LCOV - code coverage report
Current view: top level - src - compressor.cpp (source / functions) Hit Total Coverage
Test: total_coverage.info Lines: 88 106 83.0 %
Date: 2025-02-23 09:33:43 Functions: 8 8 100.0 %

          Line data    Source code
       1             : // Copyright (c) 2009-2010 Satoshi Nakamoto
       2             : // Copyright (c) 2009-2014 The Bitcoin developers
       3             : // Copyright (c) 2017-2019 The PIVX Core developers
       4             : // Distributed under the MIT software license, see the accompanying
       5             : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
       6             : 
       7             : #include "compressor.h"
       8             : 
       9             : #include "hash.h"
      10             : #include "pubkey.h"
      11             : #include "script/standard.h"
      12             : 
      13             : /*
      14             :  * These check for scripts for which a special case with a shorter encoding is defined.
      15             :  * They are implemented separately from the CScript test, as these test for exact byte
      16             :  * sequence correspondences, and are more strict. For example, IsToPubKey also verifies
      17             :  * whether the public key is valid (as invalid ones cannot be represented in compressed
      18             :  * form).
      19             :  */
      20             : 
      21     2563127 : static bool IsToKeyID(const CScript& script, CKeyID &hash)
      22             : {
      23    14001770 :     if (script.size() == 25 && script[0] == OP_DUP && script[1] == OP_HASH160 && script[2] == 20 && script[23] == OP_EQUALVERIFY && script[24] == OP_CHECKSIG) {
      24     4574974 :         memcpy(&hash, &script[3], 20);
      25     2287487 :         return true;
      26             :     }
      27             :     return false;
      28             : }
      29             : 
      30      275639 : static bool IsToScriptID(const CScript& script, CScriptID &hash)
      31             : {
      32      733101 :     if (script.size() == 23 && script[0] == OP_HASH160 && script[1] == 20 && script[22] == OP_EQUAL) {
      33      304172 :         memcpy(&hash, &script[2], 20);
      34      152086 :         return true;
      35             :     }
      36             :     return false;
      37             : }
      38             : 
      39      123553 : static bool IsToPubKey(const CScript& script, CPubKey &pubkey)
      40             : {
      41      127523 :     if (script.size() == 35 && script[0] == 33 && script[34] == OP_CHECKSIG && (script[1] == 0x02 || script[1] == 0x03)) {
      42         922 :         pubkey.Set(&script[1], &script[34]);
      43         922 :         return true;
      44             :     }
      45      122631 :     if (script.size() == 67 && script[0] == 65 && script[66] == OP_CHECKSIG && script[1] == 0x04) {
      46           0 :         pubkey.Set(&script[1], &script[66]);
      47           0 :         return pubkey.IsFullyValid(); // if not fully valid, a case that would not be compressible
      48             :     }
      49             :     return false;
      50             : }
      51             : 
      52     2563127 : bool CompressScript(const CScript& script, std::vector<unsigned char> &out)
      53             : {
      54     2563127 :     CKeyID keyID;
      55     2563127 :     if (IsToKeyID(script, keyID)) {
      56     2287487 :         out.resize(21);
      57     2287487 :         out[0] = 0x00;
      58     2287487 :         memcpy(&out[1], &keyID, 20);
      59     2287487 :         return true;
      60             :     }
      61      275639 :     CScriptID scriptID;
      62      275639 :     if (IsToScriptID(script, scriptID)) {
      63      152086 :         out.resize(21);
      64      152086 :         out[0] = 0x01;
      65      152086 :         memcpy(&out[1], &scriptID, 20);
      66      152086 :         return true;
      67             :     }
      68      123553 :     CPubKey pubkey;
      69      123553 :     if (IsToPubKey(script, pubkey)) {
      70         922 :         out.resize(33);
      71         922 :         memcpy(&out[1], &pubkey[1], 32);
      72         922 :         if (pubkey[0] == 0x02 || pubkey[0] == 0x03) {
      73         922 :             out[0] = pubkey[0];
      74         922 :             return true;
      75           0 :         } else if (pubkey[0] == 0x04) {
      76           0 :             out[0] = 0x04 | (pubkey[64] & 0x01);
      77           0 :             return true;
      78             :         }
      79             :     }
      80             :     return false;
      81             : }
      82             : 
      83     7145518 : unsigned int GetSpecialScriptSize(unsigned int nSize)
      84             : {
      85     7145518 :     if (nSize == 0 || nSize == 1)
      86             :         return 20;
      87         633 :     if (nSize == 2 || nSize == 3 || nSize == 4 || nSize == 5)
