New function `inaddr2str' to convert an IP address into a verified

hostname or a string of the form x.y.z.a


git-svn-id: svn://svn.h5l.se/heimdal/trunk/heimdal@656 ec53bebd-3082-4978-b11e-865c3cabbd6b

lib/roken/inaddr2str.c

@@ -0,0 +1,42 @@
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+RCSID("$Id$");
+#endif
+
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#ifdef HAVE_ARPA_INET_H
+#include <arpa/inet.h>
+#endif
+#include <netdb.h>
+#include "roken.h"
+
+/*
+ * Get a verified name for `addr'.
+ * If unable to find it in the DNS, return x.y.z.a
+ */
+
+void
+inaddr2str(struct in_addr addr, char *s, size_t len)
+{
+  struct hostent *h;
+  char *p;
+
+  h = gethostbyaddr ((const char *)&addr, sizeof(addr), AF_INET);
+  if (h) {
+    h = gethostbyname (h->h_name);
+    if(h)
+      while ((p = *(h->h_addr_list)++))
+	if (memcmp (p, &addr, h->h_length) == 0) {
+	  strncpy (s, h->h_name, len);
+	  s[len - 1] = '\0';
+	  return;
+	}
+  }
+  strncpy (s, inet_ntoa (addr), len);
+  s[len - 1] = '\0';
+  return;
+}