321 lines
12 KiB
Zig
321 lines
12 KiB
Zig
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const std = @import("std");
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const testing = std.testing;
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const fmt = std.fmt;
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const net = std.net;
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const ipc = @import("./main.zig");
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const Message = ipc.Message;
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const CBEventType = ipc.CBEvent.Type;
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const Allocator = std.mem.Allocator;
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const util = @import("./util.zig");
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const print_eq = util.print_eq;
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const log = std.log.scoped(.libipc_switch);
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const Event = ipc.Event;
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/// SwitchDB: store relations between clients and services.
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///
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/// A protocol service, such as TPCd can handle "external" communications (TCP in this case)
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/// meaning that a client can connect to this service through a canal that isn't a simple
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/// libipc UNIX socket, and this client is then connected to a local service.
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/// OTOH, a local client can ask TCPd to establish a connection to a remote service.
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/// In both cases, at least one of the connection isn't libipc-based and should be
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/// handled in a specific way that only TPCd (or another protocol service) can.
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///
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/// TCPd marks both file descriptors as "related" (add_switch) so libipc can automatically
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/// handle messages between the client and the service. Any input from one end will be sent
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/// to the other.
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/// TCPd registers functions to handle specific input and output operations from and to the
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/// remote connection (set_callbacks).
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///
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/// At any point, TCPd can safely close a connection and remote it from the SwitchDB (nuke),
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/// resulting in the removal of both the connection's FD and its related FD (both the client
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/// and the service connections are removed).
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///
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/// Currently, libipc automatically closes both the client and its service when an error occurs.
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pub const SwitchDB = struct {
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const Self = @This();
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db: std.AutoArrayHashMap(i32, ManagedConnection),
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pub fn init (allocator: Allocator) Self {
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return Self {
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.db = std.AutoArrayHashMap(i32, ManagedConnection).init(allocator),
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};
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}
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pub fn deinit (self: *Self) void {
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self.db.deinit();
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}
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pub fn format(self: Self, comptime _: []const u8, _: fmt.FormatOptions, out_stream: anytype) !void {
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for(self.db.keys()) |k,i| {
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try fmt.format(out_stream, "({},{})", .{k, self.db.values()[i].dest});
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}
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}
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pub fn add_switch(self: *Self, fd1: i32, fd2: i32) !void {
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try self.db.put(fd1, ManagedConnection {.dest = fd2});
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try self.db.put(fd2, ManagedConnection {.dest = fd1});
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}
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pub fn set_callbacks(self: *Self, fd: i32
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, in : *const fn (origin: i32, mcontent: [*]u8, mlen: *u32) CBEventType
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, out : *const fn (origin: i32, mcontent: [*]const u8, mlen: u32) CBEventType) !void {
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var managedconnection = self.db.get(fd) orelse return error.unregisteredFD;
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managedconnection.in = in;
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managedconnection.out = out;
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}
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/// Dig the "db" hashmap, perform "in" fn, may provide a message.
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/// Errors from the "in" fn are reported as Zig errors.
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pub fn read (self: *Self, fd: i32) !?Message {
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// assert there is an entry with this fd as a key.
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var managedconnection = self.db.get(fd) orelse return error.unregisteredFD;
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var buffer = [_]u8{0} ** 100000; // TODO: buffer size
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var message_size: u32 = @truncate(u32, buffer.len);
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var r: CBEventType = managedconnection.in(fd, &buffer, &message_size);
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switch (r) {
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// The message should be ignored (protocol specific).
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CBEventType.IGNORE => { return null; },
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CBEventType.NO_ERROR => {
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// TODO: read message
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// TODO: better allocator?
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// TODO: better errors?
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var message: Message
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= Message.read(managedconnection.dest
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, buffer[0..message_size]
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, std.heap.c_allocator) catch {
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return error.generic;
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};
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return message;
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},
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CBEventType.FD_CLOSING => { return error.closeFD; },
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// Generic error, or the message was read but with errors.
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CBEventType.ERROR => { return error.generic; },
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}
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unreachable;
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}
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/// Dig the "db" hashmap and perform "out" fn.
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/// Errors from the "out" fn are reported as Zig errors.
