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rlp: add docs; refactor for readability
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@dckc
dckc committed Dec 20, 2018
1 parent 950fe26 commit 5c172fa
Showing 1 changed file with 154 additions and 108 deletions.
262 changes: 154 additions & 108 deletions src/rlp.rho
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Original file line number Diff line number Diff line change
@@ -1,57 +1,186 @@
// Toward decoding ethereum signed transactions
// https://github.com/ethereum/wiki/wiki/RLP
/** rlp.rho - Recursive Length Prefix
*
* "This is a serialisation method for encoding arbitrarily
* structured binary data (byte arrays)."
*
* Appendix B. of the Ethereum yellow paper
* https://ethereum.github.io/yellowpaper/paper.pdf
*/
new encode, decode, oneByte, encodeVarInt, decodeVarInt,
ListOpsCh, test,
trace(`rho:io:stderr`), stdout(`rho:io:stdout`),
ri(`rho:registry:insertArbitrary`), rl(`rho:registry:lookup`)
insertArbitrary(`rho:registry:insertArbitrary`), lookup(`rho:registry:lookup`)
in {
// TODO: only register if all tests pass
new uriCh in {
ri!({
// ISSUE: only register if all tests pass?
insertArbitrary!({
"decode": bundle+{*decode},
"encode": bundle+{*encode},
"encodeVarInt": bundle+{*encodeVarInt},
"decodeVarInt": bundle+{*decodeVarInt},
"oneByte": bundle+{*oneByte}
}, *uriCh) |
for (@uri <- uriCh) {
stdout!({"rlp uri": uri}) |
rl!(uri, *uriCh)
stdout!({"rlp uri": uri})
}
} |

rl!(`rho:id:dputnspi15oxxnyymjrpu7rkaok3bjkiwq84z7cqcrx4ktqfpyapn4`, *ListOpsCh) |

// Examples are taken from https://github.com/ethereum/wiki/wiki/RLP
// ISSUE: move tests to a separate file?

// • If the byte-array contains solely a single byte and that single
// byte is less than 128, then the input is exactly equal to the
// output.
test!("The encoded integer 0", "00", "00".hexToBytes(), Nil) |
test!("The encoded integer 15", "0f", "0f".hexToBytes(), Nil) |

// • If the byte-array contains fewer than 56 bytes, then the output
// is equal to the input prefixed by the byte equal to the length
// of the byte array plus 128.
test!("The empty string ('null')", "80", "".hexToBytes(), Nil) |
test!("The integer 0", "80", "".hexToBytes(), Nil) |
test!("The string \"dog\"", "83646f67", "646f67".hexToBytes(), Nil) |
test!("The encoded integer 1024", "820400", "0400".hexToBytes(), Nil) |

// • Otherwise, the output is equal to the input prefixed by the
// minimal-length byte-array which when interpreted as a
// big-endian integer is equal to the length of the input byte
// array, which is itself prefixed by the number of bytes required
// to faithfully encode this length value plus 183.
test!("The string \"Lorem ipsum dolor sit amet, consectetur adipisicing elit\"",
"b8384c6f72656d20697073756d20646f6c6f722073697420616d65742c20636f6e7365637465747572206164697069736963696e6720656c6974",
"4c6f72656d20697073756d20646f6c6f722073697420616d65742c20636f6e7365637465747572206164697069736963696e6720656c6974".hexToBytes(), Nil) |

// • If the concatenated serialisations of each contained item is
// less than 56 bytes in length, then the output is equal to that
// concatenation prefixed by the byte equal to the length of this
// byte array plus 192.
test!("The empty list", "c0", [], Nil) |
test!("The list [ \"cat\", \"dog\" ]", "c88363617483646f67",
["636174".hexToBytes(), "646f67".hexToBytes()], Nil) |
test!("The set theoretical representation of three",
"c7c0c1c0c3c0c1c0", [ [], [[]], [ [], [[]] ] ], Nil) |

// • Otherwise, the output is equal to the concatenated
// serialisations prefixed by the minimal-length byte-array which
// when interpreted as a big-endian integer is equal to the length
// of the concatenated serialisations byte array, which is itself
// prefixed by the number of bytes required to faithfully encode
// this length value plus 247.
test!("EIP155 test case",
"f864808504a817c800825208943535353535353535353535353535353535353535808025a0044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116da0044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d",
[
"".hexToBytes(), // nonce
"4a817c800".hexToBytes(), // gasPrice
"5208".hexToBytes(), // gasLimit
"3535353535353535353535353535353535353535".hexToBytes(), // to
"".hexToBytes(), // value
"".hexToBytes(), // data
"25".hexToBytes(), // v
"044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d".hexToBytes(), // r
"044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d".hexToBytes() // s
], Nil) |

test!("ill-formed", "", Nil, Nil) |

trace!("testing") | // Signal that this code is running at all.


