esp8266/scripts/webrepl: Add "first connection" mode to setup password.

If there's no port_config.py file, or it lacks WEBREPL_PASS variable,
"initial setup mode" will be entered on first WebREPLconnection. User
will be asked for password, which will be written to
port_config.WEBREPL_PASS, and system restarted to work in normal mode
with password active.

esp8266/scripts/webrepl.py

@@ -9,7 +9,7 @@ import _webrepl
 listen_s = None
 client_s = None
 
-def setup_conn(port):
+def setup_conn(port, accept_handler):
     global listen_s, client_s
     listen_s = socket.socket()
     listen_s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
@@ -19,7 +19,7 @@ def setup_conn(port):
 
     listen_s.bind(addr)
     listen_s.listen(1)
-    listen_s.setsockopt(socket.SOL_SOCKET, 20, accept_conn)
+    listen_s.setsockopt(socket.SOL_SOCKET, 20, accept_handler)
     for i in (network.AP_IF, network.STA_IF):
         iface = network.WLAN(i)
         if iface.active():
@@ -51,4 +51,12 @@ def stop():
 
 def start(port=8266):
     stop()
-    setup_conn(port)
+    try:
+        import port_config
+        _webrepl.password(port_config.WEBREPL_PASS)
+        setup_conn(port, accept_conn)
+        print("Started webrepl in normal mode")
+    except:
+        import webrepl_setup
+        setup_conn(port, webrepl_setup.handle_conn)
+        print("Started webrepl in setup mode")

esp8266/scripts/webrepl_setup.py

@@ -0,0 +1,77 @@
+import sys
+import socket
+import time
+
+from websocket import *
+import websocket_helper
+
+
+def setup_server():
+    s = socket.socket()
+    s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+
+    ai = socket.getaddrinfo("0.0.0.0", 8266)
+    addr = ai[0][4]
+
+    s.bind(addr)
+    s.listen(1)
+    return s
+
+def getpass(stream, prompt):
+    stream.write(prompt)
+    passwd = b""
+    while 1:
+        c = stream.read(1)
+        if c in (b"\r", b"\n"):
+            stream.write("\r\n")
+            return passwd
+        passwd += c
+#        stream.write("*")
+
+def handle_conn(listen_sock):
+    cl, remote_addr = listen_sock.accept()
+
+    print("""
+
+First-time WebREPL connection has been received. WebREPL initial setup
+will now start over this connection. During setup, UART REPL will be
+non-responsive. After setup finishes, the board will be rebooted. In
+case of error during setup, current session will continue.
+
+If you receive this message unexpectedly, it may mean that your WebREPL
+connection is being hacked (power off board if unsure).
+""")
+
+    websocket_helper.server_handshake(cl)
+    ws = websocket(cl)
+
+    ws.write("""\
+Welcome to MicroPython WebREPL!\r
+\r
+This is the first time you connect to WebREPL, so please set a password\r
+to use for the following WebREPL sessions. Once you enter the password\r
+twice, your board will reboot with WebREPL running in active mode. On\r
+some boards, you may need to press reset button or reconnect power.\r
+\r
+""")
+
+    while 1:
+        passwd1 = getpass(ws, "New password: ")
+        passwd2 = getpass(ws, "Confirm password: ")
+        if passwd1 == passwd2:
+            break
+        ws.write("Passwords do not match\r\n")
+
+    with open("port_config.py", "w") as f:
+        f.write("WEBREPL_PASS = %r\n" % passwd1.decode("ascii"))
+
+    ws.write("Password successfully set, restarting...\r\n")
+    cl.close()
+    time.sleep(2)
+    import machine
+    machine.reset()
+
+
+def test():
+    s = setup_server()
+    handle_conn(s)