nix/libutil/hash.hh

   1 #pragma once
   2
   3 #include <gcrypt.h>
   4
   5 #include "types.hh"
   6 #include "serialise.hh"
   7
   8
   9 namespace nix {
  10
  11
  12 extern const string base32Chars;
  13
  14 typedef enum {
  15     htUnknown = 0,
  16     htMD5 = GCRY_MD_MD5,
  17     htSHA1 = GCRY_MD_SHA1,
  18     htSHA256 = GCRY_MD_SHA256,
  19     htSHA512 = GCRY_MD_SHA512,
  20     htSHA3_256 = GCRY_MD_SHA3_256,
  21     htSHA3_512 = GCRY_MD_SHA3_512,
  22     htBLAKE2s_256 = GCRY_MD_BLAKE2S_256
  23 } HashType;
  24
  25 struct Hash
  26 {
  27     static const unsigned int maxHashSize = 64;
  28     unsigned int hashSize;
  29     unsigned char hash[maxHashSize];
  30
  31     HashType type;
  32
  33     /* Create an unusable hash object. */
  34     Hash();
  35
  36     /* Create a zero-filled hash object. */
  37     Hash(HashType type);
  38
  39     /* Check whether two hash are equal. */
  40     bool operator == (const Hash & h2) const;
  41
  42     /* Check whether two hash are not equal. */
  43     bool operator != (const Hash & h2) const;
  44
  45     /* For sorting. */
  46     bool operator < (const Hash & h) const;
  47 };
  48
  49
  50 /* Convert a hash to a hexadecimal representation. */
  51 string printHash(const Hash & hash);
  52
  53 /* Parse a hexadecimal representation of a hash code. */
  54 Hash parseHash(HashType ht, const string & s);
  55
  56 /* Returns the length of a base-32 hash representation. */
  57 unsigned int hashLength32(const Hash & hash);
  58
  59 /* Convert a hash to a base-32 representation. */
  60 string printHash32(const Hash & hash);
  61
  62 /* Print a hash in base-16 if it's MD5, or base-32 otherwise. */
  63 string printHash16or32(const Hash & hash);
  64
  65 /* Parse a base-32 representation of a hash code. */
  66 Hash parseHash32(HashType ht, const string & s);
  67
  68 /* Parse a base-16 or base-32 representation of a hash code. */
  69 Hash parseHash16or32(HashType ht, const string & s);
  70
  71 /* Verify that the given string is a valid hash code. */
  72 bool isHash(const string & s);
  73
  74 /* Compute the hash of the given string. */
  75 Hash hashString(HashType ht, const string & s);
  76
  77 /* Compute the hash of the given file. */
  78 Hash hashFile(HashType ht, const Path & path);
  79
  80 /* Compute the hash of the given path.  The hash is defined as
  81    (essentially) hashString(ht, dumpPath(path)). */
  82 struct PathFilter;
  83 extern PathFilter defaultPathFilter;
  84 typedef std::pair<Hash, unsigned long long> HashResult;
  85 HashResult hashPath(HashType ht, const Path & path,
  86     PathFilter & filter = defaultPathFilter);
  87
  88 /* Compress a hash to the specified number of bytes by cyclically
  89    XORing bytes together. */
  90 Hash compressHash(const Hash & hash, unsigned int newSize);
  91
  92 /* Parse a string representing a hash type. */
  93 HashType parseHashType(const string & s);
  94
  95 /* And the reverse. */
  96 string printHashType(HashType ht);
  97
  98
  99 struct Ctx;
 100
 101 class HashSink : public BufferedSink
 102 {
 103 private:
 104     HashType ht;
 105     Ctx * ctx;
 106     unsigned long long bytes;
 107
 108 public:
 109     HashSink(HashType ht);
 110     HashSink(const HashSink & h);
 111     ~HashSink();
 112     void write(const unsigned char * data, size_t len);
 113     HashResult finish();
 114     HashResult currentHash();
 115 };
 116
 117
 118 }