449 lines
14 KiB
C
449 lines
14 KiB
C
/***
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This file is part of systemd.
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Copyright 2016 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include "fd-util.h"
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#include "fileio.h"
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#include "hostname-util.h"
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#include "resolved-etc-hosts.h"
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#include "resolved-dns-synthesize.h"
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#include "string-util.h"
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#include "strv.h"
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#include "time-util.h"
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/* Recheck /etc/hosts at most once every 2s */
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#define ETC_HOSTS_RECHECK_USEC (2*USEC_PER_SEC)
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typedef struct EtcHostsItem {
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int family;
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union in_addr_union address;
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char **names;
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} EtcHostsItem;
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typedef struct EtcHostsItemByName {
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char *name;
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EtcHostsItem **items;
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size_t n_items, n_allocated;
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} EtcHostsItemByName;
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void manager_etc_hosts_flush(Manager *m) {
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EtcHostsItem *item;
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EtcHostsItemByName *bn;
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while ((item = set_steal_first(m->etc_hosts_by_address))) {
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strv_free(item->names);
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free(item);
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}
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while ((bn = hashmap_steal_first(m->etc_hosts_by_name))) {
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free(bn->name);
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free(bn->items);
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free(bn);
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}
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m->etc_hosts_by_address = set_free(m->etc_hosts_by_address);
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m->etc_hosts_by_name = hashmap_free(m->etc_hosts_by_name);
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m->etc_hosts_mtime = USEC_INFINITY;
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}
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static void etc_hosts_item_hash_func(const void *p, struct siphash *state) {
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const EtcHostsItem *item = p;
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siphash24_compress(&item->family, sizeof(item->family), state);
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if (item->family == AF_INET)
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siphash24_compress(&item->address.in, sizeof(item->address.in), state);
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else if (item->family == AF_INET6)
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siphash24_compress(&item->address.in6, sizeof(item->address.in6), state);
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}
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static int etc_hosts_item_compare_func(const void *a, const void *b) {
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const EtcHostsItem *x = a, *y = b;
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if (x->family != y->family)
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return x->family - y->family;
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if (x->family == AF_INET)
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return memcmp(&x->address.in.s_addr, &y->address.in.s_addr, sizeof(struct in_addr));
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if (x->family == AF_INET6)
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return memcmp(&x->address.in6.s6_addr, &y->address.in6.s6_addr, sizeof(struct in6_addr));
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return trivial_compare_func(a, b);
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}
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static const struct hash_ops etc_hosts_item_ops = {
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.hash = etc_hosts_item_hash_func,
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.compare = etc_hosts_item_compare_func,
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};
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static int add_item(Manager *m, int family, const union in_addr_union *address, char **names) {
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EtcHostsItem key = {
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.family = family,
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.address = *address,
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};
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EtcHostsItem *item;
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char **n;
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int r;
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assert(m);
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assert(address);
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r = in_addr_is_null(family, address);
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if (r < 0)
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return r;
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if (r > 0)
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/* This is an 0.0.0.0 or :: item, which we assume means that we shall map the specified hostname to
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* nothing. */
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item = NULL;
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else {
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/* If this is a normal address, then, simply add entry mapping it to the specified names */
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item = set_get(m->etc_hosts_by_address, &key);
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if (item) {
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r = strv_extend_strv(&item->names, names, true);
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if (r < 0)
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return log_oom();
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} else {
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r = set_ensure_allocated(&m->etc_hosts_by_address, &etc_hosts_item_ops);
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if (r < 0)
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return log_oom();
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item = new0(EtcHostsItem, 1);
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if (!item)
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return log_oom();
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item->family = family;
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item->address = *address;
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item->names = names;
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r = set_put(m->etc_hosts_by_address, item);
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if (r < 0) {
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free(item);
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return log_oom();
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}
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}
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}
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STRV_FOREACH(n, names) {
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EtcHostsItemByName *bn;
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bn = hashmap_get(m->etc_hosts_by_name, *n);
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if (!bn) {
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r = hashmap_ensure_allocated(&m->etc_hosts_by_name, &dns_name_hash_ops);
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if (r < 0)
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return log_oom();
