This check works also with to non-configure platforms.
#ifdef USE_NGHTTP2
+/* Check for OpenSSL 1.0.2 which has ALPN support. */
#undef HAS_ALPN
-#if defined(HAVE_SSL_CTX_SET_ALPN_PROTOS) && \
- defined(HAVE_SSL_CTX_SET_ALPN_SELECT_CB)
-# define HAS_ALPN 1
-#endif
-
-#if !defined(HAVE_SSL_CTX_SET_NEXT_PROTO_SELECT_CB) || \
- defined(OPENSSL_NO_NEXTPROTONEG)
-# if !defined(HAS_ALPN)
-# error http2 builds require OpenSSL with NPN or ALPN support
-# endif
+#if OPENSSL_VERSION_NUMBER >= 0x10002000L && !defined(OPENSSL_NO_NEXTPROTONEG) \
+ && !defined(OPENSSL_NO_TLSEXT)
+# define HAS_ALPN
+#else
+# error http2 builds require OpenSSL with NPN or ALPN support
#endif