Finished Reviews

Pangolin Process Quality Review

Score: 36%

Overview

This is a Pangolin Process Quality Review completed on June 24th 2021. It was performed using the Process Review process (version 0.7.2) and is documented here. The review was performed by Nic of DeFiSafety. Check out our Telegram.

The final score of the review is 36%, a fail. The breakdown of the scoring is in Scoring Appendix. For our purposes, a pass is 70%.

Summary of the Process

Very simply, the review looks for the following declarations from the developer's site. With these declarations, it is reasonable to trust the smart contracts.

  • Here are my smart contracts on the blockchain

  • Here is the documentation that explains what my smart contracts do

  • Here are the tests I ran to verify my smart contract

  • Here are the audit(s) performed on my code by third party experts

  • Here are the admin controls and strategies

Disclaimer

This report is for informational purposes only and does not constitute investment advice of any kind, nor does it constitute an offer to provide investment advisory or other services. Nothing in this report shall be considered a solicitation or offer to buy or sell any security, token, future, option or other financial instrument or to offer or provide any investment advice or service to any person in any jurisdiction. Nothing contained in this report constitutes investment advice or offers any opinion with respect to the suitability of any security, and the views expressed in this report should not be taken as advice to buy, sell or hold any security. The information in this report should not be relied upon for the purpose of investing. In preparing the information contained in this report, we have not taken into account the investment needs, objectives and financial circumstances of any particular investor. This information has no regard to the specific investment objectives, financial situation and particular needs of any specific recipient of this information and investments discussed may not be suitable for all investors.

Any views expressed in this report by us were prepared based upon the information available to us at the time such views were written. The views expressed within this report are limited to DeFiSafety and the author and do not reflect those of any additional or third party and are strictly based upon DeFiSafety, its authors, interpretations and evaluation of relevant data. Changed or additional information could cause such views to change. All information is subject to possible correction. Information may quickly become unreliable for various reasons, including changes in market conditions or economic circumstances.

This completed report is copyright (c) DeFiSafety 2021. Permission is given to copy in whole, retaining this copyright label.

Chain

This section indicates the blockchain used by this protocol.

Chain: Avalanche

Guidance: Ethereum Binance Smart Chain Polygon Avalanche

Code and Team

This section looks at the code deployed on the Mainnet that gets reviewed and its corresponding software repository. The document explaining these questions is here. This review will answer the questions;

1) Are the executing code addresses readily available? (%) 2) Is the code actively being used? (%) 3) Is there a public software repository? (Y/N) 4) Is there a development history visible? (%) 5) Is the team public (not anonymous)? (Y/N)

1) Are the executing code addresses readily available? (%)

Answer: 70%

They are available at website https://github.com/pangolindex/exchange-contracts as indicated in the Appendix.

Note: gave them a 70% because they direct you to the smart contract address from their core repo in their GitHub. It definitely takes some searching for relatively inexperienced users.

Guidance: 100% Clearly labelled and on website, docs or repo, quick to find 70% Clearly labelled and on website, docs or repo but takes a bit of looking 40% Addresses in mainnet.json, in discord or sub graph, etc 20% Address found but labelling not clear or easy to find 0% Executing addresses could not be found

How to improve this score

Make the Ethereum addresses of the smart contract utilized by your application available on either your website or your GitHub (in the README for instance). Ensure the addresses is up to date. This is a very important question wrt to the final score.

2) Is the code actively being used? (%)

Answer: 100%

Activity is more than 10 transactions a day on contract Avalanche PangolinRouter.sol, as indicated in the Appendix.

Percentage Score Guidance

100% More than 10 transactions a day 70% More than 10 transactions a week 40% More than 10 transactions a month 10% Less than 10 transactions a month 0% No activity

3) Is there a public software repository? (Y/N)

Answer: Yes

GitHub: https://github.com/pangolindex

Is there a public software repository with the code at a minimum, but normally test and scripts also (Y/N). Even if the repo was created just to hold the files and has just 1 transaction, it gets a Yes. For teams with private repos, this answer is No.

