resolved: rework parsing of /etc/hosts
Do not treat various errors (missing hostname, invalid address) as fatal, just warn and continue. /etc/hosts is written by humans and we should not reject the whole file just because a singly entry is not to our liking. Handle comments as described in hosts(5): everything from the comment character until the end of the line should be ignored. Fixes #10779. Add tests.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
parent
c9ff152e92
commit
bd00527779
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@ -46,19 +46,20 @@ static int parse_line(EtcHosts *hosts, unsigned nr, const char *line) {
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r = extract_first_word(&line, &address_str, NULL, EXTRACT_RELAX);
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if (r < 0)
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return log_error_errno(r, "Couldn't extract address, in line /etc/hosts:%u.", nr);
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if (r == 0)
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"Premature end of line, in line /etc/hosts:%u.",
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nr);
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return log_error_errno(r, "/etc/hosts:%u: failed to extract address: %m", nr);
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assert(r > 0); /* We already checked that the line is not empty, so it should contain *something* */
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r = in_addr_ifindex_from_string_auto(address_str, &address.family, &address.address, NULL);
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if (r < 0)
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return log_error_errno(r, "Address '%s' is invalid, in line /etc/hosts:%u.", address_str, nr);
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if (r < 0) {
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log_warning_errno(r, "/etc/hosts:%u: address '%s' is invalid, ignoring: %m", nr, address_str);
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return 0;
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}
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r = in_addr_is_null(address.family, &address.address);
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if (r < 0)
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return r;
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if (r < 0) {
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log_warning_errno(r, "/etc/hosts:%u: address '%s' is invalid, ignoring: %m", nr, address_str);
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return 0;
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}
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if (r > 0)
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/* This is an 0.0.0.0 or :: item, which we assume means that we shall map the specified hostname to
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* nothing. */
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@ -92,16 +93,18 @@ static int parse_line(EtcHosts *hosts, unsigned nr, const char *line) {
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r = extract_first_word(&line, &name, NULL, EXTRACT_RELAX);
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if (r < 0)
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return log_error_errno(r, "Couldn't extract host name, in line /etc/hosts:%u.", nr);
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return log_error_errno(r, "/etc/hosts:%u: couldn't extract host name: %m", nr);
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if (r == 0)
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break;
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r = dns_name_is_valid(name);
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if (r <= 0)
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return log_error_errno(r, "Hostname %s is not valid, ignoring, in line /etc/hosts:%u.", name, nr);
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found = true;
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r = dns_name_is_valid(name);
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if (r <= 0) {
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log_warning_errno(r, "/etc/hosts:%u: hostname \"%s\" is not valid, ignoring.", nr, name);
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continue;
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}
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if (is_localhost(name))
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/* Suppress the "localhost" line that is often seen */
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continue;
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@ -152,9 +155,7 @@ static int parse_line(EtcHosts *hosts, unsigned nr, const char *line) {
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}
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if (!found)
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return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
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"Line is missing any host names, in line /etc/hosts:%u.",
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nr);
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log_warning("/etc/hosts:%u: line is missing any host names", nr);
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return 0;
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}
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@ -176,11 +177,13 @@ int etc_hosts_parse(EtcHosts *hosts, FILE *f) {
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nr++;
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l = strchr(line, '#');
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if (l)
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*l = '\0';
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l = strstrip(line);
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if (isempty(l))
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continue;
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if (l[0] == '#')
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continue;
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r = parse_line(&t, nr, l);
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if (r < 0)
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@ -1,9 +1,15 @@
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/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <arpa/inet.h>
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#include <netinet/in.h>
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#include <sys/socket.h>
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#include "fd-util.h"
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#include "fileio.h"
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#include "fs-util.h"
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#include "log.h"
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#include "resolved-etc-hosts.h"
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#include "strv.h"
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#include "tmpfile-util.h"
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static void test_parse_etc_hosts_system(void) {
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@ -21,6 +27,14 @@ static void test_parse_etc_hosts_system(void) {
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assert_se(etc_hosts_parse(&hosts, f) == 0);
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}
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#define address_equal_4(_addr, _address) \
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((_addr)->family == AF_INET && \
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!memcmp(&(_addr)->address.in, &(struct in_addr) { .s_addr = (_address) }, 4))
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#define address_equal_6(_addr, ...) \
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((_addr)->family == AF_INET6 && \
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!memcmp(&(_addr)->address.in6, &(struct in6_addr) { .s6_addr = __VA_ARGS__}, 16) )
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static void test_parse_etc_hosts(void) {
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_cleanup_(unlink_tempfilep) char
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t[] = "/tmp/test-resolved-etc-hosts.XXXXXX";
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@ -29,19 +43,31 @@ static void test_parse_etc_hosts(void) {
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int fd;
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_cleanup_fclose_ FILE *f;
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const char *s;
