Add support for custom/overriden HTTP headers when using JsonRpcProvider.

[MicahZoltu]

I would like to use the JsonRpcProvider, but my node is behind a firewall that needs me to add some custom headers to route through. I would like the ability to provide arbitrary headers along with all payloads. Ideally, there would be a headers?: Map<string, string> key on the ConnectionInfo object that can be passed into JsonRpcProider constructor. This way I could specify any headers needed to access the backing node. This would also address another user's request for Bearer token authentication support, as they could provide that header through this mechanism.

[ricmoo]

Excellent idea!

[MicahZoltu]

I can create a separate ticket, but at the same time it would be nice to be able to provide other connection options. I am having a problem right now where a backend node I'm talking to is silently dropping my connections sometimes. The default timeout for the underlying connection in ethers is 2 minutes it appears, but if it has been more than 2 second I want a timeout propagated. The frequency of this connection dropping combined with the 2 minute timeout before I hear about it makes me have to choose between dropping ethers or building a new Ethereum node (both are large tasks).

[ricmoo]

It is trivial to implement a Customer Provider if you want a 2s timeout. This is off the top of my head, but you will get the idea.

class ShortTimeoutProvider extends ethers.types.Provider {
    readonly provider: ethers.types.Provider;
    constructor(provider: ethers.types.Provider) {
        this.provider = provider;
    } 
    perform(method, params): Promise<any> {
        return new Promise((resolve, reject) => {
            setTimeout(() => { reject('over 2 seconds!'); }, 2000);
            provider.perform(method, params).then((result) => {
                resolve(result);
            },
            (error) => {
                reject(error);
            })
        }
    }
}

[ricmoo]

Also, there seems to be something wrong with your backend if it is silently dropping so many connection. :p

[MicahZoltu]

Yeah, something is wrong with my connection but I can't figure out what it is. Thanks for the workaround suggestion, that should buy me time to solve the real problem. :)

Related in adding timeout makes the roadmap: driverdan/node-XMLHttpRequest#148

[ricmoo]

This is now available in 4.0.0-beta.14. The ConnectionInfo now supports headers which is a mapping of header keys and values as well as a timeout parameter.

Let me know if you have any issues with them.

Thanks! :)