4) Is there a development history visible? (%)

Answer: 0%

With 17 commits and 2 branches in their smart contract repo, this is an unhealthy repository.

This checks if the software repository demonstrates a strong steady history. This is normally demonstrated by commits, branches and releases in a software repository. A healthy history demonstrates a history of more than a month (at a minimum).

Guidance: 100% Any one of 100+ commits, 10+branches 70% Any one of 70+ commits, 7+branches 50% Any one of 50+ commits, 5+branches 30% Any one of 30+ commits, 3+branches 0% Less than 2 branches or less than 10 commits

How to improve this score

Continue to test and perform other verification activities after deployment, including routine maintenance updating to new releases of testing and deployment tools. A public development history indicates clearly to the public the level of continued investment and activity by the developers on the application. This gives a level of security and faith in the application.

5) Is the team public (not anonymous)? (Y/N)

Answer: Yes

Team member info can be found at https://www.linkedin.com/company/pangolindex

For a yes in this question the real names of some team members must be public on the website or other documentation. If the team is anonymous and then this question is a No.

Documentation

This section looks at the software documentation. The document explaining these questions is here.

Required questions are;

6) Is there a whitepaper? (Y/N) 7) Are the basic software functions documented? (Y/N) 8) Does the software function documentation fully (100%) cover the deployed contracts? (%) 9) Are there sufficiently detailed comments for all functions within the deployed contract code (%) 10) Is it possible to trace from software documentation to the implementation in code (%)

6) Is there a whitepaper? (Y/N)

Answer: Yes

Location: https://pangolin.exchange/litepaper/

7) Are the basic software functions documented? (Y/N)

Answer: No

No software documentation found.

8) Does the software function documentation fully (100%) cover the deployed contracts? (%)

Answer: 0%

Pangolin has API documentation at https://github.com/pangolindex/pangolin-api, but does not state any documentation of their actual smart contract functions anywhere.

Guidance:

100% All contracts and functions documented 80% Only the major functions documented 79-1% Estimate of the level of software documentation 0% No software documentation

How to improve this score

This score can improve by adding content to the requirements document such that it comprehensively covers the requirements. For guidance, refer to the SecurEth System Description Document . Using tools that aid traceability detection will help.

9) Are there sufficiently detailed comments for all functions within the deployed contract code (%)

Answer: 0%

Code examples are in the Appendix. As per the SLOC, there is 8% commenting to code (CtC).

The Comments to Code (CtC) ratio is the primary metric for this score.

Guidance: 100% CtC > 100 Useful comments consistently on all code 90-70% CtC > 70 Useful comment on most code 60-20% CtC > 20 Some useful commenting 0% CtC < 20 No useful commenting

How to improve this score

This score can improve by adding comments to the deployed code such that it comprehensively covers the code. For guidance, refer to the SecurEth Software Requirements.

10) Is it possible to trace from software documentation to the implementation in code (%)

Answer: 0%

There was no tracability between any functions and their documentation.

Guidance: 100% Clear explicit traceability between code and documentation at a requirement level for all code 60% Clear association between code and documents via non explicit traceability 40% Documentation lists all the functions and describes their functions 0% No connection between documentation and code

How to improve this score

This score can improve by adding traceability from requirements to code such that it is clear where each requirement is coded. For reference, check the SecurEth guidelines on traceability.

Testing

This section looks at the software testing available. It is explained in this document. This section answers the following questions;

11) Full test suite (Covers all the deployed code) (%) 12) Code coverage (Covers all the deployed lines of code, or explains misses) (%) 13) Scripts and instructions to run the tests (Y/N) 14) Report of the results (%) 15) Formal Verification test done (%) 16) Stress Testing environment (%)

11) Is there a Full test suite? (%)

Answer: 40%

Code examples are in the Appendix. As per the SLOC, there is 37% testing to code (TtC).

This score is guided by the Test to Code ratio (TtC). Generally a good test to code ratio is over 100%. However the reviewers best judgement is the final deciding factor.