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bn = new0(EtcHostsItemByName, 1);
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if (!bn)
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return log_oom();
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bn->name = strdup(*n);
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if (!bn->name) {
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free(bn);
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return log_oom();
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}
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r = hashmap_put(m->etc_hosts_by_name, bn->name, bn);
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if (r < 0) {
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free(bn->name);
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free(bn);
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return log_oom();
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}
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}
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if (item) {
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if (!GREEDY_REALLOC(bn->items, bn->n_allocated, bn->n_items+1))
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return log_oom();
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bn->items[bn->n_items++] = item;
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}
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}
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return 0;
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}
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static int parse_line(Manager *m, unsigned nr, const char *line) {
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_cleanup_free_ char *address = NULL;
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_cleanup_strv_free_ char **names = NULL;
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union in_addr_union in;
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bool suppressed = false;
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int family, r;
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assert(m);
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assert(line);
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r = extract_first_word(&line, &address, NULL, EXTRACT_RELAX);
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if (r < 0)
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return log_error_errno(r, "Couldn't extract address, in line /etc/hosts:%u.", nr);
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if (r == 0) {
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log_error("Premature end of line, in line /etc/hosts:%u.", nr);
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return -EINVAL;
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}
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r = in_addr_from_string_auto(address, &family, &in);
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if (r < 0)
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return log_error_errno(r, "Address '%s' is invalid, in line /etc/hosts:%u.", address, nr);
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for (;;) {
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_cleanup_free_ char *name = NULL;
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r = extract_first_word(&line, &name, NULL, EXTRACT_RELAX);
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if (r < 0)
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return log_error_errno(r, "Couldn't extract host name, in line /etc/hosts:%u.", nr);
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if (r == 0)
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break;
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r = dns_name_is_valid(name);
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if (r <= 0)
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return log_error_errno(r, "Hostname %s is not valid, ignoring, in line /etc/hosts:%u.", name, nr);
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if (is_localhost(name)) {
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/* Suppress the "localhost" line that is often seen */
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suppressed = true;
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continue;
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}
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r = strv_push(&names, name);
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if (r < 0)
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return log_oom();
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name = NULL;
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}
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if (strv_isempty(names)) {
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if (suppressed)
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return 0;
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log_error("Line is missing any host names, in line /etc/hosts:%u.", nr);
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return -EINVAL;
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}
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/* Takes possession of the names strv */
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r = add_item(m, family, &in, names);
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if (r < 0)
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return r;
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names = NULL;
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return r;
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}
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int manager_etc_hosts_read(Manager *m) {
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_cleanup_fclose_ FILE *f = NULL;
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char line[LINE_MAX];
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struct stat st;
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usec_t ts;
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unsigned nr = 0;
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int r;
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assert_se(sd_event_now(m->event, clock_boottime_or_monotonic(), &ts) >= 0);
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/* See if we checked /etc/hosts recently already */
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if (m->etc_hosts_last != USEC_INFINITY && m->etc_hosts_last + ETC_HOSTS_RECHECK_USEC > ts)
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return 0;
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m->etc_hosts_last = ts;
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if (m->etc_hosts_mtime != USEC_INFINITY) {
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if (stat("/etc/hosts", &st) < 0) {
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if (errno == ENOENT) {
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r = 0;
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goto clear;
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}
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return log_error_errno(errno, "Failed to stat /etc/hosts: %m");
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}
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/* Did the mtime change? If not, there's no point in re-reading the file. */
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if (timespec_load(&st.st_mtim) == m->etc_hosts_mtime)
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return 0;
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}
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f = fopen("/etc/hosts", "re");
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if (!f) {
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if (errno == ENOENT) {
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r = 0;
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goto clear;
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}
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return log_error_errno(errno, "Failed to open /etc/hosts: %m");
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}
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/* Take the timestamp at the beginning of processing, so that any changes made later are read on the next
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* invocation */
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r = fstat(fileno(f), &st);
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if (r < 0)
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return log_error_errno(errno, "Failed to fstat() /etc/hosts: %m");
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manager_etc_hosts_flush(m);
