HTTP/2: the "421 Misdirected Request" response (closes #848). Since 4fbef397c753 nginx rejects with the 400 error any attempts of requesting different host over the same connection, if the relevant virtual server requires verification of a client certificate. While requesting hosts other than negotiated isn't something legal in HTTP/1.x, the HTTP/2 specification explicitly permits such requests for connection reuse and has introduced a special response code 421. According to RFC 7540 Section 9.1.2 this code can be sent by a server that is not configured to produce responses for the combination of scheme and authority that are included in the request URI. And the client may retry the request over a different connection. Now this code is used for requests that aren't authorized in current connection. After receiving the 421 response a client will be able to open a new connection, provide the required certificate and retry the request. Unfortunately, not all clients currently are able to handle it well. Notably Chrome just shows an error, while at least the latest version of Firefox retries the request over a new connection.

# Copyright (C) Igor Sysoev
# Copyright (C) Nginx, Inc.


echo $ngx_n "checking for $ngx_include ...$ngx_c"

cat << END >> $NGX_AUTOCONF_ERR

----------------------------------------
checking for $ngx_include

END


ngx_found=no

cat << END > $NGX_AUTOTEST.c

$NGX_INCLUDE_SYS_PARAM_H
#include <$ngx_include>

int main() {
    return 0;
}

END


ngx_test="$CC -o $NGX_AUTOTEST $NGX_AUTOTEST.c"

eval "$ngx_test >> $NGX_AUTOCONF_ERR 2>&1"

if [ -x $NGX_AUTOTEST ]; then

    ngx_found=yes

    echo " found"

    ngx_name=`echo $ngx_include \
              | tr abcdefghijklmnopqrstuvwxyz/. ABCDEFGHIJKLMNOPQRSTUVWXYZ__`


    have=NGX_HAVE_$ngx_name . auto/have_headers

    eval "NGX_INCLUDE_$ngx_name='#include <$ngx_include>'"

    #STUB
    eval "NGX_$ngx_name='#include <$ngx_include>'"

else
    echo " not found"

    echo "----------"    >> $NGX_AUTOCONF_ERR
    cat $NGX_AUTOTEST.c  >> $NGX_AUTOCONF_ERR
    echo "----------"    >> $NGX_AUTOCONF_ERR
    echo $ngx_test       >> $NGX_AUTOCONF_ERR
    echo "----------"    >> $NGX_AUTOCONF_ERR
fi

rm -rf $NGX_AUTOTEST*