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--- a/modules/ssl/ssl_engine_kernel.c	2015/06/09 15:55:41	1684461
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+++ b/modules/ssl/ssl_engine_kernel.c	2015/06/09 16:09:28	1684462
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@@ -1940,7 +1940,7 @@
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 #ifndef OPENSSL_NO_TLSEXT
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 /*
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  * This callback function is executed when OpenSSL encounters an extended
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- * client hello with a server name indication extension ("SNI", cf. RFC 4366).
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+ * client hello with a server name indication extension ("SNI", cf. RFC 6066).
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  */
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 int ssl_callback_ServerNameIndication(SSL *ssl, int *al, modssl_ctx_t *mctx)
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 {
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@@ -1962,7 +1962,21 @@
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                               "No matching SSL virtual host for servername "
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                               "%s found (using default/first virtual host)",
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                               servername);
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-                return SSL_TLSEXT_ERR_ALERT_WARNING;
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+                /*
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+                 * RFC 6066 section 3 says "It is NOT RECOMMENDED to send
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+                 * a warning-level unrecognized_name(112) alert, because
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+                 * the client's behavior in response to warning-level alerts
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+                 * is unpredictable."
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+                 *
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+                 * To maintain backwards compatibility in mod_ssl, we
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+                 * no longer send any alert (neither warning- nor fatal-level),
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+                 * i.e. we take the second action suggested in RFC 6066:
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+                 * "If the server understood the ClientHello extension but
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+                 * does not recognize the server name, the server SHOULD take
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+                 * one of two actions: either abort the handshake by sending
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+                 * a fatal-level unrecognized_name(112) alert or continue
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+                 * the handshake."
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+                 */
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             }
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         }
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     }