nix-gh/src/libutil/hash.cc

351 lines
7.7 KiB
C++
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

#include "config.h"
#include <iostream>
#include <cstring>
#include <openssl/md5.h>
#include <openssl/sha.h>
#include "hash.hh"
#include "archive.hh"
#include "util.hh"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
namespace nix {
Hash::Hash()
{
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;
else if (type == htSHA512) hashSize = sha512HashSize;
else abort();
assert(hashSize <= maxHashSize);
memset(hash, 0, maxHashSize);
}
bool Hash::operator == (const Hash & h2) const
{
if (hashSize != h2.hashSize) return false;
for (unsigned int i = 0; i < hashSize; i++)
if (hash[i] != h2.hash[i]) return false;
return true;
}
bool Hash::operator != (const Hash & h2) const
{
return !(*this == h2);
}
bool Hash::operator < (const Hash & h) const
{
for (unsigned int i = 0; i < hashSize; i++) {
if (hash[i] < h.hash[i]) return true;
if (hash[i] > h.hash[i]) return false;
}
return false;
}
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)
{
char buf[hash.hashSize * 2];
for (unsigned int i = 0; i < hash.hashSize; i++) {
buf[i * 2] = base16Chars[hash.hash[i] >> 4];
buf[i * 2 + 1] = base16Chars[hash.hash[i] & 0x0f];
}
return string(buf, hash.hashSize * 2);
}
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)
{
assert(hash.hashSize);
size_t len = hash.base32Len();
assert(len);
string s;
s.reserve(len);
for (int n = len - 1; n >= 0; n--) {
unsigned int b = n * 5;
unsigned int i = b / 8;
unsigned int j = b % 8;
unsigned char c =
(hash.hash[i] >> j)
| (i >= hash.hashSize - 1 ? 0 : hash.hash[i + 1] << (8 - j));
s.push_back(base32Chars[c & 0x1f]);
}
return s;
}
string printHash16or32(const Hash & hash)
{
return hash.type == htMD5 ? printHash(hash) : printHash32(hash);
}
Hash parseHash32(HashType ht, const string & s)
{
Hash hash(ht);
size_t len = hash.base32Len();
assert(s.size() == len);
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);
}
return hash;
}
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;
}
return true;
}
union Ctx
{
MD5_CTX md5;
SHA_CTX sha1;
SHA256_CTX sha256;
SHA512_CTX sha512;
};
static void start(HashType ht, Ctx & ctx)
{
if (ht == htMD5) MD5_Init(&ctx.md5);
else if (ht == htSHA1) SHA1_Init(&ctx.sha1);
else if (ht == htSHA256) SHA256_Init(&ctx.sha256);
else if (ht == htSHA512) SHA512_Init(&ctx.sha512);
}
static void update(HashType ht, Ctx & ctx,
const unsigned char * bytes, unsigned int len)
{
if (ht == htMD5) MD5_Update(&ctx.md5, bytes, len);
else if (ht == htSHA1) SHA1_Update(&ctx.sha1, bytes, len);
else if (ht == htSHA256) SHA256_Update(&ctx.sha256, bytes, len);
else if (ht == htSHA512) SHA512_Update(&ctx.sha512, bytes, len);
}
static void finish(HashType ht, Ctx & ctx, unsigned char * hash)
{
if (ht == htMD5) MD5_Final(hash, &ctx.md5);
else if (ht == htSHA1) SHA1_Final(hash, &ctx.sha1);
else if (ht == htSHA256) SHA256_Final(hash, &ctx.sha256);
else if (ht == htSHA512) SHA512_Final(hash, &ctx.sha512);
}
Hash hashString(HashType ht, const string & s)
{
Ctx ctx;
Hash hash(ht);
start(ht, ctx);
update(ht, ctx, (const unsigned char *) s.data(), s.length());
finish(ht, ctx, hash.hash);
return hash;
}
Hash hashFile(HashType ht, const Path & path)
{
Ctx ctx;
Hash hash(ht);
start(ht, ctx);
AutoCloseFD fd = open(path.c_str(), O_RDONLY | O_CLOEXEC);
if (!fd) throw SysError(format("opening file %1%") % path);
unsigned char buf[8192];
ssize_t n;
while ((n = read(fd.get(), buf, sizeof(buf)))) {
checkInterrupt();
if (n == -1) throw SysError(format("reading file %1%") % path);
update(ht, ctx, buf, n);
}
finish(ht, ctx, hash.hash);
return hash;
}
HashSink::HashSink(HashType ht) : ht(ht)
{
ctx = new Ctx;
bytes = 0;
start(ht, *ctx);
}
HashSink::~HashSink()
{
bufPos = 0;
delete ctx;
}
void HashSink::write(const unsigned char * data, size_t len)
{
bytes += len;
update(ht, *ctx, data, len);
}
HashResult HashSink::finish()
{
flush();
Hash hash(ht);
nix::finish(ht, *ctx, hash.hash);
return HashResult(hash, bytes);
}
HashResult HashSink::currentHash()
{
flush();
Ctx ctx2 = *ctx;
Hash hash(ht);
nix::finish(ht, ctx2, hash.hash);
return HashResult(hash, bytes);
}
HashResult hashPath(
HashType ht, const Path & path, PathFilter & filter)
{
HashSink sink(ht);
dumpPath(path, sink, filter);
return sink.finish();
}
Hash compressHash(const Hash & hash, unsigned int newSize)
{
Hash h;
h.hashSize = newSize;
for (unsigned int i = 0; i < hash.hashSize; ++i)
h.hash[i % newSize] ^= hash.hash[i];
return h;
}
HashType parseHashType(const string & s)
{
if (s == "md5") return htMD5;
else if (s == "sha1") return htSHA1;
else if (s == "sha256") return htSHA256;
else if (s == "sha512") return htSHA512;
else return htUnknown;
}
string printHashType(HashType ht)
{
if (ht == htMD5) return "md5";
else if (ht == htSHA1) return "sha1";
else if (ht == htSHA256) return "sha256";
else if (ht == htSHA512) return "sha512";
else abort();
}
}