[thirdparty/systemd.git] / src / resolve / resolved-etc-hosts.c

/* 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 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_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;
        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_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) {
                        r = hashmap_ensure_allocated(&hosts->by_address, &in_addr_data_hash_ops);
                        if (r < 0)
                                return log_oom();

                        item = new(EtcHostsItem, 1);
                        if (!item)
                                return log_oom();

                        *item = (EtcHostsItem) {
                                .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 hostname: %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 (!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, TAKE_PTR(name));
                        if (r < 0)
                                return r;

                        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_addresses + 1))
                        return log_oom();

                bn->addresses[bn->n_addresses++] = &item->address;
        }

        if (!found)
                log_warning("/etc/hosts:%u: line is missing any 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,
                },
        };

        EtcHostsItem *item;

        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, in_order;
                char **i;

                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;
                STRV_FOREACH(i, item->names)
                        if (!is_localhost(*i)) {
                                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. */
                in_order = true;
                STRV_FOREACH(i, item->names) {
                        EtcHostsItemByName *n;
                        bool all_local_address;

                        n = hashmap_get(hosts->by_name, *i);
                        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 */
                        all_local_address = true;
                        for (size_t m = 0; m < n->n_addresses; m++)
                                if (!in_addr_is_localhost(n->addresses[m]->family, &n->addresses[m]->address)) {
                                        all_local_address = false;
                                        break;
                                }

                        if (!all_local_address) {
                                in_order = false;
                                break;
                        }
                }

                if (!in_order)
                        continue;

                STRV_FOREACH(i, item->names) {
                        EtcHostsItemByName *n;

                        n = hashmap_remove(hosts->by_name, *i);
                        if (n)
                                etc_hosts_item_by_name_free(n);
                }

                assert_se(hashmap_remove(hosts->by_address, local_in_addrs + j) == item);
                etc_hosts_item_free(item);
        }
}

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;
        }

        strip_localhost(&t);

        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_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;
}

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, NULL);
                                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, NULL);
                if (r < 0)
                        return r;
        }

