That's what I found. At first, ping calls cap_init() in capdns_setup(). cap_init() forks a process, then the parent returns and the child calls casper_main_loop(). The child and the parent both have a socket to communicate. casper_main_loop() calls zygote_init() and that one blocks on fork(). I do not know how it could be. How can fork() block?
The parent process later calls cap_service_open() and that function calls cap_xfer_nvlist(). Because the child process is stuck somewhere in zygote_init() it never sends an nvlist back. So ping blocks. All this is figured out by inserting printf()'s. LLDB refuses to run ping with 'error: Child exec failed'. вт, 5 янв. 2021 г. в 17:43, Mark Johnston <ma...@freebsd.org>: > On Tue, Jan 05, 2021 at 10:02:37AM +0300, Vasily Postnicov wrote: > > Hello. I wrote a simple daemon called ZeroDNS which provides > functionality > > similar to multicast DNS, namely it discovers other participating > machines > > over the LAN and stores their hostname and IPv4 address pairs. > > > > Here is a NSS module which allows the system to use information from that > > daemon: > > https://github.com/shamazmazum/nss-zero-dns > > > > You need to modify /etc/nsswitch.conf, changing the line 'hosts: files > dns' > > to 'hosts: files dns zerodns'. > > > > It all works on FreeBSD 12.2-RELEASE, but sometimes not on 13.0-CURRENT. > > For example, ping(8) just blocks when trying to ping a host whose name is > > resolvable with ZeroDNS. Turns out that programs built with casper > support > > (like ping(8) and some others) stop working with my NSS module (they just > > block trying to resolve the name). > > Presumably it's the casper process (i.e., cap_dns) that uses your > module? If the main ping process is blocked trying to resolve a name, > it's waiting for the cap_dns process - where exactly is it getting > stuck? > > > Is there some kind of manual on how to write casper-compatible NSS > modules? > _______________________________________________ freebsd-net@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "freebsd-net-unsubscr...@freebsd.org"