// Turn Integer into singleton ByteArray.
new hexCh in {
hexCh!({
0: "0", 1: "1", 2: "2", 3: "3",
4: "4", 5: "5", 6: "6", 7: "7",
8: "8", 9: "9", 10: "a", 11: "b",
12: "c", 13: "d", 14: "e", 15: "f"
}) |
for(@hexDigit <- hexCh) {
contract oneByte(@{i /\ Int}, return) = {
// trace!({"oneByte": i}) |
return!((
hexDigit.getOrElse(i / 16, "0") ++
// ISSUE: coming soon? i % 16
hexDigit.getOrElse(i - (i / 16 * 16), "0")
).hexToBytes())
}
}
} |

// Encode integer as big-endian ByteArray.
// See also toBuffer.
// https://github.com/ethereumjs/ethereumjs-util/blob/master/docs/index.md#tobuffer
contract encodeVarInt(@{x /\ Int}, return) = {
if (x <= 0) {
return!("".hexToBytes())
} else {
new initCh, tailCh in {
encodeVarInt!(x / 256, *initCh) |
oneByte!(x - ((x / 256) * 256), *tailCh) |
for(@init <- initCh; @tail <- tailCh) {
return!(init ++ tail)
}
}
}
} |

// Decode bytes [lo .. hi) of input as big-endian integer,
// provided lo >= 0 and hi <= input.length().
// See also bufferToInt
// https://github.com/ethereumjs/ethereumjs-util/blob/master/docs/index.md#buffertoint
contract decodeVarInt(@{input /\ ByteArray}, @{lo /\ Int}, @{hi /\ Int}, return) = {
// trace!({"toInteger lo": lo, "hi": hi}) |
if (hi <= lo) {
return!(0)
} else if (hi - lo == 1) {
// trace!({"toInteger base": input.nth(lo)}) |
return!(input.nth(lo))
} else {
new recur in {
decodeVarInt!(lo, hi - 1, *recur) |
for(@bb <- recur) {
// trace!({"toInteger recur": input, "lo": lo, "hi": hi}) |
return!(input.nth(hi - 1) + bb * 256)
}
}
}
} |


lookup!(`rho:id:pidw7mxws53r7ubyz3heebf8146ab3z1ct5zq1yw4a9mocg8387aap`, *ListOpsCh) |
for(ListOps <- ListOpsCh) {
trace!({"ListOps": *ListOps}) |

// ISSUE: pattern doesn't express type: data T = B ByteArray | L [T]
// so encode!([0], *ch) will match the pattern but hang because 0 won't match.
contract encode(@item, return) = {
// trace!({"encode item": item}) |
new shortItem, longItem, concat in {
match item {
ByteArray => {
if (item.length() == 1) {
// rholang `and` does not short-circuit???
if (item.nth(0) < 8 * 16) { return!(item) }
else { longItem!(8 * 16, item, *return) }
} else { longItem!(8 * 16, item, *return) }
if (item.nth(0) < 128) { return!(item) }
else { longItem!(128, item) }
} else { longItem!(128, item) }
}
[...items] => {
// trace!({"List": item}) |
new payloadCh in {
concat!(item, *payloadCh) |
for(@payload <- payloadCh) {
longItem!(12 * 16, payload, *return)
longItem!(192, payload)
}
}
}
_ => {
return!(("what???", item))
Nil // ISSUE: signal error to caller?
}
} |

contract longItem(@{bias /\ Int}, @{payload /\ ByteArray}, return) = {
if (payload.length() <= 55) {
shortItem!(bias, payload, *return)
contract longItem(@{bias /\ Int}, @{payload /\ ByteArray}) = {
if (payload.length() < 56) {
shortItem!(bias, payload)
} else {
new encodedLengthCh, b0Ch in {
encodeVarInt!(payload.length(), *encodedLengthCh) |
Expand All @@ -65,7 +194,7 @@ in {
}
} |

contract shortItem(@{bias /\ Int}, @{payload /\ ByteArray}, return) = {
contract shortItem(@{bias /\ Int}, @{payload /\ ByteArray}) = {
new lenCh in {
oneByte!(bias + payload.length(), *lenCh) |
for(@len <- lenCh) {
Expand All @@ -89,37 +218,7 @@ in {
}
} |

new hexCh in {
hexCh!({
0: "0", 1: "1", 2: "2", 3: "3",
4: "4", 5: "5", 6: "6", 7: "7",
8: "8", 9: "9", 10: "a", 11: "b",
12: "c", 13: "d", 14: "e", 15: "f"
}) |
for(@hexDigit <- hexCh) {
// singleton byte sequence
contract oneByte(@{i /\ Integer}, return) = {
// trace!({"oneByte": i}) |
return!((hexDigit.get(i / 16) ++ hexDigit.get(i - (i / 16 * 16))).hexToBytes())
}
}
} |

contract encodeVarInt(@{x /\ Int}, return) = {
if (x <= 0) {
return!("".hexToBytes())
} else {
new initCh, tailCh in {
encodeVarInt!(x / 256, *initCh) |
oneByte!(x - ((x / 256) * 256), *tailCh) |
for(@init <- initCh; @tail <- tailCh) {
return!(init ++ tail)
}
}
}
} |


