TON-BSC bridge: getPairGasFee function always fails because of not accepted header in fetch function

[vegancat]

Bug Type

Functional

Reproduction steps

1- open the bridge webpage
2- select "Binance Smart Chain" as the source or destination

Actual result

BSC gas fee doesn't get updated and always is the default value defined in the frontend web app.

BSC -> TON : default = 0.0002 BNB

TON -> BSC: default = 0.0008 BNB

Expected result

The bridge should fetch the current gas fee and show it to the user.
Also,
If the current gas fees are lower than the default values, users would be charged more than necessary in their transactions.
And if the current gas fees are higher than the default Gas fees, users' transactions would fail.

Reason

here is the reference to function getPairGasFee: https://github.com/ton-blockchain/bridge/blob/master/pages/index.vue#L339

This function uses bsc.main.getGasUrl to fetch current fees from the network. it works perfectly for Eth, but it fails for BSC because of Cors policy:

Seems like the header 'Cache-Control': 'no-store, max-age=0' set inside fetch is not accepted by the backend. This failing will be caught in catch block and thus this line will be executed:

this.gasPrice = 0

Because of this error local gasPrice variable never gets updated and will be 0 when runtime reaches the line below:

this.gasPrice = gasPrice > 0 ? gasPrice : this.params.defaultGwei;

And this causes the this.gasPrice to be equal to default values.

sulotion

I removed the header and everything is working perfectly without it. So I opened a pull request which deletes that specific header.

Suggested Severity

Critical

Device

Desktop (please complete the following information):

• OS: Windows
• Browser chrome, firefox
• Version 21H2

Additional Context

No response