use base58 map instead of strchr()

bitkevin · bitkevin · commit bcab47bc1b2b · 2018-03-21T11:57:57.000+08:00
diff --git a/src/base58.cpp b/src/base58.cpp
@@ -12,6 +12,24 @@
 
 /** All alphanumeric characters except for "0", "I", "O", and "l" */
 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,
+    -1, 0, 1, 2, 3, 4, 5, 6,  7, 8,-1,-1,-1,-1,-1,-1,
+    -1, 9,10,11,12,13,14,15, 16,-1,17,18,19,20,21,-1,
+    22,23,24,25,26,27,28,29, 30,31,32,-1,-1,-1,-1,-1,
+    -1,33,34,35,36,37,38,39, 40,41,42,43,-1,44,45,46,
+    47,48,49,50,51,52,53,54, 55,56,57,-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,-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,-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,
+};
 
 bool DecodeBase58(const char* psz, std::vector<unsigned char>& vch)
 {
@@ -29,13 +47,12 @@ bool DecodeBase58(const char* psz, std::vector<unsigned char>& vch)
     int size = strlen(psz) * 733 /1000 + 1; // log(58) / log(256), rounded up.
     std::vector<unsigned char> b256(size);
     // Process the characters.
+    static_assert(sizeof(mapBase58)/sizeof(mapBase58[0]) == 256, "mapBase58.size() should be 256"); // guarantee not out of range
     while (*psz && !isspace(*psz)) {
         // Decode base58 character
-        const char* ch = strchr(pszBase58, *psz);
-        if (ch == nullptr)
+        int carry = mapBase58[(uint8_t)*psz];
+        if (carry == -1)  // Invalid b58 character
             return false;
-        // Apply "b256 = b256 * 58 + ch".
-        int carry = ch - pszBase58;
         int i = 0;
         for (std::vector<unsigned char>::reverse_iterator it = b256.rbegin(); (carry != 0 || i < length) && (it != b256.rend()); ++it, ++i) {
             carry += 58 * (*it);
diff --git a/src/test/data/base58_encode_decode.json b/src/test/data/base58_encode_decode.json
@@ -10,5 +10,7 @@
 ["572e4794", "3EFU7m"],
 ["ecac89cad93923c02321", "EJDM8drfXA6uyA"],
 ["10c8511e", "Rt5zm"],
-["00000000000000000000", "1111111111"]
+["00000000000000000000", "1111111111"],
+["000111d38e5fc9071ffcd20b4a763cc9ae4f252bb4e48fd66a835e252ada93ff480d6dd43dc62a641155a5", "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"],
+["000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff", "1cWB5HCBdLjAuqGGReWE3R3CguuwSjw6RHn39s2yuDRTS5NsBgNiFpWgAnEx6VQi8csexkgYw3mdYrMHr8x9i7aEwP8kZ7vccXWqKDvGv3u1GxFKPuAkn8JCPPGDMf3vMMnbzm6Nh9zh1gcNsMvH3ZNLmP5fSG6DGbbi2tuwMWPthr4boWwCxf7ewSgNQeacyozhKDDQQ1qL5fQFUW52QKUZDZ5fw3KXNQJMcNTcaB723LchjeKun7MuGW5qyCBZYzA1KjofN1gYBV3NqyhQJ3Ns746GNuf9N2pQPmHz4xpnSrrfCvy6TVVz5d4PdrjeshsWQwpZsZGzvbdAdN8MKV5QsBDY"]
 ]

Original file line number	Diff line number	Diff line change
`@@ -10,5 +10,7 @@`
`10`	`10`	`["572e4794", "3EFU7m"],`
`11`	`11`	`["ecac89cad93923c02321", "EJDM8drfXA6uyA"],`
`12`	`12`	`["10c8511e", "Rt5zm"],`
`13`		`-["00000000000000000000", "1111111111"]`
	`13`	`+["00000000000000000000", "1111111111"],`
	`14`	`+["000111d38e5fc9071ffcd20b4a763cc9ae4f252bb4e48fd66a835e252ada93ff480d6dd43dc62a641155a5", "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"],`
	`15`	+["000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f909192939495969798999a9b9c9d9e9fa0a1a2a3a4a5a6a7a8a9aaabacadaeafb0b1b2b3b4b5b6b7b8b9babbbcbdbebfc0c1c2c3c4c5c6c7c8c9cacbcccdcecfd0d1d2d3d4d5d6d7d8d9dadbdcdddedfe0e1e2e3e4e5e6e7e8e9eaebecedeeeff0f1f2f3f4f5f6f7f8f9fafbfcfdfeff", "1cWB5HCBdLjAuqGGReWE3R3CguuwSjw6RHn39s2yuDRTS5NsBgNiFpWgAnEx6VQi8csexkgYw3mdYrMHr8x9i7aEwP8kZ7vccXWqKDvGv3u1GxFKPuAkn8JCPPGDMf3vMMnbzm6Nh9zh1gcNsMvH3ZNLmP5fSG6DGbbi2tuwMWPthr4boWwCxf7ewSgNQeacyozhKDDQQ1qL5fQFUW52QKUZDZ5fw3KXNQJMcNTcaB723LchjeKun7MuGW5qyCBZYzA1KjofN1gYBV3NqyhQJ3Ns746GNuf9N2pQPmHz4xpnSrrfCvy6TVVz5d4PdrjeshsWQwpZsZGzvbdAdN8MKV5QsBDY"]
`14`	`16`	`]`