diff --git a/libc/private/resolv_cache.h b/libc/private/resolv_cache.h
new file mode 100644
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+++ b/libc/private/resolv_cache.h
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+#ifndef _RESOLV_CACHE_H_
+#define _RESOLV_CACHE_H_
+
+struct resolv_cache;  /* forward */
+
+/* get cache instance, can be NULL if cache is disabled
+ * (e.g. through an environment variable) */
+extern struct resolv_cache*  __get_res_cache(void);
+
+/* this gets called everytime we detect some changes in the DNS configuration
+ * and will flush the cache */
+extern void   _resolv_cache_reset( unsigned  generation );
+
+typedef enum {
+    RESOLV_CACHE_UNSUPPORTED,  /* the cache can't handle that kind of queries */
+                               /* or the answer buffer is too small */
+    RESOLV_CACHE_NOTFOUND,     /* the cache doesn't know about this query */
+    RESOLV_CACHE_FOUND         /* the cache found the answer */
+} ResolvCacheStatus;
+
+extern ResolvCacheStatus
+_resolv_cache_lookup( struct resolv_cache*  cache,
+                      const void*           query,
+                      int                   querylen,
+                      void*                 answer,
+                      int                   answersize,
+                      int                  *answerlen );
+
+/* add a (query,answer) to the cache, only call if _resolv_cache_lookup
+ * did return RESOLV_CACHE_NOTFOUND
+ */
+extern void
+_resolv_cache_add( struct resolv_cache*  cache,
+                   const void*           query,
+                   int                   querylen,
+                   const void*           answer,
+                   int                   answerlen );
+
+#endif /* _RESOLV_CACHE_H_ */