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FOREACH_LINE(line, f, return log_error_errno(errno, "Failed to read /etc/hosts: %m")) {
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char *l;
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nr++;
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l = strstrip(line);
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if (isempty(l))
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continue;
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if (l[0] == '#')
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continue;
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r = parse_line(m, nr, l);
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if (r == -ENOMEM) /* On OOM we abandon the half-built-up structure. All other errors we ignore and proceed */
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goto clear;
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}
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m->etc_hosts_mtime = timespec_load(&st.st_mtim);
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m->etc_hosts_last = ts;
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return 1;
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clear:
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manager_etc_hosts_flush(m);
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return r;
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}
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int manager_etc_hosts_lookup(Manager *m, DnsQuestion* q, DnsAnswer **answer) {
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bool found_a = false, found_aaaa = false;
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EtcHostsItemByName *bn;
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EtcHostsItem k = {};
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DnsResourceKey *t;
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const char *name;
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unsigned i;
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int r;
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assert(m);
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assert(q);
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assert(answer);
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r = manager_etc_hosts_read(m);
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if (r < 0)
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return r;
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name = dns_question_first_name(q);
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if (!name)
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return 0;
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r = dns_name_address(name, &k.family, &k.address);
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if (r > 0) {
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EtcHostsItem *item;
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DnsResourceKey *found_ptr = NULL;
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item = set_get(m->etc_hosts_by_address, &k);
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if (!item)
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return 0;
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/* We have an address in /etc/hosts that matches the queried name. Let's return successful. Actual data
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* we'll only return if the request was for PTR. */
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DNS_QUESTION_FOREACH(t, q) {
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if (!IN_SET(t->type, DNS_TYPE_PTR, DNS_TYPE_ANY))
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continue;
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if (!IN_SET(t->class, DNS_CLASS_IN, DNS_CLASS_ANY))
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continue;
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r = dns_name_equal(dns_resource_key_name(t), name);
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if (r < 0)
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return r;
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if (r > 0) {
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found_ptr = t;
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break;
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}
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}
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if (found_ptr) {
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char **n;
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r = dns_answer_reserve(answer, strv_length(item->names));
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if (r < 0)
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return r;
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STRV_FOREACH(n, item->names) {
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_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
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rr = dns_resource_record_new(found_ptr);
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if (!rr)
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return -ENOMEM;
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rr->ptr.name = strdup(*n);
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if (!rr->ptr.name)
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return -ENOMEM;
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r = dns_answer_add(*answer, rr, 0, DNS_ANSWER_AUTHENTICATED);
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if (r < 0)
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return r;
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}
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}
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return 1;
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}
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bn = hashmap_get(m->etc_hosts_by_name, name);
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if (!bn)
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return 0;
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r = dns_answer_reserve(answer, bn->n_items);
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if (r < 0)
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return r;
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DNS_QUESTION_FOREACH(t, q) {
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if (!IN_SET(t->type, DNS_TYPE_A, DNS_TYPE_AAAA, DNS_TYPE_ANY))
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continue;
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if (!IN_SET(t->class, DNS_CLASS_IN, DNS_CLASS_ANY))
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continue;
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r = dns_name_equal(dns_resource_key_name(t), name);
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if (r < 0)
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return r;
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if (r == 0)
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continue;
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if (IN_SET(t->type, DNS_TYPE_A, DNS_TYPE_ANY))
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found_a = true;
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if (IN_SET(t->type, DNS_TYPE_AAAA, DNS_TYPE_ANY))
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found_aaaa = true;
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if (found_a && found_aaaa)
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break;
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}
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for (i = 0; i < bn->n_items; i++) {
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_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
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if ((found_a && bn->items[i]->family != AF_INET) &&
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(found_aaaa && bn->items[i]->family != AF_INET6))
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continue;
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r = dns_resource_record_new_address(&rr, bn->items[i]->family, &bn->items[i]->address, bn->name);
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if (r < 0)
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return r;
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r = dns_answer_add(*answer, rr, 0, DNS_ANSWER_AUTHENTICATED);
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if (r < 0)
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return r;
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}
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return 1;
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}
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