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-rw-r--r--src/resolve/resolved-etc-hosts.c448
1 files changed, 448 insertions, 0 deletions
diff --git a/src/resolve/resolved-etc-hosts.c b/src/resolve/resolved-etc-hosts.c
new file mode 100644
index 0000000000..ee82c96822
--- /dev/null
+++ b/src/resolve/resolved-etc-hosts.c
@@ -0,0 +1,448 @@
+/***
+ 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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