stcp: ed25519 pubkey exchange in handshake, fix instance destroy segfault, fix chat_tcp_test

- u_async.c: process immediate_queue BEFORE epoll_wait in uasync_poll
- stcp_link.c: defensive NULL etcp_conn/etcp_link in stcp_link_close
- utun_instance.c: move stcp_server_list_destroy_all to Phase J (before ETCP),
  add deferred drain in both Phase J and L
- stcp.h/c: STCP_HS_ENC_CLIENT 6→38, STCP_HS_ENC_SERVER 7→39,
  exchange ed25519_pubkey in both handshake directions
- etcp_connections.c: copy peer_ed25519 from STCP to ETCP_CONN in
  etcp_link_enter_ready_tcp; guard link->etcp in tcp_link_close_cb
- chat_sync.c: fix lk->conn NULL dereference for TCP links
- test_stcp.c: update stcp_server_create/stcp_client_connect callsites
- tools/chat_tcp_test: change transport udp→tcp

tools/chatgui/zxing-cpp/core/src/ECI.cpp

@@ -0,0 +1,81 @@
+/*
+* Copyright 2022 Axel Waggershauser
+*/
+// SPDX-License-Identifier: Apache-2.0
+
+#include "ECI.h"
+
+#include "ZXAlgorithms.h"
+
+#include <map>
+
+namespace ZXing {
+
+static const std::map<ECI, CharacterSet> ECI_TO_CHARSET = {
+	{ECI(0), CharacterSet::Cp437},     // Obsolete
+	{ECI(1), CharacterSet::ISO8859_1}, // Obsolete
+	{ECI::Cp437, CharacterSet::Cp437}, // Obsolete but still used by PDF417 Macro fields (ISO/IEC 15438:2015 Annex H.2.3)
+	{ECI::ISO8859_1, CharacterSet::ISO8859_1},
+	{ECI::ISO8859_2, CharacterSet::ISO8859_2},
+	{ECI::ISO8859_3, CharacterSet::ISO8859_3},
+	{ECI::ISO8859_4, CharacterSet::ISO8859_4},
+	{ECI::ISO8859_5, CharacterSet::ISO8859_5},
+	{ECI::ISO8859_6, CharacterSet::ISO8859_6},
+	{ECI::ISO8859_7, CharacterSet::ISO8859_7},
+	{ECI::ISO8859_8, CharacterSet::ISO8859_8},
+	{ECI::ISO8859_9, CharacterSet::ISO8859_9},
+	{ECI::ISO8859_10, CharacterSet::ISO8859_10},
+	{ECI::ISO8859_11, CharacterSet::ISO8859_11},
+	{ECI::ISO8859_13, CharacterSet::ISO8859_13},
+	{ECI::ISO8859_14, CharacterSet::ISO8859_14},
+	{ECI::ISO8859_15, CharacterSet::ISO8859_15},
+	{ECI::ISO8859_16, CharacterSet::ISO8859_16},
+	{ECI::Shift_JIS, CharacterSet::Shift_JIS},
+	{ECI::Cp1250, CharacterSet::Cp1250},
+	{ECI::Cp1251, CharacterSet::Cp1251},
+	{ECI::Cp1252, CharacterSet::Cp1252},
+	{ECI::Cp1256, CharacterSet::Cp1256},
+	{ECI::UTF8, CharacterSet::UTF8},
+	{ECI::UTF16BE, CharacterSet::UTF16BE},
+	{ECI::UTF16LE, CharacterSet::UTF16LE},
+	{ECI::UTF32BE, CharacterSet::UTF32BE},
+	{ECI::UTF32LE, CharacterSet::UTF32LE},
+	{ECI::ASCII, CharacterSet::ASCII},
+	{ECI::Big5, CharacterSet::Big5},
+	{ECI::GB18030, CharacterSet::GB18030},
+	{ECI::GB2312, CharacterSet::GB2312},
+	{ECI::EUC_KR, CharacterSet::EUC_KR},
+	{ECI::ISO646_Inv, CharacterSet::ASCII},
+	{ECI::Binary, CharacterSet::BINARY},
+};
+
+std::string ToString(ECI eci)
+{
+	return '\\' + ToString(ToInt(eci), 6);
+}
+
+CharacterSet ToCharacterSet(ECI eci)
+{
+	if (auto it = ECI_TO_CHARSET.find(eci); it != ECI_TO_CHARSET.end())
+		return it->second;
+
+	return CharacterSet::Unknown;
+}
+
+ECI ToECI(CharacterSet cs)
+{
+	// Special case ISO8859_1 to avoid obsolete ECI 1
+	if (cs == CharacterSet::ISO8859_1)
+		return ECI::ISO8859_1;
+	// Special case Cp437 to avoid obsolete ECI 0 for slightly less obsolete ECI 2
+	if (cs == CharacterSet::Cp437)
+		return ECI::Cp437;
+
+	for (auto& [key, value] : ECI_TO_CHARSET)
+		if (value == cs)
+			return key;
+
+	return ECI::Unknown;
+}
+
+} // namespace ZXing