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pub fn write (self: *Self, message: Message) !void {
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// assert there is an entry with this fd as a key.
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var managedconnection = self.db.get(message.fd) orelse return error.unregisteredFD;
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var buffer = [_]u8{0} ** 100000; // TODO: buffer size
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var fbs = std.io.fixedBufferStream(&buffer);
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var writer = fbs.writer();
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// returning basic errors, no details.
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_ = message.write(writer) catch return error.generic;
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var written = fbs.getWritten();
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var r = managedconnection.out(message.fd, written.ptr, @truncate(u32, written.len));
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switch (r) {
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// The message should be ignored (protocol specific).
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// No error. A message was generated.
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CBEventType.NO_ERROR => {
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return;
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},
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CBEventType.FD_CLOSING => { return error.closeFD; },
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// Generic error, or the message was read but with errors.
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CBEventType.IGNORE,
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CBEventType.ERROR => {
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return error.generic;
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},
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}
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unreachable;
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}
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/// From a message to read on a socket to an Event.
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pub fn handle_event_read (self: *Self, index: usize, fd: i32) Event {
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var message: ?Message = null;
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message = self.read (fd) catch |err| switch(err) {
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error.closeFD => {
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return Event.init(Event.Type.DISCONNECTION, index, fd, null);
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},
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error.unregisteredFD,
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error.generic => {
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return Event.init(Event.Type.ERROR, index, fd, null);
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},
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};
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return Event.init(Event.Type.SWITCH_RX, index, fd, message);
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}
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/// Message is free'd in any case.
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pub fn handle_event_write (self: *Self, index: usize, message: Message) Event {
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defer message.deinit();
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var fd = message.fd;
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self.write(message) catch |err| switch(err) {
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error.closeFD => {
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return Event.init(Event.Type.DISCONNECTION, index, fd, null);
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},
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error.unregisteredFD,
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error.generic => {
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return Event.init(Event.Type.ERROR, index, fd, null);
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},
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};
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return Event.init(Event.Type.SWITCH_TX, index, fd, null);
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}
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/// Simple wrapper around self.db.get.
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pub fn getDest (self: *Self, fd: i32) !i32 {
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return self.db.get(fd).?.dest;
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}
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/// Remove both entries (client and service) from the DB.
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pub fn nuke (self: *Self, fd: i32) void {
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if (self.db.fetchSwapRemove(fd)) |kv| {
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_ = self.db.swapRemove(kv.value.dest);
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}
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}
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};
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const ManagedConnection = struct {
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dest : i32,
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in : *const fn (origin: i32, mcontent: [*]u8, mlen: *u32) CBEventType = default_in,
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out : *const fn (origin: i32, mcontent: [*]const u8, mlen: u32) CBEventType = default_out,
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};
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test "creation and display" {
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const config = .{.safety = true};
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var gpa = std.heap.GeneralPurposeAllocator(config){};
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defer _ = gpa.deinit();
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const allocator = gpa.allocator();
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var switchdb = SwitchDB.init(allocator);
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defer switchdb.deinit();
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try switchdb.db.put(5, ManagedConnection {.dest = 6});
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try switchdb.db.put(6, ManagedConnection {.dest = 5});
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try print_eq("{ (5,6)(6,5) }", .{switchdb});
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}
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fn successful_in (_: i32, mcontent: [*]u8, mlen: *u32) CBEventType {
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var m = Message.init(8, std.heap.c_allocator, "coucou") catch unreachable;
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defer m.deinit();
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var fbs = std.io.fixedBufferStream(mcontent[0..mlen.*]);
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var writer = fbs.writer();
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const bytes_written = m.write (writer) catch unreachable;
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mlen.* = @truncate(u32, bytes_written);
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return CBEventType.NO_ERROR;
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}
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fn successful_out (_: i32, _: [*]const u8, _: u32) CBEventType {
