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-rw-r--r--src/shared/dns-domain.c62
-rw-r--r--src/shared/dns-domain.h1
-rw-r--r--src/test/test-dns-domain.c41
3 files changed, 104 insertions, 0 deletions
diff --git a/src/shared/dns-domain.c b/src/shared/dns-domain.c
index 20a44ce4e1..8a472fbcb4 100644
--- a/src/shared/dns-domain.c
+++ b/src/shared/dns-domain.c
@@ -114,6 +114,68 @@ int dns_label_unescape(const char **name, char *dest, size_t sz) {
return r;
}
+/* @label_terminal: terminal character of a label, updated to point to the terminal character of
+ * the previous label (always skipping one dot) or to NULL if there are no more
+ * labels. */
+int dns_label_unescape_suffix(const char *name, const char **label_terminal, char *dest, size_t sz) {
+ const char *terminal;
+ int r;
+
+ assert(name);
+ assert(label_terminal);
+ assert(dest);
+
+ /* no more labels */
+ if (!*label_terminal) {
+ if (sz >= 1)
+ *dest = 0;
+
+ return 0;
+ }
+
+ assert(**label_terminal == '.' || **label_terminal == 0);
+
+ /* skip current terminal character */
+ terminal = *label_terminal - 1;
+
+ /* point name to the last label, and terminal to the preceding terminal symbol (or make it a NULL pointer) */
+ for (;;) {
+ if (terminal < name) {
+ /* reached the first label, so indicate that there are no more */
+ terminal = NULL;
+ break;
+ }
+
+ /* find the start of the last label */
+ if (*terminal == '.') {
+ const char *y;
+ unsigned slashes = 0;
+
+ for (y = terminal - 1; y >= name && *y == '\\'; y--)
+ slashes ++;
+
+ if (slashes % 2 == 0) {
+ /* the '.' was not escaped */
+ name = terminal + 1;
+ break;
+ } else {
+ terminal = y;
+ continue;
+ }
+ }
+
+ terminal --;
+ }
+
+ r = dns_label_unescape(&name, dest, sz);
+ if (r < 0)
+ return r;
+
+ *label_terminal = terminal;
+
+ return r;
+}
+
int dns_label_escape(const char *p, size_t l, char **ret) {
_cleanup_free_ char *s = NULL;
char *q;
diff --git a/src/shared/dns-domain.h b/src/shared/dns-domain.h
index 00caf5d700..5728ce34bb 100644
--- a/src/shared/dns-domain.h
+++ b/src/shared/dns-domain.h
@@ -29,6 +29,7 @@
#define DNS_NAME_MAX 255
int dns_label_unescape(const char **name, char *dest, size_t sz);
+int dns_label_unescape_suffix(const char *name, const char **label_end, char *dest, size_t sz);
int dns_label_escape(const char *p, size_t l, char **ret);
int dns_label_apply_idna(const char *encoded, size_t encoded_size, char *decoded, size_t decoded_max);
diff --git a/src/test/test-dns-domain.c b/src/test/test-dns-domain.c
index 527cdd3b54..9a5a2a1c23 100644
--- a/src/test/test-dns-domain.c
+++ b/src/test/test-dns-domain.c
@@ -50,6 +50,46 @@ static void test_dns_label_unescape(void) {
test_dns_label_unescape_one("foobar.", "foobar", 20, 6);
}
+static void test_dns_label_unescape_suffix_one(const char *what, const char *expect1, const char *expect2, size_t buffer_sz, int ret1, int ret2) {
+ char buffer[buffer_sz];
+ const char *label;
+ int r;
+
+ label = what + strlen(what);
+
+ r = dns_label_unescape_suffix(what, &label, buffer, buffer_sz);
+ assert_se(r == ret1);
+ if (r >= 0)
+ assert_se(streq(buffer, expect1));
+
+ r = dns_label_unescape_suffix(what, &label, buffer, buffer_sz);
+ assert_se(r == ret2);
+ if (r >= 0)
+ assert_se(streq(buffer, expect2));
+}
+
+static void test_dns_label_unescape_suffix(void) {
+ test_dns_label_unescape_suffix_one("hallo", "hallo", "", 6, 5, 0);
+ test_dns_label_unescape_suffix_one("hallo", "hallo", "", 4, -ENOSPC, -ENOSPC);
+ test_dns_label_unescape_suffix_one("", "", "", 10, 0, 0);
+ test_dns_label_unescape_suffix_one("hallo\\.foobar", "hallo.foobar", "", 20, 12, 0);
+ test_dns_label_unescape_suffix_one("hallo.foobar", "foobar", "hallo", 10, 6, 5);
+ test_dns_label_unescape_suffix_one("hallo.foobar\n", "foobar", "foobar", 20, -EINVAL, -EINVAL);
+ test_dns_label_unescape_suffix_one("hallo\\", "hallo", "hallo", 20, -EINVAL, -EINVAL);
+ test_dns_label_unescape_suffix_one("hallo\\032 ", "hallo ", "", 20, 7, 0);
+ test_dns_label_unescape_suffix_one(".", "", "", 20, 0, 0);
+ test_dns_label_unescape_suffix_one("..", "", "", 20, 0, 0);
+ test_dns_label_unescape_suffix_one(".foobar", "foobar", "", 20, 6, -EINVAL);
+ test_dns_label_unescape_suffix_one("foobar.", "", "foobar", 20, 0, 6);
+ test_dns_label_unescape_suffix_one("foo\\\\bar", "foo\\bar", "", 20, 7, 0);
+ test_dns_label_unescape_suffix_one("foo.bar", "bar", "foo", 20, 3, 3);
+ test_dns_label_unescape_suffix_one("foo..bar", "bar", "", 20, 3, -EINVAL);
+ test_dns_label_unescape_suffix_one("foo...bar", "bar", "", 20, 3, -EINVAL);
+ test_dns_label_unescape_suffix_one("foo\\.bar", "foo.bar", "", 20, 7, 0);
+ test_dns_label_unescape_suffix_one("foo\\\\.bar", "bar", "foo\\", 20, 3, 4);
+ test_dns_label_unescape_suffix_one("foo\\\\\\.bar", "foo\\.bar", "", 20, 8, 0);
+}
+
static void test_dns_label_escape_one(const char *what, size_t l, const char *expect, int ret) {
_cleanup_free_ char *t = NULL;
int r;
@@ -180,6 +220,7 @@ static void test_dns_name_reverse(void) {
int main(int argc, char *argv[]) {
test_dns_label_unescape();
+ test_dns_label_unescape_suffix();
test_dns_label_escape();
test_dns_name_normalize();
test_dns_name_equal();