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

tinycrypt/lib/source/ecc_platform_specific.c

@@ -0,0 +1,138 @@
+/*  uECC_platform_specific.c - Implementation of platform specific functions*/
+
+/* Copyright (c) 2014, Kenneth MacKay
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *  * Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.*/
+
+/*
+ *  Copyright (C) 2017 by Intel Corporation, All Rights Reserved.
+ *
+ *  Redistribution and use in source and binary forms, with or without
+ *  modification, are permitted provided that the following conditions are met:
+ *
+ *    - Redistributions of source code must retain the above copyright notice,
+ *     this list of conditions and the following disclaimer.
+ *
+ *    - Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ *    - Neither the name of Intel Corporation nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ *  POSSIBILITY OF SUCH DAMAGE.
+ *
+ *  uECC_platform_specific.c -- Implementation of platform specific functions
+ */
+
+#include <stdint.h>
+
+#if defined(_WIN32)
+/* Windows implementation using CryptGenRandom */
+#include <windows.h>
+#include <wincrypt.h>
+
+int default_CSPRNG(uint8_t *dest, unsigned int size) {
+  /* input sanity check: */
+  if (dest == (uint8_t *) 0 || (size <= 0))
+    return 0;
+
+  HCRYPTPROV hProvider = 0;
+  
+  if (!CryptAcquireContext(&hProvider, NULL, NULL, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT | CRYPT_SILENT)) {
+    return 0;
+  }
+  
+  BOOL result = CryptGenRandom(hProvider, size, dest);
+  
+  CryptReleaseContext(hProvider, 0);
+  
+  return result ? 1 : 0;
+}
+
+#elif defined(unix) || defined(__linux__) || defined(__unix__) || \
+    defined(__unix) || (defined(__APPLE__) && defined(__MACH__)) || \
+    defined(uECC_POSIX)
+
+/* Some POSIX-like system with /dev/urandom or /dev/random. */
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <stdint.h>
+
+#ifndef O_CLOEXEC
+#define O_CLOEXEC 0
+#endif
+
+int default_CSPRNG(uint8_t *dest, unsigned int size) {
+
+  /* input sanity check: */
+  if (dest == (uint8_t *) 0 || (size <= 0))
+    return 0;
+
+  int fd = open("/dev/urandom", O_RDONLY | O_CLOEXEC);
+  if (fd == -1) {
+    fd = open("/dev/random", O_RDONLY | O_CLOEXEC);
+    if (fd == -1) {
+      return 0;
+    }
+  }
+
+  char *ptr = (char *)dest;
+  size_t left = (size_t) size;
+  while (left > 0) {
+    ssize_t bytes_read = read(fd, ptr, left);
+    if (bytes_read <= 0) { // read failed
+      close(fd);
+      return 0;
+    }
+    left -= bytes_read;
+    ptr += bytes_read;
+  }
+
+  close(fd);
+  return 1;
+}
+
+#else
+/* No CSPRNG available - return error */
+int default_CSPRNG(uint8_t *dest, unsigned int size) {
+  (void)dest;
+  (void)size;
+  return 0;
+}
+
+#endif /* platform */
+
+/* Force rebuild */