      88         633 :         return 32;
      89             :     return 0;
      90             : }
      91             : 
      92     7145518 : bool DecompressScript(CScript& script, unsigned int nSize, const std::vector<unsigned char> &in)
      93             : {
      94     7145518 :     switch (nSize) {
      95     7138213 :     case 0x00:
      96     7138213 :         script.resize(25);
      97     7138213 :         script[0] = OP_DUP;
      98     7138213 :         script[1] = OP_HASH160;
      99     7138213 :         script[2] = 20;
     100    14276466 :         memcpy(&script[3], in.data(), 20);
     101     7138213 :         script[23] = OP_EQUALVERIFY;
     102     7138213 :         script[24] = OP_CHECKSIG;
     103     7138213 :         return true;
     104        6671 :     case 0x01:
     105        6671 :         script.resize(23);
     106        6671 :         script[0] = OP_HASH160;
     107        6671 :         script[1] = 20;
     108       13342 :         memcpy(&script[2], in.data(), 20);
     109        6671 :         script[22] = OP_EQUAL;
     110        6671 :         return true;
     111         633 :     case 0x02:
     112         633 :     case 0x03:
     113         633 :         script.resize(35);
     114         633 :         script[0] = 33;
     115         633 :         script[1] = nSize;
     116        1266 :         memcpy(&script[2], in.data(), 32);
     117         633 :         script[34] = OP_CHECKSIG;
     118         633 :         return true;
     119           0 :     case 0x04:
     120           0 :     case 0x05:
     121           0 :         unsigned char vch[33] = {};
     122           0 :         vch[0] = nSize - 2;
     123           0 :         memcpy(&vch[1], in.data(), 32);
     124           0 :         CPubKey pubkey(&vch[0], &vch[33]);
     125           0 :         if (!pubkey.Decompress())
     126             :             return false;
     127           0 :         assert(pubkey.size() == 65);
     128           0 :         script.resize(67);
     129           0 :         script[0] = 65;
     130           0 :         memcpy(&script[1], pubkey.begin(), 65);
     131           0 :         script[66] = OP_CHECKSIG;
     132           0 :         return true;
     133             :     }
     134             :     return false;
     135             : }
     136             : 
     137             : // Amount compression:
     138             : // * If the amount is 0, output 0
     139             : // * first, divide the amount (in base units) by the largest power of 10 possible; call the exponent e (e is max 9)
     140             : // * if e<9, the last digit of the resulting number cannot be 0; store it as d, and drop it (divide by 10)
     141             : //   * call the result n
     142             : //   * output 1 + 10*(9*n + d - 1) + e
     143             : // * if e==9, we only know the resulting number is not zero, so output 1 + 10*(n - 1) + 9
     144             : // (this is decodable, as d is in [1-9] and e is in [0-9])
     145             : 
     146     3203133 : uint64_t CompressAmount(uint64_t n)
     147             : {
     148     3203133 :     if (n == 0)
     149             :         return 0;
     150             :     int e = 0;
     151     8821160 :     while (((n % 10) == 0) && e < 9) {
     152     5627580 :         n /= 10;
     153     5627580 :         e++;
     154             :     }
     155     3193589 :     if (e < 9) {
     156     2704915 :         int d = (n % 10);
     157     2704915 :         assert(d >= 1 && d <= 9);
     158     2704915 :         n /= 10;
     159     2704915 :         return 1 + (n * 9 + d - 1) * 10 + e;
     160             :     } else {
     161      488675 :         return 1 + (n - 1) * 10 + 9;
     162             :     }
     163             : }
     164             : 
     165     7792769 : uint64_t DecompressAmount(uint64_t x)
     166             : {
     167             :     // x = 0  OR  x = 1+10*(9*n + d - 1) + e  OR  x = 1+10*(n - 1) + 9
     168     7792769 :     if (x == 0)
     169             :         return 0;
     170     7792202 :     x--;
     171             :     // x = 10*(9*n + d - 1) + e
     172     7792202 :     int e = x % 10;
     173     7792202 :     x /= 10;
     174     7792202 :     uint64_t n = 0;
     175     7792202 :     if (e < 9) {
     176             :         // x = 9*n + d - 1
     177     7295246 :         int d = (x % 9) + 1;
     178     7295246 :         x /= 9;
     179             :         // x = n
     180     7295246 :         n = x * 10 + d;
     181             :     } else {
     182      496955 :         n = x + 1;
     183             :     }
     184    13591480 :     while (e) {
     185     5799280 :         n *= 10;
     186     5799280 :         e--;
     187             :     }
     188             :     return n;
     189             : }

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