feat: speed up decoding incoming packets (#1256)

src/zeroconf/_protocol/incoming.pxd

@@ -7,8 +7,6 @@ cdef cython.uint MAX_DNS_LABELS
 cdef cython.uint DNS_COMPRESSION_POINTER_LEN
 cdef cython.uint MAX_NAME_LENGTH
 
-cdef object current_time_millis
-
 cdef cython.uint _TYPE_A
 cdef cython.uint _TYPE_CNAME
 cdef cython.uint _TYPE_PTR
@@ -43,6 +41,7 @@ from .._dns cimport (
     DNSService,
     DNSText,
 )
+from .._utils.time cimport current_time_millis
 
 
 cdef class DNSIncoming:
@@ -62,6 +61,7 @@ cdef class DNSIncoming:
     cdef public cython.uint num_additionals
     cdef public object valid
     cdef public object now
+    cdef cython.float _now_float
     cdef public object scope_id
     cdef public object source
 
@@ -79,7 +79,9 @@ cdef class DNSIncoming:
         label_idx=cython.uint,
         length=cython.uint,
         link=cython.uint,
-        link_data=cython.uint
+        link_data=cython.uint,
+        link_py_int=object,
+        linked_labels=cython.list
     )
     cdef _decode_labels_at_offset(self, unsigned int off, cython.list labels, cython.set seen_pointers)
 
@@ -95,9 +97,12 @@ cdef class DNSIncoming:
 
     cdef _read_questions(self)
 
-    cdef bytes _read_character_string(self)
+    @cython.locals(
+        length=cython.uint,
+    )
+    cdef str _read_character_string(self)
 
-    cdef _read_string(self, unsigned int length)
+    cdef bytes _read_string(self, unsigned int length)
 
     @cython.locals(
         name_start=cython.uint

src/zeroconf/_protocol/incoming.py

@@ -89,6 +89,7 @@ class DNSIncoming:
         'num_additionals',
         'valid',
         'now',
+        '_now_float',
         'scope_id',
         'source',
     )
@@ -116,6 +117,7 @@ def __init__(
         self.valid = False
         self._did_read_others = False
         self.now = now or current_time_millis()
+        self._now_float = self.now
         self.source = source
         self.scope_id = scope_id
         try:
@@ -226,11 +228,13 @@ def _read_questions(self) -> None:
             question = DNSQuestion(name, type_, class_)
             self.questions.append(question)
 
-    def _read_character_string(self) -> bytes:
+    def _read_character_string(self) -> str:
         """Reads a character string from the packet"""
         length = self.data[self.offset]
         self.offset += 1
-        return self._read_string(length)
+        info = self.data[self.offset : self.offset + length].decode('utf-8', 'replace')
+        self.offset += length
+        return info
 
     def _read_string(self, length: _int) -> bytes:
         """Reads a string of a given length from the packet"""
@@ -273,7 +277,7 @@ def _read_record(
         """Read known records types and skip unknown ones."""
         if type_ == _TYPE_A:
             dns_address = DNSAddress(domain, type_, class_, ttl, self._read_string(4))
-            dns_address.created = self.now
+            dns_address.created = self._now_float
             return dns_address
         if type_ in (_TYPE_CNAME, _TYPE_PTR):
             return DNSPointer(domain, type_, class_, ttl, self._read_name(), self.now)
@@ -299,13 +303,13 @@ def _read_record(
                 type_,
                 class_,
                 ttl,
-                self._read_character_string().decode('utf-8', 'replace'),
-                self._read_character_string().decode('utf-8', 'replace'),
+                self._read_character_string(),
+                self._read_character_string(),
                 self.now,
             )
         if type_ == _TYPE_AAAA:
             dns_address = DNSAddress(domain, type_, class_, ttl, self._read_string(16))
-            dns_address.created = self.now
+            dns_address.created = self._now_float
             dns_address.scope_id = self.scope_id
             return dns_address
         if type_ == _TYPE_NSEC:
@@ -377,7 +381,7 @@ def _decode_labels_at_offset(self, off: _int, labels: List[str], seen_pointers:
             # We have a DNS compression pointer
             link_data = self.data[off + 1]
             link = (length & 0x3F) * 256 + link_data
-            lint_int = int(link)
+            link_py_int = link
             if link > self._data_len:
                 raise IncomingDecodeError(
                     f"DNS compression pointer at {off} points to {link} beyond packet from {self.source}"
@@ -386,16 +390,16 @@ def _decode_labels_at_offset(self, off: _int, labels: List[str], seen_pointers:
                 raise IncomingDecodeError(
                     f"DNS compression pointer at {off} points to itself from {self.source}"
                 )
-            if lint_int in seen_pointers:
+            if link_py_int in seen_pointers:
                 raise IncomingDecodeError(
                     f"DNS compression pointer at {off} was seen again from {self.source}"
                 )
-            linked_labels = self.name_cache.get(lint_int)
+            linked_labels = self.name_cache.get(link_py_int)
             if not linked_labels:
                 linked_labels = []
-                seen_pointers.add(lint_int)
+                seen_pointers.add(link_py_int)
                 self._decode_labels_at_offset(link, linked_labels, seen_pointers)
-                self.name_cache[lint_int] = linked_labels
+                self.name_cache[link_py_int] = linked_labels
             labels.extend(linked_labels)
             if len(labels) > MAX_DNS_LABELS:
                 raise IncomingDecodeError(