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systemd/src/resolve/resolved-etc-hosts.c
Vito Caputo 313cefa1d9 tree-wide: make ++/-- usage consistent WRT spacing 
Throughout the tree there's spurious use of spaces separating ++ and --
operators from their respective operands.  Make ++ and -- operator
consistent with the majority of existing uses; discard the spaces.
2016-02-22 20:32:04 -08:00

449 lines
14 KiB
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/***
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 <http://www.gnu.org/licenses/>.
***/
#include "fd-util.h"
#include "fileio.h"
#include "hostname-util.h"
#include "resolved-etc-hosts.h"
#include "resolved-dns-synthesize.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)
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;
}
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