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authorRubidium <rubidium@openttd.org>2021-04-18 14:56:25 +0200
committerrubidium42 <rubidium42@users.noreply.github.com>2021-04-25 21:27:54 +0200
commit21f58ab437992761caefd11f931c45086cc3d216 (patch)
treec0cecc4d612b75f6d71a0212a47856faff3d9f57 /src/network/core
parentd6000c2ec5f61c599d8859b981f2dac6a92e0755 (diff)
downloadopenttd-21f58ab437992761caefd11f931c45086cc3d216.tar.xz
Change: use 32 KiB packets to transfer the savegame
Diffstat (limited to 'src/network/core')
-rw-r--r--src/network/core/config.h16
1 files changed, 15 insertions, 1 deletions
diff --git a/src/network/core/config.h b/src/network/core/config.h
index 572b4720d..866d1791d 100644
--- a/src/network/core/config.h
+++ b/src/network/core/config.h
@@ -31,7 +31,21 @@ static const uint16 NETWORK_ADMIN_PORT = 3977; ///< The defau
static const uint16 NETWORK_DEFAULT_DEBUGLOG_PORT = 3982; ///< The default port debug-log is sent to (TCP)
static const uint16 UDP_MTU = 1460; ///< Number of bytes we can pack in a single UDP packet
-static const uint16 TCP_MTU = 1460; ///< Number of bytes we can pack in a single TCP packet
+/*
+ * Technically a TCP packet could become 64kiB, however the high bit is kept so it becomes possible in the future
+ * to go to (significantly) larger packets if needed. This would entail a strategy such as employed for UTF-8.
+ *
+ * Packets up to 32 KiB have the high bit not set:
+ * 00000000 00000000 0bbbbbbb aaaaaaaa -> aaaaaaaa 0bbbbbbb
+ * Send_uint16(GB(size, 0, 15)
+ *
+ * Packets up to 1 GiB, first uint16 has high bit set so it knows to read a
+ * next uint16 for the remaining bits of the size.
+ * 00dddddd cccccccc bbbbbbbb aaaaaaaa -> cccccccc 10dddddd aaaaaaaa bbbbbbbb
+ * Send_uint16(GB(size, 16, 14) | 0b10 << 14)
+ * Send_uint16(GB(size, 0, 16))
+ */
+static const uint16 TCP_MTU = 32767; ///< Number of bytes we can pack in a single TCP packet
static const uint16 COMPAT_MTU = 1460; ///< Number of bytes we can pack in a single packet for backward compatibility
static const byte NETWORK_GAME_ADMIN_VERSION = 1; ///< What version of the admin network do we use?