docs: add project description and server setup instructions to README

esp/microcoapy/coap_reader.py

@@ -0,0 +1,88 @@
+from . import coap_macros as macros
+from .coap_option import CoapOption
+
+
+def parseOption(packet, runningDelta, buffer, i):
+    option = CoapOption()
+    headlen = 1
+
+    errorMessage = (False, runningDelta, i)
+
+    if buffer is None:
+        return errorMessage
+
+    buflen = len(buffer) - i
+
+    if buflen < headlen:
+        return errorMessage
+
+    delta = (buffer[i] & 0xF0) >> 4
+    length = buffer[i] & 0x0F
+
+    if delta == 15 or length == 15:
+        return errorMessage
+
+    if delta == 13:
+        headlen += 1
+        if buflen < headlen:
+            return errorMessage
+        delta = buffer[i + 1] + 13
+        i += 1
+    elif delta == 14:
+        headlen += 2
+        if buflen < headlen:
+            return errorMessage
+        delta = ((buffer[i + 1] << 8) | buffer[i + 2]) + 269
+        i += 2
+
+    if length == 13:
+        headlen += 1
+        if buflen < headlen:
+            return errorMessage
+        length = buffer[i + 1] + 13
+        i += 1
+    elif length == 14:
+        headlen += 2
+        if buflen < headlen:
+            return errorMessage
+        length = ((buffer[i + 1] << 8) | buffer[i + 2]) + 269
+        i += 2
+
+    endOfOptionIndex = (i + 1 + length)
+
+    if endOfOptionIndex > len(buffer):
+        return errorMessage
+
+    option.number = delta + runningDelta
+    option.buffer = buffer[i + 1:i + 1 + length]
+    packet.options.append(option)
+
+    return (True, runningDelta + delta, endOfOptionIndex)
+
+
+def parsePacketHeaderInfo(buffer, packet):
+    packet.version = (buffer[0] & 0xC0) >> 6
+    packet.type = (buffer[0] & 0x30) >> 4
+    packet.tokenLength = buffer[0] & 0x0F
+    packet.method = buffer[1]
+    packet.messageid = 0xFF00 & (buffer[2] << 8)
+    packet.messageid |= 0x00FF & buffer[3]
+
+
+def parsePacketOptionsAndPayload(buffer, packet):
+    bufferLen = len(buffer)
+    if (macros._COAP_HEADER_SIZE + packet.tokenLength) < bufferLen:
+        delta = 0
+        bufferIndex = macros._COAP_HEADER_SIZE + packet.tokenLength
+        while (len(packet.options) < macros._MAX_OPTION_NUM) and \
+              (bufferIndex < bufferLen) and \
+              (buffer[bufferIndex] != 0xFF):
+            (status, delta, bufferIndex) = parseOption(packet, delta, buffer, bufferIndex)
+            if status is False:
+                return False
+
+        if ((bufferIndex + 1) < bufferLen) and (buffer[bufferIndex] == 0xFF):
+            packet.payload = buffer[bufferIndex + 1:]
+        else:
+            packet.payload = None
+    return True