libndb: move mkptrname() into libndb to avoid duplication

1 files changed, 29 insertions, 0 deletions

diff --git a/sys/src/libndb/mkptrname.c b/sys/src/libndb/mkptrname.c
new file mode 100644
index 000000000..759aad5bd
--- /dev/null
+++ b/sys/src/libndb/mkptrname.c
@@ -0,0 +1,29 @@
+#include <u.h>
+#include <libc.h>
+#include <ip.h>
+
+/*
+ *  convert address into a reverse lookup address
+ */
+void
+mkptrname(char *ip, char *rip, int rlen)
+{
+	uchar a[IPaddrlen];
+	char *p, *e;
+	int i;
+
+	if(cistrstr(ip, "in-addr.arpa") || cistrstr(ip, "ip6.arpa") || parseip(a, ip) == -1)
+		snprint(rip, rlen, "%s", ip);
+	else if(isv4(a))
+		snprint(rip, rlen, "%ud.%ud.%ud.%ud.in-addr.arpa",
+			a[15], a[14], a[13], a[12]);
+	else{
+		p = rip;
+		e = rip + rlen;
+		for(i = 15; i >= 0; i--){
+			p = seprint(p, e, "%ux.", a[i]&0xf);
+			p = seprint(p, e, "%ux.", a[i]>>4);
+		}
+		seprint(p, e, "ip6.arpa");
+	}
+}