rust-bitcoin-unsafe-fast/src/blockdata/script.rs

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// Rust Bitcoin Library
// Written in 2014 by
// Andrew Poelstra <apoelstra@wpsoftware.net>
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//
// To the extent possible under law, the author(s) have dedicated all
// copyright and related and neighboring rights to this software to
// the public domain worldwide. This software is distributed without
// any warranty.
//
// You should have received a copy of the CC0 Public Domain Dedication
// along with this software.
// If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
//
//! # Script
//!
//! Scripts define Bitcoin's digital signature scheme: a signature is formed
//! from a script (the second half of which is defined by a coin to be spent,
//! and the first half provided by the spending transaction), and is valid
//! iff the script leaves `TRUE` on the stack after being evaluated.
//! Bitcoin's script is a stack-based assembly language similar in spirit to
//! Forth.
//!
//! This module provides the structures and functions needed to support scripts.
//!
use std::default::Default;
use std::{error, fmt};
use serde;
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use blockdata::opcodes;
use network::encodable::{ConsensusDecodable, ConsensusEncodable};
use network::serialize::{SimpleDecoder, SimpleEncoder};
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#[derive(Clone, PartialEq, Eq, Hash)]
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/// A Bitcoin script
pub struct Script(Box<[u8]>);
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impl fmt::Debug for Script {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
let mut index = 0;
try!(f.write_str("Script("));
while index < self.0.len() {
let opcode = opcodes::All::from(self.0[index]);
let data_len = if let opcodes::Class::PushBytes(n) = opcode.classify() {
n as usize
} else {
match opcode {
opcodes::All::OP_PUSHDATA1 => {
if self.0.len() < index + 1 {
try!(f.write_str("<unexpected end>"));
break;
}
match read_uint(&self.0[index..], 1) {
Ok(n) => { index += 1; n as usize }
Err(_) => { try!(f.write_str("<bad length>")); break; }
}
}
opcodes::All::OP_PUSHDATA2 => {
if self.0.len() < index + 2 {
try!(f.write_str("<unexpected end>"));
break;
}
match read_uint(&self.0[index..], 2) {
Ok(n) => { index += 2; n as usize }
Err(_) => { try!(f.write_str("<bad length>")); break; }
}
}
opcodes::All::OP_PUSHDATA4 => {
if self.0.len() < index + 4 {
try!(f.write_str("<unexpected end>"));
break;
}
match read_uint(&self.0[index..], 4) {
Ok(n) => { index += 4; n as usize }
Err(_) => { try!(f.write_str("<bad length>")); break; }
}
}
_ => 0
}
};
if index > 0 { try!(f.write_str(" ")); }
// Write the opcode
if opcode == opcodes::All::OP_PUSHBYTES_0 {
try!(f.write_str("OP_0"));
} else {
try!(write!(f, "{:?}", opcode));
}
index += 1;
// Write any pushdata
if data_len > 0 {
try!(f.write_str(" "));
if index + data_len < self.0.len() {
for ch in &self.0[index..index + data_len] {
try!(write!(f, "{:02x}", ch));
}
index += data_len;
} else {
try!(f.write_str("<push past end>"));
break;
}
}
}
f.write_str(")")
}
}
impl fmt::Display for Script {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
fmt::Debug::fmt(self, f)
}
}
impl fmt::LowerHex for Script {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
for &ch in self.0.iter() {
try!(write!(f, "{:02x}", ch));
}
Ok(())
}
}
impl fmt::UpperHex for Script {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
for &ch in self.0.iter() {
try!(write!(f, "{:02X}", ch));
}
Ok(())
}
}
#[derive(PartialEq, Eq, Debug, Clone)]
/// An object which can be used to construct a script piece by piece
pub struct Builder(Vec<u8>);
display_from_debug!(Builder);
/// Ways that a script might fail. Not everything is split up as
/// much as it could be; patches welcome if more detailed errors
/// would help you.
