feat(cast): add ability to specify request headers

[sebastiendan]

Component

Cast

Have you ensured that all of these are up to date?

• Foundry
• Foundryup

What version of Foundry are you on?

No response

What command(s) is the bug in?

No response

Operating System

None

Describe the bug

When using cast with an RPC endpoint behind Cloudflare Proxy, responses are 403s.
When testing the same rpc call with curl, it works fine. It seems that using curl without a user agent also returns 403s, so it could be that cast doesn't set any user agent.

I found no option in cast to set request headers.

[zerosnacks]

Generally supportive of this

We already support adding of custom headers in Alloy, should be relatively easy to add this to cast

https://github.com/alloy-rs/examples/blob/3b6d4a7cb465a0cb62a396735a8e26baa188ea55/examples/layers/examples/hyper_http_layer.rs#L92-L94

[yash-atreya]

Generally supportive of this

We already support adding of custom headers in Alloy, should be relatively easy to add this to cast

https://github.com/alloy-rs/examples/blob/3b6d4a7cb465a0cb62a396735a8e26baa188ea55/examples/layers/examples/hyper_http_layer.rs#L92-L94

I don't think we need a layer for this, the current foundy_common::provider implementation supports adding custom headers to the underlying reqwest::Client. See:

foundry/crates/common/src/provider/mod.rs

Line 238 in 16a013f

pub fn headers(mut self, headers: Vec<String>) -> Self {

.

We just need to expose a cli flag headers: Vec<String> in RpcOpts

foundry/crates/cli/src/opts/ethereum.rs

Line 19 in 16a013f

pub struct RpcOpts {

, then instantiate a provider with headers set.

e.g usage:
cast call 0x.. "balanceOf(address)" 0x. --rpc-url --headers name:value

[sebastiendan]

Would setting a default user-agent be a valid additional change? (might be tedious to keep specifying it)

[zerosnacks]

Would setting a default user-agent be a valid additional change? (might be tedious to keep specifying it)

Given that cast is meant to be invoked standalone - independent of the context of a foundry project it cannot rely on the foundry.toml configuration. I would recommend assigning it to an environment variable and passing that in.

[yash-atreya]

Would setting a default user-agent be a valid additional change? (might be tedious to keep specifying it)

Given that cast is meant to be invoked standalone - independent of the context of a foundry project it cannot rely on the foundry.toml configuration. I would recommend assigning it to an environment variable and passing that in.

We can use an env variable instead: ETH_RPC_HEADERS

PR is up

[DaniPopes]

I think a default user-agent still makes sense, curl does this too