        return found_a || found_aaaa;
}
Commit	Line	Data
db9ecf05	1	/* SPDX-License-Identifier: LGPL-2.1-or-later */
dd0bc0f1	2
ca78ad1d ZJS	3	#include <sys/stat.h>
	4	#include <sys/types.h>
	5	#include <unistd.h>
	6
dd0bc0f1 LP	7	#include "fd-util.h"
	8	#include "fileio.h"
	9	#include "hostname-util.h"
dd0bc0f1	10	#include "resolved-dns-synthesize.h"
7c777a77	11	#include "resolved-etc-hosts.h"
5c3fa98d	12	#include "socket-netlink.h"
36d892b7	13	#include "stat-util.h"
dd0bc0f1 LP	14	#include "string-util.h"
	15	#include "strv.h"
	16	#include "time-util.h"
	17
	18	/* Recheck /etc/hosts at most once every 2s */
	19	#define ETC_HOSTS_RECHECK_USEC (2*USEC_PER_SEC)
	20
a1e92eee	21	static void etc_hosts_item_free(EtcHostsItem *item) {
37b7cc8d ZJS	22	strv_free(item->names);
	23	free(item);
	24	}
dd0bc0f1	25
a1e92eee	26	static void etc_hosts_item_by_name_free(EtcHostsItemByName *item) {
37b7cc8d ZJS	27	free(item->name);
	28	free(item->addresses);
	29	free(item);
	30	}
dd0bc0f1	31
78fc21a1	32	void etc_hosts_free(EtcHosts *hosts) {
37b7cc8d ZJS	33	hosts->by_address = hashmap_free_with_destructor(hosts->by_address, etc_hosts_item_free);
37b7cc8d ZJS	34	hosts->by_name = hashmap_free_with_destructor(hosts->by_name, etc_hosts_item_by_name_free);
fd373593	35	hosts->no_address = set_free_free(hosts->no_address);
37b7cc8d	36	}
dd0bc0f1	37
37b7cc8d ZJS	38	void manager_etc_hosts_flush(Manager *m) {
37b7cc8d ZJS	39	etc_hosts_free(&m->etc_hosts);
36d892b7	40	m->etc_hosts_stat = (struct stat) {};
dd0bc0f1 LP	41	}
dd0bc0f1 LP	42
37b7cc8d	43	static int parse_line(EtcHosts hosts, unsigned nr, const char line) {
0351eb11 YW	44	_cleanup_free_ char *address_str = NULL;
0351eb11 YW	45	struct in_addr_data address = {};
fd373593	46	bool found = false;
dd0bc0f1	47	EtcHostsItem *item;
dd0bc0f1 LP	48	int r;
dd0bc0f1 LP	49
37b7cc8d	50	assert(hosts);
0351eb11	51	assert(line);
dd0bc0f1	52
0351eb11 YW	53	r = extract_first_word(&line, &address_str, NULL, EXTRACT_RELAX);
0351eb11 YW	54	if (r < 0)
bd005277 ZJS	55	return log_error_errno(r, "/etc/hosts:%u: failed to extract address: %m", nr);
bd005277 ZJS	56	assert(r > 0); /* We already checked that the line is not empty, so it should contain something */
0351eb11	57
7bf8c3de	58	r = in_addr_ifindex_from_string_auto(address_str, &address.family, &address.address, NULL);
bd005277 ZJS	59	if (r < 0) {
	60	log_warning_errno(r, "/etc/hosts:%u: address '%s' is invalid, ignoring: %m", nr, address_str);
	61	return 0;
	62	}
0351eb11	63
94876904	64	r = in_addr_data_is_null(&address);
bd005277 ZJS	65	if (r < 0) {
	66	log_warning_errno(r, "/etc/hosts:%u: address '%s' is invalid, ignoring: %m", nr, address_str);
	67	return 0;
	68	}
dd0bc0f1 LP	69	if (r > 0)
	70	/* This is an 0.0.0.0 or :: item, which we assume means that we shall map the specified hostname to
	71	* nothing. */
	72	item = NULL;
	73	else {
78fc21a1	74	/* If this is a normal address, then simply add entry mapping it to the specified names */
dd0bc0f1	75
37b7cc8d	76	item = hashmap_get(hosts->by_address, &address);
0351eb11	77	if (!item) {
37b7cc8d	78	r = hashmap_ensure_allocated(&hosts->by_address, &in_addr_data_hash_ops);
dd0bc0f1 LP	79	if (r < 0)
	80	return log_oom();
	81
1ed31408	82	item = new(EtcHostsItem, 1);
dd0bc0f1 LP	83	if (!item)
	84	return log_oom();
	85
1ed31408 LP	86	*item = (EtcHostsItem) {
	87	.address = address,
	88	};
dd0bc0f1	89
37b7cc8d	90	r = hashmap_put(hosts->by_address, &item->address, item);
dd0bc0f1 LP	91	if (r < 0) {
	92	free(item);
	93	return log_oom();
	94	}
	95	}
	96	}
	97
0351eb11 YW	98	for (;;) {
0351eb11 YW	99	_cleanup_free_ char *name = NULL;
dd0bc0f1 LP	100	EtcHostsItemByName *bn;
