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-rw-r--r--src/shared/dns-domain.c62
-rw-r--r--src/shared/dns-domain.h1
2 files changed, 63 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);