# af_alg.m4 serial 4

dnl Copyright 2018 Free Software Foundation, Inc.

dnl This file is free software; the Free Software Foundation

dnl gives unlimited permission to copy and/or distribute it,

dnl with or without modifications, as long as this notice is preserved.

dnl From Matteo Croce.

AC_DEFUN_ONCE([gl_AF_ALG],

[

  AC_REQUIRE([gl_HEADER_SYS_SOCKET])

  AC_REQUIRE([AC_C_INLINE])

  dnl Check whether linux/if_alg.h has needed features.

  AC_CACHE_CHECK([whether linux/if_alg.h has struct sockaddr_alg.],

    [gl_cv_header_linux_if_alg_salg],

    [AC_COMPILE_IFELSE(

       [AC_LANG_PROGRAM([[#include <sys/socket.h>

                          #include <linux/if_alg.h>

                          struct sockaddr_alg salg = {

                            .salg_family = AF_ALG,

                            .salg_type = "hash",

                            .salg_name = "sha1",

                          };]])],

       [gl_cv_header_linux_if_alg_salg=yes],

       [gl_cv_header_linux_if_alg_salg=no])])

  if test "$gl_cv_header_linux_if_alg_salg" = yes; then

    AC_DEFINE([HAVE_LINUX_IF_ALG_H], [1],

      [Define to 1 if you have 'struct sockaddr_alg' defined.])

  fi

  dnl The default is to not use AF_ALG if available,

  dnl as it's system dependent as to whether the kernel

  dnl routines are faster than libcrypto for example.

  use_af_alg=no

  AC_ARG_WITH([linux-crypto],

    [AS_HELP_STRING([[--with-linux-crypto]],

       [use Linux kernel cryptographic API (if available)])],

    [use_af_alg=$withval],

    [use_af_alg=no])

  dnl We cannot use it if it is not available.

  if test "$gl_cv_header_linux_if_alg_salg" != yes; then

    if test "$use_af_alg" != no; then

      AC_MSG_WARN([Linux kernel cryptographic API not found])

    fi

    use_af_alg=no

  fi

  if test "$use_af_alg" != no; then

    USE_AF_ALG=1

  else

    USE_AF_ALG=0

  fi

  AC_DEFINE_UNQUOTED([USE_LINUX_CRYPTO_API], [$USE_AF_ALG],

    [Define to 1 if you want to use the Linux kernel cryptographic API.])

])