Guidance: 100% TtC > 120% Both unit and system test visible 80% TtC > 80% Both unit and system test visible 40% TtC < 80% Some tests visible 0% No tests obvious

How to improve this score

This score can improve by adding tests to fully cover the code. Document what is covered by traceability or test results in the software repository.

12) Code coverage (Covers all the deployed lines of code, or explains misses) (%)

Answer: 30%

No test for coverage seen, but some testing evident.

Guidance: 100% Documented full coverage 99-51% Value of test coverage from documented results 50% No indication of code coverage but clearly there is a reasonably complete set of tests 30% Some tests evident but not complete 0% No test for coverage seen

How to improve this score

This score can improve by adding tests achieving full code coverage. A clear report and scripts in the software repository will guarantee a high score.

13) Scripts and instructions to run the tests (Y/N)

Answer: Yes

Found at the bottom of https://github.com/pangolindex/exchange-contracts.

14) Report of the results (%)

Answer: 0%

No test report found in any of their documentation.

Guidance: 100% Detailed test report as described below 70% GitHub Code coverage report visible 0% No test report evident

How to improve this score

Add a report with the results. The test scripts should generate the report or elements of it.

15) Formal Verification test done (%)

Answer: 0%

No evidence of a Pangolin Exchange formal verification has been found in their documentation or on the web.

16) Stress Testing environment (%)

Answer: 0%

No evidence of test-net smart contract address usage in any of their documentation.

Security

This section looks at the 3rd party software audits done. It is explained in this document. This section answers the following questions;

17) Did 3rd Party audits take place? (%) 18) Is the bounty value acceptably high?

17) Did 3rd Party audits take place? (%)

Answer: 20%

They have not done any audits because they are a fork of Compound and Uniswap: two very audited protocols.

Guidance: 100% Multiple Audits performed before deployment and results public and implemented or not required 90% Single audit performed before deployment and results public and implemented or not required 70% Audit(s) performed after deployment and no changes required. Audit report is public

50% Audit(s) performed after deployment and changes needed but not implemented 20% No audit performed 0% Audit Performed after deployment, existence is public, report is not public and no improvements deployed OR smart contract address' not found, question

18) Is the bounty value acceptably high (%)

Answer: 70%

Found at https://hackenproof.com/avalanche/avalanche-general.

Guidance:

100% Bounty is 10% TVL or at least $1M AND active program (see below) 90% Bounty is 5% TVL or at least 500k AND active program 80% Bounty is 5% TVL or at least 500k 70% Bounty is 100k or over AND active program 60% Bounty is 100k or over 50% Bounty is 50k or over AND active program 40% Bounty is 50k or over 20% Bug bounty program bounty is less than 50k 0% No bug bounty program offered

Active program means a third party actively driving hackers to the site. Inactive program would be static mention on the docs.

Access Controls

This section covers the documentation of special access controls for a DeFi protocol. The admin access controls are the contracts that allow updating contracts or coefficients in the protocol. Since these contracts can allow the protocol admins to "change the rules", complete disclosure of capabilities is vital for user's transparency. It is explained in this document. The questions this section asks are as follow;

19) Can a user clearly and quickly find the status of the admin controls? 20) Is the information clear and complete? 2`) Is the information in non-technical terms that pertain to the investments? 22) Is there Pause Control documentation including records of tests?

19) Can a user clearly and quickly find the status of the access controls (%)

Answer: 100%

Found in their Litepaper at https://pangolin.exchange/litepaper#png-governance.

Guidance: 100% Clearly labelled and on website, docs or repo, quick to find 70% Clearly labelled and on website, docs or repo but takes a bit of looking 40% Access control docs in multiple places and not well labelled 20% Access control docs in multiple places and not labelled 0% Admin Control information could not be found

20) Is the information clear and complete (%)

Answer: 60%

a) Clearly labelled as upgradeable

b) Defined voting roles

Source: https://gov.pangolin.exchange/t/how-governance-works/1082/2.

