lix/src/libutil/hash.cc
Eelco Dolstra 4c356acd04 * In `nix-store --export', abort if the contents of a path has
changed.  This prevents corrupt paths from spreading to other
  machines.  Note that checking the hash is cheap because we're
  hashing anyway (because of the --sign feature).
2010-03-09 14:32:03 +00:00

355 lines
7.2 KiB
C++

#include "config.h"
#include <iostream>
#include <cstring>
#ifdef HAVE_OPENSSL
#include <openssl/md5.h>
#include <openssl/sha.h>
#else
extern "C" {
#include "md5.h"
#include "sha1.h"
#include "sha256.h"
}
#endif
#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 throw Error("unknown hash type");
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;
}
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(HashType ht, const string & s)
{
Hash hash(ht);
if (s.length() != hash.hashSize * 2)
throw Error(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 Error(format("invalid hash `%1%'") % s);
std::istringstream str(s2);
int n;
str >> std::hex >> n;
hash.hash[i] = n;
}
return hash;
}
static unsigned char divMod(unsigned char * bytes, unsigned char y)
{
unsigned int borrow = 0;
int pos = Hash::maxHashSize - 1;
while (pos >= 0 && !bytes[pos]) --pos;
for ( ; pos >= 0; --pos) {
unsigned int s = bytes[pos] + (borrow << 8);
unsigned int d = s / y;
borrow = s % y;
bytes[pos] = d;
}
return borrow;
}
unsigned int hashLength32(const Hash & hash)
{
return (hash.hashSize * 8 - 1) / 5 + 1;
}
// omitted: E O U T
const string base32Chars = "0123456789abcdfghijklmnpqrsvwxyz";
string printHash32(const Hash & hash)
{
Hash hash2(hash);
unsigned int len = hashLength32(hash);
const char * chars = base32Chars.c_str();
string s(len, '0');
int pos = len - 1;
while (pos >= 0) {
unsigned char digit = divMod(hash2.hash, 32);
s[pos--] = chars[digit];
}
for (unsigned int i = 0; i < hash2.maxHashSize; ++i)
assert(hash2.hash[i] == 0);
return s;
}
static bool mul(unsigned char * bytes, unsigned char y, int maxSize)
{
unsigned char carry = 0;
for (int pos = 0; pos < maxSize; ++pos) {
unsigned int m = bytes[pos] * y + carry;
bytes[pos] = m & 0xff;
carry = m >> 8;
}
return carry;
}
static bool add(unsigned char * bytes, unsigned char y, int maxSize)
{
unsigned char carry = y;
for (int pos = 0; pos < maxSize; ++pos) {
unsigned int m = bytes[pos] + carry;
bytes[pos] = m & 0xff;
carry = m >> 8;
if (carry == 0) break;
}
return carry;
}
Hash parseHash32(HashType ht, const string & s)
{
Hash hash(ht);
const char * chars = base32Chars.c_str();
for (unsigned int i = 0; i < s.length(); ++i) {
char c = s[i];
unsigned char digit;
for (digit = 0; digit < base32Chars.size(); ++digit) /* !!! slow */
if (chars[digit] == c) break;
if (digit >= 32)
throw Error(format("invalid base-32 hash `%1%'") % s);
if (mul(hash.hash, 32, hash.hashSize) ||
add(hash.hash, digit, hash.hashSize))
throw Error(format("base-32 hash `%1%' is too large") % s);
}
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;
};
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);
}
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);
}
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);
}
Hash hashString(HashType ht, const string & s)
{
Ctx ctx;
Hash hash(ht);
start(ht, ctx);
update(ht, ctx, (const unsigned char *) s.c_str(), 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);
if (fd == -1) throw SysError(format("opening file `%1%'") % path);
unsigned char buf[8192];
ssize_t n;
while ((n = read(fd, 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;
start(ht, *ctx);
}
HashSink::HashSink(const HashSink & h)
{
ht = h.ht;
ctx = new Ctx;
*ctx = *h.ctx;
}
HashSink::~HashSink()
{
delete ctx;
}
void HashSink::operator ()
(const unsigned char * data, unsigned int len)
{
update(ht, *ctx, data, len);
}
Hash HashSink::finish()
{
Hash hash(ht);
nix::finish(ht, *ctx, hash.hash);
return hash;
}
Hash 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 return htUnknown;
}
string printHashType(HashType ht)
{
if (ht == htMD5) return "md5";
else if (ht == htSHA1) return "sha1";
else if (ht == htSHA256) return "sha256";
else throw Error("cannot print unknown hash type");
}
}