From 1bd5250e5e723d162592f78785b2e9434b368aab Mon Sep 17 00:00:00 2001
From: Martin Teichmann <martin.teichmann@xfel.eu>
Date: Tue, 27 Feb 2024 16:01:28 +0000
Subject: [PATCH] do not send to big packets
---
ebpfcat/ethercat.py | 36 +++++++++++++++++++++++++-----------
1 file changed, 25 insertions(+), 11 deletions(-)
diff --git a/ebpfcat/ethercat.py b/ebpfcat/ethercat.py
index c7d54aa..b6e02a7 100644
--- a/ebpfcat/ethercat.py
+++ b/ebpfcat/ethercat.py
@@ -215,7 +215,7 @@ class Packet:
packets. We implicitly add a datagram in the front which later serves
as an identifier for the packet.
"""
- MAXSIZE = 1000 # maximum size we use for an EtherCAT packet
+ MAXSIZE = 1500 # maximum size we use for an EtherCAT packet
ETHERNET_HEADER = 14
PACKET_HEADER = 16
DATAGRAM_HEADER = 10
@@ -236,8 +236,15 @@ class Packet:
Depending on the command, one or two more parameters represent the
address, either terminal and offset for position or node addressing,
or one value for logical addressing."""
+ newsize = self.size + len(data) + self.DATAGRAM_HEADER \
+ + self.DATAGRAM_TAIL
+ if newsize > self.MAXSIZE:
+ raise OverflowError("ethercat packet size too big")
+ elif len(self.data) > 14:
+ raise OverflowError("Too many datagrams per packet")
+
self.data.append((cmd, data, idx) + address)
- self.size += len(data) + self.DATAGRAM_HEADER + self.DATAGRAM_TAIL
+ self.size = newsize
def assemble(self, index):
"""Assemble the datagrams into a packet
@@ -306,17 +313,24 @@ class EtherCat(Protocol):
to be sent from a queue, packs them in a packet and ships them
out. """
try:
- packet = Packet()
dgrams = []
+ packet = Packet()
+ sent = True
while True:
- *dgram, future = await self.send_queue.get()
- lastsize = packet.size
- packet.append(*dgram)
- dgrams.append((lastsize + 10, packet.size - 2, future))
- if packet.full() or self.send_queue.empty():
- ensure_future(self.process_packet(dgrams, packet))
- dgrams = []
- packet = Packet()
+ if sent:
+ *dgram, future = await self.send_queue.get()
+ try:
+ lastsize = packet.size
+ packet.append(*dgram)
+ dgrams.append((lastsize + 10, packet.size - 2, future))
+ sent = True
+ if not self.send_queue.empty():
+ continue
+ except OverflowError:
+ sent = False
+ ensure_future(self.process_packet(dgrams, packet))
+ dgrams = []
+ packet = Packet()
except CancelledError:
raise
except Exception:
--
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