Guidance: All the contracts are immutable -- 100% OR

a) All contracts are clearly labelled as upgradeable (or not) -- 30% AND b) The type of ownership is clearly indicated (OnlyOwner / MultiSig / Defined Roles) -- 30% AND c) The capabilities for change in the contracts are described -- 30%

How to improve this score

Create a document that covers the items described above. An example is enclosed.

21) Is the information in non-technical terms that pertain to the investments (%)

Answer: 30%

Guidance: 100% All the contracts are immutable 90% Description relates to investments safety and updates in clear, complete non-software l language 30% Description all in software specific language 0% No admin control information could not be found

How to improve this score

Create a document that covers the items described above in plain language that investors can understand. An example is enclosed.

22) Is there Pause Control documentation including records of tests (%)

Answer: 0%

No Pause Control info in their documentation and no testing evidence found in their GitHub.

Guidance: 100% All the contracts are immutable or no pause control needed and this is explained OR 100% Pause control(s) are clearly documented and there is records of at least one test within 3 months 80% Pause control(s) explained clearly but no evidence of regular tests 40% Pause controls mentioned with no detail on capability or tests 0% Pause control not documented or explained

How to improve this score

Create a document that covers the items described above in plain language that investors can understand. An example is enclosed.

Appendices

Author Details

The author of this review is Rex of DeFi Safety.

Email : [email protected] Twitter : @defisafety

I started with Ethereum just before the DAO and that was a wonderful education. It showed the importance of code quality. The second Parity hack also showed the importance of good process. Here my aviation background offers some value. Aerospace knows how to make reliable code using quality processes.

I was coaxed to go to EthDenver 2018 and there I started SecuEth.org with Bryant and Roman. We created guidelines on good processes for blockchain code development. We got EthFoundation funding to assist in their development.

Process Quality Reviews are an extension of the SecurEth guidelines that will further increase the quality processes in Solidity and Vyper development.

DeFiSafety is my full time gig and we are working on funding vehicles for a permanent staff.

