CMake: add HTTP/3 support (ngtcp2+nghttp3, quiche)

Add three new CMake Find modules (using the curl license, but I grant
others the right to apply the CMake BSD license instead).

This CMake config is simpler than the autotools one because it assumes
ngtcp2 and nghttp3 to be used together. Another difference is that this
CMake config checks whether QUIC is actually supported by the TLS
library (patched OpenSSL or boringssl) since this can be a common
configuration mistake that could result in build errors later.

Unlike autotools, CMake does not warn you that the features are
experimental. The user is supposed to already know that and read the
documentation. It requires a very special build environment anyway.

Tested with ngtcp2+OpenSSL+nghttp3 and quiche+boringssl, both built from
current git master. Use `LD_DEBUG=files src/curl |& grep need` to figure
out which features (libldap-2.4, libssh2) to disable due to conflicts
with boringssl.

Closes #5359

1 files changed, 68 insertions, 0 deletions

diff --git a/CMake/FindQUICHE.cmake b/CMake/FindQUICHE.cmake
new file mode 100644
index 000000000..01d17582b
--- /dev/null
+++ b/CMake/FindQUICHE.cmake
@@ -0,0 +1,68 @@
+#***************************************************************************
+#                                  _   _ ____  _
+#  Project                     ___| | | |  _ \| |
+#                             / __| | | | |_) | |
+#                            | (__| |_| |  _ <| |___
+#                             \___|\___/|_| \_\_____|
+#
+# Copyright (C) 1998 - 2020, Daniel Stenberg, <daniel@haxx.se>, et al.
+#
+# This software is licensed as described in the file COPYING, which
+# you should have received as part of this distribution. The terms
+# are also available at https://curl.haxx.se/docs/copyright.html.
+#
+# You may opt to use, copy, modify, merge, publish, distribute and/or sell
+# copies of the Software, and permit persons to whom the Software is
+# furnished to do so, under the terms of the COPYING file.
+#
+# This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+# KIND, either express or implied.
+#
+###########################################################################
+
+#[=======================================================================[.rst:
+FindQUICHE
+----------
+
+Find the quiche library
+
+Result Variables
+^^^^^^^^^^^^^^^^
+
+``QUICHE_FOUND``
+  System has quiche
+``QUICHE_INCLUDE_DIRS``
+  The quiche include directories.
+``QUICHE_LIBRARIES``
+  The libraries needed to use quiche
+#]=======================================================================]
+if(UNIX)
+  find_package(PkgConfig QUIET)
+  pkg_search_module(PC_QUICHE quiche)
+endif()
+
+find_path(QUICHE_INCLUDE_DIR quiche.h
+  HINTS
+    ${PC_QUICHE_INCLUDEDIR}
+    ${PC_QUICHE_INCLUDE_DIRS}
+)
+
+find_library(QUICHE_LIBRARY NAMES quiche
+  HINTS
+    ${PC_QUICHE_LIBDIR}
+    ${PC_QUICHE_LIBRARY_DIRS}
+)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(QUICHE
+  REQUIRED_VARS
+    QUICHE_LIBRARY
+    QUICHE_INCLUDE_DIR
+)
+
+if(QUICHE_FOUND)
+  set(QUICHE_LIBRARIES    ${QUICHE_LIBRARY})
+  set(QUICHE_INCLUDE_DIRS ${QUICHE_INCLUDE_DIR})
+endif()
+
+mark_as_advanced(QUICHE_INCLUDE_DIRS QUICHE_LIBRARIES)