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Support base-64 hashes

Browse source 
Also simplify the Hash API.

Fixes #1437.
This commit is contained in:
Eelco Dolstra 2017-07-04 14:47:59 +02:00
parent fe97c69898
commit c0015e87af
No known key found for this signature in database
GPG key ID: 8170B4726D7198DE
23 changed files with 205 additions and 213 deletions
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185
src/libutil/hash.cc
View file

@ -16,17 +16,8 @@
namespace nix {
Hash::Hash()
void Hash::init()
{
type = htUnknown;
hashSize = 0;
memset(hash, 0, maxHashSize);
}
Hash::Hash(HashType type)
{
this->type = type;
if (type == htMD5) hashSize = md5HashSize;
else if (type == htSHA1) hashSize = sha1HashSize;
else if (type == htSHA256) hashSize = sha256HashSize;
@ -62,16 +53,10 @@ bool Hash::operator < (const Hash & h) const
}
std::string Hash::to_string(bool base32) const
{
return printHashType(type) + ":" + (base32 ? printHash32(*this) : printHash(*this));
}
const string base16Chars = "0123456789abcdef";
string printHash(const Hash & hash)
static string printHash16(const Hash & hash)
{
char buf[hash.hashSize * 2];
for (unsigned int i = 0; i < hash.hashSize; i++) {
@ -82,42 +67,11 @@ string printHash(const Hash & hash)
}
Hash parseHash(const string & s)
{
string::size_type colon = s.find(':');
if (colon == string::npos)
throw BadHash(format("invalid hash ‘%s’") % s);
string hts = string(s, 0, colon);
HashType ht = parseHashType(hts);
if (ht == htUnknown)
throw BadHash(format("unknown hash type ‘%s’") % hts);
return parseHash16or32(ht, string(s, colon + 1));
}
Hash parseHash(HashType ht, const string & s)
{
Hash hash(ht);
if (s.length() != hash.hashSize * 2)
throw BadHash(format("invalid hash ‘%1%’") % s);
for (unsigned int i = 0; i < hash.hashSize; i++) {
string s2(s, i * 2, 2);
if (!isxdigit(s2[0]) || !isxdigit(s2[1]))
throw BadHash(format("invalid hash ‘%1%’") % s);
istringstream_nocopy str(s2);
int n;
str >> std::hex >> n;
hash.hash[i] = n;
}
return hash;
}
// omitted: E O U T
const string base32Chars = "0123456789abcdfghijklmnpqrsvwxyz";
string printHash32(const Hash & hash)
static string printHash32(const Hash & hash)
{
assert(hash.hashSize);
size_t len = hash.base32Len();
@ -142,66 +96,103 @@ string printHash32(const Hash & hash)
string printHash16or32(const Hash & hash)
{
return hash.type == htMD5 ? printHash(hash) : printHash32(hash);
return hash.to_string(hash.type == htMD5 ? Base16 : Base32);
}
Hash parseHash32(HashType ht, const string & s)
std::string Hash::to_string(Base base, bool includeType) const
{
Hash hash(ht);
size_t len = hash.base32Len();
assert(s.size() == len);
std::string s;
if (includeType) {
s += printHashType(type);
s += ':';
}
switch (base) {
case Base16:
s += printHash16(*this);
break;
case Base32:
s += printHash32(*this);
break;
case Base64:
s += base64Encode(std::string((const char *) hash, hashSize));
break;
}
return s;
}
for (unsigned int n = 0; n < len; ++n) {
char c = s[len - n - 1];
unsigned char digit;
for (digit = 0; digit < base32Chars.size(); ++digit) /* !!! slow */
if (base32Chars[digit] == c) break;
if (digit >= 32)
throw BadHash(format("invalid base-32 hash ‘%1%’") % s);
unsigned int b = n * 5;
unsigned int i = b / 8;
unsigned int j = b % 8;
hash.hash[i] |= digit << j;
if (i < hash.hashSize - 1) {
hash.hash[i + 1] |= digit >> (8 - j);
} else {
if (digit >> (8 - j))
throw BadHash(format("invalid base-32 hash ‘%1%’") % s);
Hash::Hash(const std::string & s, HashType type)
: type(type)
{
auto colon = s.find(':');
size_t pos = 0;
if (colon == string::npos) {
if (type == htUnknown)
throw BadHash("hash ‘%s’ does not include a type", s);
} else {
string hts = string(s, 0, colon);
this->type = parseHashType(hts);
if (this->type == htUnknown)
throw BadHash("unknown hash type ‘%s’", hts);
if (type != htUnknown && type != this->type)
throw BadHash("hash ‘%s’ should have type ‘%s’", s, printHashType(type));
pos = colon + 1;
}
init();
size_t size = s.size() - pos;
if (size == base16Len()) {
auto parseHexDigit = [&](char c) {
if (c >= '0' && c <= '9') return c - '0';
if (c >= 'A' && c <= 'F') return c - 'A' + 10;
if (c >= 'a' && c <= 'f') return c - 'a' + 10;
throw BadHash("invalid base-16 hash ‘%s’", s);
};
for (unsigned int i = 0; i < hashSize; i++) {
hash[i] =
parseHexDigit(s[pos + i * 2]) << 4
| parseHexDigit(s[pos + i * 2 + 1]);
}
}
return hash;
}
else if (size == base32Len()) {
for (unsigned int n = 0; n < size; ++n) {
char c = s[pos + size - n - 1];
unsigned char digit;
for (digit = 0; digit < base32Chars.size(); ++digit) /* !!! slow */
if (base32Chars[digit] == c) break;
if (digit >= 32)
throw BadHash("invalid base-32 hash ‘%s’", s);
unsigned int b = n * 5;
unsigned int i = b / 8;
unsigned int j = b % 8;
hash[i] |= digit << j;
Hash parseHash16or32(HashType ht, const string & s)
{
Hash hash(ht);
if (s.size() == hash.hashSize * 2)
/* hexadecimal representation */
hash = parseHash(ht, s);
else if (s.size() == hash.base32Len())
/* base-32 representation */
hash = parseHash32(ht, s);
else
throw BadHash(format("hash ‘%1%’ has wrong length for hash type ‘%2%’")
% s % printHashType(ht));
return hash;
}
bool isHash(const string & s)
{
if (s.length() != 32) return false;
for (int i = 0; i < 32; i++) {
char c = s[i];
if (!((c >= '0' && c <= '9') ||
(c >= 'a' && c <= 'f')))
return false;
if (i < hashSize - 1) {
hash[i + 1] |= digit >> (8 - j);
} else {
if (digit >> (8 - j))
throw BadHash("invalid base-32 hash ‘%s’", s);
}
}
}
return true;
else if (size == base64Len()) {
auto d = base64Decode(std::string(s, pos));
assert(d.size() == hashSize);
memcpy(hash, d.data(), hashSize);
}
else
throw BadHash("hash ‘%s’ has wrong length for hash type ‘%s’", s, printHashType(type));
}

