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Prevent unexpected UDP client read callbacks

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The network manager UDP code was misinterpreting when the libuv called
the udp_recv_cb with nrecv == 0 and addr == NULL -> this doesn't really
mean that the "stream" has ended, but the libuv indicates that the
receive buffer can be freed.  This could lead to assertion failure in
the code that calls isc_nm_read() from the network manager read callback
due to the extra spurious callbacks.

Properly handle the extra callback calls from the libuv in the client
read callback, and refactor the UDP isc_nm_read() implementation to be
synchronous, so no datagram is lost between the time that we stop the
reading from the UDP socket and we restart it again in the asychronous
udpread event.

Add a unit test that tests the isc_nm_read() call from the read
callback to receive two datagrams.
This commit is contained in:
Ondřej Surý
2022-09-15 09:48:34 +02:00
parent 94b32f2e0b
commit eac8bc5c1a
4 changed files with 218 additions and 90 deletions
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2
lib/isc/netmgr/netmgr.c
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@@ -449,7 +449,6 @@ process_netievent(void *arg) {
NETIEVENT_CASE(udplisten);
NETIEVENT_CASE(udpstop);
NETIEVENT_CASE(udpcancel);
NETIEVENT_CASE(udpread);
NETIEVENT_CASE(tcpaccept);
NETIEVENT_CASE(tcpconnect);
@@ -536,7 +535,6 @@ NETIEVENT_SOCKET_HANDLE_DEF(tlscancel);
NETIEVENT_SOCKET_DEF(udplisten);
NETIEVENT_SOCKET_DEF(udpstop);
NETIEVENT_SOCKET_HANDLE_DEF(udpcancel);
NETIEVENT_SOCKET_DEF(udpread);
NETIEVENT_SOCKET_DEF(tcpdnsclose);
NETIEVENT_SOCKET_DEF(tcpdnsread);