Added proxy support. Bug fixes in APIHandler. RTSP support (adding)

Proxy support allows contacting the camera behind a proxy (GET and POST requests).
Adding RTSP support - still in progress.

RtspClient.py

@@ -0,0 +1,85 @@
+import socket
+
+import cv2
+import numpy
+import socks
+
+
+class RtspClient:
+
+    def __init__(self, ip, username, password, port=554, profile="main", **kwargs):
+        """
+
+        :param ip:
+        :param username:
+        :param password:
+        :param port: rtsp port
+        :param profile: "main" or "sub"
+        :param proxies: {"host": "localhost", "port": 8000}
+        """
+        self.ip = ip
+        self.username = username
+        self.password = password
+        self.port = port
+        self.sockt = None
+        self.url = "rtsp://" + self.username + ":" + self.password + "@" + self.ip + ":" + str(
+            self.port) + "//h264Preview_01_" + profile
+        self.proxy = kwargs.get("proxies")
+
+    def __enter__(self):
+        self.sockt = self.connect()
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.sockt.close()
+
+    def connect(self) -> socket:
+        try:
+            sockt = socks.socksocket(socket.AF_INET, socket.SOCK_STREAM)
+            sockt.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+            if self.proxy is not None:
+                sockt.set_proxy(socks.SOCKS5, self.proxy["host"], self.proxy["port"])
+            sockt.connect((self.ip, self.port))
+            return sockt
+        except Exception as e:
+            print(e)
+
+    def get_frame(self) -> bytearray:
+        try:
+            self.sockt.send(str.encode(self.url))
+            data = b''
+            while True:
+                try:
+                    r = self.sockt.recv(90456)
+                    if len(r) == 0:
+                        break
+                    a = r.find(b'END!')
+                    if a != -1:
+                        data += r[:a]
+                        break
+                    data += r
+                except Exception as e:
+                    print(e)
+                    continue
+            nparr = numpy.fromstring(data, numpy.uint8)
+            frame = cv2.imdecode(nparr, cv2.IMREAD_COLOR)
+            return frame
+        except Exception as e:
+            print(e)
+
+    def preview(self):
+        """ Blocking function. Opens OpenCV window to display stream. """
+        self.connect()
+        win_name = 'RTSP'
+        cv2.namedWindow(win_name, cv2.WINDOW_AUTOSIZE)
+        cv2.moveWindow(win_name, 20, 20)
+
+        while True:
+            cv2.imshow(win_name, self.get_frame())
+            # if self._latest is not None:
+            #    cv2.imshow(win_name,self._latest)
+            if cv2.waitKey(25) & 0xFF == ord('q'):
+                break
+        cv2.waitKey()
+        cv2.destroyAllWindows()
+        cv2.waitKey()