std.net.getAddressList on android platform

[Iced-Sun]

Zig Version

0.13.0, 0.14.0-dev.2211+05a3ac43e, 0.14.0-dev.2254+73f2671c7

Steps to Reproduce and Observed Behavior

1. create a simple snippet:

const std = @import("std");

pub fn main() !void {
    const address_list = try std.net.getAddressList(std.heap.page_allocator, "google.com", 443);

    std.debug.print("{any}\n", .{address_list});
}

2. create android-libc.txt to point ndk libc:

include_dir=thirdparty/android/sysroot/usr/include/
sys_include_dir=thirdparty/android/sysroot/usr/include/arm-linux-androideabi
crt_dir=thirdparty/android/sysroot/usr/lib/arm-linux-androideabi/30
static_crt_dir=thirdparty/android/sysroot/usr/lib/arm-linux-androideabi
msvc_lib_dir=
kernel32_lib_dir=
gcc_dir=

3. build exe with target=arm-linux-android, link_libc=true, linkage=dynamic, libc_file=android-libc.txt, run exe on android:

net.AddressList{ .arena = heap.arena_allocator.ArenaAllocator{ .child_allocator = mem.Allocator{ .ptr = anyopaque@0, .vtable = mem.Allocator.VTable{ ... } }, .state = heap.arena_allocator.ArenaAllocator.State{ .buffer_list = linked_list.SinglyLinkedList(usize){ ... }, .end_index = 32 } }, .addrs = {  }, .canon_name = null }

4. build exe with simply target=arm-linux-android, run exe on android

error.TemporaryNameServerFailure

5. run exe from step 4 on linux host with qemu-arm

net.AddressList{ .arena = heap.arena_allocator.ArenaAllocator{ .child_allocator = mem.Allocator{ .ptr = anyopaque@0, .vtable = mem.Allocator.VTable{ ... } }, .state = heap.arena_allocator.ArenaAllocator.State{ .buffer_list = linked_list.SinglyLinkedList(usize){ ... }, .end_index = 276 } }, .addrs = { 93.46.8.90:443, [2404:6800:4012:5::200e]:443 }, .canon_name = { 103, 111, 111, 103, 108, 101, 46, 99, 111, 109 } }

Expected Behavior

The result in step 5 is expected.

The result in step 4 is not expected, although intentional. std.net.getAddressList invokes std.net.linuxLookupName, which requires a hard-coded /etc/resolv.conf to work. Android has no /etc/resolv.conf.

The result in step 3 is not expected and seems to be a bug. std.net.getAddressList invokes std.posix.system.getaddrinfo with link_libc=true. By providing an wrapped getaddrinfo, I confirm that getaddrinfo does write a valid sockaddr on C-side, but the resulting zig-side addr is null, producing an empty address list. As a workaround, I have to wrap getaddrinfo to fill back result.addrs.