#[derive(PartialEq, Eq, Debug, Clone)]
pub enum Error {
/// Some opcode expected a parameter, but it was missing or truncated
EarlyEndOfScript,
/// Tried to read an array off the stack as a number when it was more than 4 bytes
NumericOverflow,
}
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.write_str(error::Error::description(self))
}
}
impl error::Error for Error {
fn cause(&self) -> Option<&error::Error> { None }
fn description(&self) -> &'static str {
match *self {
Error::EarlyEndOfScript => "unexpected end of script",
Error::NumericOverflow => "numeric overflow (number on stack larger than 4 bytes)",
}
}
}
/// Helper to encode an integer in script format
fn build_scriptint(n: i64) -> Vec<u8> {
if n == 0 { return vec![] }
let neg = n < 0;
let mut abs = if neg { -n } else { n } as usize;
let mut v = vec![];
while abs > 0xFF {
v.push((abs & 0xFF) as u8);
abs >>= 8;
}
// If the number's value causes the sign bit to be set, we need an extra
// byte to get the correct value and correct sign bit
if abs & 0x80 != 0 {
v.push(abs as u8);
v.push(if neg { 0x80u8 } else { 0u8 });
}
// Otherwise we just set the sign bit ourselves
else {
abs |= if neg { 0x80 } else { 0 };
v.push(abs as u8);
}
v
}
/// Helper to decode an integer in script format
/// Notice that this fails on overflow: the result is the same as in
/// bitcoind, that only 4-byte signed-magnitude values may be read as
/// numbers. They can be added or subtracted (and a long time ago,
/// multiplied and divided), and this may result in numbers which
/// can't be written out in 4 bytes or less. This is ok! The number
/// just can't be read as a number again.
/// This is a bit crazy and subtle, but it makes sense: you can load
/// 32-bit numbers and do anything with them, which back when mult/div
/// was allowed, could result in up to a 64-bit number. We don't want
/// overflow since that's suprising --- and we don't want numbers that
/// don't fit in 64 bits (for efficiency on modern processors) so we
/// simply say, anything in excess of 32 bits is no longer a number.
/// This is basically a ranged type implementation.
pub fn read_scriptint(v: &[u8]) -> Result<i64, Error> {
let len = v.len();
if len == 0 { return Ok(0); }
if len > 4 { return Err(Error::NumericOverflow); }
let (mut ret, sh) = v.iter()
.fold((0, 0), |(acc, sh), n| (acc + ((*n as i64) << sh), sh + 8));
if v[len - 1] & 0x80 != 0 {
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ret &= (1 << (sh - 1)) - 1;
ret = -ret;
}
Ok(ret)
}
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/// This is like "`read_scriptint` then map 0 to false and everything
/// else as true", except that the overflow rules don't apply.
#[inline]
pub fn read_scriptbool(v: &[u8]) -> bool {
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!(v.is_empty() ||
((v[v.len() - 1] == 0 || v[v.len() - 1] == 0x80) &&
v.iter().rev().skip(1).all(|&w| w == 0)))
}
/// Read a script-encoded unsigned integer
pub fn read_uint(data: &[u8], size: usize) -> Result<usize, Error> {
if data.len() < size {
Err(Error::EarlyEndOfScript)
} else {
let mut ret = 0;
for (i, item) in data.iter().take(size).enumerate() {
ret += (*item as usize) << (i * 8);
}
Ok(ret)
}
}
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impl Script {
/// Creates a new empty script
pub fn new() -> Script { Script(vec![].into_boxed_slice()) }
/// The length in bytes of the script
pub fn len(&self) -> usize { self.0.len() }
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/// Whether the script is the empty script
pub fn is_empty(&self) -> bool { self.0.is_empty() }
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/// Convert the script into a byte vector
pub fn into_vec(self) -> Vec<u8> { self.0.into_vec() }
/// Checks whether a script pubkey is a p2sh output
#[inline]
pub fn is_p2sh(&self) -> bool {
self.0.len() == 23 &&
self.0[0] == opcodes::All::OP_HASH160 as u8 &&
self.0[1] == opcodes::All::OP_PUSHBYTES_20 as u8 &&
self.0[22] == opcodes::All::OP_EQUAL as u8
}
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/// Whether a script can be proven to have no satisfying input
pub fn is_provably_unspendable(&self) -> bool {
!self.0.is_empty() && (opcodes::All::from(self.0[0]).classify() == opcodes::Class::ReturnOp ||
opcodes::All::from(self.0[0]).classify() == opcodes::Class::IllegalOp)
}
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}
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impl Default for Script {
fn default() -> Script { Script(vec![].into_boxed_slice()) }
}
/// Creates a new script from an existing vector
