docs: add project description and server setup instructions to README

esp/microcoapy/coap_packet.py

@@ -0,0 +1,83 @@
+from . import coap_macros as macros
+from .coap_option import CoapOption
+
+
+class CoapPacket:
+    def __init__(self):
+        self.version = macros.COAP_VERSION.COAP_VERSION_UNSUPPORTED
+        self.type = macros.COAP_TYPE.COAP_CON
+        self.method = macros.COAP_METHOD.COAP_GET
+        self.token = bytearray()
+        self.payload = bytearray()
+        self.messageid = 0
+        self.content_format = macros.COAP_CONTENT_FORMAT.COAP_NONE
+        self.query = bytearray()
+        self.options = []
+
+    def addOption(self, number, opt_payload):
+        if len(self.options) >= macros._MAX_OPTION_NUM:
+            return
+        self.options.append(CoapOption(number, opt_payload))
+
+    def setUriHost(self, address):
+        self.addOption(macros.COAP_OPTION_NUMBER.COAP_URI_HOST, address)
+
+    def setUriPath(self, url):
+        for subPath in url.split('/'):
+            self.addOption(macros.COAP_OPTION_NUMBER.COAP_URI_PATH, subPath)
+
+    def setObserve(self, value):
+        """Set the Observe option (RFC 7641).
+
+        For requests:
+            value=0: register as observer
+            value=1: deregister
+
+        For notifications:
+            value=sequence number (24-bit, 0-16777215)
+        """
+        if value < 256:
+            buf = bytearray([value & 0xFF])
+        elif value < 65536:
+            buf = bytearray([(value >> 8) & 0xFF, value & 0xFF])
+        else:
+            buf = bytearray([(value >> 16) & 0xFF, (value >> 8) & 0xFF, value & 0xFF])
+        self.addOption(macros.COAP_OPTION_NUMBER.COAP_OBSERVE, buf)
+
+    def setMaxAge(self, seconds):
+        """Set the Max-Age option (seconds until resource is considered stale)."""
+        if seconds < 256:
+            buf = bytearray([seconds & 0xFF])
+        elif seconds < 65536:
+            buf = bytearray([(seconds >> 8) & 0xFF, seconds & 0xFF])
+        else:
+            buf = bytearray([
+                (seconds >> 24) & 0xFF, (seconds >> 16) & 0xFF,
+                (seconds >> 8) & 0xFF, seconds & 0xFF
+            ])
+        self.addOption(macros.COAP_OPTION_NUMBER.COAP_MAX_AGE, buf)
+
+    def getObserveValue(self):
+        """Extract the Observe option value from the packet, or None if absent."""
+        for opt in self.options:
+            if opt.number == macros.COAP_OPTION_NUMBER.COAP_OBSERVE:
+                val = 0
+                for b in opt.buffer:
+                    val = (val << 8) | b
+                return val
+        return None
+
+    def getUriPath(self):
+        """Reconstruct the URI path from URI_PATH options."""
+        parts = []
+        for opt in self.options:
+            if opt.number == macros.COAP_OPTION_NUMBER.COAP_URI_PATH and len(opt.buffer) > 0:
+                parts.append(opt.buffer.decode("utf-8"))
+        return "/".join(parts)
+
+    def toString(self):
+        class_, detail = macros.CoapResponseCode.decode(self.method)
+        return "type: {}, method: {}.{:02d}, messageid: {}, payload: {}".format(
+            macros.coapTypeToString(self.type), class_, detail,
+            self.messageid, self.payload
+        )