HTTP/3 and php POST

[Ryan Gould]

hello team,

i have found that https://hg.nginx.org/nginx-quic (current as of 06 Nov 2020)
is having some trouble properly POSTing back to PayPal using php 7.3.24 on
a Debian Buster box. things work as expected using current mainline nginx
or current quiche.  i have verified that PageSpeed is not causing the problem.

the PayPal IPN php script is one of those things that has been working so
long it has cobwebs on it.  it gets a POST, it adds a key / value to the
payload and POSTs it back.  it is instantaneous and thoughtless.  the PHP
script is getting a 200 return code from the return POST and everything
seems great on my side.  but PayPal is complaining about the return POST
and they cant tell me why.  i have enabled logging on the script and in
PHP and dont see anything out of the ordinary.  the only thing i see is
when i use Postman 7.34.0 i am getting a "Parse Error: Invalid character
in chunk size" error, which i am having no luck tracking down information
on.

i would like to generate some --debug logs for you but wont because of the
sensitive PayPal customer payment information.

any thoughts or suggestions?

nginx -V
nginx version: nginx/1.19.4
built by gcc 6.3.0 20170516 (Debian 6.3.0-18+deb9u1)
built with OpenSSL 1.1.1 (compatible; BoringSSL) (running with BoringSSL)
TLS SNI support enabled
configure arguments: --with-cc-opt=-I../boringssl/include --with-ld-opt='-L../boringssl/build/ssl -L../boringssl/build/crypto' --with-http_v3_module --with-http_quic_module --with-stream_quic_module --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --conf-path=/etc/nginx/nginx.conf --pid-path=/var/run/nginx.pid --lock-path=/var/lock/nginx.lock --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --user=www-data --group=www-data --without-http_uwsgi_module --without-http_scgi_module --without-http_memcached_module --without-mail_pop3_module --without-mail_imap_module --without-mail_smtp_module --with-http_ssl_module --with-http_v2_module --with-http_stub_status_module --with-http_gzip_static_module --with-http_realip_module --with-file-aio --add-module=../../headers-more-nginx-module --add-module=../../pagespeed --http-client-body-temp-path=/var/cache/nginx/client_temp --http-proxy-temp-path=/var/cache/nginx/proxy_temp --http-fastcgi-temp-path=/var/cache/nginx/fastcgi_temp --http-uwsgi-temp-path=/var/cache/nginx/uwsgi_temp --http-scgi-temp-path=/var/cache/nginx/scgi_temp --with-openssl=../boringssl

as always, thank you for being awesome.
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