impl From<Vec<u8>> for Script {
fn from(v: Vec<u8>) -> Script { Script(v.into_boxed_slice()) }
}
impl_index_newtype!(Script, u8);
/// A "parsed opcode" which allows iterating over a Script in a more sensible way
#[derive(Debug, PartialEq, Eq, Clone)]
pub enum Instruction<'a> {
/// Push a bunch of data
PushBytes(&'a [u8]),
/// Some non-push opcode
Op(opcodes::All),
/// An opcode we were unable to parse
Error(Error)
}
/// Iterator over a script returning parsed opcodes
pub struct Instructions<'a> {
data: &'a [u8]
}
impl<'a> IntoIterator for &'a Script {
type Item = Instruction<'a>;
type IntoIter = Instructions<'a>;
fn into_iter(self) -> Instructions<'a> { Instructions { data: &self.0[..] } }
}
impl<'a> Iterator for Instructions<'a> {
type Item = Instruction<'a>;
fn next(&mut self) -> Option<Instruction<'a>> {
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if self.data.is_empty() {
return None;
}
match opcodes::All::from(self.data[0]).classify() {
opcodes::Class::PushBytes(n) => {
let n = n as usize;
if self.data.len() < n + 1 {
return Some(Instruction::Error(Error::EarlyEndOfScript));
}
let ret = Some(Instruction::PushBytes(&self.data[1..n+1]));
self.data = &self.data[n + 1..];
ret
}
opcodes::Class::Ordinary(opcodes::Ordinary::OP_PUSHDATA1) => {
if self.data.len() < 2 { return Some(Instruction::Error(Error::EarlyEndOfScript)); }
let n = match read_uint(&self.data[1..], 1) {
Ok(n) => n,
Err(e) => { return Some(Instruction::Error(e)); }
};
if self.data.len() < n + 2 { return Some(Instruction::Error(Error::EarlyEndOfScript)); }
let ret = Some(Instruction::PushBytes(&self.data[2..n+2]));
self.data = &self.data[n + 2..];
ret
}
opcodes::Class::Ordinary(opcodes::Ordinary::OP_PUSHDATA2) => {
if self.data.len() < 3 { return Some(Instruction::Error(Error::EarlyEndOfScript)); }
let n = match read_uint(&self.data[1..], 2) {
Ok(n) => n,
Err(e) => { return Some(Instruction::Error(e)); }
};
if self.data.len() < n + 3 { return Some(Instruction::Error(Error::EarlyEndOfScript)); }
let ret = Some(Instruction::PushBytes(&self.data[3..n + 3]));
self.data = &self.data[n + 3..];
ret
}
opcodes::Class::Ordinary(opcodes::Ordinary::OP_PUSHDATA4) => {
if self.data.len() < 5 { return Some(Instruction::Error(Error::EarlyEndOfScript)); }
let n = match read_uint(&self.data[1..], 4) {
Ok(n) => n,
Err(e) => { return Some(Instruction::Error(e)); }
};
if self.data.len() < n + 5 { return Some(Instruction::Error(Error::EarlyEndOfScript)); }
let ret = Some(Instruction::PushBytes(&self.data[5..n + 5]));
self.data = &self.data[n + 5..];
ret
}
// Everything else we can push right through
_ => {
let ret = Some(Instruction::Op(opcodes::All::from(self.data[0])));
self.data = &self.data[1..];
ret
}
}
}
}
impl Builder {
/// Creates a new empty script
pub fn new() -> Builder { Builder(vec![]) }
/// The length in bytes of the script
pub fn len(&self) -> usize { self.0.len() }
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/// Whether the script is the empty script
pub fn is_empty(&self) -> bool { self.0.is_empty() }
/// Adds instructions to push an integer onto the stack. Integers are
/// encoded as little-endian signed-magnitude numbers, but there are
/// dedicated opcodes to push some small integers.
pub fn push_int(mut self, data: i64) -> Builder {
// We can special-case -1, 1-16
if data == -1 || (data >= 1 && data <= 16) {
self.0.push((data + opcodes::OP_TRUE as i64) as u8);
self
}
// We can also special-case zero
else if data == 0 {
self.0.push(opcodes::OP_FALSE as u8);
self
}
// Otherwise encode it as data
else { self.push_scriptint(data) }
}
/// Adds instructions to push an integer onto the stack, using the explicit
/// encoding regardless of the availability of dedicated opcodes.
pub fn push_scriptint(self, data: i64) -> Builder {
self.push_slice(&build_scriptint(data))
}
/// Adds instructions to push some arbitrary data onto the stack
pub fn push_slice(mut self, data: &[u8]) -> Builder {
// Start with a PUSH opcode
match data.len() {
n if n < opcodes::Ordinary::OP_PUSHDATA1 as usize => { self.0.push(n as u8); },
n if n < 0x100 => {
self.0.push(opcodes::Ordinary::OP_PUSHDATA1 as u8);
self.0.push(n as u8);
},
n if n < 0x10000 => {
self.0.push(opcodes::Ordinary::OP_PUSHDATA2 as u8);
self.0.push((n % 0x100) as u8);
self.0.push((n / 0x100) as u8);
},
n if n < 0x100000000 => {
self.0.push(opcodes::Ordinary::OP_PUSHDATA4 as u8);
self.0.push((n % 0x100) as u8);
self.0.push(((n / 0x100) % 0x100) as u8);
self.0.push(((n / 0x10000) % 0x100) as u8);
self.0.push((n / 0x1000000) as u8);
}
_ => panic!("tried to put a 4bn+ sized object into a script!")
