| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| |
| #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 "stat-util.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 EtcHostsItemByAddress *etc_hosts_item_by_address_free(EtcHostsItemByAddress *item) { |
| if (!item) |
| return NULL; |
| |
| set_free(item->names); |
| return mfree(item); |
| } |
| |
| DEFINE_TRIVIAL_CLEANUP_FUNC(EtcHostsItemByAddress*, etc_hosts_item_by_address_free); |
| |
| DEFINE_PRIVATE_HASH_OPS_WITH_VALUE_DESTRUCTOR( |
| by_address_hash_ops, |
| struct in_addr_data, |
| in_addr_data_hash_func, |
| in_addr_data_compare_func, |
| EtcHostsItemByAddress, |
| etc_hosts_item_by_address_free); |
| |
| static EtcHostsItemByName *etc_hosts_item_by_name_free(EtcHostsItemByName *item) { |
| if (!item) |
| return NULL; |
| |
| free(item->name); |
| set_free(item->addresses); |
| return mfree(item); |
| } |
| |
| DEFINE_TRIVIAL_CLEANUP_FUNC(EtcHostsItemByName*, etc_hosts_item_by_name_free); |
| |
| DEFINE_PRIVATE_HASH_OPS_WITH_VALUE_DESTRUCTOR( |
| by_name_hash_ops, |
| char, |
| dns_name_hash_func, |
| dns_name_compare_func, |
| EtcHostsItemByName, |
| etc_hosts_item_by_name_free); |
| |
| void etc_hosts_clear(EtcHosts *hosts) { |
| assert(hosts); |
| |
| hosts->by_address = hashmap_free(hosts->by_address); |
| hosts->by_name = hashmap_free(hosts->by_name); |
| hosts->no_address = set_free(hosts->no_address); |
| } |
| |
| void manager_etc_hosts_flush(Manager *m) { |
| etc_hosts_clear(&m->etc_hosts); |
| m->etc_hosts_stat = (struct stat) {}; |
| } |
| |
| 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; |
| EtcHostsItemByAddress *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_data_is_null(&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) { |
| _cleanup_(etc_hosts_item_by_address_freep) EtcHostsItemByAddress *new_item = NULL; |
| |
| new_item = new(EtcHostsItemByAddress, 1); |
| if (!new_item) |
| return log_oom(); |
| |
| *new_item = (EtcHostsItemByAddress) { |
| .address = address, |
| }; |
| |
| r = hashmap_ensure_put(&hosts->by_address, &by_address_hash_ops, &new_item->address, new_item); |
| if (r < 0) |
| return log_oom(); |
| |
| item = TAKE_PTR(new_item); |
| } |
| } |
| |
| 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 hostname: %m", nr); |
| if (r == 0) |
| break; |
| |
| r = dns_name_is_valid_ldh(name); |
| if (r <= 0) { |
| if (r < 0) |
| log_warning_errno(r, "/etc/hosts:%u: Failed to check the validity of hostname \"%s\", ignoring: %m", nr, name); |
| else |
| log_warning("/etc/hosts:%u: hostname \"%s\" is not valid, ignoring.", nr, name); |
| continue; |
| } |
| |
| found = true; |
| |
| 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_consume(&hosts->no_address, &dns_name_hash_ops_free, TAKE_PTR(name)); |
| if (r < 0) |
| return log_oom(); |
| |
| continue; |
| } |
| |
| bn = hashmap_get(hosts->by_name, name); |
| if (!bn) { |
| _cleanup_(etc_hosts_item_by_name_freep) EtcHostsItemByName *new_item = NULL; |
| _cleanup_free_ char *name_copy = NULL; |
| |
| name_copy = strdup(name); |
| if (!name_copy) |
| return log_oom(); |
| |
| new_item = new(EtcHostsItemByName, 1); |
| if (!new_item) |
| return log_oom(); |
| |
| *new_item = (EtcHostsItemByName) { |
| .name = TAKE_PTR(name_copy), |
| }; |
| |
| r = hashmap_ensure_put(&hosts->by_name, &by_name_hash_ops, new_item->name, new_item); |
| if (r < 0) |
| return log_oom(); |
| |
| bn = TAKE_PTR(new_item); |
| } |
| |
| if (!set_contains(bn->addresses, &address)) { |
| _cleanup_free_ struct in_addr_data *address_copy = NULL; |
| |
| address_copy = newdup(struct in_addr_data, &address, 1); |
| if (!address_copy) |
| return log_oom(); |
| |
| r = set_ensure_consume(&bn->addresses, &in_addr_data_hash_ops_free, TAKE_PTR(address_copy)); |
| if (r < 0) |
| return log_oom(); |
| } |
| |
| r = set_ensure_consume(&item->names, &dns_name_hash_ops_free, TAKE_PTR(name)); |
| if (r < 0) |
| return log_oom(); |
| } |
| |
| if (!found) |
| log_warning("/etc/hosts:%u: line is missing any valid hostnames", nr); |
| |
| return 0; |
| } |
| |
| static void strip_localhost(EtcHosts *hosts) { |
| static const struct in_addr_data local_in_addrs[] = { |
| { |
| .family = AF_INET, |
| #if __BYTE_ORDER == __LITTLE_ENDIAN |
| /* We want constant expressions here, that's why we don't use htole32() here */ |
| .address.in.s_addr = UINT32_C(0x0100007F), |
| #else |
| .address.in.s_addr = UINT32_C(0x7F000001), |
| #endif |
| }, |
| { |
| .family = AF_INET6, |
| .address.in6 = IN6ADDR_LOOPBACK_INIT, |
| }, |
| }; |
| |
| assert(hosts); |
| |
| /* Removes the 'localhost' entry from what we loaded. But only if the mapping is exclusively between |