dd0bc0f1 LP	101
0351eb11 YW	102	r = extract_first_word(&line, &name, NULL, EXTRACT_RELAX);
0351eb11 YW	103	if (r < 0)
38b38500	104	return log_error_errno(r, "/etc/hosts:%u: couldn't extract hostname: %m", nr);
0351eb11 YW	105	if (r == 0)
	106	break;
	107
fd373593 ZJS	108	found = true;
fd373593 ZJS	109
7470cc4c	110	r = dns_name_is_valid_ldh(name);
bd005277 ZJS	111	if (r <= 0) {
	112	log_warning_errno(r, "/etc/hosts:%u: hostname \"%s\" is not valid, ignoring.", nr, name);
	113	continue;
	114	}
	115
fd373593 ZJS	116	if (!item) {
	117	/* Optimize the case where we don't need to store any addresses, by storing
	118	* only the name in a dedicated Set instead of the hashmap */
	119
ab9dd0b9	120	r = set_ensure_consume(&hosts->no_address, &dns_name_hash_ops, TAKE_PTR(name));
fd373593 ZJS	121	if (r < 0)
	122	return r;
	123
fd373593	124	continue;
0351eb11 YW	125	}
0351eb11 YW	126
fd373593 ZJS	127	r = strv_extend(&item->names, name);
	128	if (r < 0)
	129	return log_oom();
	130
37b7cc8d	131	bn = hashmap_get(hosts->by_name, name);
dd0bc0f1	132	if (!bn) {
37b7cc8d	133	r = hashmap_ensure_allocated(&hosts->by_name, &dns_name_hash_ops);
dd0bc0f1 LP	134	if (r < 0)
	135	return log_oom();
	136
	137	bn = new0(EtcHostsItemByName, 1);
	138	if (!bn)
	139	return log_oom();
	140
37b7cc8d	141	r = hashmap_put(hosts->by_name, name, bn);
dd0bc0f1	142	if (r < 0) {
dd0bc0f1 LP	143	free(bn);
	144	return log_oom();
	145	}
0351eb11 YW	146
0351eb11 YW	147	bn->name = TAKE_PTR(name);
dd0bc0f1 LP	148	}
dd0bc0f1 LP	149
319a4f4b	150	if (!GREEDY_REALLOC(bn->addresses, bn->n_addresses + 1))
fd373593	151	return log_oom();
dd0bc0f1	152
fd373593	153	bn->addresses[bn->n_addresses++] = &item->address;
dd0bc0f1 LP	154	}
dd0bc0f1 LP	155
baaa35ad	156	if (!found)
38b38500	157	log_warning("/etc/hosts:%u: line is missing any hostnames", nr);
dd0bc0f1	158
0351eb11	159	return 0;
dd0bc0f1 LP	160	}
dd0bc0f1 LP	161
9ca875e8 LP	162	static void strip_localhost(EtcHosts *hosts) {
	163	static const struct in_addr_data local_in_addrs[] = {
	164	{
	165	.family = AF_INET,
	166	#if __BYTE_ORDER == __LITTLE_ENDIAN
	167	/* We want constant expressions here, that's why we don't use htole32() here */
	168	.address.in.s_addr = UINT32_C(0x0100007F),
	169	#else
	170	.address.in.s_addr = UINT32_C(0x7F000001),
	171	#endif
	172	},
	173	{
	174	.family = AF_INET6,
	175	.address.in6 = IN6ADDR_LOOPBACK_INIT,
	176	},
	177	};
	178
	179	EtcHostsItem *item;
	180
	181	assert(hosts);
	182
	183	/* Removes the 'localhost' entry from what we loaded. But only if the mapping is exclusively between
	184	* 127.0.0.1 and localhost (or aliases to that we recognize). If there's any other name assigned to
	185	* it, we leave the entry in.
	186	*
	187	* This way our regular synthesizing can take over, but only if it would result in the exact same
	188	* mappings. */
	189
	190	for (size_t j = 0; j < ELEMENTSOF(local_in_addrs); j++) {
	191	bool all_localhost, in_order;
	192	char **i;
	193
	194	item = hashmap_get(hosts->by_address, local_in_addrs + j);
	195	if (!item)
	196	continue;
	197
	198	/* Check whether all hostnames the loopback address points to are localhost ones */
	199	all_localhost = true;
	200	STRV_FOREACH(i, item->names)
	201	if (!is_localhost(*i)) {
	202	all_localhost = false;
	203	break;
	204	}
	205
	206	if (!all_localhost) /* Not all names are localhost, hence keep the entries for this address. */
	207	continue;
	208
	209	/* Now check if the names listed for this address actually all point back just to this
	210	* address (or the other loopback address). If not, let's stay away from this too. */
	211	in_order = true;
	212	STRV_FOREACH(i, item->names) {