}
// Then push the acraw
self.0.extend(data.iter().cloned());
self
}
/// Adds a single opcode to the script
pub fn push_opcode(mut self, data: opcodes::All) -> Builder {
self.0.push(data as u8);
self
}
/// Converts the `Builder` into an unmodifiable `Script`
pub fn into_script(self) -> Script {
Script(self.0.into_boxed_slice())
}
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}
/// Adds an individual opcode to the script
impl Default for Builder {
fn default() -> Builder { Builder(vec![]) }
}
/// Creates a new script from an existing vector
impl From<Vec<u8>> for Builder {
fn from(v: Vec<u8>) -> Builder { Builder(v) }
}
impl_index_newtype!(Builder, u8);
// User-facing serialization
impl serde::Serialize for Script {
fn serialize<S>(&self, s: &mut S) -> Result<(), S::Error>
where S: serde::Serializer,
{
s.visit_str(&format!("{:x}", self))
}
}
impl serde::Deserialize for Script {
fn deserialize<D>(d: &mut D) -> Result<Script, D::Error>
where D: serde::Deserializer
{
use serialize::hex::FromHex;
struct ScriptVisitor;
impl serde::de::Visitor for ScriptVisitor {
type Value = Script;
fn visit_string<E>(&mut self, v: String) -> Result<Script, E>
where E: serde::de::Error
{
self.visit_str(&v)
}
fn visit_str<E>(&mut self, hex_str: &str) -> Result<Script, E>
where E: serde::de::Error
{
let raw_vec: Vec<u8> = try!(hex_str.from_hex()
.map_err(|_| serde::de::Error::syntax("bad script hex")));
Ok(Script::from(raw_vec))
}
}
d.visit(ScriptVisitor)
}
}
// Network serialization
impl<S: SimpleEncoder> ConsensusEncodable<S> for Script {
#[inline]
fn consensus_encode(&self, s: &mut S) -> Result<(), S::Error> {
self.0.consensus_encode(s)
}
}
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impl<D: SimpleDecoder> ConsensusDecodable<D> for Script {
#[inline]
fn consensus_decode(d: &mut D) -> Result<Script, D::Error> {
Ok(Script(try!(ConsensusDecodable::consensus_decode(d))))
}
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}
#[cfg(test)]
mod test {
use serialize::hex::FromHex;
use super::*;
use super::build_scriptint;
use network::serialize::{deserialize, serialize};
use blockdata::opcodes;
#[test]
fn script() {
let mut comp = vec![];
let mut script = Builder::new();
assert_eq!(&script[..], &comp[..]);
// small ints
script = script.push_int(1); comp.push(82u8); assert_eq!(&script[..], &comp[..]);
script = script.push_int(0); comp.push(0u8); assert_eq!(&script[..], &comp[..]);
script = script.push_int(4); comp.push(85u8); assert_eq!(&script[..], &comp[..]);
script = script.push_int(-1); comp.push(80u8); assert_eq!(&script[..], &comp[..]);
// forced scriptint
script = script.push_scriptint(4); comp.extend([1u8, 4].iter().cloned()); assert_eq!(&script[..], &comp[..]);
// big ints
script = script.push_int(17); comp.extend([1u8, 17].iter().cloned()); assert_eq!(&script[..], &comp[..]);
script = script.push_int(10000); comp.extend([2u8, 16, 39].iter().cloned()); assert_eq!(&script[..], &comp[..]);
// notice the sign bit set here, hence the extra zero/128 at the end
script = script.push_int(10000000); comp.extend([4u8, 128, 150, 152, 0].iter().cloned()); assert_eq!(&script[..], &comp[..]);
script = script.push_int(-10000000); comp.extend([4u8, 128, 150, 152, 128].iter().cloned()); assert_eq!(&script[..], &comp[..]);
// data
script = script.push_slice("NRA4VR".as_bytes()); comp.extend([6u8, 78, 82, 65, 52, 86, 82].iter().cloned()); assert_eq!(&script[..], &comp[..]);
// opcodes
script = script.push_opcode(opcodes::All::OP_CHECKSIG); comp.push(0xACu8); assert_eq!(&script[..], &comp[..]);
