Sorry, I misunderstood how writes to network file discriptors work.
Sent with ProtonMail Secure Email. ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Friday, November 9, 2018 3:10 PM, Guilhem Moulin <guil...@debian.org> wrote: > On Fri, 09 Nov 2018 at 19:16:39 +0000, Mendelmunkis wrote: > > > > Which error(s) do you have in mind? > > > > “destination unreachable” comes to mind. > > Right now it only checks for connection refused > > I'm confused, if write(2) returns -1 and sets errno to ‘ECONNREFUSED’, > it might be because an ICMP “Destination unreachable” message was just > received on the socket. > > E.g, for the following trace > > $ strace -e trace=write nc -vuN 127.0.0.1 12345 > write(3, "X", 1) = 1 > write(3, "X", 1) = -1 ECONNREFUSED (Connection refused) > +++ exited with 1 +++ > > I captured these UDP & ICMP packets on the loopback interface: > > 21:04:31.475446 IP 127.0.0.1.55080 > 127.0.0.1.12345: UDP, length 1 > > 21:04:31.475469 IP 127.0.0.1 > 127.0.0.1: ICMP 127.0.0.1 udp port 12345 > unreachable, length 37 > > > (using`tcpdump -n -i lo "icmp or udp dst portrange 12345"`). The > received ICMP packet is what caused the second write to fail with > ‘ECONNREFUSED’. > > ----------------------------------------------------------------------------------------------------------------------------------------------------- > > Guilhem.