	213	EtcHostsItemByName *n;
	214	bool all_local_address;
	215
	216	n = hashmap_get(hosts->by_name, *i);
	217	if (!n) /* No reverse entry? Then almost certainly the entry already got deleted from
	218	* the previous iteration of this loop, i.e. via the other protocol */
	219	break;
	220
	221	/* Now check if the addresses of this item are all localhost addresses */
	222	all_local_address = true;
	223	for (size_t m = 0; m < n->n_addresses; m++)
	224	if (!in_addr_is_localhost(n->addresses[m]->family, &n->addresses[m]->address)) {
	225	all_local_address = false;
226	break;
227	}
228
229	if (!all_local_address) {
230	in_order = false;
231	break;
232	}
233	}
234
235	if (!in_order)
236	continue;
237
238	STRV_FOREACH(i, item->names) {
239	EtcHostsItemByName *n;
240
241	n = hashmap_remove(hosts->by_name, *i);
242	if (n)
243	etc_hosts_item_by_name_free(n);
244	}
245
246	assert_se(hashmap_remove(hosts->by_address, local_in_addrs + j) == item);
247	etc_hosts_item_free(item);
248	}
249	}
250
78fc21a1	251	int etc_hosts_parse(EtcHosts hosts, FILE f) {
37b7cc8d	252	_cleanup_(etc_hosts_free) EtcHosts t = {};
37b7cc8d ZJS	253	unsigned nr = 0;
	254	int r;
	255
7c777a77 LP	256	for (;;) {
7c777a77 LP	257	_cleanup_free_ char *line = NULL;
37b7cc8d ZJS	258	char *l;
37b7cc8d ZJS	259
7c777a77 LP	260	r = read_line(f, LONG_LINE_MAX, &line);
	261	if (r < 0)
	262	return log_error_errno(r, "Failed to read /etc/hosts: %m");
	263	if (r == 0)
	264	break;
	265
37b7cc8d ZJS	266	nr++;
37b7cc8d ZJS	267
bd005277 ZJS	268	l = strchr(line, '#');
	269	if (l)
	270	*l = '\0';
	271
37b7cc8d ZJS	272	l = strstrip(line);
	273	if (isempty(l))
	274	continue;
37b7cc8d ZJS	275
	276	r = parse_line(&t, nr, l);
	277	if (r < 0)
	278	return r;
	279	}
	280
9ca875e8 LP	281	strip_localhost(&t);
9ca875e8 LP	282
be19cdf3	283	etc_hosts_free(hosts);
37b7cc8d ZJS	284	*hosts = t;
	285	t = (EtcHosts) {}; /* prevent cleanup */
	286	return 0;
	287	}
	288
452ca091	289	static int manager_etc_hosts_read(Manager *m) {
dd0bc0f1	290	_cleanup_fclose_ FILE *f = NULL;
dd0bc0f1 LP	291	struct stat st;
dd0bc0f1 LP	292	usec_t ts;
dd0bc0f1 LP	293	int r;
	294
	295	assert_se(sd_event_now(m->event, clock_boottime_or_monotonic(), &ts) >= 0);
	296
	297	/* See if we checked /etc/hosts recently already */
	298	if (m->etc_hosts_last != USEC_INFINITY && m->etc_hosts_last + ETC_HOSTS_RECHECK_USEC > ts)
	299	return 0;
	300
	301	m->etc_hosts_last = ts;
	302
36d892b7	303	if (m->etc_hosts_stat.st_mode != 0) {
dd0bc0f1	304	if (stat("/etc/hosts", &st) < 0) {
37b7cc8d ZJS	305	if (errno != ENOENT)
37b7cc8d ZJS	306	return log_error_errno(errno, "Failed to stat /etc/hosts: %m");
dd0bc0f1	307
37b7cc8d ZJS	308	manager_etc_hosts_flush(m);
37b7cc8d ZJS	309	return 0;
dd0bc0f1 LP	310	}
dd0bc0f1 LP	311
aa5408e2	312	/* Did the mtime or ino/dev change? If not, there's no point in re-reading the file. */
36d892b7	313	if (stat_inode_unmodified(&m->etc_hosts_stat, &st))
dd0bc0f1 LP	314	return 0;
	315	}
	316
	317	f = fopen("/etc/hosts", "re");
	318	if (!f) {
37b7cc8d ZJS	319	if (errno != ENOENT)
37b7cc8d ZJS	320	return log_error_errno(errno, "Failed to open /etc/hosts: %m");
dd0bc0f1	321
37b7cc8d ZJS	322	manager_etc_hosts_flush(m);
37b7cc8d ZJS	323	return 0;
dd0bc0f1 LP	324	}
	325
	326	/* Take the timestamp at the beginning of processing, so that any changes made later are read on the next
	327	* invocation */
	328	r = fstat(fileno(f), &st);
	329	if (r < 0)
	330	return log_error_errno(errno, "Failed to fstat() /etc/hosts: %m");
	331
37b7cc8d	332	r = etc_hosts_parse(&m->etc_hosts, f);
be19cdf3	333	if (r < 0)
37b7cc8d	334	return r;
dd0bc0f1	335
36d892b7	336	m->etc_hosts_stat = st;