Scoring Appendix

Executing Code Appendix

Code Used Appendix

Example Code Appendix

receive() external payable {
assert(msg.sender == WAVAX); // only accept AVAX via fallback from the WAVAX contract
}
// **** ADD LIQUIDITY ****
function _addLiquidity(
address tokenA,
address tokenB,
uint amountADesired,
uint amountBDesired,
uint amountAMin,
uint amountBMin
) internal virtual returns (uint amountA, uint amountB) {
// create the pair if it doesn't exist yet
if (IPangolinFactory(factory).getPair(tokenA, tokenB) == address(0)) {
IPangolinFactory(factory).createPair(tokenA, tokenB);
}
(uint reserveA, uint reserveB) = PangolinLibrary.getReserves(factory, tokenA, tokenB);
if (reserveA == 0 && reserveB == 0) {
(amountA, amountB) = (amountADesired, amountBDesired);
} else {
uint amountBOptimal = PangolinLibrary.quote(amountADesired, reserveA, reserveB);
if (amountBOptimal <= amountBDesired) {
require(amountBOptimal >= amountBMin, 'PangolinRouter: INSUFFICIENT_B_AMOUNT');
(amountA, amountB) = (amountADesired, amountBOptimal);
} else {
uint amountAOptimal = PangolinLibrary.quote(amountBDesired, reserveB, reserveA);
assert(amountAOptimal <= amountADesired);
require(amountAOptimal >= amountAMin, 'PangolinRouter: INSUFFICIENT_A_AMOUNT');
(amountA, amountB) = (amountAOptimal, amountBDesired);
}
}
}
function addLiquidity(
address tokenA,
address tokenB,
uint amountADesired,
uint amountBDesired,
uint amountAMin,
uint amountBMin,
address to,
uint deadline
) external virtual override ensure(deadline) returns (uint amountA, uint amountB, uint liquidity) {
(amountA, amountB) = _addLiquidity(tokenA, tokenB, amountADesired, amountBDesired, amountAMin, amountBMin);
address pair = PangolinLibrary.pairFor(factory, tokenA, tokenB);
TransferHelper.safeTransferFrom(tokenA, msg.sender, pair, amountA);
TransferHelper.safeTransferFrom(tokenB, msg.sender, pair, amountB);
liquidity = IPangolinPair(pair).mint(to);
}
function addLiquidityAVAX(
address token,
uint amountTokenDesired,
uint amountTokenMin,
uint amountAVAXMin,
address to,
uint deadline
) external virtual override payable ensure(deadline) returns (uint amountToken, uint amountAVAX, uint liquidity) {
(amountToken, amountAVAX) = _addLiquidity(
token,
WAVAX,
amountTokenDesired,
msg.value,
amountTokenMin,
amountAVAXMin
);
address pair = PangolinLibrary.pairFor(factory, token, WAVAX);
TransferHelper.safeTransferFrom(token, msg.sender, pair, amountToken);
IWAVAX(WAVAX).deposit{value: amountAVAX}();
assert(IWAVAX(WAVAX).transfer(pair, amountAVAX));
liquidity = IPangolinPair(pair).mint(to);
// refund dust AVAX, if any
if (msg.value > amountAVAX) TransferHelper.safeTransferAVAX(msg.sender, msg.value - amountAVAX);
}
// **** REMOVE LIQUIDITY ****
function removeLiquidity(
address tokenA,
address tokenB,
uint liquidity,
uint amountAMin,
uint amountBMin,
address to,
uint deadline
) public virtual override ensure(deadline) returns (uint amountA, uint amountB) {
address pair = PangolinLibrary.pairFor(factory, tokenA, tokenB);
IPangolinPair(pair).transferFrom(msg.sender, pair, liquidity); // send liquidity to pair
(uint amount0, uint amount1) = IPangolinPair(pair).burn(to);
(address token0,) = PangolinLibrary.sortTokens(tokenA, tokenB);
(amountA, amountB) = tokenA == token0 ? (amount0, amount1) : (amount1, amount0);
require(amountA >= amountAMin, 'PangolinRouter: INSUFFICIENT_A_AMOUNT');
require(amountB >= amountBMin, 'PangolinRouter: INSUFFICIENT_B_AMOUNT');
}
function removeLiquidityAVAX(
address token,
uint liquidity,
uint amountTokenMin,
uint amountAVAXMin,
address to,
uint deadline
) public virtual override ensure(deadline) returns (uint amountToken, uint amountAVAX) {
(amountToken, amountAVAX) = removeLiquidity(
token,
