/*** This file is part of systemd. Copyright 2016 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 . ***/ #include "systemd-basic/fd-util.h" #include "systemd-basic/fileio.h" #include "systemd-basic/hostname-util.h" #include "systemd-basic/string-util.h" #include "systemd-basic/strv.h" #include "systemd-basic/time-util.h" #include "resolved-dns-synthesize.h" #include "resolved-etc-hosts.h" /* Recheck /etc/hosts at most once every 2s */ #define ETC_HOSTS_RECHECK_USEC (2*USEC_PER_SEC) typedef struct EtcHostsItem { int family; union in_addr_union address; char **names; } EtcHostsItem; typedef struct EtcHostsItemByName { char *name; EtcHostsItem **items; size_t n_items, n_allocated; } EtcHostsItemByName; void manager_etc_hosts_flush(Manager *m) { EtcHostsItem *item; EtcHostsItemByName *bn; while ((item = set_steal_first(m->etc_hosts_by_address))) { strv_free(item->names); free(item); } while ((bn = hashmap_steal_first(m->etc_hosts_by_name))) { free(bn->name); free(bn->items); free(bn); } m->etc_hosts_by_address = set_free(m->etc_hosts_by_address); m->etc_hosts_by_name = hashmap_free(m->etc_hosts_by_name); m->etc_hosts_mtime = USEC_INFINITY; } static void etc_hosts_item_hash_func(const void *p, struct siphash *state) { const EtcHostsItem *item = p; siphash24_compress(&item->family, sizeof(item->family), state); if (item->family == AF_INET) siphash24_compress(&item->address.in, sizeof(item->address.in), state); else if (item->family == AF_INET6) siphash24_compress(&item->address.in6, sizeof(item->address.in6), state); } static int etc_hosts_item_compare_func(const void *a, const void *b) { const EtcHostsItem *x = a, *y = b; if (x->family != y->family) return x->family - y->family; if (x->family == AF_INET) return memcmp(&x->address.in.s_addr, &y->address.in.s_addr, sizeof(struct in_addr)); if (x->family == AF_INET6) return memcmp(&x->address.in6.s6_addr, &y->address.in6.s6_addr, sizeof(struct in6_addr)); return trivial_compare_func(a, b); } static const struct hash_ops etc_hosts_item_ops = { .hash = etc_hosts_item_hash_func, .compare = etc_hosts_item_compare_func, }; static int add_item(Manager *m, int family, const union in_addr_union *address, char **names) { EtcHostsItem key = { .family = family, .address = *address, }; EtcHostsItem *item; char **n; int r; assert(m); assert(address); r = in_addr_is_null(family, address); if (r < 0) return r; 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 = set_get(m->etc_hosts_by_address, &key); if (item) { r = strv_extend_strv(&item->names, names, true); if (r < 0) return log_oom(); } else { r = set_ensure_allocated(&m->etc_hosts_by_address, &etc_hosts_item_ops); if (r < 0) return log_oom(); item = new0(EtcHostsItem, 1); if (!item) return log_oom(); item->family = family; item->address = *address; item->names = names; r = set_put(m->etc_hosts_by_address, item); if (r < 0) { free(item); return log_oom(); } } } STRV_FOREACH(n, names) { EtcHostsItemByName *bn; bn = hashmap_get(m->etc_hosts_by_name, *n); if (!bn) { r = hashmap_ensure_allocated(&m->etc_hosts_by_name, &dns_name_hash_ops); if (r < 0) return log_oom(); bn = new0(EtcHostsItemByName, 1); if (!bn) return log_oom(); bn->name = strdup(*n); if (!bn->name) { free(bn); return log_oom(); } r = hashmap_put(m->etc_hosts_by_name, bn->name, bn); if (r < 0) { free(bn->name); free(bn); return log_oom(); } } if (item) { if (!GREEDY_REALLOC(bn->items, bn->n_allocated, bn->n_items+1)) return log_oom(); bn->items[bn->n_items++] = item; } } return 0; } static int parse_line(Manager *m, unsigned nr, const char *line) { _cleanup_free_ char *address = NULL; _cleanup_strv_free_ char **names = NULL; union in_addr_union in; bool suppressed = false; int family, r; assert(m); assert(line); r = extract_first_word(&line, &address, NULL, EXTRACT_RELAX); if (r < 0) return log_error_errno(r, "Couldn't extract address, in line /etc/hosts:%u.", nr); if (r == 0) { log_error("Premature end of line, in line /etc/hosts:%u.", nr); return -EINVAL; } r = in_addr_from_string_auto(address, &family, &in); if (r < 0) return log_error_errno(r, "Address '%s' is invalid, in line /etc/hosts:%u.", address, nr); for (;;) { _cleanup_free_ char *name = NULL; r = extract_first_word(&line, &name, NULL, EXTRACT_RELAX); if (r < 0) return log_error_errno(r, "Couldn't extract host name, in line /etc/hosts:%u.", nr); if (r == 0) break; r = dns_name_is_valid(name); if (r <= 0) return log_error_errno(r, "Hostname %s is not valid, ignoring, in line /etc/hosts:%u.", name, nr); if (is_localhost(name)) { /* Suppress the "localhost" line that is often seen */ suppressed = true; continue; } r = strv_push(&names, name); if (r < 0) return log_oom(); name = NULL; } if (strv_isempty(names)) { if (suppressed) return 0; log_error("Line is missing any host names, in line /etc/hosts:%u.", nr); return -EINVAL; } /* Takes possession of the names strv */ r = add_item(m, family, &in, names); if (r < 0) return r; names = NULL; return r; } int manager_etc_hosts_read(Manager *m) { _cleanup_fclose_ FILE *f = NULL; char line[LINE_MAX]; struct stat st; usec_t ts; unsigned nr = 0; 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) { r = 0; goto clear; } return log_error_errno(errno, "Failed to stat /etc/hosts: %m"); } /* 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) { r = 0; goto clear; } return log_error_errno(errno, "Failed to open /etc/hosts: %m"); } /* 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"); manager_etc_hosts_flush(m); FOREACH_LINE(line, f, return log_error_errno(errno, "Failed to read /etc/hosts: %m")) { char *l; nr++; l = strstrip(line); if (isempty(l)) continue; if (l[0] == '#') continue; r = parse_line(m, nr, l); if (r == -ENOMEM) /* On OOM we abandon the half-built-up structure. All other errors we ignore and proceed */ goto clear; } m->etc_hosts_mtime = timespec_load(&st.st_mtim); m->etc_hosts_last = ts; return 1; clear: manager_etc_hosts_flush(m); return r; } int manager_etc_hosts_lookup(Manager *m, DnsQuestion* q, DnsAnswer **answer) { bool found_a = false, found_aaaa = false; EtcHostsItemByName *bn; EtcHostsItem k = {}; DnsResourceKey *t; const char *name; unsigned i; int r; assert(m); assert(q); assert(answer); r = manager_etc_hosts_read(m); if (r < 0) return r; 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 = set_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) return 0; r = dns_answer_reserve(answer, bn->n_items); if (r < 0) return r; 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; i < bn->n_items; i++) { _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; if ((found_a && bn->items[i]->family != AF_INET) && (found_aaaa && bn->items[i]->family != AF_INET6)) continue; r = dns_resource_record_new_address(&rr, bn->items[i]->family, &bn->items[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 1; }