Bitcoin: add centralized RPC and monetary validation policy

Author: mearvk

source/bitcoin/base/BitcoinRpcPolicy.java

@@ -0,0 +1,83 @@
+package bitcoin.base;
+
+import java.math.BigDecimal;
+import java.math.RoundingMode;
+import java.util.Set;
+import java.util.regex.Pattern;
+
+/**
+ * Central validation policy for Bitcoin RPC operations exposed by the server.
+ *
+ * The policy intentionally permits only the RPC methods used by the application
+ * and validates monetary inputs before they reach bitcoin-cli.
+ */
+public final class BitcoinRpcPolicy
+{
+    private static final Set<String> ALLOWED_RPC_METHODS = Set.of(
+        "stop",
+        "loadwallet",
+        "unloadwallet",
+        "createwallet",
+        "getwalletinfo",
+        "getbalance",
+        "getnewaddress",
+        "getblockchaininfo",
+        "getblockcount",
+        "sendtoaddress"
+    );
+
+    private static final Pattern WALLET_NAME = Pattern.compile("[A-Za-z0-9._ -]{1,128}");
+    private static final Pattern BITCOIN_ADDRESS = Pattern.compile("(?:[123][1-9A-HJ-NP-Za-km-z]{25,90}|bc1[ac-hj-np-z02-9]{11,87}|tb1[ac-hj-np-z02-9]{11,87}|bcrt1[ac-hj-np-z02-9]{11,87})");
+
+    private BitcoinRpcPolicy() {}
+
+    public static boolean isAllowed(final String method)
+    {
+        return method != null && ALLOWED_RPC_METHODS.contains(method);
+    }
+
+    public static void requireAllowed(final String method)
+    {
+        if (!isAllowed(method))
+            throw new IllegalArgumentException("Bitcoin RPC method is not permitted: " + method);
+    }
+
+    public static String requireWalletName(final String name)
+    {
+        if (name == null || !WALLET_NAME.matcher(name).matches())
+            throw new IllegalArgumentException("Invalid Bitcoin wallet name");
+        return name;
+    }
+
+    public static String requireAddress(final String address)
+    {
+        if (address == null || !BITCOIN_ADDRESS.matcher(address).matches())
+            throw new IllegalArgumentException("Invalid Bitcoin address format");
+        return address;
+    }
+
+    /** Parse BTC without floating-point conversion and convert exactly to satoshis. */
+    public static long requireSatoshis(final String amount)
+    {
+        if (amount == null || amount.isBlank())
+            throw new IllegalArgumentException("BTC amount is required");
+
+        final BigDecimal value;
+        try
+        {
+            value = new BigDecimal(amount.trim());
+        }
+        catch (NumberFormatException e)
+        {
+            throw new IllegalArgumentException("Invalid BTC amount", e);
+        }
+
+        if (value.signum() <= 0 || value.scale() > 8)
+            throw new IllegalArgumentException("BTC amount must be positive and use at most 8 decimal places");
+
+        final BigDecimal satoshis = value.movePointRight(8).setScale(0, RoundingMode.UNNECESSARY);
+        if (satoshis.compareTo(BigDecimal.valueOf(Long.MAX_VALUE)) > 0)
+            throw new IllegalArgumentException("BTC amount is too large");
+        return satoshis.longValueExact();
+    }
+}