51
src/libutil/hash.hh
View file

@ -20,20 +20,30 @@ const int sha512HashSize = 64;
extern const string base32Chars;
enum Base : int { Base64, Base32, Base16 };
struct Hash
{
static const unsigned int maxHashSize = 64;
unsigned int hashSize;
unsigned char hash[maxHashSize];
unsigned int hashSize = 0;
unsigned char hash[maxHashSize] = {};
HashType type;
HashType type = htUnknown;
/* Create an unset hash object. */
Hash();
Hash() { };
/* Create a zero-filled hash object. */
Hash(HashType type);
Hash(HashType type) : type(type) { init(); };
/* Initialize the hash from a string representation, in the format
"[<type>:]<base16|base32|base64>". If the ‘type’ argument is
htUnknown, then the hash type must be specified in the
string. */
Hash(const std::string & s, HashType type = htUnknown);
void init();
/* Check whether a hash is set. */
operator bool () const { return type != htUnknown; }
@ -59,33 +69,22 @@ struct Hash
return (hashSize * 8 - 1) / 5 + 1;
}
std::string to_string(bool base32 = true) const;
/* Returns the length of a base-64 representation of this hash. */
size_t base64Len() const
{
return ((4 * hashSize / 3) + 3) & ~3;
}
/* Return a string representation of the hash, in base-16, base-32
or base-64. By default, this is prefixed by the hash type
(e.g. "sha256:"). */
std::string to_string(Base base = Base32, bool includeType = true) const;
};
/* Convert a hash to a hexadecimal representation. */
string printHash(const Hash & hash);
Hash parseHash(const string & s);
/* Parse a hexadecimal representation of a hash code. */
Hash parseHash(HashType ht, const string & s);
/* Convert a hash to a base-32 representation. */
string printHash32(const Hash & hash);
/* Print a hash in base-16 if it's MD5, or base-32 otherwise. */
string printHash16or32(const Hash & hash);
/* Parse a base-32 representation of a hash code. */
Hash parseHash32(HashType ht, const string & s);
/* Parse a base-16 or base-32 representation of a hash code. */
Hash parseHash16or32(HashType ht, const string & s);
/* Verify that the given string is a valid hash code. */
bool isHash(const string & s);
/* Compute the hash of the given string. */
Hash hashString(HashType ht, const string & s);