| /* SPDX-License-Identifier: LGPL-2.1+ */ |
| |
| #include <sys/stat.h> |
| #include <sys/types.h> |
| #include <unistd.h> |
| |
| #include "fd-util.h" |
| #include "fileio.h" |
| #include "hostname-util.h" |
| #include "resolved-dns-synthesize.h" |
| #include "resolved-etc-hosts.h" |
| #include "socket-netlink.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; |
| m->etc_hosts_ino = 0; |
| m->etc_hosts_dev = 0; |
| } |
| |
| 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 or ino/dev change? If not, there's no point in re-reading the file. */ |
| if (timespec_load(&st.st_mtim) == m->etc_hosts_mtime && |
| st.st_ino == m->etc_hosts_ino && st.st_dev == m->etc_hosts_dev) |
| 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_ino = st.st_ino; |
| m->etc_hosts_dev = st.st_dev; |
| 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; |
| } |