barehttp 0.1.0

Blocking HTTP/1.1 client for no_std + alloc
Documentation 
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use crate::dns::os::host_cstring;
use crate::error::DnsError;
use crate::util::IpAddr;
use alloc::vec::Vec;
use core::net::{Ipv4Addr, Ipv6Addr};
use core::ptr;
use libc::{AF_INET, AF_INET6, addrinfo, sockaddr_in, sockaddr_in6};

pub fn resolve_host(host: &str) -> Result<Vec<IpAddr>, DnsError> {
  let host_c = host_cstring(host)?;

  let hints = addrinfo {
    ai_family: 0,
    ai_socktype: 0,
    ai_protocol: 0,
    ai_flags: 0,
    ai_addrlen: 0,
    ai_canonname: ptr::null_mut(),
    ai_addr: ptr::null_mut(),
    ai_next: ptr::null_mut(),
  };

  let mut result: *mut addrinfo = ptr::null_mut();

  // SAFETY: `host_c` is a NUL-terminated CString; `hints`/`result` are valid for getaddrinfo.
  let ret = unsafe { libc::getaddrinfo(host_c.as_ptr(), ptr::null(), &raw const hints, &raw mut result) };

  if ret != 0 {
    return Err(DnsError::ResolutionFailed(ret));
  }

  let mut addresses = Vec::new();
  let mut current = result;

  // SAFETY: `result` is a getaddrinfo-owned linked list until `freeaddrinfo`; each `ai_addr`
  // is valid for its `ai_family` when non-null. Freed exactly once after the walk.
  unsafe {
    while !current.is_null() {
      let info = &*current;

      if info.ai_family == AF_INET && !info.ai_addr.is_null() {
        let sockaddr = ptr::read_unaligned(info.ai_addr.cast::<sockaddr_in>());
        addresses.push(IpAddr::V4(Ipv4Addr::from(sockaddr.sin_addr.s_addr.to_ne_bytes())));
      } else if info.ai_family == AF_INET6 && !info.ai_addr.is_null() {
        let sockaddr = ptr::read_unaligned(info.ai_addr.cast::<sockaddr_in6>());
        addresses.push(IpAddr::V6(Ipv6Addr::from(sockaddr.sin6_addr.s6_addr)));
      }

      current = info.ai_next;
    }

    libc::freeaddrinfo(result);
  }

  if addresses.is_empty() {
    return Err(DnsError::NoAddressesFound);
  }

  Ok(addresses)
}