| * 127.0.0.1 and localhost (or aliases to that we recognize). If there's any other name assigned to |
| * it, we leave the entry in. |
| * |
| * This way our regular synthesizing can take over, but only if it would result in the exact same |
| * mappings. */ |
| |
| for (size_t j = 0; j < ELEMENTSOF(local_in_addrs); j++) { |
| bool all_localhost, all_local_address; |
| EtcHostsItemByAddress *item; |
| const char *name; |
| |
| item = hashmap_get(hosts->by_address, local_in_addrs + j); |
| if (!item) |
| continue; |
| |
| /* Check whether all hostnames the loopback address points to are localhost ones */ |
| all_localhost = true; |
| SET_FOREACH(name, item->names) |
| if (!is_localhost(name)) { |
| all_localhost = false; |
| break; |
| } |
| |
| if (!all_localhost) /* Not all names are localhost, hence keep the entries for this address. */ |
| continue; |
| |
| /* Now check if the names listed for this address actually all point back just to this |
| * address (or the other loopback address). If not, let's stay away from this too. */ |
| all_local_address = true; |
| SET_FOREACH(name, item->names) { |
| EtcHostsItemByName *n; |
| struct in_addr_data *a; |
| |
| n = hashmap_get(hosts->by_name, name); |
| if (!n) /* No reverse entry? Then almost certainly the entry already got deleted from |
| * the previous iteration of this loop, i.e. via the other protocol */ |
| break; |
| |
| /* Now check if the addresses of this item are all localhost addresses */ |
| SET_FOREACH(a, n->addresses) |
| if (!in_addr_is_localhost(a->family, &a->address)) { |
| all_local_address = false; |
| break; |
| } |
| |
| if (!all_local_address) |
| break; |
| } |
| |
| if (!all_local_address) |
| continue; |
| |
| SET_FOREACH(name, item->names) |
| etc_hosts_item_by_name_free(hashmap_remove(hosts->by_name, name)); |
| |
| assert_se(hashmap_remove(hosts->by_address, local_in_addrs + j) == item); |
| etc_hosts_item_by_address_free(item); |
| } |
| } |
| |
| int etc_hosts_parse(EtcHosts *hosts, FILE *f) { |
| _cleanup_(etc_hosts_clear) 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; |
| } |
| |
| strip_localhost(&t); |
| |
| etc_hosts_clear(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, &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_stat.st_mode != 0) { |
| 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 (stat_inode_unmodified(&m->etc_hosts_stat, &st)) |
| 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_stat = st; |
| m->etc_hosts_last = ts; |
| |
| return 1; |
| } |
| |
| static int etc_hosts_lookup_by_address( |
| EtcHosts *hosts, |
| DnsQuestion *q, |
| const char *name, |
| const struct in_addr_data *address, |
| DnsAnswer **answer) { |
| |
| DnsResourceKey *t, *found_ptr = NULL; |
| EtcHostsItemByAddress *item; |
| int r; |
| |
| assert(hosts); |
| assert(q); |
| assert(name); |
| assert(address); |
| assert(answer); |
| |
| item = hashmap_get(hosts->by_address, address); |
| 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) { |
| const char *n; |
| |
| r = dns_answer_reserve(answer, set_size(item->names)); |
| if (r < 0) |
| return r; |
| |
| SET_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, NULL); |
| if (r < 0) |
| return r; |
| } |
| } |
| |
| return 1; |
| } |
| |
| static int etc_hosts_lookup_by_name( |
| EtcHosts *hosts, |
| DnsQuestion *q, |
| const char *name, |
| DnsAnswer **answer) { |
| |
| bool found_a = false, found_aaaa = false; |
| const struct in_addr_data *a; |
| EtcHostsItemByName *item; |
| DnsResourceKey *t; |
| int r; |
| |
| assert(hosts); |
| assert(q); |
| assert(name); |
| assert(answer); |
| |
| item = hashmap_get(hosts->by_name, name); |
| if (item) { |
| r = dns_answer_reserve(answer, set_size(item->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(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; |
| } |
| |
| SET_FOREACH(a, item ? item->addresses : NULL) { |
| _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; |
| |
| if ((!found_a && a->family == AF_INET) || |
| (!found_aaaa && a->family == AF_INET6)) |
| continue; |
| |
| r = dns_resource_record_new_address(&rr, a->family, &a->address, item->name); |
| if (r < 0) |
| return r; |
| |
| r = dns_answer_add(*answer, rr, 0, DNS_ANSWER_AUTHENTICATED, NULL); |
| if (r < 0) |
| return r; |
| } |
| |
| return found_a || found_aaaa; |
| } |
| |
| int manager_etc_hosts_lookup(Manager *m, DnsQuestion *q, DnsAnswer **answer) { |
| struct in_addr_data k; |
| const char *name; |
| |
| 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; |
| |
| if (dns_name_address(name, &k.family, &k.address) > 0) |
| return etc_hosts_lookup_by_address(&m->etc_hosts, q, name, &k, answer); |
| |
| return etc_hosts_lookup_by_name(&m->etc_hosts, q, name, answer); |
| } |