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fd = mkostemp_safe(t);
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assert_se(fd >= 0);
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f = fdopen(fd, "r+");
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assert_se(f);
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fputs("1.2.3.4 some.where\n", f);
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fputs("1.2.3.5 some.where\n", f);
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fputs("::0 some.where some.other\n", f);
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fputs("0.0.0.0 black.listed\n", f);
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fputs("::5 some.where some.other foobar.foo.foo\n", f);
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fputs(" \n", f);
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fflush(f);
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fputs("1.2.3.4 some.where\n"
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"1.2.3.5 some.where\n"
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"1.2.3.6 dash dash-dash.where-dash\n"
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"1.2.3.7 bad-dash- -bad-dash -bad-dash.bad-\n"
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"1.2.3.8\n"
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"1.2.3.9 before.comment # within.comment\n"
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"1.2.3.10 before.comment#within.comment2\n"
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"1.2.3.11 before.comment# within.comment3\n"
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"1.2.3.12 before.comment#\n"
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"1.2.3 short.address\n"
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"1.2.3.4.5 long.address\n"
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"1::2::3 multi.colon\n"
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"::0 some.where some.other\n"
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"0.0.0.0 black.listed\n"
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"::5\t\t\t \tsome.where\tsome.other foobar.foo.foo\t\t\t\n"
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" \n", f);
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assert_se(fflush_and_check(f) >= 0);
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rewind(f);
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_cleanup_(etc_hosts_free) EtcHosts hosts = {};
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@ -51,23 +77,54 @@ static void test_parse_etc_hosts(void) {
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assert_se(bn = hashmap_get(hosts.by_name, "some.where"));
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assert_se(bn->n_addresses == 3);
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assert_se(bn->n_allocated >= 3);
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assert_se(address_equal_4(bn->addresses[0], inet_addr("1.2.3.4")));
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assert_se(address_equal_4(bn->addresses[1], inet_addr("1.2.3.5")));
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assert_se(address_equal_6(bn->addresses[2], {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5}));
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assert_se(bn->addresses[0]->family == AF_INET);
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assert_se(memcmp(&bn->addresses[0]->address.in,
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&(struct in_addr) { .s_addr = htobe32(0x01020304) }, 4) == 0);
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assert_se(bn->addresses[1]->family == AF_INET);
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assert_se(memcmp(&bn->addresses[1]->address.in,
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&(struct in_addr) { .s_addr = htobe32(0x01020305) }, 4) == 0);
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assert_se(bn->addresses[2]->family == AF_INET6);
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assert_se(memcmp(&bn->addresses[2]->address.in6,
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&(struct in6_addr) { .s6_addr = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5} }, 16 ) == 0);
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assert_se(bn = hashmap_get(hosts.by_name, "dash"));
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assert_se(bn->n_addresses == 1);
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assert_se(bn->n_allocated >= 1);
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assert_se(address_equal_4(bn->addresses[0], inet_addr("1.2.3.6")));
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assert_se(bn = hashmap_get(hosts.by_name, "dash-dash.where-dash"));
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assert_se(bn->n_addresses == 1);
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assert_se(bn->n_allocated >= 1);
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assert_se(address_equal_4(bn->addresses[0], inet_addr("1.2.3.6")));
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/* Those names do not follow the LDH rule, but so far we allow them.
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* Let's make this explicit by adding a test.
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* See https://tools.ietf.org/html/rfc1035#section-2.3.1 */
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FOREACH_STRING(s, "bad-dash-", "-bad-dash", "-bad-dash.bad-") {
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assert_se(bn = hashmap_get(hosts.by_name, s));
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assert_se(bn->n_addresses == 1);
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assert_se(bn->n_allocated >= 1);
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assert_se(address_equal_4(bn->addresses[0], inet_addr("1.2.3.7")));
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}
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assert_se(bn = hashmap_get(hosts.by_name, "before.comment"));
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assert_se(bn->n_addresses == 4);
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assert_se(bn->n_allocated >= 4);
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assert_se(address_equal_4(bn->addresses[0], inet_addr("1.2.3.9")));
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assert_se(address_equal_4(bn->addresses[1], inet_addr("1.2.3.10")));
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assert_se(address_equal_4(bn->addresses[2], inet_addr("1.2.3.11")));
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assert_se(address_equal_4(bn->addresses[3], inet_addr("1.2.3.12")));
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assert(!hashmap_get(hosts.by_name, "within.comment"));
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assert(!hashmap_get(hosts.by_name, "within.comment2"));
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assert(!hashmap_get(hosts.by_name, "within.comment3"));
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assert(!hashmap_get(hosts.by_name, "#"));
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assert(!hashmap_get(hosts.by_name, "short.address"));
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assert(!hashmap_get(hosts.by_name, "long.address"));
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assert(!hashmap_get(hosts.by_name, "multi.colon"));
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assert_se(!set_contains(hosts.no_address, "short.address"));
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assert_se(!set_contains(hosts.no_address, "long.address"));
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assert_se(!set_contains(hosts.no_address, "multi.colon"));
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assert_se(bn = hashmap_get(hosts.by_name, "some.other"));
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assert_se(bn->n_addresses == 1);
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assert_se(bn->n_allocated >= 1);
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assert_se(bn->addresses[0]->family == AF_INET6);
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assert_se(memcmp(&bn->addresses[0]->address.in6,
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&(struct in6_addr) { .s6_addr = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5} }, 16 ) == 0);
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assert_se(address_equal_6(bn->addresses[0], {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 5}));
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assert_se( set_contains(hosts.no_address, "some.where"));
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assert_se( set_contains(hosts.no_address, "some.other"));
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