script = script.push_opcode(opcodes::All::OP_CHECKSIG); comp.push(0xACu8); assert_eq!(&script[..], &comp[..]);
}
#[test]
fn script_builder() {
// from txid 3bb5e6434c11fb93f64574af5d116736510717f2c595eb45b52c28e31622dfff which was in my mempool when I wrote the test
let script = Builder::new().push_opcode(opcodes::All::OP_DUP)
.push_opcode(opcodes::All::OP_HASH160)
.push_slice(&"16e1ae70ff0fa102905d4af297f6912bda6cce19".from_hex().unwrap())
.push_opcode(opcodes::All::OP_EQUALVERIFY)
.push_opcode(opcodes::All::OP_CHECKSIG)
.into_script();
assert_eq!(&format!("{:x}", script), "76a91416e1ae70ff0fa102905d4af297f6912bda6cce1988ac");
}
#[test]
fn script_serialize() {
let hex_script = "6c493046022100f93bb0e7d8db7bd46e40132d1f8242026e045f03a0efe71bbb8e3f475e970d790221009337cd7f1f929f00cc6ff01f03729b069a7c21b59b1736ddfee5db5946c5da8c0121033b9b137ee87d5a812d6f506efdd37f0affa7ffc310711c06c7f3e097c9447c52".from_hex().unwrap();
let script: Result<Script, _> = deserialize(&hex_script);
assert!(script.is_ok());
assert_eq!(serialize(&script.unwrap()).ok(), Some(hex_script));
}
#[test]
fn scriptint_round_trip() {
assert_eq!(build_scriptint(-1), vec![0x81]);
assert_eq!(build_scriptint(255), vec![255, 0]);
assert_eq!(build_scriptint(256), vec![0, 1]);
assert_eq!(build_scriptint(257), vec![1, 1]);
assert_eq!(build_scriptint(511), vec![255, 1]);
for &i in [10, 100, 255, 256, 1000, 10000, 25000, 200000, 5000000, 1000000000,
(1 << 31) - 1, -((1 << 31) - 1)].iter() {
assert_eq!(Ok(i), read_scriptint(&build_scriptint(i)));
assert_eq!(Ok(-i), read_scriptint(&build_scriptint(-i)));
}
assert!(read_scriptint(&build_scriptint(1 << 31)).is_err());
assert!(read_scriptint(&build_scriptint(-(1 << 31))).is_err());
}
macro_rules! hex_script (($s:expr) => (Script::from($s.from_hex().unwrap())));
#[test]
fn provably_unspendable_test() {
// p2pk
assert_eq!(hex_script!("410446ef0102d1ec5240f0d061a4246c1bdef63fc3dbab7733052fbbf0ecd8f41fc26bf049ebb4f9527f374280259e7cfa99c48b0e3f39c51347a19a5819651503a5ac").is_provably_unspendable(), false);
assert_eq!(hex_script!("4104ea1feff861b51fe3f5f8a3b12d0f4712db80e919548a80839fc47c6a21e66d957e9c5d8cd108c7a2d2324bad71f9904ac0ae7336507d785b17a2c115e427a32fac").is_provably_unspendable(), false);
// p2pkhash
assert_eq!(hex_script!("76a914ee61d57ab51b9d212335b1dba62794ac20d2bcf988ac").is_provably_unspendable(), false);
assert_eq!(hex_script!("6aa9149eb21980dc9d413d8eac27314938b9da920ee53e87").is_provably_unspendable(), true);
}
#[test]
fn script_json_serialize() {
use strason;
let original = hex_script!("827651a0698faaa9a8a7a687");
let json = strason::from_serialize(&original).unwrap();
assert_eq!(json.to_bytes(), b"\"827651a0698faaa9a8a7a687\"");
assert_eq!(json.string(), Some("827651a0698faaa9a8a7a687"));
let des = json.into_deserialize().unwrap();
assert_eq!(original, des);
}
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#[test]
fn script_debug_display() {
assert_eq!(format!("{:?}", hex_script!("6363636363686868686800")),
"Script(OP_IF OP_IF OP_IF OP_IF OP_IF OP_ENDIF OP_ENDIF OP_ENDIF OP_ENDIF OP_ENDIF OP_0)");
assert_eq!(format!("{}", hex_script!("6363636363686868686800")),
"Script(OP_IF OP_IF OP_IF OP_IF OP_IF OP_ENDIF OP_ENDIF OP_ENDIF OP_ENDIF OP_ENDIF OP_0)");
assert_eq!(format!("{}", hex_script!("2102715e91d37d239dea832f1460e91e368115d8ca6cc23a7da966795abad9e3b699ac")),
"Script(OP_PUSHBYTES_33 02715e91d37d239dea832f1460e91e368115d8ca6cc23a7da966795abad9e3b699 OP_CHECKSIG)");
}
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}