nix-gh/src/libutil/hash.cc
Eelco Dolstra 26f7e8305b
Fix hash computation when importing NARs greater than 4 GiB
This caused "nix-store --import" to compute an incorrect hash on NARs
that don't fit in an unsigned int. The import would succeed, but
"nix-store --verify-path" or subsequent exports would detect an
incorrect hash.

A deeper issue is that the export/import format does not contain a
hash, so we can't detect such issues early.

Also, I learned that -Wall does not warn about this.

(cherry picked from commit 41c4558afe)
2017-05-01 11:26:27 +02:00

336 lines
7.3 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 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;
}
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)
{
unsigned int len = hashLength32(hash);
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);
unsigned int len = hashLength32(ht);
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 Error(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() == hashLength32(hash))
/* base-32 representation */
hash = parseHash32(ht, s);
else
throw Error(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, size_t 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);
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;
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 throw Error("cannot print unknown hash type");
}
}