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Support SRI hashes

Browse source 
SRI hashes (https://www.w3.org/TR/SRI/) combine the hash algorithm and
a base-64 hash. This allows more concise and standard hash
specifications. For example, instead of

  import <nix/fetchurl.nl> {
    url = https://nixos.org/releases/nix/nix-2.1.3/nix-2.1.3.tar.xz;
    sha256 = "5d22dad058d5c800d65a115f919da22938c50dd6ba98c5e3a183172d149840a4";
  };

you can write

  import <nix/fetchurl.nl> {
    url = https://nixos.org/releases/nix/nix-2.1.3/nix-2.1.3.tar.xz;
    hash = "sha256-XSLa0FjVyADWWhFfkZ2iKTjFDda6mMXjoYMXLRSYQKQ=";
  };

In fixed-output derivations, the outputHashAlgo is no longer mandatory
if outputHash specifies the hash (either as an SRI or in the old
"<type>:<hash>" format).

'nix hash-{file,path}' now print hashes in SRI format by default. I
also reverted them to use SHA-256 by default because that's what we're
using most of the time in Nixpkgs.

Suggested by @zimbatm.
This commit is contained in:
Eelco Dolstra 2018-12-13 14:30:52 +01:00
parent c37e6d77ea
commit 6024dc1d97
No known key found for this signature in database
GPG key ID: 8170B4726D7198DE
8 changed files with 72 additions and 34 deletions
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10
src/libexpr/primops.cc
View file

@ -724,16 +724,14 @@ static void prim_derivationStrict(EvalState & state, const Pos & pos, Value * *
if (outputs.size() != 1 || *(outputs.begin()) != "out")
throw Error(format("multiple outputs are not supported in fixed-output derivations, at %1%") % posDrvName);
HashType ht = parseHashType(outputHashAlgo);
if (ht == htUnknown)
throw EvalError(format("unknown hash algorithm '%1%', at %2%") % outputHashAlgo % posDrvName);
HashType ht = outputHashAlgo.empty() ? htUnknown : parseHashType(outputHashAlgo);
Hash h(*outputHash, ht);
outputHash = h.to_string(Base16, false);
if (outputHashRecursive) outputHashAlgo = "r:" + outputHashAlgo;
Path outPath = state.store->makeFixedOutputPath(outputHashRecursive, h, drvName);
if (!jsonObject) drv.env["out"] = outPath;
drv.outputs["out"] = DerivationOutput(outPath, outputHashAlgo, *outputHash);
drv.outputs["out"] = DerivationOutput(outPath,
(outputHashRecursive ? "r:" : "") + printHashType(h.type),
h.to_string(Base16, false));
}
else {

32
src/libutil/hash.cc
View file

@ -105,9 +105,9 @@ string printHash16or32(const Hash & hash)
std::string Hash::to_string(Base base, bool includeType) const
{
std::string s;
if (includeType) {
if (base == SRI || includeType) {
s += printHashType(type);
s += ':';
s += base == SRI ? '-' : ':';
}
switch (base) {
case Base16:
@ -117,6 +117,7 @@ std::string Hash::to_string(Base base, bool includeType) const
s += printHash32(*this);
break;
case Base64:
case SRI:
s += base64Encode(std::string((const char *) hash, hashSize));
break;
}
@ -127,28 +128,33 @@ std::string Hash::to_string(Base base, bool includeType) const
Hash::Hash(const std::string & s, HashType type)
: type(type)
{
auto colon = s.find(':');
size_t pos = 0;
bool isSRI = false;
if (colon == string::npos) {
if (type == htUnknown)
auto sep = s.find(':');
if (sep == string::npos) {
sep = s.find('-');
if (sep != string::npos) {
isSRI = true;
} else if (type == htUnknown)
throw BadHash("hash '%s' does not include a type", s);
} else {
string hts = string(s, 0, colon);
}
if (sep != string::npos) {
string hts = string(s, 0, sep);
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;
pos = sep + 1;
}
init();
size_t size = s.size() - pos;
if (size == base16Len()) {
if (!isSRI && size == base16Len()) {
auto parseHexDigit = [&](char c) {
if (c >= '0' && c <= '9') return c - '0';
@ -164,7 +170,7 @@ Hash::Hash(const std::string & s, HashType type)
}
}
else if (size == base32Len()) {
else if (!isSRI && size == base32Len()) {
for (unsigned int n = 0; n < size; ++n) {
char c = s[pos + size - n - 1];
@ -187,10 +193,10 @@ Hash::Hash(const std::string & s, HashType type)
}
}
else if (size == base64Len()) {
else if (isSRI || size == base64Len()) {
auto d = base64Decode(std::string(s, pos));
if (d.size() != hashSize)
throw BadHash("invalid base-64 hash '%s'", s);
throw BadHash("invalid %s hash '%s'", isSRI ? "SRI" : "base-64", s);
assert(hashSize);
memcpy(hash, d.data(), hashSize);
}

