untested first draft of simple WSGI server

Author: mscosti

adafruit_esp32spi/adafruite_esp32spi_wsgiserver.py

@@ -0,0 +1,210 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2019 Matt Costi for Adafruit Industries
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
+"""
+`adafruit_esp32spi_wsgiserver`
+================================================================================
+
+A simple WSGI (Web Server Gateway Interface) server that interfaces with the ESP32 over SPI.
+Opens a specified port on the ESP32 to listen for incoming HTTP Requests and
+Accepts an Application object that must be callable, which gets called
+whenever a new HTTP Request has been received.
+
+The Application MUST accept 2 ordered parameters:
+    1. environ object (incoming request data)
+    2. start_response function. Must be called before the Application
+        callable returns, in order to set the response status and headers.
+
+The Application MUST return a single string in a list,
+which is the response data
+
+Requires update_poll being called in the applications main event loop.
+
+For more details about Python WSGI see:
+https://www.python.org/dev/peps/pep-0333/
+
+* Author(s): Matt Costi
+"""
+# pylint: disable=no-name-in-module
+
+import io
+from micropython import const
+import adafruit_esp32spi.adafruit_esp32spi_socket as socket
+from adafruit_esp32spi.adafruit_esp32spi_requests import parse_headers
+
+_the_interface = None   # pylint: disable=invalid-name
+def set_interface(iface):
+    """Helper to set the global internet interface"""
+    global _the_interface   # pylint: disable=global-statement, invalid-name
+    _the_interface = iface
+    socket.set_interface(iface)
+
+NO_SOCK_AVAIL = const(255)
+
+# pylint: disable=invalid-name
+class WSGIServer:
+    """
+    A simple server that implements the WSGI interface
+    """
+
+    def __init__(self, port=80, debug=False, application=None):
+        self.application = application
+        self.port = port
+        self._server_sock = socket.socket(socknum=NO_SOCK_AVAIL)
+        self._client_sock = socket.socket(socknum=NO_SOCK_AVAIL)
+        self._debug = debug
+
+        self._response_status = None
+        self._response_headers = []
+
+    def start(self):
+        """
+        starts the server and begins listening for incoming connections.
+        Call update_poll in the main loop for the application callable to be
+        invoked on receiving an incoming request.
+        """
+        self._server_sock = socket.socket()
+        _the_interface.start_server(self.port, self._server_sock.socknum)
+        if self._debug:
+            ip = _the_interface.pretty_ip(_the_interface.ip_address)
+            print("Server available at {0}:{1}".format(ip, self.port))
+            print("Sever status: ", _the_interface.get_server_state(self._server_sock.socknum))
+
+    def update_poll(self):
+        """
+        Call this method inside your main event loop to get the server
+        check for new incoming client requests. When a request comes in,
+        the application callable will be invoked.
+        """
+        self.client_available()
+        if (self._client_sock and self._client_sock.available()):
+            environ = self._get_environ(self._client_sock)
+            result = self.application(environ, self._start_response)
+            self.finish_response(result)
+
+    def finish_response(self, result):
+        """
+        Called after the application callbile returns result data to respond with.
+        Creates the HTTP Response payload from the response_headers and results data,
+        and sends it back to client.
+
+        :param string result: the data string to send back in the response to the client.
+        """
+        try:
+            response = "HTTP/1.1 {0}\r\n".format(self._response_status)
+            for header in self._response_headers:
+                response += "{0}: {1}\r\n".format(*header)
+            response += "\r\n"
+            for data in result:
+                response += data
+            self._client_sock.write(response.encode("utf-8"))
+        finally:
+            self._client_sock.close()
+
+    def client_available(self):
+        """
+        returns a client socket connection if available.
+        Otherwise, returns None
+        :return: the client
+        :rtype: Socket
+        """
+        sock = None
+        if self._server_sock.socknum != NO_SOCK_AVAIL:
+            if self._client_sock.socknum != NO_SOCK_AVAIL:
+                # check previous received client socket
+                if self._debug > 2:
+                    print("checking if last client sock still valid")
+                if self._client_sock.connected() and self._client_sock.available():
+                    sock = self._client_sock
+            if not sock:
+                # check for new client sock
+                if self._debug > 2:
+                    print("checking for new client sock")
+                client_sock_num = _the_interface.socket_available(self._server_sock.socknum)
+                sock = socket.socket(socknum=client_sock_num)
+        else:
+            print("Server has not been started, cannot check for clients!")
+
+        if sock and sock.socknum != NO_SOCK_AVAIL:
+            if self._debug > 2:
+                print("client sock num is: ", sock.socknum)
+            self._client_sock = sock
+            return self._client_sock
+
+        return None
+
+    def _start_response(self, status, response_headers):
+        """
+        The application callable will be given this method as the second param
+        This is to be called before the application callable returns, to signify
+        the response can be started with the given status and headers.
+
+        :param string status: a status string including the code and reason. ex: "200 OK"
+        :param list response_headers: a list of tuples to represent the headers.
+            ex ("header-name", "header value")
+        """
+        self._response_status = status
+        self._response_headers = [("Server", "esp32WSGIServer")] + response_headers
+
+    def _get_environ(self, client):
+        """
+        The application callable will be given the resulting environ dictionary.
+        It contains metadata about the incoming request and the request body ("wsgi.input")
+
+        :param Socket client: socket to read the request from
+        """
+        env = {}
+        line = str(client.readline(), "utf-8")
+        (method, path, ver) = line.rstrip("\r\n").split(None, 2)
+
+        env["wsgi.version"] = (1, 0)
+        env["wsgi.url_scheme"] = "http"
+        env["wsgi.multithread"] = False
+        env["wsgi.multiprocess"] = False
+        env["wsgi.run_once"] = False
+
+        env["REQUEST_METHOD"] = method
+        env["SCRIPT_NAME"] = ""
+        env["PATH_INFO"] = path
+        env["SERVER_NAME"] = _the_interface.pretty_ip(_the_interface.ip_address)
+        env["SERVER_PROTOCOL"] = ver
+        env["SERVER_PORT"] = self.port
+        if line.find("?"):
+            env["QUERY_STRING"] = line.split("?")[1]
+
+        headers = parse_headers(client)
+        if "content-type" in headers:
+            env["CONTENT_TYPE"] = headers.get("content-type")
+        if "content-length" in headers:
+            env["CONTENT_LENGTH"] = headers.get("content-length")
+            body = client.read(env["CONTENT_LENGTH"])
+            env["wsgi.input"] = io.StringIO(body)
+        else:
+            body = client.read()
+            env["wsgi.input"] = io.StringIO(body)
+        for name, value in headers:
+            key = "HTTP_" + name.replace('-', '_').upper()
+            if key in env:
+                value = "{0},{1}".format(env[key], value)
+            env[key] = value
+
+        return env