viceroy-lib 0.17.0

Viceroy implementation details.
Documentation 
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//! fastly_geo` hostcall implementations.

use std::{
    convert::TryInto,
    net::{IpAddr, Ipv4Addr, Ipv6Addr},
};

use {
    crate::{error::Error, session::Session, wiggle_abi::fastly_geo::FastlyGeo},
    std::convert::TryFrom,
    wiggle::{GuestMemory, GuestPtr},
};

impl FastlyGeo for Session {
    fn lookup(
        &mut self,
        memory: &mut GuestMemory<'_>,
        addr_octets: GuestPtr<u8>,
        addr_len: u32,
        buf: GuestPtr<u8>,
        buf_len: u32,
        nwritten_out: GuestPtr<u32>,
    ) -> Result<(), Error> {
        let octets = memory.to_vec(addr_octets.as_array(addr_len))?;

        let ip_addr: IpAddr = match addr_len {
            4 => IpAddr::V4(Ipv4Addr::from(
                TryInto::<[u8; 4]>::try_into(octets).unwrap(),
            )),
            16 => IpAddr::V6(Ipv6Addr::from(
                TryInto::<[u8; 16]>::try_into(octets).unwrap(),
            )),
            _ => return Err(Error::InvalidArgument),
        };

        let result = self.geolocation_lookup(&ip_addr).unwrap_or_default();

        if result.len() > buf_len as usize {
            memory.write(nwritten_out, u32::try_from(result.len()).unwrap_or(0))?;
            return Err(Error::BufferLengthError {
                buf: "geolocation_lookup",
                len: "geolocation_lookup_max_len",
            });
        }

        let result_len =
            u32::try_from(result.len()).expect("smaller than value_max_len means it must fit");

        memory.copy_from_slice(result.as_bytes(), buf.as_array(result_len))?;
        memory.write(nwritten_out, result_len)?;
        Ok(())
    }
}