7
src/libutil/hash.hh
View file

@ -20,7 +20,7 @@ const int sha512HashSize = 64;
extern const string base32Chars;
enum Base : int { Base64, Base32, Base16 };
enum Base : int { Base64, Base32, Base16, SRI };
struct Hash
@ -38,8 +38,9 @@ struct Hash
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
"[<type>:]<base16|base32|base64>" or "<type>-<base64>" (a
Subresource Integrity hash expression). If the 'type' argument
is htUnknown, then the hash type must be specified in the
string. */
Hash(const std::string & s, HashType type = htUnknown);

3
src/nix-store/nix-store.cc
View file

@ -1000,6 +1000,9 @@ static int _main(int argc, char * * argv)
Strings opFlags, opArgs;
Operation op = 0;
Hash h("sha512-Q2bFTOhEALkN8hOms2FKTDLy7eugP2zFZ1T8LCvX42Fp3WoNr3bjZSAHeOsHrbV1Fu9/A0EzCinRE7Af1ofPrw==");
printError("GOT HASH %s", h.to_string(Base64));
parseCmdLine(argc, argv, [&](Strings::iterator & arg, const Strings::iterator & end) {
Operation oldOp = op;

23
src/nix/hash.cc
View file

@ -9,13 +9,14 @@ struct CmdHash : Command
{
enum Mode { mFile, mPath };
Mode mode;
Base base = Base16;
Base base = SRI;
bool truncate = false;
HashType ht = htSHA512;
HashType ht = htSHA256;
std::vector<std::string> paths;
CmdHash(Mode mode) : mode(mode)
{
mkFlag(0, "sri", "print hash in SRI format", &base, SRI);
mkFlag(0, "base64", "print hash in base-64", &base, Base64);
mkFlag(0, "base32", "print hash in base-32 (Nix-specific)", &base, Base32);
mkFlag(0, "base16", "print hash in base-16", &base, Base16);
@ -43,7 +44,7 @@ struct CmdHash : Command
Hash h = mode == mFile ? hashFile(ht, path) : hashPath(ht, path).first;
if (truncate && h.hashSize > 20) h = compressHash(h, 20);
std::cout << format("%1%\n") %
h.to_string(base, false);
h.to_string(base, base == SRI);
}
}
};
@ -54,7 +55,7 @@ static RegisterCommand r2(make_ref<CmdHash>(CmdHash::mPath));
struct CmdToBase : Command
{
Base base;
HashType ht = htSHA512;
HashType ht = htUnknown;
std::vector<std::string> args;
CmdToBase(Base base) : base(base)
@ -70,26 +71,30 @@ struct CmdToBase : Command
return
base == Base16 ? "to-base16" :
base == Base32 ? "to-base32" :
"to-base64";
base == Base64 ? "to-base64" :
"to-sri";
}
std::string description() override
{
return fmt("convert a hash to base-%d representation",
base == Base16 ? 16 :
base == Base32 ? 32 : 64);
return fmt("convert a hash to %s representation",
base == Base16 ? "base-16" :
base == Base32 ? "base-32" :
base == Base64 ? "base-64" :
"SRI");
}
void run() override
{
for (auto s : args)
std::cout << fmt("%s\n", Hash(s, ht).to_string(base, false));
std::cout << fmt("%s\n", Hash(s, ht).to_string(base, base == SRI));
}
};
static RegisterCommand r3(make_ref<CmdToBase>(Base16));
static RegisterCommand r4(make_ref<CmdToBase>(Base32));
static RegisterCommand r5(make_ref<CmdToBase>(Base64));
static RegisterCommand r6(make_ref<CmdToBase>(SRI));
/* Legacy nix-hash command. */
static int compatNixHash(int argc, char * * argv)