build/pkgs/openssl/spkg-configure.m4: Reject openssl < 1.1.1

Author: Matthias Koeppe

build/pkgs/openssl/spkg-configure.m4

@@ -1,11 +1,25 @@
 SAGE_SPKG_CONFIGURE([openssl], [
-  AX_CHECK_OPENSSL([], [
+  AX_CHECK_OPENSSL([
+    AC_MSG_CHECKING([whether OpenSSL >= 1.1.1, as required by PEP 644])
+    AC_COMPILE_IFELSE(
+        dnl Trac #32580: Need OpenSSL >= 1.1.1 for PEP 644
+        dnl If M  is the number from OPENSSL_VERSION_MAJOR
+        dnl    NN is the number from OPENSSL_VERSION_MINOR
+        dnl    PP is the number from OPENSSL_VERSION_PATCH
+        dnl -> OPENSSL_VERSION_NUMBER is 0xMNN00PP0L
+        [AC_LANG_PROGRAM([[
+            #include <openssl/ssl.h>
+            #if OPENSSL_VERSION_NUMBER < 0x10100010L
+            #  error OpenSSL >= 1.1.1 is required according to PEP 644
+            #endif
+        ]], [])], [
+            AC_MSG_RESULT([yes])
+            sage_spkg_install_openssl=no
+        ], [
+            AC_MSG_RESULT([no])
+            sage_spkg_install_openssl=yes
+        ])
+  ], [dnl No openssl found
       sage_spkg_install_openssl=yes
-      AC_MSG_WARN([Because your system does not have a suitable OpenSSL library,
-Sage will install a prerelease version of OpenSSL from the 3.0 alpha series.
-The OpenSSL Project Team indicates that this prerelease version has been provided
-for testing ONLY.  It should NOT be used for security critical purposes.
-We strongly recommend to install OpenSSL using the system package manager and
-to re-run configure.])
   ])
 ])