From e6692778d3f6507eb1325785cdd424073a945ff7 Mon Sep 17 00:00:00 2001
From: Elichai Turkel <elichai.turkel@gmail.com>
Date: Wed, 21 Oct 2020 14:39:52 +0300
Subject: [PATCH] Modify bitcoin_secp.m4's openssl check to call all the
 functions that we use in the tests/benchmarks. That way linking will fail if
 those symbols are missing

---
 build-aux/m4/bitcoin_secp.m4 | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/build-aux/m4/bitcoin_secp.m4 b/build-aux/m4/bitcoin_secp.m4
index 57595f4499d8e..ece3d655edc30 100644
--- a/build-aux/m4/bitcoin_secp.m4
+++ b/build-aux/m4/bitcoin_secp.m4
@@ -36,16 +36,39 @@ if test x"$has_libcrypto" = x"yes" && test x"$has_openssl_ec" = x; then
   CPPFLAGS_TEMP="$CPPFLAGS"
   CPPFLAGS="$CRYPTO_CPPFLAGS $CPPFLAGS"
   AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+    #include <openssl/bn.h>
     #include <openssl/ec.h>
     #include <openssl/ecdsa.h>
     #include <openssl/obj_mac.h>]],[[
-    EC_KEY *eckey = EC_KEY_new_by_curve_name(NID_secp256k1);
-    ECDSA_sign(0, NULL, 0, NULL, NULL, eckey);
+    # if OPENSSL_VERSION_NUMBER < 0x10100000L
+    void ECDSA_SIG_get0(const ECDSA_SIG *sig, const BIGNUM **pr, const BIGNUM **ps) {(void)sig->r; (void)sig->s;}
+    # endif
+
+    unsigned int zero = 0;
+    const unsigned char *zero_ptr = (unsigned char*)&zero;
+    EC_KEY_free(EC_KEY_new_by_curve_name(NID_secp256k1));
+    EC_KEY *eckey = EC_KEY_new();
+    EC_GROUP *group = EC_GROUP_new_by_curve_name(NID_secp256k1);
+    EC_KEY_set_group(eckey, group);
+    ECDSA_sign(0, NULL, 0, NULL, &zero, eckey);
     ECDSA_verify(0, NULL, 0, NULL, 0, eckey);
+    o2i_ECPublicKey(&eckey, &zero_ptr, 0);
+    d2i_ECPrivateKey(&eckey, &zero_ptr, 0);
+    EC_KEY_check_key(eckey);
     EC_KEY_free(eckey);
+    EC_GROUP_free(group);
     ECDSA_SIG *sig_openssl;
     sig_openssl = ECDSA_SIG_new();
+    d2i_ECDSA_SIG(&sig_openssl, &zero_ptr, 0);
+    i2d_ECDSA_SIG(sig_openssl, NULL);
+    ECDSA_SIG_get0(sig_openssl, NULL, NULL);
     ECDSA_SIG_free(sig_openssl);
+    const BIGNUM *bignum = BN_value_one();
+    BN_is_negative(bignum);
+    BN_num_bits(bignum);
+    if (sizeof(zero) >= BN_num_bytes(bignum)) {
+        BN_bn2bin(bignum, (unsigned char*)&zero);
+    }
   ]])],[has_openssl_ec=yes],[has_openssl_ec=no])
   AC_MSG_RESULT([$has_openssl_ec])
   CPPFLAGS="$CPPFLAGS_TEMP"