Implement SNI when using DNS-over-TLS

Some DNS providers need SNI to identify client.

This can be used by adding #name to a DNS.
Example:
[Resolve]
DNS=192.168.1.1#example.com

1 files changed, 36 insertions, 0 deletions

diff --git a/src/resolve/resolved-util.c b/src/resolve/resolved-util.c
new file mode 100644
index 0000000000..2f18f8c19d
--- /dev/null
+++ b/src/resolve/resolved-util.c
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include "alloc-util.h"
+#include "in-addr-util.h"
+#include "macro.h"
+#include "resolved-util.h"
+
+int in_addr_ifindex_name_from_string_auto(const char *s, int *family, union in_addr_union *ret, int *ifindex, char **server_name) {
+        _cleanup_free_ char *buf = NULL, *name = NULL;
+        const char *m;
+        int r;
+
+        assert(s);
+
+        m = strchr(s, '#');
+        if (m) {
+                name = strdup(m+1);
+                if (!name)
+                        return -ENOMEM;
+
+                buf = strndup(s, m - s);
+                if (!buf)
+                        return -ENOMEM;
+
+                s = buf;
+        }
+
+        r = in_addr_ifindex_from_string_auto(s, family, ret, ifindex);
+        if (r < 0)
+                return r;
+
+        if (server_name)
+                *server_name = TAKE_PTR(name);
+
+        return r;
+}