Updates.

Author: csev

.gitignore

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+*.swp
+__pycache__

mini_django.py

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+# https://docs.python.org/3/howto/sockets.html
+# https://stackoverflow.com/questions/8627986/how-to-keep-a-socket-open-until-client-closes-it
+# https://stackoverflow.com/questions/10091271/how-can-i-implement-a-simple-web-server-using-python-without-using-any-libraries
+
+from socket import *
+import traceback, json
+from dataclasses import dataclass
+from dataclasses import field
+import sys
+
+@dataclass
+class HttpRequest:
+    method: str = ""
+    path: str = ""
+    headers: dict = field(default_factory=dict)
+    body: str = ""
+
+@dataclass
+class HttpResponse:
+    code: str = "200"
+    headers: dict = field(default_factory=dict)
+    _body: list = field(default_factory=list)
+
+    def println(self, line: str) :
+        self._body.append(line)
+
+def parseRequest(rd:str) -> HttpRequest:
+    retval = HttpRequest()
+    retval.body = rd
+    ipos = rd.find("\r\n\r\n")
+    if ipos < 1 : 
+        print('Incorrectly formatted request input')
+        print(repr(rd))
+        return None
+
+    # Find the blank line between HEAD and BODY
+    head = rd[0:ipos-1]
+    lines = head.split("\n")
+
+    # GET / HTTP/1.1
+    if len(lines) > 0 :
+        firstline = lines[0]
+        pieces = firstline.split(' ')
+        if len(pieces) >= 2 :
+            retval.method = pieces[0] or 'Missing';
+            retval.path = pieces[1] or 'Missing';
+
+    # Accept-Language: en-US,en;q=0.5
+    for line in lines:
+        line = line.strip()
+        pieces = line.split(": ", 1)
+        if len(pieces) != 2 : continue
+        retval.headers[pieces[0].strip()] = pieces[1].strip()
+    return retval
+
+def responseSend(clientsocket, response: HttpResponse) :
+
+    try:
+        print('==== Sending Response Headers')
+        firstline = "HTTP/1.1 "+response.code+" OK\r\n"
+        clientsocket.sendall(firstline.encode())
+        for key, value in response.headers.items():
+            print(key+': '+value)
+            clientsocket.sendall(key.encode())
+            clientsocket.sendall(": ".encode())
+            clientsocket.sendall(value.encode())
+            clientsocket.sendall("\r\n".encode())
+    
+
+        clientsocket.sendall("\r\n".encode())
+        chars = 0
+        for line in response._body:
+            line = patchAutograder(line)
+
+            chars += len(line)
+            clientsocket.sendall(line.replace("\n", "\r\n").encode())
+            clientsocket.sendall("\r\n".encode())
+        print("==== Sent",chars,"characters body output")
+
+    except Exception as exc :
+        print(exc)
+        print(response)
+        print(traceback.format_exc())
+
+# If we are sending HTML, include the endpoint for the DJ4E JavaScript autograder
+# For local dev testing, this can be run as
+# python runserver.py 9000 http://localhost:8888/dj4e/tools/jsauto/autograder.js
+
+def patchAutograder(line: str) -> str:
+    if line.find('</body>') == -1 : return line
+    dj4e_autograder = "https://www.dj4e.com/tools/jsauto/autograder.js"
+    if len(sys.argv) > 2 :
+        dj4e_autograder = sys.argv[2]
+    return line.replace('</body>', '\n<script src="'+dj4e_autograder+'"></script>\n</body>');
+
+def httpServer(router):
+    port = 9000
+    if len(sys.argv) > 1 :
+        port = int(sys.argv[1])
+
+    print('\n================ Starting mini_django server on '+str(port))
+    serversocket = socket(AF_INET, SOCK_STREAM)
+    try :
+        serversocket.bind(('localhost',port))
+        serversocket.listen(5)
+        while(1):
+            print('\n================ Waiting for the Next Request')
+            (clientsocket, address) = serversocket.accept()
+
+            rd = clientsocket.recv(5000).decode()
+            print('====== Received Headers')
+            print(rd)
+            request = parseRequest(rd)
+
+            # If we did not get a valid request, send a 500
+            if not isinstance(request, HttpRequest) :
+                response = view_fail(request, "500", "Request could not be parsed")
+
+            # Send valid request to the router (urls.py)
+            else:
+                response = router(request)
+
+                # If we did not get a valid response, log it and send back a 500
+                if not isinstance(response, HttpResponse) :
+                    response = view_fail(request, "500", "Response returned from router / view is not of type HttpResponse")
+
+            try:
+                responseSend(clientsocket, response)
+                clientsocket.shutdown(SHUT_WR)
+            except Exception as exc :
+                print(exc)
+                print(traceback.format_exc())
+
+    except KeyboardInterrupt :
+        print("\nShutting down...\n")
+    except Exception as exc :
+        print(exc)
+        print(traceback.format_exc())
+
+    print("Closing socket")
+    serversocket.close()
+
+def view_fail(req: HttpRequest, code: str, failure: str) -> HttpResponse:
+    res = HttpResponse()
+
+    print(" ")
+    print("Sending view_fail, code="+code+" failure="+failure)
+
+    res.code = code
+
+    res.headers['Content-Type'] = 'text/html; charset=utf-8'
+
+    res.println('<html><body>')
+    if res.code == "404" :
+        res.println('<div style="background-color: rgb(255, 255, 204);">')
+    else :
+        res.println('<div style="background-color: pink;">')
+
+    res.println('<b>Page has errors</b>')
+    res.println('<div><b>Request Method:</b> '+req.method+"</div>")
+    res.println('<div><b>Request URL:</b> '+req.path+'</div>')
+    res.println('<div><b>Response Failure:</b> '+failure+'</div>')
+    res.println('<div><b>Response Code:</b> '+res.code+'</div>')
+    res.println("</div><pre>")
+    res.println("Valid paths: /dj4e /js4e or /404")
+    res.println("\nRequest header data:")
+    res.println(json.dumps(req.headers, indent=4))
+    res.println("</pre></body></html>")
+    return res
+
+

