init

game_server/net/packet.py

@@ -0,0 +1,93 @@
+from dataclasses import dataclass
+import struct
+
+HEAD_MAGIC = 0x9D74C714
+TAIL_MAGIC = 0xD7A152C8
+
+
+@dataclass
+class NetPacket:
+    cmd_type: int
+    head: bytes
+    body: bytes
+
+    def to_message(self, m) -> "NetPacket":
+        return m.parse(self.body)
+
+    @staticmethod
+    def from_message(c, m) -> "NetPacket":
+        return NetPacket(cmd_type=c, head=[], body=bytes(m))
+
+    def to_bytes(self) -> bytes:
+        # packet_length = 12 + len(self.head) + len(self.body) + 4
+        b = bytearray()
+
+        b.extend(struct.pack(">I", HEAD_MAGIC))
+        b.extend(struct.pack(">H", self.cmd_type))
+        b.extend(struct.pack(">H", len(self.head)))
+        b.extend(struct.pack(">I", len(self.body)))
+        b.extend(self.head)
+        b.extend(self.body)
+        b.extend(struct.pack(">I", TAIL_MAGIC))
+
+        return bytes(b)
+
+    @staticmethod
+    def from_bytes(b: bytes) -> "NetPacket":
+        if len(b) < 16:
+            raise ValueError("len(b) < 16")
+
+        head_magic = struct.unpack_from(">I", b, 0)[0]
+
+        if head_magic != HEAD_MAGIC:
+            raise ValueError("Invalid head magic")
+
+        cmd_type = struct.unpack_from(">H", b, 4)[0]
+        head_length = struct.unpack_from(">H", b, 6)[0]
+        body_length = struct.unpack_from(">I", b, 8)[0]
+
+        head_start = 12
+        head_end = head_start + head_length
+
+        if head_end > len(b):
+            raise ValueError("Head data > packet length")
+
+        head = b[head_start:head_end]
+
+        body_start = head_end
+        body_end = body_start + body_length
+
+        if body_end + 4 > len(b):
+            raise ValueError("Body data > packet length")
+
+        body = b[body_start:body_end]
+
+        tail_magic = struct.unpack_from(">I", b, body_end)[0]
+
+        if tail_magic != TAIL_MAGIC:
+            raise ValueError("Invalid tail magic")
+
+        return NetPacket(cmd_type, head, body)
+
+
+@dataclass
+class NetOperation:
+    head: int
+    conv_id: int
+    session_token: int
+    data: int
+    tail: int
+
+    def to_bytes(self) -> bytes:
+        return struct.pack(
+            ">IIIII", self.head, self.conv_id, self.session_token, self.data, self.tail
+        )
+
+    @staticmethod
+    def from_bytes(b: bytes) -> "NetOperation":
+        if len(b) != 20:
+            raise ValueError("len(b) != 20")
+
+        head, conv_id, session_token, data, tail = struct.unpack(">IIIII", b)
+
+        return NetOperation(head, conv_id, session_token, data, tail)