HTTP/3 with ngtcp2+wolfssl reports non-zero early data but does not send 0-RTT data

[eeverett6]

I did this

• Built curl with ngtcp2, wolfssl, nghttp3, and --enable-ssls-export
• Made a request to a test HTTP/3 server with SSL sessions

/curl --http3-only --ssl-sessions my-sessions --tls-earlydata -w 'Early: %{tls_earlydata}\n' https://127.0.0.1

• Repeated the request with the SSL session file populated

I then repeated the above with gnutls.

With wolfssl, a packet capture showed that neither connection used 0-RTT data, although tls_earlydata was 0 the first time and 89 the second time.

With gnutls, the first connection did not use 0-RTT and reported 0 for tls_earlydata, the second connection did use 0-RTT and reported 89 for tls_earlydata.

Finally, I tried adding the line

wolfSSL_set_max_early_data(wss->ssl, scs->earlydata_max);

in wssl_setup_session(), and then I did see curl use 0-RTT data on session reuse when built with wolfssl.

I expected the following

I expected curl to send 0-RTT data when re-using SSL session data for an HTTP/3 connection, or to report a value of 0 for tls_earlydata.

curl/libcurl version

curl 8.14.1-DEV (x86_64-pc-linux-gnu) libcurl/8.14.1-DEV wolfSSL/5.8.0 libidn2/2.3.7 libpsl/0.21.2 nghttp2/1.66.0-DEV ngtcp2/1.13.0-DEV nghttp3/1.1
Release-Date: [unreleased]
Protocols: dict file ftp ftps gopher gophers http https imap imaps ipfs ipns mqtt pop3 pop3s rtsp smb smbs smtp smtps telnet tftp ws wss
Features: alt-svc AsynchDNS HSTS HTTP2 HTTP3 HTTPS-proxy IDN IPv6 Largefile NTLM PSL SSL SSLS-EXPORT threadsafe UnixSockets

operating system

Linux 5.15.167.4-microsoft-standard-WSL2 #1 SMP Tue Nov 5 00:21:55 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux

[icing]

Thanks, your suggested change is correct. Without this, wolfSSL reports everything as fine and early data to have been accepted, only it was never sent (as early data).

Made your fix into #17488. If you could verify this works for you as well, that'd be great.

Update: seems to need some ifdef massaging.

[eeverett6]

I can confirm I see 0-RTT data after building with your fix, thanks!