Random numbers

[sonhal]

I am building a module that needs random numbers, preferably CSPRNG. Is there a good way of getting a hold of this?

[PiotrSikora]

Use getrandom crate, see example:

proxy-wasm-rust-sdk/examples/hello_world.rs

Line 51 in 1534ef2

getrandom(&mut buf).unwrap();

[sonhal]

Do I then need use the wasm32-wasi target? with cargo build --target wasm32-unknown-unknown --release I get: error[E0425]: cannot find function getrandom in this scope

Cargo.toml:

[package]
name = "authn-filter"
version = "0.1.0"
authors = ["Sondre"]
edition = "2018"

# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html

[lib]
path = "src/filter.rs"
crate-type = ["cdylib"]

[dependencies]
log = "0.4.14"
proxy-wasm = "0.1.3" # The Rust SDK for proxy-wasm
serde = { version = "1.0", features = ["derive"] }
serde_json = "1.0"
url = "2.2.1"
oauth2 = { version = "3.0",  default-features = false }
base64 = "0.13.0"

[target.'cfg(not(all(target_arch = "wasm32", target_os = "unknown")))'.dependencies]
getrandom = "0.2"

[PiotrSikora]

Yes, you need to use wasm32-wasi target. There is no random function defined in plain Wasm.

[sonhal]

Thank you, that worked great! Is there any docs you can point to regarding WASI support in Envoy?