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const base64Enc = std.base64.Base64Encoder.init(std.base64.standard_alphabet_chars, '=');
const base64Dec = std.base64.Base64Decoder.init(std.base64.standard_alphabet_chars, '=');
rand: Random,
socket: gcat.nic.RawSocket,
const Self = @This();
const max_message_size = 2048;
pub fn init(interface_name: [:0]const u8) !Self {
var prng = Random.DefaultPrng.init(blk: {
var seed: u64 = undefined;
try posix.getrandom(mem.asBytes(&seed));
break :blk seed;
});
const rand = prng.random();
const socket: gcat.nic.RawSocket = try .init(interface_name);
return .{
.rand = rand,
.socket = socket,
};
}
pub fn deinit(self: *Self) void {
self.socket.deinit();
}
/// Used for relay messages and connection handshake.
/// Assumes Client .init has been called.
fn broadcastInitialInterestMessage(self: *Self, msg_bytes: []align(@alignOf(SaprusMessage)) u8) !void {
var packet_bytes: [max_message_size]u8 = comptime blk: {
var b: [max_message_size]u8 = @splat(0);
// Destination MAC addr to FF:FF:FF:FF:FF:FF
for (0..6) |i| {
b[i] = 0xff;
}
// Set Ethernet type to IPv4
b[0x0c] = 0x08;
b[0x0d] = 0x00;
// Set IPv4 version to 4
b[0x0e] = 0x45;
// Destination broadcast
for (0x1e..0x22) |i| {
b[i] = 0xff;
}
// Set TTL
b[0x16] = 0x40;
// Set IPv4 protocol to UDP
b[0x17] = 0x11;
// Set interest filter value to 8888.
b[0x24] = 0x22;
b[0x25] = 0xb8;
break :blk b;
};
var msg: *SaprusMessage = try .bytesAsValue(msg_bytes);
try msg.networkFromNativeEndian();
defer msg.nativeFromNetworkEndian() catch unreachable;
// The byte position within the packet that the saprus message starts at.
const saprus_start_byte = 42;
@memcpy(packet_bytes[saprus_start_byte .. saprus_start_byte + msg_bytes.len], msg_bytes);
try self.socket.linkLayer().send(packet_bytes[0 .. saprus_start_byte + msg_bytes.len]);
}
// fn broadcastSaprusMessage(msg_bytes: []align(@alignOf(SaprusMessage)) u8) !void {}
fn broadcastSaprusMessage(msg_bytes: []align(@alignOf(SaprusMessage)) u8, udp_port: u16) !void {
if (false) {
var foo: gcat.nic.RawSocket = try .init("enp7s0"); // /proc/net/dev
defer foo.deinit();
}
const msg: *SaprusMessage = try .bytesAsValue(msg_bytes);
try msg.networkFromNativeEndian();
defer msg.nativeFromNetworkEndian() catch unreachable;
var sock = try network.Socket.create(.ipv4, .udp);
defer sock.close();
try sock.setBroadcast(true);
// Bind to 0.0.0.0:0
const bind_addr = network.EndPoint{
.address = network.Address{ .ipv4 = network.Address.IPv4.any },
.port = 0,
};
const dest_addr = network.EndPoint{
.address = network.Address{ .ipv4 = network.Address.IPv4.broadcast },
.port = udp_port,
};
try sock.bind(bind_addr);
std.debug.print("{x}\n", .{msg_bytes});
_ = try sock.sendTo(dest_addr, msg_bytes);
}
pub fn sendRelay(self: *Self, payload: []const u8, dest: [4]u8) !void {
var buf: [max_message_size]u8 align(@alignOf(SaprusMessage)) = undefined;
const msg_bytes = buf[0..try SaprusMessage.calcSize(
.relay,
base64Enc.calcSize(payload.len),
)];
const msg: *SaprusMessage = .init(.relay, msg_bytes);
const relay = (try msg.getSaprusTypePayload()).relay;
relay.dest = dest;
_ = base64Enc.encode(relay.getPayload(), payload);
try self.broadcastInitialInterestMessage(msg_bytes);
}
fn randomPort(self: Self) u16 {
return self.rand.intRangeAtMost(u16, 1024, 65000);
}
pub fn sendInitialConnection(
self: Self,
payload: []const u8,
output_bytes: []align(@alignOf(SaprusMessage)) u8,
initial_port: u16,
) !*SaprusMessage {
const dest_port = self.randomPort();
const msg_bytes = output_bytes[0..try SaprusMessage.calcSize(
.connection,
base64Enc.calcSize(payload.len),
)];
const msg: *SaprusMessage = .init(.connection, msg_bytes);
const connection = (try msg.getSaprusTypePayload()).connection;
connection.src_port = initial_port;
connection.dest_port = dest_port;
_ = base64Enc.encode(connection.getPayload(), payload);
try broadcastSaprusMessage(msg_bytes, 8888);
return msg;
}
pub fn connect(self: Self, payload: []const u8) !?SaprusConnection {
const initial_port = self.randomPort();
var initial_conn_res: ?*SaprusMessage = null;
var sock = try network.Socket.create(.ipv4, .udp);
defer sock.close();
// Bind to 255.255.255.255:8888
const bind_addr = network.EndPoint{
.address = network.Address{ .ipv4 = network.Address.IPv4.broadcast },
.port = 8888,
};
// timeout 1s
try sock.setReadTimeout(1 * std.time.us_per_s);
try sock.bind(bind_addr);
var sent_msg_bytes: [max_message_size]u8 align(@alignOf(SaprusMessage)) = undefined;
const msg = try self.sendInitialConnection(payload, &sent_msg_bytes, initial_port);
var response_buf: [max_message_size]u8 align(@alignOf(SaprusMessage)) = undefined;
_ = try sock.receive(&response_buf); // Ignore message that I sent.
const len = try sock.receive(&response_buf);
initial_conn_res = try .networkBytesAsValue(response_buf[0..len]);
// Complete handshake after awaiting response
try broadcastSaprusMessage(msg.asBytes(), self.randomPort());
if (false) {
return initial_conn_res.?;
}
return null;
}
const SaprusMessage = @import("message.zig").Message;
const SaprusConnection = @import("Connection.zig");
const std = @import("std");
const Random = std.Random;
const posix = std.posix;
const mem = std.mem;
const network = @import("network");
const gcat = @import("gatorcat");
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