lix/src/libutil/hash.cc
2023-03-29 10:54:27 +01:00

422 lines
10 KiB
C++

#include <iostream>
#include <cstring>
#include <openssl/md5.h>
#include <openssl/sha.h>
#include "args.hh"
#include "hash.hh"
#include "archive.hh"
#include "split.hh"
#include "util.hh"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
namespace nix {
static size_t regularHashSize(HashType type) {
switch (type) {
case htMD5: return md5HashSize;
case htSHA1: return sha1HashSize;
case htSHA256: return sha256HashSize;
case htSHA512: return sha512HashSize;
}
abort();
}
std::set<std::string> hashTypes = { "md5", "sha1", "sha256", "sha512" };
Hash::Hash(HashType type) : type(type)
{
hashSize = regularHashSize(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
{
if (hashSize < h.hashSize) return true;
if (hashSize > h.hashSize) return false;
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 std::string base16Chars = "0123456789abcdef";
static std::string printHash16(const Hash & hash)
{
std::string buf;
buf.reserve(hash.hashSize * 2);
for (unsigned int i = 0; i < hash.hashSize; i++) {
buf.push_back(base16Chars[hash.hash[i] >> 4]);
buf.push_back(base16Chars[hash.hash[i] & 0x0f]);
}
return buf;
}
// omitted: E O U T
const std::string base32Chars = "0123456789abcdfghijklmnpqrsvwxyz";
static std::string printHash32(const Hash & hash)
{
assert(hash.hashSize);
size_t len = hash.base32Len();
assert(len);
std::string s;
s.reserve(len);
for (int n = (int) 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;
}
std::string printHash16or32(const Hash & hash)
{
assert(hash.type);
return hash.to_string(hash.type == htMD5 ? Base16 : Base32, false);
}
std::string Hash::to_string(Base base, bool includeType) const
{
std::string s;
if (base == SRI || includeType) {
s += printHashType(type);
s += base == SRI ? '-' : ':';
}
switch (base) {
case Base16:
s += printHash16(*this);
break;
case Base32:
s += printHash32(*this);
break;
case Base64:
case SRI:
s += base64Encode(std::string_view((const char *) hash, hashSize));
break;
}
return s;
}
Hash Hash::dummy(htSHA256);
Hash Hash::parseSRI(std::string_view original) {
auto rest = original;
// Parse the has type before the separater, if there was one.
auto hashRaw = splitPrefixTo(rest, '-');
if (!hashRaw)
throw BadHash("hash '%s' is not SRI", original);
HashType parsedType = parseHashType(*hashRaw);
return Hash(rest, parsedType, true);
}
// Mutates the string to eliminate the prefixes when found
static std::pair<std::optional<HashType>, bool> getParsedTypeAndSRI(std::string_view & rest)
{
bool isSRI = false;
// Parse the hash type before the separator, if there was one.
std::optional<HashType> optParsedType;
{
auto hashRaw = splitPrefixTo(rest, ':');
if (!hashRaw) {
hashRaw = splitPrefixTo(rest, '-');
if (hashRaw)
isSRI = true;
}
if (hashRaw)
optParsedType = parseHashType(*hashRaw);
}
return {optParsedType, isSRI};
}
Hash Hash::parseAnyPrefixed(std::string_view original)
{
auto rest = original;
auto [optParsedType, isSRI] = getParsedTypeAndSRI(rest);
// Either the string or user must provide the type, if they both do they
// must agree.
if (!optParsedType)
throw BadHash("hash '%s' does not include a type", rest);
return Hash(rest, *optParsedType, isSRI);
}
Hash Hash::parseAny(std::string_view original, std::optional<HashType> optType)
{
auto rest = original;
auto [optParsedType, isSRI] = getParsedTypeAndSRI(rest);
// Either the string or user must provide the type, if they both do they
// must agree.
