Create sda_checkpoints.pl

For generating checkpoints in SDA. Modify start/end and run
./contrib/sda_checkpoints.pl > checkpoints.json

contrib/sda_checkpoints.pl

@@ -0,0 +1,48 @@
+#!/usr/bin/perl
+# Copyright (c) 2016-2022 The Hush developers
+# Distributed under the GPLv3 software license, see the accompanying
+# file COPYING or https://www.gnu.org/licenses/gpl-3.0.en.html
+
+# This script is used to generate the checkpoint data used by the SilentDragon Android SDK
+# https://git.hush.is/fekt/hush-android-wallet-sdk/src/branch/main/sdk-lib/src/main/assets/co.electriccoin.zcash/checkpoint/mainnet
+
+use warnings;
+use strict;
+my $hush    = "./src/hush-cli";
+my $getblock= "$hush getblock";
+my $gethash = "$hush getblockhash";
+my $gettree = "$hush getblockmerkletree";
+my $start   = shift || 1190000;
+my $end     = shift || 1260000;
+my $stride  = shift || 10000;
+
+my $blocks  = qx{$hush getblockcount};
+if($?) {
+    print "ERROR, is hushd running? exiting...\n";
+    exit 1;
+}
+
+if ($end > $blocks) {
+    print "The block $end is beyond how many blocks this node knows about, exiting...\n";
+    exit 1;
+}
+
+if ($start < 1) {
+    print "Invalid start block $start, exiting...\n";
+    exit 1;
+}
+
+my $block = $start;
+while (1) {
+    last if $block > $end;
+	my $blockhash = qx{$gethash $block};
+	my $blocktime = qx{$getblock $block | grep time};
+	my $merkle    = qx{$gettree $block};
+    chomp $merkle;
+    chomp $blockhash;
+    chomp $blocktime;
+    $blocktime =~ s/^\s+|\s+$//g ;
+    print qq{{\n\t"network": "main",\n\t"height": "$block",\n\t"hash": "$blockhash",\n\t$blocktime\n\t"saplingTree": "$merkle"\n},\n};
+
+    $block += $stride;
+}