build: check required rustls-ffi version

[cpu]

Try to enforce that the Rustls vTLS backend is only used with rustls-ffi 0.15 - the documentation already describes this as the required version.

CMake rejecting rustls-ffi 0.14 w/ pkg-config:

$ PKG_CONFIG_PATH=/tmp/rustls-ffi-0.14/lib/pkgconfig  cmake -S . -B cmake-build-vcheck -DCURL_USE_RUSTLS=on
<snip>
-- Checking for module 'rustls'
--   Found rustls, version 0.14.1
-- Found Rustls (via pkg-config): /tmp/rustls-ffi-0.14/include (found version "0.14.1")
CMake Error at CMakeLists.txt:959 (message):
  rustls-ffi library does not provide rustls_supported_hpke function.
  Required version is 0.15 or newer.

CMake rejecting rustls-ffi 0.14 w/o pkg-config:

$ cmake -S . -B cmake-build-vcheck -DCURL_USE_RUSTLS=on -DRUSTLS_INCLUDE_DIR=/tmp/rustls-ffi-0.14/include -DRUSTLS_LIBRARY=/tmp/rustls-ffi-0.14/lib/librustls.so
<snipped>
-- Found Rustls: /tmp/rustls-ffi-0.14/include
-- Looking for rustls_supported_hpke
-- Looking for rustls_supported_hpke - not found
CMake Error at CMakeLists.txt:959 (message):
  rustls-ffi library does not provide rustls_supported_hpke function.
  Required version is 0.15 or newer.

CMake accepting 0.15 w/ pkg-config

$ PKG_CONFIG_PATH=/tmp/rustls-ffi-0.15/lib/pkgconfig  cmake -S . -B cmake-build-vcheck -DCURL_USE_RUSTLS=on
<snipped>
-- Checking for module 'rustls'
--   Found rustls, version 0.15.0
-- Found Rustls (via pkg-config): /tmp/rustls-ffi-0.15/include (found version "0.15.0")
-- Found ZLIB: /nix/store/6ghariqqf33l5xqn7alx58dys7kz2wm5-zlib-1.3.1/lib/libz.so (found version "1.3.1")
<snipped>

CMake accepting 0.15 w/o pkg-config)

$ cmake -S . -B cmake-build-vcheck -DCURL_USE_RUSTLS=on -DRUSTLS_INCLUDE_DIR=/tmp/rustls-ffi-0.15/include -DRUSTLS_LIBRARY=/tmp/rustls-ffi-0.15/lib/librustls.so
<snipped>
-- Found Rustls: /tmp/rustls-ffi-0.15/include
-- Looking for rustls_supported_hpke
-- Looking for rustls_supported_hpke - found
-- Found ZLIB: /nix/store/6ghariqqf33l5xqn7alx58dys7kz2wm5-zlib-1.3.1/lib/libz.so (found version "1.3.1")
<snipped>

configure rejecting rustls-ffi 0.14 w/ pkg-config

$ ./configure --with-rustls=/tmp/rustls-ffi-0.14/
<snipped>
configure: PKG_CONFIG_LIBDIR will be set to "/tmp/rustls-ffi-0.14//lib/pkgconfig"
checking for rustls options with pkg-config... found
configure: pkg-config: SSL_LIBS: "-lrustls"
configure: pkg-config: SSL_LDFLAGS: "-L/tmp/rustls-ffi-0.14/lib"
configure: pkg-config: SSL_CPPFLAGS: "-I/tmp/rustls-ffi-0.14/include"
checking for rustls_supported_hpke in -lrustls... no
configure: error: --with-rustls was specified but could not find Rustls.

configure rejecting rustls-ffi 0.14 w/o pkg-config

$ ./configure --with-rustls=/tmp/rustls-ffi-0.14-nopkgconf
<snipped>
configure: detected Rustls
configure: Added /tmp/rustls-ffi-0.14-nopkgconf/lib to CURL_LIBRARY_PATH
checking for rustls_supported_hpke in -lrustls... no
configure: error: --with-rustls was specified but could not find Rustls.

configure accepting rustls-ffi 0.15 w/ pkg-config

$ ./configure --with-rustls=/tmp/rustls-ffi-0.15/
<snipped>
checking for rustls options with pkg-config... found
configure: pkg-config: SSL_LIBS: "-lrustls"
configure: pkg-config: SSL_LDFLAGS: "-L/tmp/rustls-ffi-0.15/lib"
configure: pkg-config: SSL_CPPFLAGS: "-I/tmp/rustls-ffi-0.15/include"
configure: detected Rustls
configure: Added /tmp/rustls-ffi-0.15/lib to CURL_LIBRARY_PATH
checking for rustls_supported_hpke in -lrustls... yes
<snipped>

configure accepting rustls-ffi 0.15 w/o pkg-config

$ ./configure --with-rustls=/tmp/rustls-ffi-0.15-nopkgconf
<snipped>
configure: detected Rustls
configure: Added /tmp/rustls-ffi-0.15-nopkgconf/lib to CURL_LIBRARY_PATH
checking for rustls_supported_hpke in -lrustls... yes
<snipped>

Follow-up from #16890

[testclutch]

Analysis of PR #16922 at 57500c80:

Test ../../tests/http/test_02_download.py::TestDownload::test_02_31_parallel_upgrade failed, which has NOT been flaky recently, so there could be a real issue in this PR.

Generated by Testclutch

[cpu]

I'm not 100% sure I got the autoconf working right for 0.15 with and without pkg-config. I'm going to do a bit more testing.
cpu marked this pull request as ready for review 1 minute ago

Phew! I think it's good now. I fixed the unnecessary duplication in the .m4 and tested the whole range of build options:

• cmake with/without pkg-config, rejecting 0.14 and accepting 0.15
• autotools with/without pkg-config, rejecting 0.14 and accepting 0.15

PR description updated accordingly.

[cpu]

@vszakats Are there any other changes you'd like to see here? Thanks! 🙇

[vszakats]

Thanks, this is looking good!

(sorry for my slowness on this)

[vszakats]

Thank you @cpu, merged now!

[cpu]

@Kangie Thanks for suggesting this in #16890 👍