if (!optParsedType && !optType)
throw BadHash("hash '%s' does not include a type, nor is the type otherwise known from context", rest);
else if (optParsedType && optType && *optParsedType != *optType)
throw BadHash("hash '%s' should have type '%s'", original, printHashType(*optType));
HashType hashType = optParsedType ? *optParsedType : *optType;
return Hash(rest, hashType, isSRI);
}
Hash Hash::parseNonSRIUnprefixed(std::string_view s, HashType type)
{
return Hash(s, type, false);
}
Hash::Hash(std::string_view rest, HashType type, bool isSRI)
: Hash(type)
{
if (!isSRI && rest.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'", rest);
};
for (unsigned int i = 0; i < hashSize; i++) {
hash[i] =
parseHexDigit(rest[i * 2]) << 4
| parseHexDigit(rest[i * 2 + 1]);
}
}
else if (!isSRI && rest.size() == base32Len()) {
for (unsigned int n = 0; n < rest.size(); ++n) {
char c = rest[rest.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'", rest);
unsigned int b = n * 5;
unsigned int i = b / 8;
unsigned int j = b % 8;
hash[i] |= digit << j;
if (i < hashSize - 1) {
hash[i + 1] |= digit >> (8 - j);
} else {
if (digit >> (8 - j))
throw BadHash("invalid base-32 hash '%s'", rest);
}
}
}
else if (isSRI || rest.size() == base64Len()) {
auto d = base64Decode(rest);
if (d.size() != hashSize)
throw BadHash("invalid %s hash '%s'", isSRI ? "SRI" : "base-64", rest);
assert(hashSize);
memcpy(hash, d.data(), hashSize);
}
else
throw BadHash("hash '%s' has wrong length for hash type '%s'", rest, printHashType(this->type));
}
Hash newHashAllowEmpty(std::string_view hashStr, std::optional<HashType> ht)
{
if (hashStr.empty()) {
if (!ht)
throw BadHash("empty hash requires explicit hash type");
Hash h(*ht);
warn("found empty hash, assuming '%s'", h.to_string(SRI, true));
return h;
} else
return Hash::parseAny(hashStr, ht);
}
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,
std::string_view data)
{
if (ht == htMD5) MD5_Update(&ctx.md5, data.data(), data.size());
else if (ht == htSHA1) SHA1_Update(&ctx.sha1, data.data(), data.size());
else if (ht == htSHA256) SHA256_Update(&ctx.sha256, data.data(), data.size());
else if (ht == htSHA512) SHA512_Update(&ctx.sha512, data.data(), data.size());
}
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, std::string_view s)
{
Ctx ctx;
Hash hash(ht);
start(ht, ctx);
update(ht, ctx, s);
finish(ht, ctx, hash.hash);
return hash;
}
Hash hashFile(HashType ht, const Path & path)
{
HashSink sink(ht);
readFile(path, sink);
return sink.finish().first;
}
HashSink::HashSink(HashType ht) : ht(ht)
{
ctx = new Ctx;
bytes = 0;
start(ht, *ctx);
}
HashSink::~HashSink()
{
bufPos = 0;
delete ctx;
}
void HashSink::write(std::string_view data)
{
bytes += data.size();
update(ht, *ctx, data);
}
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(hash.type);
h.hashSize = newSize;
for (unsigned int i = 0; i < hash.hashSize; ++i)
h.hash[i % newSize] ^= hash.hash[i];
return h;
}
std::optional<HashType> parseHashTypeOpt(std::string_view 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 std::optional<HashType> {};
}
HashType parseHashType(std::string_view s)
{
auto opt_h = parseHashTypeOpt(s);
if (opt_h)
return *opt_h;
else
throw UsageError("unknown hash algorithm '%1%'", s);
}
std::string_view printHashType(HashType ht)
{
switch (ht) {
case htMD5: return "md5";
case htSHA1: return "sha1";
case htSHA256: return "sha256";
case htSHA512: return "sha512";
default:
// illegal hash type enum value internally, as opposed to external input
// which should be validated with nice error message.
assert(false);
}
}
}