shared: recognize DNS names with more than one trailing dot as invalid (#4111)

One trailing dot is valid, but more than one isn't. This also fixes glibc's
posix/tst-getaddrinfo5 test.

Fixes #3978.

diff --git a/src/shared/dns-domain.c b/src/shared/dns-domain.c
index 835557c..892f0aa 100644 (file)
--- a/src/shared/dns-domain.c
+++ b/src/shared/dns-domain.c
@@ -131,6 +131,10 @@ int dns_label_unescape(const char **name, char *dest, size_t sz) {
         if (r == 0 && *n)
                 return -EINVAL;
 
+        /* More than one trailing dot? */
+        if (*n == '.')
+                return -EINVAL;
+
         if (sz >= 1 && d)
                 *d = 0;
 

diff --git a/src/test/test-dns-domain.c b/src/test/test-dns-domain.c
index a9d09f5..e2f097c 100644 (file)
--- a/src/test/test-dns-domain.c
+++ b/src/test/test-dns-domain.c
@@ -48,6 +48,7 @@ static void test_dns_label_unescape(void) {
         test_dns_label_unescape_one("..", "", 20, -EINVAL);
         test_dns_label_unescape_one(".foobar", "", 20, -EINVAL);
         test_dns_label_unescape_one("foobar.", "foobar", 20, 6);
+        test_dns_label_unescape_one("foobar..", "foobar", 20, -EINVAL);
 }
 
 static void test_dns_name_to_wire_format_one(const char *what, const char *expect, size_t buffer_sz, int ret) {
@@ -359,6 +360,7 @@ static void test_dns_name_is_valid_one(const char *s, int ret) {
 static void test_dns_name_is_valid(void) {
         test_dns_name_is_valid_one("foo", 1);
         test_dns_name_is_valid_one("foo.", 1);
+        test_dns_name_is_valid_one("foo..", 0);
         test_dns_name_is_valid_one("Foo", 1);
         test_dns_name_is_valid_one("foo.bar", 1);
         test_dns_name_is_valid_one("foo.bar.baz", 1);
@@ -366,6 +368,7 @@ static void test_dns_name_is_valid(void) {
         test_dns_name_is_valid_one("foo..bar", 0);
         test_dns_name_is_valid_one(".foo.bar", 0);
         test_dns_name_is_valid_one("foo.bar.", 1);
+        test_dns_name_is_valid_one("foo.bar..", 0);
         test_dns_name_is_valid_one("\\zbar", 0);
         test_dns_name_is_valid_one("ä", 1);
         test_dns_name_is_valid_one("\n", 0);