1 files changed, 19 insertions, 0 deletions
diff --git a/src/libs6dns/s6dns_domain_arpafromip4.c b/src/libs6dns/s6dns_domain_arpafromip4.c
new file mode 100644
index 0000000..d77938f
--- /dev/null
+++ b/src/libs6dns/s6dns_domain_arpafromip4.c
@@ -0,0 +1,19 @@
+/* ISC license. */
+
+#include <skalibs/bytestr.h>
+#include <skalibs/uint.h>
+#include <s6-dns/s6dns-domain.h>
+
+void s6dns_domain_arpafromip4 (s6dns_domain_t *d, char const *ip)
+{
+  register unsigned int i = 0 ;
+  d->len = 0 ;
+  d->s[d->len++] = '.' ;  
+  for (; i < 4 ; i++)
+  {
+    register unsigned int u = ((unsigned char *)ip)[3-i] ;
+    d->len += uint_fmt(d->s + d->len, u) ;
+    d->s[d->len++] = '.' ;
+  }
+  byte_copy(d->s + d->len, 13, "in-addr.arpa.") ; d->len += 13 ;
+}