chore: reorganize code

src/main.zig

@@ -4,8 +4,6 @@ const network = @import("network");
 const Allocator = std.mem.Allocator;
 const Socket = network.Socket;
 
-const port: u16 = 2424;
-
 const target: []const u8 =
     \\<target version="1.0">
     \\    <architecture>armv4t</architecture>
@@ -33,103 +31,136 @@ const target: []const u8 =
 ;
 
 pub fn main() !void {
-    const log = std.log.scoped(.Server);
+    const log = std.log.scoped(.Main);
 
     var gpa = std.heap.GeneralPurposeAllocator(.{}){};
     defer std.debug.assert(!gpa.deinit());
 
     const allocator = gpa.allocator();
 
-    try network.init();
-    defer network.deinit();
+    var server = try Server.init();
+    defer server.deinit(allocator);
 
-    var socket = try Socket.create(.ipv4, .tcp);
-    defer socket.close();
-
-    try socket.bindToPort(port);
-    try socket.listen();
-
-    var client = try socket.accept();
-    defer client.close();
-
-    const endpoint = try client.getLocalEndPoint();
-    log.info("client connected from {}", .{endpoint});
-
-    try gdbStubServer(allocator, client);
+    try server.run(allocator);
 
     log.info("Client disconnected", .{});
 }
 
-fn gdbStubServer(allocator: Allocator, client: Socket) !void {
-    var buf: [Packet.size]u8 = undefined;
-    var previous: ?[]const u8 = null;
-    defer if (previous) |packet| allocator.free(packet);
+const Server = struct {
+    const Self = @This();
+    const log = std.log.scoped(.Server);
+    const port: u16 = 2424;
 
-    while (true) {
-        const len = try client.receive(&buf);
-        if (len == 0) break;
+    // FIXME: Shouldn't this be a Packet Struct?
+    pkt_cache: ?[]const u8 = null,
 
-        switch (try parse(allocator, client, previous, buf[0..len])) {
-            .send => |response| {
-                if (previous) |packet| allocator.free(packet);
-                previous = response;
-            },
-            .recv_ack => {
-                if (previous) |packet| allocator.free(packet);
-                previous = null;
-            },
-            .recv_nack => {},
+    client: Socket,
+    _socket: Socket,
+
+    pub fn init() !Self {
+        try network.init();
+
+        var socket = try Socket.create(.ipv4, .tcp);
+        try socket.bindToPort(port);
+        try socket.listen();
+
+        var client = try socket.accept(); // TODO: This blocks, is this OK?
+
+        const endpoint = try client.getLocalEndPoint();
+        log.info("client connected from {}", .{endpoint});
+
+        return .{ ._socket = socket, .client = client };
+    }
+
+    pub fn deinit(self: *Self, allocator: Allocator) void {
+        self.reset(allocator);
+
+        self.client.close();
+        self._socket.close();
+        network.deinit();
+
+        self.* = undefined;
+    }
+
+    const Action = union(enum) {
+        nothing,
+        send: []const u8,
+        retry,
+        ack,
+        nack,
+    };
+
+    pub fn run(self: *Self, allocator: Allocator) !void {
+        var buf: [Packet.max_len]u8 = undefined;
+
+        while (true) {
+            const len = try self.client.receive(&buf);
+            if (len == 0) break;
+
+            const action = try Self.parse(allocator, buf[0..len]);
+            try self.send(allocator, action);
         }
     }
-}
 
-const Action = union(enum) {
-    send: []const u8,
-    recv_nack,
-    recv_ack,
+    fn parse(allocator: Allocator, input: []const u8) !Action {
+        return switch (input[0]) {
+            '+' => .nothing,
+            '-' => .retry,
+            '$' => blk: {
+                // Packet
+                var packet = Packet.from(allocator, input) catch return .nack;
+                defer packet.deinit(allocator);
+
+                var string = packet.parse(allocator) catch return .nack;
+                defer string.deinit(allocator);
+
+                const reply = string.inner();
+
+                // deallocated by the caller
+                const response = try std.fmt.allocPrint(allocator, "${s}#{x:0>2}", .{ reply, Packet.checksum(reply) });
+
+                break :blk .{ .send = response };
+            },
+            else => std.debug.panic("Unknown: {s}", .{input}),
+        };
+    }
+
+    fn send(self: *Self, allocator: Allocator, action: Action) !void {
+        switch (action) {
+            .send => |pkt| {
+                _ = try self.client.send("+"); // ACK
+                _ = try self.client.send(pkt);
+
+                self.reset(allocator);
+                self.pkt_cache = pkt;
+            },
+            .retry => {
+                log.warn("received nack, resending: \"{?s}\"", .{self.pkt_cache});
+
+                if (self.pkt_cache) |pkt| _ = try self.client.send(pkt); // FIXME: is an ack to a nack necessary?
+            },
+            .ack => {
+                _ = try self.client.send("+");
+                self.reset(allocator);
+            },
+            .nack => {
+                _ = try self.client.send("-");
+                self.reset(allocator);
+            },
+            .nothing => self.reset(allocator),
+        }
+    }
+
+    fn reset(self: *Self, allocator: Allocator) void {
+        if (self.pkt_cache) |pkt| allocator.free(pkt);
+        self.pkt_cache = null;
+    }
 };
 
-fn parse(allocator: Allocator, client: Socket, previous: ?[]const u8, input: []const u8) !Action {
-    const log = std.log.scoped(.GdbStubParser);
-
-    return switch (input[0]) {
-        '+' => .recv_ack,
-        '-' => blk: {
-            if (previous) |packet| {
-                log.warn("received nack, resending: \"{s}\"", .{packet});
-                _ = try client.send(packet);
-            } else {
-                log.err("received nack, but we don't recall sending anything", .{});
-            }
-
-            break :blk .recv_nack;
-        },
-        '$' => blk: {
-            // Packet
-            var packet = try Packet.from(allocator, input);
-            defer packet.deinit(allocator);
-
-            var string = try packet.parse(allocator);
-            defer string.deinit(allocator);
-
-            const reply = string.inner();
-
-            _ = try client.send("+"); // Acknowledge
-
-            // deallocated by the caller
-            const response = try std.fmt.allocPrint(allocator, "${s}#{x:0>2}", .{ reply, Packet.checksum(reply) });
-            _ = try client.send(response);
-
-            break :blk .{ .send = response };
-        },
-        else => std.debug.panic("Unknown: {s}", .{input}),
-    };
-}
-
 const Packet = struct {
     const Self = @This();
     const log = std.log.scoped(.Packet);
-    const size: usize = 0x1000;
+    const max_len: usize = 0x1000;
 
     contents: []const u8,
 
@@ -212,7 +243,7 @@ const Packet = struct {
                     const format = "PacketSize={x:};qXfer:features:read+;qXfer:memory-map:read+";
                     // TODO: Anything else?
 
-                    const ret = try std.fmt.allocPrint(allocator, format, .{Packet.size});
+                    const ret = try std.fmt.allocPrint(allocator, format, .{Packet.max_len});
                     return .{ .alloc = ret };
                 }