;
+
+                r = dns_answer_add(*answer, rr, 0, DNS_ANSWER_AUTHENTICATED);
+                if (r < 0)
+                        return r;
+        }
+
+        return found_a || found_aaaa;
+}