cmake: add wolfSSH support

Enable with CMake option `-DCURL_USE_WOLFSSH=ON`. Customize with
`-DWOLFSSH_INCLUDE_DIR=<path-to-wolfssh>/include`,
`-DWOLFSSH_LIBRARY=<path-to-wolfssh>/lib/libwolfssh.a`.

It requires the wolfSSL TLS backend.

Closes #14568

CMake/FindWolfSSH.cmake

@@ -0,0 +1,56 @@
+#***************************************************************************
+#                                  _   _ ____  _
+#  Project                     ___| | | |  _ \| |
+#                             / __| | | | |_) | |
+#                            | (__| |_| |  _ <| |___
+#                             \___|\___/|_| \_\_____|
+#
+# Copyright (C) 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.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.
+#
+# SPDX-License-Identifier: curl
+#
+###########################################################################
+# Find the wolfssh library
+#
+# Result Variables:
+#
+# WOLFSSH_FOUND         System has wolfssh
+# WOLFSSH_INCLUDE_DIRS  The wolfssh include directories
+# WOLFSSH_LIBRARIES     The wolfssh library names
+# WOLFSSH_VERSION       Version of wolfssh
+
+find_path(WOLFSSH_INCLUDE_DIR "wolfssh/ssh.h")
+find_library(WOLFSSH_LIBRARY NAMES "wolfssh" "libwolfssh")
+
+if(WOLFSSH_INCLUDE_DIR)
+  file(STRINGS "${WOLFSSH_INCLUDE_DIR}/wolfssh/version.h" _wolfssh_version_str REGEX "#[\t ]*define[\t ]+LIBWOLFSSH_VERSION_STRING[\t ]+\"(.*)\"")
+  string(REGEX REPLACE "^.*\"([^\"]+)\"" "\\1" WOLFSSH_VERSION "${_wolfssh_version_str}")
+  unset(_wolfssh_version_str)
+endif()
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(WolfSSH
+  REQUIRED_VARS
+    WOLFSSH_INCLUDE_DIR
+    WOLFSSH_LIBRARY
+  VERSION_VAR
+    WOLFSSH_VERSION
+)
+
+if(WOLFSSH_FOUND)
+  set(WOLFSSH_INCLUDE_DIRS ${WOLFSSH_INCLUDE_DIR})
+  set(WOLFSSH_LIBRARIES    ${WOLFSSH_LIBRARY})
+endif()
+
+mark_as_advanced(WOLFSSH_INCLUDE_DIR WOLFSSH_LIBRARY)

CMakeLists.txt

@@ -1097,6 +1097,24 @@ if(NOT USE_LIBSSH2 AND CURL_USE_LIBSSH)
   endif()
 endif()
 
+# wolfSSH
+option(CURL_USE_WOLFSSH "Use wolfssh" OFF)
+mark_as_advanced(CURL_USE_WOLFSSH)
+set(USE_WOLFSSH OFF)
+if(NOT USE_LIBSSH2 AND NOT USE_LIBSSH AND CURL_USE_WOLFSSH)
+  if(USE_WOLFSSL)
+    find_package(WolfSSH)
+    if(WOLFSSH_FOUND)
+      list(APPEND CURL_LIBS ${WOLFSSH_LIBRARIES})
+      list(APPEND CMAKE_REQUIRED_INCLUDES "${WOLFSSH_INCLUDE_DIRS}")
+      include_directories(${WOLFSSH_INCLUDE_DIRS})
+      set(USE_WOLFSSH ON)
+    endif()
+  else()
+    message(WARNING "wolfSSH requires wolfSSL. Skipping.")
+  endif()
+endif()
+
 option(CURL_USE_GSASL "Use GSASL implementation" OFF)
 mark_as_advanced(CURL_USE_GSASL)
 if(CURL_USE_GSASL)
@@ -1822,8 +1840,8 @@ if(NOT CURL_DISABLE_INSTALL)
                           _use_curl_ntlm_core AND (SIZEOF_CURL_OFF_T GREATER 4))
   _add_if("SMTP"          NOT CURL_DISABLE_SMTP)
   _add_if("SMTPS"         NOT CURL_DISABLE_SMTP AND _ssl_enabled)
-  _add_if("SCP"           USE_LIBSSH2 OR USE_LIBSSH)
+  _add_if("SCP"           USE_LIBSSH2 OR USE_LIBSSH OR USE_WOLFSSH)
-  _add_if("SFTP"          USE_LIBSSH2 OR USE_LIBSSH)
+  _add_if("SFTP"          USE_LIBSSH2 OR USE_LIBSSH OR USE_WOLFSSH)
   _add_if("RTSP"          NOT CURL_DISABLE_RTSP)
   _add_if("RTMP"          USE_LIBRTMP)
   _add_if("MQTT"          NOT CURL_DISABLE_MQTT)

Makefile.am

@@ -45,6 +45,7 @@ CMAKE_DIST =                                    \
  CMake/FindNGTCP2.cmake                         \
  CMake/FindNettle.cmake                         \
  CMake/FindQUICHE.cmake                         \
+ CMake/FindWolfSSH.cmake                        \
  CMake/FindWolfSSL.cmake                        \
  CMake/FindZstd.cmake                           \
  CMake/Findrustls.cmake                         \

lib/curl_config.h.cmake

@@ -707,6 +707,9 @@ ${SIZEOF_TIME_T_CODE}
 /* if libssh2 is in use */
 #cmakedefine USE_LIBSSH2 1
 
+/* if wolfssh is in use */
+#cmakedefine USE_WOLFSSH 1
+
 /* if libpsl is in use */
 #cmakedefine USE_LIBPSL 1