WAVAX,
liquidity,
amountTokenMin,
amountAVAXMin,
address(this),
deadline
);
TransferHelper.safeTransfer(token, to, amountToken);
IWAVAX(WAVAX).withdraw(amountAVAX);
TransferHelper.safeTransferAVAX(to, amountAVAX);
}
function removeLiquidityWithPermit(
address tokenA,
address tokenB,
uint liquidity,
uint amountAMin,
uint amountBMin,
address to,
uint deadline,
bool approveMax, uint8 v, bytes32 r, bytes32 s
) external virtual override returns (uint amountA, uint amountB) {
address pair = PangolinLibrary.pairFor(factory, tokenA, tokenB);
uint value = approveMax ? uint(-1) : liquidity;
IPangolinPair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
(amountA, amountB) = removeLiquidity(tokenA, tokenB, liquidity, amountAMin, amountBMin, to, deadline);
}
function removeLiquidityAVAXWithPermit(
address token,
uint liquidity,
uint amountTokenMin,
uint amountAVAXMin,
address to,
uint deadline,
bool approveMax, uint8 v, bytes32 r, bytes32 s
) external virtual override returns (uint amountToken, uint amountAVAX) {
address pair = PangolinLibrary.pairFor(factory, token, WAVAX);
uint value = approveMax ? uint(-1) : liquidity;
IPangolinPair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
(amountToken, amountAVAX) = removeLiquidityAVAX(token, liquidity, amountTokenMin, amountAVAXMin, to, deadline);
}
// **** REMOVE LIQUIDITY (supporting fee-on-transfer tokens) ****
function removeLiquidityAVAXSupportingFeeOnTransferTokens(
address token,
uint liquidity,
uint amountTokenMin,
uint amountAVAXMin,
address to,
uint deadline
) public virtual override ensure(deadline) returns (uint amountAVAX) {
(, amountAVAX) = removeLiquidity(
token,
WAVAX,
liquidity,
amountTokenMin,
amountAVAXMin,
address(this),
deadline
);
TransferHelper.safeTransfer(token, to, IERC20(token).balanceOf(address(this)));
IWAVAX(WAVAX).withdraw(amountAVAX);
TransferHelper.safeTransferAVAX(to, amountAVAX);
}
function removeLiquidityAVAXWithPermitSupportingFeeOnTransferTokens(
address token,
uint liquidity,
uint amountTokenMin,
uint amountAVAXMin,
address to,
uint deadline,
bool approveMax, uint8 v, bytes32 r, bytes32 s
) external virtual override returns (uint amountAVAX) {
address pair = PangolinLibrary.pairFor(factory, token, WAVAX);
uint value = approveMax ? uint(-1) : liquidity;
IPangolinPair(pair).permit(msg.sender, address(this), value, deadline, v, r, s);
amountAVAX = removeLiquidityAVAXSupportingFeeOnTransferTokens(
token, liquidity, amountTokenMin, amountAVAXMin, to, deadline
);
}
// **** SWAP ****
// requires the initial amount to have already been sent to the first pair
function _swap(uint[] memory amounts, address[] memory path, address _to) internal virtual {
for (uint i; i < path.length - 1; i++) {
(address input, address output) = (path[i], path[i + 1]);
(address token0,) = PangolinLibrary.sortTokens(input, output);
uint amountOut = amounts[i + 1];
(uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOut) : (amountOut, uint(0));
address to = i < path.length - 2 ? PangolinLibrary.pairFor(factory, output, path[i + 2]) : _to;
IPangolinPair(PangolinLibrary.pairFor(factory, input, output)).swap(
amount0Out, amount1Out, to, new bytes(0)
);
}
}
function swapExactTokensForTokens(
uint amountIn,
uint amountOutMin,
address[] calldata path,
address to,
uint deadline
) external virtual override ensure(deadline) returns (uint[] memory amounts) {
amounts = PangolinLibrary.getAmountsOut(factory, amountIn, path);
require(amounts[amounts.length - 1] >= amountOutMin, 'PangolinRouter: INSUFFICIENT_OUTPUT_AMOUNT');
TransferHelper.safeTransferFrom(
path[0], msg.sender, PangolinLibrary.pairFor(factory, path[0], path[1]), amounts[0]
);
_swap(amounts, path, to);
}
function swapTokensForExactTokens(
