<div dir="ltr"><div dir="ltr">On Thu, Jul 18, 2019 at 12:44 PM Ulrich Windl <<a href="mailto:Ulrich.Windl@rz.uni-regensburg.de" target="_blank">Ulrich.Windl@rz.uni-regensburg.de</a>> wrote:<br></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">>>> Mantas Mikulenas <<a href="mailto:grawity@gmail.com" target="_blank">grawity@gmail.com</a>> schrieb am 18.07.2019 um 10:06 in<br>
Nachricht<br>
<<a href="mailto:CAPWNY8XS1jw9iU_a-tagNw-v0NqeMAcWDRpftPdeKW_NFanqtA@mail.gmail.com" target="_blank">CAPWNY8XS1jw9iU_a-tagNw-v0NqeMAcWDRpftPdeKW_NFanqtA@mail.gmail.com</a>>:<br>
> On Thu, Jul 18, 2019 at 10:32 AM Ulrich Windl <<br>
> <a href="mailto:Ulrich.Windl@rz.uni-regensburg.de" target="_blank">Ulrich.Windl@rz.uni-regensburg.de</a>> wrote:<br>
> <br>
>> >>> Vaibhav Dahiya <<a href="mailto:vdahiya@ncsu.edu" target="_blank">vdahiya@ncsu.edu</a>> schrieb am 18.07.2019 um 02:53 in<br>
>> Nachricht<br>
>> <<a href="mailto:5d2fc2f0.1c69fb81.214d0.1aca@mx.google.com" target="_blank">5d2fc2f0.1c69fb81.214d0.1aca@mx.google.com</a>>:<br>
>> > Hello,<br>
>> ><br>
>> > I am using sd_journal_send api() api call to log messages on syslog<br>
>> server.<br>
>> > I see that this uses<br>
>> > sendmsg(fd, &mh, MSG_NOSIGNAL) call.<br>
>><br>
>> Aren't syslog messages UDP anyway? When would an UDP send block?<br>
>><br>
> <br>
> No, program APIs use Unix sockets (/dev/log, /run/systemd/journal/socket).<br>
> You only get UDP when your local syslog daemon is configured to forward<br>
> elsewhere.<br>
> <br>
> That said, both are datagram sockets, I'm not sure whether sending to Unix<br>
> dgram sockets can block or not?<br>
<br>
??? Datagram _is_ UDP<br></blockquote><div><br></div><div>UDP is datagram, but datagram is not always UDP.</div><div><br></div><div>"UDP" specifically means the datagram transport protocol that runs over IPv4/IPv6, nothing else. Unix sockets (AF_UNIX) have a datagram mode but they do not use UDP (or IP). Netlink is datagram-based but it isn't UDP-based. &c.</div></div><div><br></div>-- <br><div dir="ltr" class="m_7452679602634841818gmail_signature"><div dir="ltr">Mantas Mikulėnas</div></div></div>