motiejus/nyotun
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Motiejus Jakštys 2024-10-20 23:19:43 +03:00
parent 961de327fe
commit 02d1d9f0c0
1 changed files with 18 additions and 7 deletions
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25
src/tunnel.zig
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@ -1,3 +1,4 @@
const builtin = @import("builtin");
const std = @import("std"); const std = @import("std");
const os = std.os; const os = std.os;
const mem = std.mem; const mem = std.mem;
@ -6,18 +7,25 @@ const log = std.log.scoped(.nyotun);
const IFF_TUN = 0x0001; // <linux/if_tun.h> const IFF_TUN = 0x0001; // <linux/if_tun.h>
const IFF_NO_PI = 0x1000; // <linux/if_tun.h> const IFF_NO_PI = 0x1000; // <linux/if_tun.h>
const TUNSETIFF = 0x400454ca; // write a C program, run and see
// git -C ~/code/go grep TUNSETIFF
const TUNSETIFF = switch (builtin.target.cpu.arch) {
.x86, .x86_64, .arm, .aarch64 => 0x400454ca,
else => @compileError("unsupported architecture"),
};
dev: [posix.IFNAMESIZE:0]u8, dev: [posix.IFNAMESIZE:0]u8,
tunFile: posix.fd_t, tun_file: posix.fd_t,
pub fn init(devname: ?[]const u8) !Tunnel { pub fn init(devname: ?[]const u8) !Tunnel {
const tunFile = try posix.open( const tun_file = try posix.open(
"/dev/net/tun", "/dev/net/tun",
// NB: vtun just uses RDWR, tailscale-go adds O_NONBLOCK.
// Not sure why I would add O_NONBLOCK, so just not doing that.
posix.O{ .ACCMODE = .RDWR, .CLOEXEC = true }, posix.O{ .ACCMODE = .RDWR, .CLOEXEC = true },
0, 0,
); );
errdefer posix.close(tunFile); errdefer posix.close(tun_file);
var ifr = mem.zeroInit( var ifr = mem.zeroInit(
posix.ifreq, posix.ifreq,
@ -29,20 +37,23 @@ pub fn init(devname: ?[]const u8) !Tunnel {
@memcpy(ifr.ifrn.name[0..name.len], name); @memcpy(ifr.ifrn.name[0..name.len], name);
} }
const err = posix.system.ioctl(tunFile, TUNSETIFF, @intFromPtr(&ifr)); const err = posix.system.ioctl(tun_file, TUNSETIFF, @intFromPtr(&ifr));
if (posix.errno(err) != .SUCCESS) { if (posix.errno(err) != .SUCCESS) {
log.err("unable to set TUNSETIFF: {s}", .{@tagName(posix.errno(err))}); log.err("unable to set TUNSETIFF: {s}", .{@tagName(posix.errno(err))});
return error.OpenDevTun; return error.OpenDevTun;
} }
var tunnel = Tunnel{ .dev = .{0} ** posix.IFNAMESIZE, .tunFile = tunFile }; var tunnel = Tunnel{
.dev = .{0} ** posix.IFNAMESIZE,
.tun_file = tun_file,
};
const ifname = mem.sliceTo(&ifr.ifrn.name, 0); const ifname = mem.sliceTo(&ifr.ifrn.name, 0);
@memcpy(tunnel.dev[0..ifname.len], ifname); @memcpy(tunnel.dev[0..ifname.len], ifname);
return tunnel; return tunnel;
} }
pub fn close(self: *Tunnel) void { pub fn close(self: *Tunnel) void {
posix.close(self.tunFile); posix.close(self.tun_file);
} }
const Tunnel = @This(); const Tunnel = @This();