From 0b06e720c0182dee8b560d2e8d3891b036f63ea7 Mon Sep 17 00:00:00 2001
From: Samuel Dobson <dobsonsa68@gmail.com>
Date: Fri, 1 Oct 2021 12:14:48 +1300
Subject: More detailed error checking for base58 addresses

---
 src/key_io.cpp | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

(limited to 'src/key_io.cpp')

diff --git a/src/key_io.cpp b/src/key_io.cpp
index 615f4c9312..9e246c0b81 100644
--- a/src/key_io.cpp
+++ b/src/key_io.cpp
@@ -81,7 +81,11 @@ CTxDestination DecodeDestination(const std::string& str, const CChainParams& par
     std::vector<unsigned char> data;
     uint160 hash;
     error_str = "";
-    if (DecodeBase58Check(str, data, 21)) {
+
+    // Note this will be false if it is a valid Bech32 address for a different network
+    bool is_bech32 = (ToLower(str.substr(0, params.Bech32HRP().size())) == params.Bech32HRP());
+
+    if (!is_bech32 && DecodeBase58Check(str, data, 21)) {
         // base58-encoded Bitcoin addresses.
         // Public-key-hash-addresses have version 0 (or 111 testnet).
         // The data vector contains RIPEMD160(SHA256(pubkey)), where pubkey is the serialized public key.
@@ -98,15 +102,27 @@ CTxDestination DecodeDestination(const std::string& str, const CChainParams& par
             return ScriptHash(hash);
         }
 
-        // Set potential error message.
-        // This message may be changed if the address can also be interpreted as a Bech32 address.
-        error_str = "Invalid prefix for Base58-encoded address";
+        if (!std::equal(script_prefix.begin(), script_prefix.end(), data.begin()) &&
+            !std::equal(pubkey_prefix.begin(), pubkey_prefix.end(), data.begin())) {
+            error_str = "Invalid prefix for Base58-encoded address";
+        } else {
+            error_str = "Invalid length for Base58 address";
+        }
+        return CNoDestination();
+    } else if (!is_bech32) {
+        // Try Base58 decoding without the checksum, using a much larger max length
+        if (!DecodeBase58(str, data, 100)) {
+            error_str = "Invalid HRP or Base58 character in address";
+        } else {
+            error_str = "Invalid checksum or length of Base58 address";
+        }
+        return CNoDestination();
     }
+
     data.clear();
     const auto dec = bech32::Decode(str);
     if ((dec.encoding == bech32::Encoding::BECH32 || dec.encoding == bech32::Encoding::BECH32M) && dec.data.size() > 0) {
         // Bech32 decoding
-        error_str = "";
         if (dec.hrp != params.Bech32HRP()) {
             error_str = "Invalid prefix for Bech32 address";
             return CNoDestination();
@@ -168,8 +184,8 @@ CTxDestination DecodeDestination(const std::string& str, const CChainParams& par
         }
     }
 
-    // Set error message if address can't be interpreted as Base58 or Bech32.
-    if (error_str.empty()) error_str = "Invalid address format";
+    //TODO: locate Bech32 errors
+    error_str = "Error in Bech32 encoding";
 
     return CNoDestination();
 }
-- 
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