uint amountOut,
uint amountInMax,
address[] calldata path,
address to,
uint deadline
) external virtual override ensure(deadline) returns (uint[] memory amounts) {
amounts = PangolinLibrary.getAmountsIn(factory, amountOut, path);
require(amounts[0] <= amountInMax, 'PangolinRouter: EXCESSIVE_INPUT_AMOUNT');
TransferHelper.safeTransferFrom(
path[0], msg.sender, PangolinLibrary.pairFor(factory, path[0], path[1]), amounts[0]
);
_swap(amounts, path, to);
}
function swapExactAVAXForTokens(uint amountOutMin, address[] calldata path, address to, uint deadline)
external
virtual
override
payable
ensure(deadline)
returns (uint[] memory amounts)
{
require(path[0] == WAVAX, 'PangolinRouter: INVALID_PATH');
amounts = PangolinLibrary.getAmountsOut(factory, msg.value, path);
require(amounts[amounts.length - 1] >= amountOutMin, 'PangolinRouter: INSUFFICIENT_OUTPUT_AMOUNT');
IWAVAX(WAVAX).deposit{value: amounts[0]}();
assert(IWAVAX(WAVAX).transfer(PangolinLibrary.pairFor(factory, path[0], path[1]), amounts[0]));
_swap(amounts, path, to);
}
function swapTokensForExactAVAX(uint amountOut, uint amountInMax, address[] calldata path, address to, uint deadline)
external
virtual
override
ensure(deadline)
returns (uint[] memory amounts)
{
require(path[path.length - 1] == WAVAX, 'PangolinRouter: INVALID_PATH');
amounts = PangolinLibrary.getAmountsIn(factory, amountOut, path);
require(amounts[0] <= amountInMax, 'PangolinRouter: EXCESSIVE_INPUT_AMOUNT');
TransferHelper.safeTransferFrom(
path[0], msg.sender, PangolinLibrary.pairFor(factory, path[0], path[1]), amounts[0]
);
_swap(amounts, path, address(this));
IWAVAX(WAVAX).withdraw(amounts[amounts.length - 1]);
TransferHelper.safeTransferAVAX(to, amounts[amounts.length - 1]);
}
function swapExactTokensForAVAX(uint amountIn, uint amountOutMin, address[] calldata path, address to, uint deadline)
external
virtual
override
ensure(deadline)
returns (uint[] memory amounts)
{
require(path[path.length - 1] == WAVAX, 'PangolinRouter: INVALID_PATH');
amounts = PangolinLibrary.getAmountsOut(factory, amountIn, path);
require(amounts[amounts.length - 1] >= amountOutMin, 'PangolinRouter: INSUFFICIENT_OUTPUT_AMOUNT');
TransferHelper.safeTransferFrom(
path[0], msg.sender, PangolinLibrary.pairFor(factory, path[0], path[1]), amounts[0]
);
_swap(amounts, path, address(this));
IWAVAX(WAVAX).withdraw(amounts[amounts.length - 1]);
TransferHelper.safeTransferAVAX(to, amounts[amounts.length - 1]);
}
function swapAVAXForExactTokens(uint amountOut, address[] calldata path, address to, uint deadline)
external
virtual
override
payable
ensure(deadline)
returns (uint[] memory amounts)
{
require(path[0] == WAVAX, 'PangolinRouter: INVALID_PATH');
amounts = PangolinLibrary.getAmountsIn(factory, amountOut, path);
require(amounts[0] <= msg.value, 'PangolinRouter: EXCESSIVE_INPUT_AMOUNT');
IWAVAX(WAVAX).deposit{value: amounts[0]}();
assert(IWAVAX(WAVAX).transfer(PangolinLibrary.pairFor(factory, path[0], path[1]), amounts[0]));
_swap(amounts, path, to);
// refund dust AVAX, if any
if (msg.value > amounts[0]) TransferHelper.safeTransferAVAX(msg.sender, msg.value - amounts[0]);
}
// **** SWAP (supporting fee-on-transfer tokens) ****
// requires the initial amount to have already been sent to the first pair
function _swapSupportingFeeOnTransferTokens(address[] memory path, address _to) internal virtual {
for (uint i; i < path.length - 1; i++) {
(address input, address output) = (path[i], path[i + 1]);
(address token0,) = PangolinLibrary.sortTokens(input, output);
IPangolinPair pair = IPangolinPair(PangolinLibrary.pairFor(factory, input, output));
uint amountInput;
uint amountOutput;
{ // scope to avoid stack too deep errors