runserver.py

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+import mini_django
+import urls
+
+print('Access http://localhost:9000')
+mini_django.httpServer(urls.router)
+

urls.py

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+
+from mini_django import HttpRequest, HttpResponse, view_fail
+import views
+
+# This is similar to Django's urls.py
+
+def router(request: HttpRequest) -> HttpResponse:
+    print('==== Routing to path:', request.path);
+    if request.path == '/' : 
+        return views.root(request)
+    elif request.path.startswith('/dj4e') : 
+        return views.dj4e(request)
+    elif request.path == '/js4e' : 
+        return views.js4e(request)
+    elif request.path == '/broken' : 
+        return views.broken(request)
+
+    # When all else fails send the 404 screen
+    else :
+        return view_fail(request, "404", "urls.py could not find a view for the path")
+

views.py

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+
+from mini_django import HttpRequest, HttpResponse
+
+# This is similar to Django's views.py
+
+def root(req: HttpRequest) -> HttpResponse:
+    res = HttpResponse()
+    res.headers['Content-Type'] = 'text/html; charset=utf-8'
+    res.println("<html><head></head><body>")
+    res.println("This is the page at the root path, try another path")
+    res.println("Try /dj4e /js4e /ca4e or /broken")
+    res.println("</body></html>")
+    return res
+
+def dj4e(req: HttpRequest) -> HttpResponse:
+    res = HttpResponse()
+    res.headers['Content-Type'] = 'text/plain; charset=utf-8'
+    res.println("Django is fun")
+    return res
+
+def js4e(req: HttpRequest) -> HttpResponse:
+    res = HttpResponse()
+    res.code = "302"    # Lets do a temporary redirect...
+    res.headers['Location'] = '/dj4e'
+    res.headers['Content-Type'] = 'text/plain; charset=utf-8'
+    res.println("You will only see this in the debugger!")
+    return res
+
+def broken(req: HttpRequest):
+    return "I am a broken view, returning a string by mistake"
+