refactor base58_address.[cpp/h] into base58[.cpp/h]

Signed-off-by: russeree <git@qrsnap.io>

src/Makefile.am

@@ -289,7 +289,6 @@ BITCOIN_CORE_H = \
   undo.h \
   util/any.h \
   util/asmap.h \
-  util/base58_address.h \
   util/batchpriority.h \
   util/bip32.h \
   util/bitdeque.h \
@@ -729,7 +728,6 @@ libbitcoin_util_a_SOURCES = \
   support/cleanse.cpp \
   sync.cpp \
   util/asmap.cpp \
-  util/base58_address.cpp \
   util/batchpriority.cpp \
   util/bip32.cpp \
   util/bytevectorhash.cpp \

src/base58.cpp

@@ -9,14 +9,15 @@
 #include <util/strencodings.h>
 #include <util/string.h>
 
+#include <algorithm>
 #include <assert.h>
 #include <string.h>
 
 #include <limits>
 
 /** All alphanumeric characters except for "0", "I", "O", and "l" */
-const char* pszBase58 = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
-const int8_t mapBase58[256] = {
+static const char* pszBase58 = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz";
+static const int8_t mapBase58[256] = {
     -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1,
     -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1,
     -1,-1,-1,-1,-1,-1,-1,-1, -1,-1,-1,-1,-1,-1,-1,-1,
@@ -165,3 +166,38 @@ bool DecodeBase58Check(const std::string& str, std::vector<unsigned char>& vchRe
     }
     return DecodeBase58Check(str.c_str(), vchRet, max_ret);
 }
+
+std::vector<char> Base58PrefixesFromVersionByte(size_t length, unsigned char version_byte)
+{
+    std::vector<char> base58_prefix_char_range;
+
+    if (length) {
+        static const unsigned char MIN_PAYLOAD_FILL = 0x00;
+        static const unsigned char MAX_PAYLOAD_FILL = 0xFF;
+        static const char ENCODED_LEADING_ZEROES = '1';
+
+        const std::vector<unsigned char> payload_range = { MIN_PAYLOAD_FILL, MAX_PAYLOAD_FILL };
+        std::vector<unsigned char> base58_prefix_min_max;
+
+        for (const auto& payload : payload_range) {
+            std::vector<unsigned char> range_test_bound(std::max(1, (int)length), payload);
+            range_test_bound.at(0) = version_byte;
+            base58_prefix_min_max.emplace_back(EncodeBase58(range_test_bound).at(0));
+        }
+
+        auto IsBase58Char = [&](char c) { return std::string_view(pszBase58).find_first_of(c) != std::string::npos; };
+
+        if (base58_prefix_min_max.front() == ENCODED_LEADING_ZEROES) {
+            base58_prefix_char_range.emplace_back(base58_prefix_min_max.front());
+        } else if(IsBase58Char(base58_prefix_min_max.front()) && IsBase58Char(base58_prefix_min_max.back())) {
+            for (int i = 1; pszBase58[i] != '\0'; i++) {
+                base58_prefix_char_range.emplace_back(pszBase58[i]);
+            }
+            auto start_position = std::find(base58_prefix_char_range.begin(), base58_prefix_char_range.end(), base58_prefix_min_max.front());
+            std::rotate(base58_prefix_char_range.begin(), start_position, base58_prefix_char_range.end());
+            base58_prefix_char_range.erase(++std::find(base58_prefix_char_range.begin(), base58_prefix_char_range.end(), base58_prefix_min_max.back()), base58_prefix_char_range.end());
+        }
+    }
+
+    return base58_prefix_char_range;
+};

src/base58.h

@@ -19,9 +19,6 @@
 #include <string>
 #include <vector>
 
-extern const char* pszBase58;
-extern const int8_t mapBase58[256];
-
 /**
  * Encode a byte span as a base58-encoded string
  */
@@ -44,4 +41,16 @@ std::string EncodeBase58Check(Span<const unsigned char> input);
  */
 [[nodiscard]] bool DecodeBase58Check(const std::string& str, std::vector<unsigned char>& vchRet, int max_ret_len);
 
+/** Derives the first Base58 character prefixes for a given version byte and a length
+ *
+ * @param[in] length length of pre-encoded base58 data
+ * @param[in] version_byte The address version byte
+ * @return The possible range of base58 prefixes (eg. ['m','n'])
+ * @code
+ * std::vector result = Base58PrefixesFromVersionByte(31,0x05);
+ * // result will be ['3']
+ * @endcode
+ */
+std::vector<char> Base58PrefixesFromVersionByte(size_t length, unsigned char version_byte);
+
 #endif // BITCOIN_BASE58_H

src/key_io.cpp

@@ -9,7 +9,6 @@
 #include <script/interpreter.h>
 #include <script/solver.h>
 #include <tinyformat.h>
-#include <util/base58_address.h>
 #include <util/strencodings.h>
 
 #include <algorithm>

src/test/base58_prefix_decoder_tests.cpp

@@ -1,5 +1,4 @@
 #include <base58.h>
-#include <util/base58_address.h>
 #include <boost/test/unit_test.hpp>
 
 #include <string>