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return CBEventType.NO_ERROR;
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}
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test "successful exchanges" {
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const config = .{.safety = true};
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var gpa = std.heap.GeneralPurposeAllocator(config){};
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defer _ = gpa.deinit();
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const allocator = gpa.allocator();
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var switchdb = SwitchDB.init(allocator);
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defer switchdb.deinit();
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try switchdb.db.put(5, ManagedConnection {.dest = 6, .in = successful_in, .out = successful_out});
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try switchdb.db.put(6, ManagedConnection {.dest = 5, .in = successful_in, .out = successful_out});
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// should return a new message (hardcoded: fd 8, payload "coucou")
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var event_1: Event = switchdb.handle_event_read (1, 5);
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if (event_1.m) |m| { m.deinit(); }
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else { return error.NoMessage; }
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// should return a new message (hardcoded: fd 8, payload "coucou")
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var event_2: Event = switchdb.handle_event_read (1, 6);
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if (event_2.m) |m| { m.deinit(); }
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else { return error.NoMessage; }
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var message = try Message.init(6, allocator, "coucou");
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var event_3 = switchdb.handle_event_write (5, message);
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if (event_3.m) |_| { return error.ShouldNotCarryMessage; }
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}
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fn unsuccessful_in (_: i32, _: [*]const u8, _: *u32) CBEventType {
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return CBEventType.ERROR;
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}
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fn unsuccessful_out (_: i32, _: [*]const u8, _: u32) CBEventType {
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return CBEventType.ERROR;
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}
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test "unsuccessful exchanges" {
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const config = .{.safety = true};
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var gpa = std.heap.GeneralPurposeAllocator(config){};
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defer _ = gpa.deinit();
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const allocator = gpa.allocator();
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var switchdb = SwitchDB.init(allocator);
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defer switchdb.deinit();
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try switchdb.db.put(5, ManagedConnection {.dest = 6, .in = unsuccessful_in, .out = unsuccessful_out});
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try switchdb.db.put(6, ManagedConnection {.dest = 5, .in = unsuccessful_in, .out = unsuccessful_out});
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// should return a new message (hardcoded: fd 8, payload "coucou")
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var event_1: Event = switchdb.handle_event_read (1, 5);
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if (event_1.m) |_| { return error.ShouldNotCarryMessage; }
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// should return a new message (hardcoded: fd 8, payload "coucou")
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var event_2: Event = switchdb.handle_event_read (1, 6);
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if (event_2.m) |_| { return error.ShouldNotCarryMessage; }
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var message = try Message.init(6, allocator, "coucou");
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var event_3 = switchdb.handle_event_write (5, message);
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if (event_3.m) |_| { return error.ShouldNotCarryMessage; }
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}
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test "nuke 'em" {
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const config = .{.safety = true};
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var gpa = std.heap.GeneralPurposeAllocator(config){};
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defer _ = gpa.deinit();
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const allocator = gpa.allocator();
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var switchdb = SwitchDB.init(allocator);
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defer switchdb.deinit();
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try switchdb.db.put(5, ManagedConnection {.dest = 6, .in = unsuccessful_in, .out = unsuccessful_out});
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try switchdb.db.put(6, ManagedConnection {.dest = 5, .in = unsuccessful_in, .out = unsuccessful_out});
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try testing.expect(switchdb.db.count() == 2);
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switchdb.nuke(5);
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try testing.expect(switchdb.db.count() == 0);
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}
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fn default_in (origin: i32, mcontent: [*]u8, mlen: *u32) CBEventType {
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// This may be kinda hacky, idk.
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var stream: net.Stream = .{ .handle = origin };
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var packet_size: usize = stream.read(mcontent[0..mlen.*]) catch return CBEventType.ERROR;
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// Let's handle this as a disconnection.
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if (packet_size < 4) {
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log.debug("message is less than 4 bytes ({} bytes)", .{packet_size});
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return CBEventType.FD_CLOSING;
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}
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mlen.* = @truncate(u32, packet_size);
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return CBEventType.NO_ERROR;
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}
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fn default_out (fd: i32, mcontent: [*]const u8, mlen: u32) CBEventType {
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// Message contains the fd, no need to search for the right structure to copy,
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// let's just recreate a Stream from the fd.
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var to_send = mcontent[0..mlen];
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var stream = net.Stream { .handle = fd };
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_ = stream.write (to_send) catch return CBEventType.ERROR;
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return CBEventType.NO_ERROR;
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}
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