// Decode the input or fail and indicate where the problem is.
contract decode(@{input /\ ByteArray}, fail, return) = {
// trace!({"rlp input": input}) |
new decodeItem, outCh in {
Expand All @@ -139,18 +238,17 @@ in {
new stringOrList, returnSlice,
decodeString, shortString, longString,
decodeList, shortList, longList, listItems in {
stringOrList!(input.nth(lo))
|
stringOrList!(input.nth(lo)) |
contract stringOrList(@b0) = {
if (b0 <= 127 /* 0x7f */) { returnSlice!(lo, lo + 1) }
else if (b0 <= 191 /* 0xbf */) { decodeString!(lo + 1) }
if (b0 < 128) { returnSlice!(lo, lo + 1) }
else if (b0 < 192) { decodeString!(lo + 1) }
else { decodeList!(lo + 1) }
|
contract returnSlice(@lo, @hi) = { return!(input.slice(lo, hi), hi) } |
contract decodeString(@lo1) = {
// trace!({"decodeString": lo1, "b0": b0}) |
if (b0 <= 183 /* 0xb7 */) { shortString!(lo1 + b0 - 128) }
else { longString!(lo1 + b0 - 183) }
if (b0 < 128 + 56) { shortString!(lo1 + b0 - 128) }
else { longString!(lo1 + b0 + 1 - 128 - 56) }
|
contract shortString(@end) = {
if (end > hi) { fail!(lo) }
Expand All @@ -171,8 +269,8 @@ in {
}
|
contract decodeList(@lo1) = {
if (b0 <= 247 /* 0xf7 */) { shortList!(lo1 + b0 - 192 /* 0xc0*/) }
else { longList!(lo1 + b0 - 247) }
if (b0 < 192 + 56) { shortList!(lo1 + b0 - 192) }
else { longList!(lo1 + b0 + 1 - 192 - 56) }
|
contract shortList(@end) = {
if (end > hi) { fail!(lo) }
Expand Down Expand Up @@ -213,24 +311,6 @@ in {
}
}
|
contract decodeVarInt(@input, @lo, @hi, return) = {
// trace!({"toInteger lo": lo, "hi": hi}) |
if (hi <= lo) {
return!(0)
} else if (hi - lo == 1) {
// trace!({"toInteger base": input.nth(lo)}) |
return!(input.nth(lo))
} else {
new recur in {
decodeVarInt!(lo, hi - 1, *recur) |
for(@bb <- recur) {
// trace!({"toInteger recur": input, "lo": lo, "hi": hi}) |
return!(input.nth(hi - 1) + bb * 256)
}
}
}
}
|
contract test(@label, @inputHex, @expected, ack) = {
new errCh, okCh in {
decode!(inputHex.hexToBytes(), *errCh, *okCh) |
Expand All @@ -257,38 +337,4 @@ in {
}
}
}
|

test!("ill-formed", "", Nil, Nil) |
test!("The string \"dog\"", "83646f67", "646f67".hexToBytes(), Nil) |
test!("The empty string ('null')", "80", "".hexToBytes(), Nil) |
test!("The integer 0", "80", "".hexToBytes(), Nil) |
test!("The empty list", "c0", [], Nil) |
test!("The encoded integer 0", "00", "00".hexToBytes(), Nil) |
test!("The encoded integer 15", "0f", "0f".hexToBytes(), Nil) |
test!("The encoded integer 1024", "820400", "0400".hexToBytes(), Nil) |
test!("The string \"Lorem ipsum dolor sit amet, consectetur adipisicing elit\"",
"b8384c6f72656d20697073756d20646f6c6f722073697420616d65742c20636f6e7365637465747572206164697069736963696e6720656c6974",
"4c6f72656d20697073756d20646f6c6f722073697420616d65742c20636f6e7365637465747572206164697069736963696e6720656c6974".hexToBytes(), Nil) |
test!("The set theoretical representation of three",
"c7c0c1c0c3c0c1c0", [ [], [[]], [ [], [[]] ] ], Nil) |
test!("The list [ \"cat\", \"dog\" ]", "c88363617483646f67",
["636174".hexToBytes(), "646f67".hexToBytes()], Nil) |

test!("EIP155 test case",
"f864808504a817c800825208943535353535353535353535353535353535353535808025a0044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116da0044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d",
[
"".hexToBytes(), // nonce
"4a817c800".hexToBytes(), // gasPrice
"5208".hexToBytes(), // gasLimit
"3535353535353535353535353535353535353535".hexToBytes(), // to
"".hexToBytes(), // value
"".hexToBytes(), // data
"25".hexToBytes(), // v
"044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d".hexToBytes(), // r
"044852b2a670ade5407e78fb2863c51de9fcb96542a07186fe3aeda6bb8a116d".hexToBytes() // s
], Nil) |


trace!("testing")
}

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