1 files changed, 36 insertions, 0 deletions
diff --git a/src/rexmpp_dns.c b/src/rexmpp_dns.c
new file mode 100644
index 0000000..6a8e743
--- /dev/null
+++ b/src/rexmpp_dns.c
@@ -0,0 +1,36 @@
+/**
+   @file rexmpp_dns.c
+   @brief DNS helper functions
+   @author defanor <defanor@uberspace.net>
+   @date 2020
+   @copyright MIT license.
+*/
+
+#include "rexmpp_dns.h"
+#include <memory.h>
+
+/* https://tools.ietf.org/html/rfc1035#section-3.1 */
+int rexmpp_parse_srv (char *in, int in_len, struct rexmpp_dns_srv *out) {
+  int i;
+  char *name;
+  if (in_len < 7 || in_len > 255 + 6) {
+    return -1;
+  }
+  out->priority = in[0] * 0x100 + in[1];
+  out->weight = in[2] * 0x100 + in[3];
+  out->port = in[4] * 0x100 + in[5];
+  name = in + 6;
+  i = 0;
+  while (name[i]) {
+    if (i + name[i] < 255) {
+      memcpy(out->target + i, name + i + 1, name[i]);
+      i += name[i];
+      out->target[i] = '.';
+      i++;
+      out->target[i] = '\0';
+    } else {
+      return -1;
+    }
+  }
+  return 0;
+}