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|
//! Wraps a writer with UDP headers.
//! This is useful for wrapping RawSocket Writer with appropriate headers.
rand: Random,
wrapped: *Writer,
interface: Writer,
pub fn init(w: *Writer) !NetWriter {
std.debug.assert(w.buffer.len > @sizeOf(EthernetHeaders) + @sizeOf(IpHeaders) + @sizeOf(UdpHeaders));
var prng = Random.DefaultPrng.init(blk: {
var seed: u64 = undefined;
try posix.getrandom(mem.asBytes(&seed));
break :blk seed;
});
return .{
.rand = prng.random(),
.wrapped = w,
.interface = .{
.vtable = &.{
.drain = drain,
.flush = flush,
},
.buffer = &.{},
},
};
}
fn drain(io_w: *Writer, data: []const []const u8, splat: usize) Writer.Error!usize {
const w: *NetWriter = @alignCast(@fieldParentPtr("interface", io_w));
var res: usize = 0;
if (io_w.end == 0) {
const ether_headers: EthernetHeaders = .{
.dest_mac = .{ 0xff, 0xff, 0xff, 0xff, 0xfe, 0xff },
.src_mac = blk: {
var output_bytes: [6]u8 = undefined;
output_bytes[0] = 0xee;
w.rand.bytes(output_bytes[1..]);
break :blk output_bytes;
},
.ether_type = 0x0800,
};
const ip_headers: IpHeaders = .{
.total_length = @intCast(res - 92),
.ttl = 0x64,
.protocol = 0x11,
.src_ip = .{ 0xff, 0x02, 0x03, 0x04 },
.dest_ip = .{ 0xff, 0xff, 0xff, 0xff },
};
const udp_headers: UdpHeaders = .{
.src_port = 0xbbbb,
.dest_port = 8888,
.length = @intCast(res),
};
res += try ether_headers.write(w.wrapped);
res += try ip_headers.write(w.wrapped);
res += try udp_headers.write(w.wrapped);
}
res += try w.wrapped.writeSplat(data, splat);
return res;
}
fn flush(io_w: *Writer) Writer.Error!void {
const w: *NetWriter = @alignCast(@fieldParentPtr("interface", io_w));
try w.wrapped.flush();
}
const EthernetHeaders = struct {
dest_mac: @Vector(6, u8),
src_mac: @Vector(6, u8),
ether_type: u16,
fn write(hdr: EthernetHeaders, writer: *std.Io.Writer) Writer.Error!usize {
comptime var res: usize = 0;
res += @sizeOf(u48);
try writer.writeInt(u48, @bitCast(hdr.dest_mac), .big);
res += @sizeOf(u48);
try writer.writeInt(u48, @bitCast(hdr.src_mac), .big);
res += @sizeOf(u16);
try writer.writeInt(u16, hdr.ether_type, .big);
return res;
}
const byte_len = @bitSizeOf(EthernetHeaders) / 8;
fn bytes(hdr: EthernetHeaders) [byte_len]u8 {
var res: [byte_len]u8 = undefined;
hdr.write(Writer.fixed(&res)) catch unreachable;
}
};
const IpHeaders = struct {
// ip_version: u4,
// header_length: u4 = 0,
type_of_service: u8 = 0,
total_length: u16 = 0x04,
identification: u16 = 0,
// ethernet_flags: u3 = 0,
// fragment_offset: u13 = 0,
ttl: u8 = 0,
protocol: u8 = 0,
header_checksum: @Vector(2, u8) = .{ 0, 0 },
src_ip: @Vector(4, u8),
dest_ip: @Vector(4, u8),
fn write(hdr: @This(), writer: *std.Io.Writer) Writer.Error!usize {
comptime var res: usize = 0;
res += @sizeOf(u8);
try writer.writeInt(u8, 0x45, .big); // ip version and header length
res += @sizeOf(u8);
try writer.writeByte(hdr.type_of_service);
res += @sizeOf(u16);
try writer.writeInt(u16, hdr.total_length, .big);
res += @sizeOf(u16);
try writer.writeInt(u16, hdr.identification, .big);
res += @sizeOf(u16);
try writer.writeInt(u16, 0x00, .big); // ethernet flags and fragment offset
res += @sizeOf(u8);
try writer.writeByte(hdr.ttl);
res += @sizeOf(u8);
try writer.writeByte(hdr.protocol);
res += @sizeOf(u16);
try writer.writeInt(u16, @bitCast(hdr.header_checksum), .big);
res += @sizeOf(u32);
try writer.writeInt(u32, @bitCast(hdr.src_ip), .big);
res += @sizeOf(u32);
try writer.writeInt(u32, @bitCast(hdr.dest_ip), .big);
return res;
}
const byte_len = @bitSizeOf(IpHeaders) / 8;
fn bytes(hdr: IpHeaders) [byte_len]u8 {
var res: [byte_len]u8 = undefined;
hdr.write(Writer.fixed(&res)) catch unreachable;
}
};
const UdpHeaders = packed struct {
src_port: u16,
dest_port: u16,
length: u16,
checksum: @Vector(2, u8) = .{ 0, 0 },
fn write(hdr: @This(), writer: *std.Io.Writer) Writer.Error!usize {
comptime var res: usize = 0;
res += @sizeOf(u16);
try writer.writeInt(u16, hdr.src_port, .big);
res += @sizeOf(u16);
try writer.writeInt(u16, hdr.dest_port, .big);
res += @sizeOf(u16);
try writer.writeInt(u16, hdr.length, .big);
res += @sizeOf(u16);
try writer.writeInt(u16, @bitCast(hdr.checksum), .big);
return res;
}
const byte_len = @bitSizeOf(UdpHeaders) / 8;
fn bytes(hdr: UdpHeaders) [byte_len]u8 {
var res: [byte_len]u8 = undefined;
hdr.write(Writer.fixed(&res)) catch unreachable;
}
};
const std = @import("std");
const Random = std.Random;
const posix = std.posix;
const Writer = std.Io.Writer;
const mem = std.mem;
const NetWriter = @This();
|
