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Understanding MetaMask and USDT in Smart Contract Transactions

As a developer building decentralized applications (dApps) on the Ethereum blockchain, you are probably familiar with smart contracts and their interaction with various external services. One such service that facilitates transactions is MetaMask, a popular browser extension for Ethereum users.

In this article, we will examine why the “buyNode” function in your contract is processing ETH instead of USDT, even though you specifically passed USDT as the payment token parameter.

The “buyNode” function: a key component

The “buyNode” function is a key component of a smart contract. Its purpose is to acquire new nodes from the Ethereum network, allowing users to access decentralized applications (dApps) that rely on these nodes for their functionality.

When you call the “buyNode” function with a USDT payment token, MetaMask attempts to execute the transaction and pay the Ether price of the USDT in ETH. This process is facilitated by the Ethereum Virtual Machine (EVM), which converts USDT to ETH using the smart contract’s built-in conversion rate.

The problem: conversion rate vs. price

There is a catch, however. The “buyNode” function does not directly convert USDT to ETH; instead, it relies on an external service called MetaMask’s “convertFromETH” method, which converts ETH to USDT at the current market price (for example, 0.000025 USD/ETH).

This conversion rate is not fixed and can change depending on market conditions. As a result, even if you explicitly specify USDT as a payment token parameter, MetaMask may decide to convert it to ETH before processing the transaction.

Why is there a difference in conversion rates?

The main reason for this difference lies in the implementation of MetaMask’s “buyNode” function. When using the “buyNode” function, MetaMask needs to find a new node on the Ethereum network that supports the USDT exchange rate used by the contract. This process involves querying multiple nodes and selecting one that matches the desired conversion rate.

Conversely, if you explicitly specify USDT as the payment token parameter, MetaMask can use its own built-in conversion rate without relying on an external service such as “convertFromETH”. However, this means that the conversion rate used in the contract may not always match the current market rate.

Conclusion

To avoid potential issues with exchange rates and ensure that your smart contracts function properly, it is essential to understand how MetaMask handles USDT payment tokens in different scenarios. In summary:

• When using the “buyNode” function, MetaMask converts USDT to ETH at the current market price (for example, 0.000025 USD/ETH).

• Even if you explicitly provide USDT as a payment token parameter, MetaMask may choose to convert it to ETH before processing the transaction.

• To ensure reliable transactions with smart contracts, you should look for alternative methods or solutions that circumvent these conversion rate issues.

I hope this article helped clarify the situation and provided valuable insight for developers building decentralized applications on the Ethereum blockchain.