dd0bc0f1 LP	337	m->etc_hosts_last = ts;
	338
	339	return 1;
dd0bc0f1 LP	340	}
	341
	342	int manager_etc_hosts_lookup(Manager m, DnsQuestion q, DnsAnswer **answer) {
	343	bool found_a = false, found_aaaa = false;
0351eb11	344	struct in_addr_data k = {};
dd0bc0f1	345	EtcHostsItemByName *bn;
dd0bc0f1 LP	346	DnsResourceKey *t;
	347	const char *name;
	348	unsigned i;
	349	int r;
	350
	351	assert(m);
	352	assert(q);
	353	assert(answer);
	354
86317087 YW	355	if (!m->read_etc_hosts)
	356	return 0;
	357
be19cdf3	358	(void) manager_etc_hosts_read(m);
dd0bc0f1 LP	359
	360	name = dns_question_first_name(q);
	361	if (!name)
	362	return 0;
	363
	364	r = dns_name_address(name, &k.family, &k.address);
	365	if (r > 0) {
	366	EtcHostsItem *item;
	367	DnsResourceKey *found_ptr = NULL;
	368
37b7cc8d	369	item = hashmap_get(m->etc_hosts.by_address, &k);
dd0bc0f1 LP	370	if (!item)
	371	return 0;
	372
	373	/* We have an address in /etc/hosts that matches the queried name. Let's return successful. Actual data
	374	* we'll only return if the request was for PTR. */
	375
	376	DNS_QUESTION_FOREACH(t, q) {
	377	if (!IN_SET(t->type, DNS_TYPE_PTR, DNS_TYPE_ANY))
	378	continue;
	379	if (!IN_SET(t->class, DNS_CLASS_IN, DNS_CLASS_ANY))
	380	continue;
	381
1c02e7ba	382	r = dns_name_equal(dns_resource_key_name(t), name);
dd0bc0f1 LP	383	if (r < 0)
	384	return r;
	385	if (r > 0) {
	386	found_ptr = t;
	387	break;
	388	}
	389	}
	390
	391	if (found_ptr) {
	392	char **n;
	393
	394	r = dns_answer_reserve(answer, strv_length(item->names));
	395	if (r < 0)
	396	return r;
	397
	398	STRV_FOREACH(n, item->names) {
	399	_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
	400
	401	rr = dns_resource_record_new(found_ptr);
	402	if (!rr)
	403	return -ENOMEM;
	404
	405	rr->ptr.name = strdup(*n);
	406	if (!rr->ptr.name)
	407	return -ENOMEM;
	408
04617bf8	409	r = dns_answer_add(*answer, rr, 0, DNS_ANSWER_AUTHENTICATED, NULL);
dd0bc0f1 LP	410	if (r < 0)
	411	return r;
	412	}
	413	}
	414
	415	return 1;
	416	}
	417
37b7cc8d	418	bn = hashmap_get(m->etc_hosts.by_name, name);
fd373593 ZJS	419	if (bn) {
	420	r = dns_answer_reserve(answer, bn->n_addresses);
	421	if (r < 0)
	422	return r;
	423	} else {
	424	/* Check if name was listed with no address. If yes, continue to return an answer. */
	425	if (!set_contains(m->etc_hosts.no_address, name))
	426	return 0;
	427	}
dd0bc0f1 LP	428
	429	DNS_QUESTION_FOREACH(t, q) {
	430	if (!IN_SET(t->type, DNS_TYPE_A, DNS_TYPE_AAAA, DNS_TYPE_ANY))
	431	continue;
	432	if (!IN_SET(t->class, DNS_CLASS_IN, DNS_CLASS_ANY))
	433	continue;
	434
1c02e7ba	435	r = dns_name_equal(dns_resource_key_name(t), name);
dd0bc0f1 LP	436	if (r < 0)
	437	return r;
	438	if (r == 0)
	439	continue;
	440
	441	if (IN_SET(t->type, DNS_TYPE_A, DNS_TYPE_ANY))
	442	found_a = true;
	443	if (IN_SET(t->type, DNS_TYPE_AAAA, DNS_TYPE_ANY))
	444	found_aaaa = true;
	445
	446	if (found_a && found_aaaa)
	447	break;
	448	}
	449
fd373593	450	for (i = 0; bn && i < bn->n_addresses; i++) {
dd0bc0f1 LP	451	_cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL;
dd0bc0f1 LP	452
0351eb11 YW	453	if ((!found_a && bn->addresses[i]->family == AF_INET) \|\|
0351eb11 YW	454	(!found_aaaa && bn->addresses[i]->family == AF_INET6))
dd0bc0f1 LP	455	continue;
dd0bc0f1 LP	456
0351eb11	457	r = dns_resource_record_new_address(&rr, bn->addresses[i]->family, &bn->addresses[i]->address, bn->name);
dd0bc0f1 LP	458	if (r < 0)
	459	return r;
	460
04617bf8	461	r = dns_answer_add(*answer, rr, 0, DNS_ANSWER_AUTHENTICATED, NULL);
dd0bc0f1 LP	462	if (r < 0)
	463	return r;
	464	}
	465
4050e04b	466	return found_a \|\| found_aaaa;
dd0bc0f1	467	}