(uint reserve0, uint reserve1,) = pair.getReserves();
(uint reserveInput, uint reserveOutput) = input == token0 ? (reserve0, reserve1) : (reserve1, reserve0);
amountInput = IERC20(input).balanceOf(address(pair)).sub(reserveInput);
amountOutput = PangolinLibrary.getAmountOut(amountInput, reserveInput, reserveOutput);
}
(uint amount0Out, uint amount1Out) = input == token0 ? (uint(0), amountOutput) : (amountOutput, uint(0));
address to = i < path.length - 2 ? PangolinLibrary.pairFor(factory, output, path[i + 2]) : _to;
pair.swap(amount0Out, amount1Out, to, new bytes(0));
}
}
function swapExactTokensForTokensSupportingFeeOnTransferTokens(
uint amountIn,
uint amountOutMin,
address[] calldata path,
address to,
uint deadline
) external virtual override ensure(deadline) {
TransferHelper.safeTransferFrom(
path[0], msg.sender, PangolinLibrary.pairFor(factory, path[0], path[1]), amountIn
);
uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);
_swapSupportingFeeOnTransferTokens(path, to);
require(
IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,
'PangolinRouter: INSUFFICIENT_OUTPUT_AMOUNT'
);
}
function swapExactAVAXForTokensSupportingFeeOnTransferTokens(
uint amountOutMin,
address[] calldata path,
address to,
uint deadline
)
external
virtual
override
payable
ensure(deadline)
{
require(path[0] == WAVAX, 'PangolinRouter: INVALID_PATH');
uint amountIn = msg.value;
IWAVAX(WAVAX).deposit{value: amountIn}();
assert(IWAVAX(WAVAX).transfer(PangolinLibrary.pairFor(factory, path[0], path[1]), amountIn));
uint balanceBefore = IERC20(path[path.length - 1]).balanceOf(to);
_swapSupportingFeeOnTransferTokens(path, to);
require(
IERC20(path[path.length - 1]).balanceOf(to).sub(balanceBefore) >= amountOutMin,
'PangolinRouter: INSUFFICIENT_OUTPUT_AMOUNT'
);
}
function swapExactTokensForAVAXSupportingFeeOnTransferTokens(
uint amountIn,
uint amountOutMin,
address[] calldata path,
address to,
uint deadline
)
external
virtual
override
ensure(deadline)
{
require(path[path.length - 1] == WAVAX, 'PangolinRouter: INVALID_PATH');
TransferHelper.safeTransferFrom(
path[0], msg.sender, PangolinLibrary.pairFor(factory, path[0], path[1]), amountIn
);
_swapSupportingFeeOnTransferTokens(path, address(this));
uint amountOut = IERC20(WAVAX).balanceOf(address(this));
require(amountOut >= amountOutMin, 'PangolinRouter: INSUFFICIENT_OUTPUT_AMOUNT');
IWAVAX(WAVAX).withdraw(amountOut);
TransferHelper.safeTransferAVAX(to, amountOut);
}
// **** LIBRARY FUNCTIONS ****
function quote(uint amountA, uint reserveA, uint reserveB) public pure virtual override returns (uint amountB) {
return PangolinLibrary.quote(amountA, reserveA, reserveB);
}
function getAmountOut(uint amountIn, uint reserveIn, uint reserveOut)
public
pure
virtual
override
returns (uint amountOut)
{
return PangolinLibrary.getAmountOut(amountIn, reserveIn, reserveOut);
}
function getAmountIn(uint amountOut, uint reserveIn, uint reserveOut)
public
pure
virtual
override
returns (uint amountIn)
{
return PangolinLibrary.getAmountIn(amountOut, reserveIn, reserveOut);
}
function getAmountsOut(uint amountIn, address[] memory path)
public
view
virtual
override
returns (uint[] memory amounts)
{
return PangolinLibrary.getAmountsOut(factory, amountIn, path);
}
function getAmountsIn(uint amountOut, address[] memory path)
public
view
virtual
override
returns (uint[] memory amounts)
{
return PangolinLibrary.getAmountsIn(factory, amountOut, path);
}
}

SLOC Appendix

Solidity Contracts

Language

Files

Lines

Blanks

Comments

Code

Complexity

Solidity

23

1650

174

115

1361

146

Comments to Code 115/1361 = 8%

Javascript Tests

Language

Files

Lines

Blanks

Comments

Code

Complexity

JavaScript

11

619

104

18

497

12

Tests to Code 497/1361 = 37%