id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	uname	nginx_version
1330	OCSP stapling non-functional on IPv6-only host	ramcq@…		"I have an IPv6-only host running CentOS 7. I have a Lets Encrypt certificate on the host and I've enabled OCSP stapling per the Mozilla preferred SSL stuff.  My provider has NAT64 set-up so I've configured their NAT64 resolvers in the resolve entry in nginx.conf.

{{{
        # OCSP Stapling ---
        # fetch OCSP records from URL in ssl_certificate and cache them
        ssl_stapling on;
        ssl_stapling_verify on;

        # verify chain of trust of OCSP response using Root CA and Intermediate certs
        ssl_trusted_certificate /etc/dehydrated/certs/flathub.org/chain.pem;

        resolver [2a00:1098:0:80:1000:3b:0:1] [2a00:1098:0:82:1000:3b:0:1];
}}}

I see this error:

{{{
2017/07/24 14:02:23 [error] 16637#0: connect() to 88.221.134.147:80 failed (101: Network is unreachable) while requesting certificate status, responder: ocsp.int-x3.letsencrypt.org
}}}

I believe that it's because this host returns two A and two AAAA results:

{{{
[root@front nginx]# host ocsp.int-x3.letsencrypt.org
ocsp.int-x3.letsencrypt.org is an alias for ocsp.int-x3.letsencrypt.org.edgesuite.net.
ocsp.int-x3.letsencrypt.org.edgesuite.net is an alias for a771.dscq.akamai.net.
a771.dscq.akamai.net has address 88.221.134.114
a771.dscq.akamai.net has address 88.221.134.147
a771.dscq.akamai.net has IPv6 address 2a02:26f0:e8::6856:6fb0
a771.dscq.akamai.net has IPv6 address 2a02:26f0:e8::6856:6f88
}}}

However the SSL stapling code only attempts to connect the first one: https://github.com/nginx/nginx/blob/9197a3c8741a8832e6f6ed24a72dc5b078d840fd/src/event/ngx_event_openssl_stapling.c#L1028

I've tried to work around with /etc/hosts but that seems unused, and OCSP stapling seems to disable itself if I have no resolver configuration entry. I can't seem to place an IPv6 address in the ssl_stapling_responder either.
"	defect	closed	major		nginx-core	1.10.x	fixed			Linux front.flathub.org 3.10.0-514.26.2.el7.x86_64 #1 SMP Tue Jul 4 15:04:05 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux	"ginx version: nginx/1.10.2
built by gcc 4.8.5 20150623 (Red Hat 4.8.5-4) (GCC) 
built with OpenSSL 1.0.1e-fips 11 Feb 2013
TLS SNI support enabled
configure arguments: --prefix=/usr/share/nginx --sbin-path=/usr/sbin/nginx --modules-path=/usr/lib64/nginx/modules --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --http-client-body-temp-path=/var/lib/nginx/tmp/client_body --http-proxy-temp-path=/var/lib/nginx/tmp/proxy --http-fastcgi-temp-path=/var/lib/nginx/tmp/fastcgi --http-uwsgi-temp-path=/var/lib/nginx/tmp/uwsgi --http-scgi-temp-path=/var/lib/nginx/tmp/scgi --pid-path=/run/nginx.pid --lock-path=/run/lock/subsys/nginx --user=nginx --group=nginx --with-file-aio --with-ipv6 --with-http_ssl_module --with-http_v2_module --with-http_realip_module --with-http_addition_module --with-http_xslt_module=dynamic --with-http_image_filter_module=dynamic --with-http_geoip_module=dynamic --with-http_sub_module --with-http_dav_module --with-http_flv_module --with-http_mp4_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_random_index_module --with-http_secure_link_module --with-http_degradation_module --with-http_slice_module --with-http_stub_status_module --with-http_perl_module=dynamic --with-mail=dynamic --with-mail_ssl_module --with-pcre --with-pcre-jit --with-stream=dynamic --with-stream_ssl_module --with-google_perftools_module --with-debug --with-cc-opt='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -mtune=generic' --with-ld-opt='-Wl,-z,relro -specs=/usr/lib/rpm/redhat/redhat-hardened-ld -Wl,-E'"