On Fri, Dec 13, 2019 at 08:02:53AM +0100, Oleksij Rempel wrote: > Hi Elenita, > > On Thu, Dec 12, 2019 at 03:49:48PM -0600, Elenita Hinds wrote: > > Hi Kurt, > > > > I tried using getsockname() to retrieve the source address that was > > successfully claimed by jacd but was always getting 0xfe (I was > > expecting it to be 0xf9 as claimed by jacd). > > Is getsockname() expected to be functional for J1939 with kernel v5.4? > > Is there another way to retrieving the dynamically claimed address real-time? > > Current stack implementation will return on getsockname(sock, ...) and > getpeername(sock, ...) values provided by user via bind() and/or connect(). If > we configure the socket by name, then address are automatically resolved > over address claim cache. Hm.. this sentence can be misinterpreted. I'll rephrase it: The address are automatically resolved for internal use. And could be potentially resolved for get[sock,peer]name() as well. > The question is, should we return some thing different? > If yes, it will be interesting to know, why is it needed? What is the > use case? > > > --elenita > > > > > > > > > > On Fri, Dec 6, 2019 at 2:59 AM Kurt Van Dijck > > > <dev.kurt@xxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > > > > > Hi, > > > > > > > > On do, 05 dec 2019 14:55:53 -0600, Elenita Hinds wrote: > > > > > Hi all, > > > > > > > > > > I am hoping to re-use the can-utils' jacd as default Address Claiming > > > > > daemon but runs into some issues: > > > > > > > > > > (1) " err(0, <string>, ...) " is called in several places, even though > > > > > looking at the code logic, there is no error and the program should be > > > > > able to continue. The program exits because err() never returns. > > > > > For example: > > > > > > > > commit 791b6de7 introduced the problem. > > > > it replaced all error(x, y, sss) calls with err(y, sss) > > > > but it should have become warn(y, sss) when x=0. > > > > > > > > Feel free to fix that. > > > > > > > > > (2) The socket is configured to also set the SO_BINDTODEVICE option. > > > > > In our system, this requires the program to have root permissions to > > > > > run but we'd rather not do this for security reasons. Is this option > > > > > required? What are the side-effects if this option is not set? Can it > > > > > be made optional such that the program does not exit if the > > > > > setsockoption(SO_BINDTODEVICE) call fails (seems to work without it)? > > > > > > > > It appears on first sight that SO_BINDTODEVICE isn't strictly necessary > > > > since bind() will have sockaddr_can.can_ifindex set anyway. > > > > In that case, rather then ignore the result, > > > > remove the call to SO_BINDTODEVICE completely. > > > > > > > > > > > > > > (3) The claimed address is only saved to a file when the program > > > > > terminates. What is the reason for this? Can it not be saved after > > > > > one is claimed already so that another process can read it real-time > > > > > if needed? > > > > > > > > That should not be necessary. > > > > At time of writing jacd, you could consult 'ip addr show can0' to find > > > > out. I'm not sure what option remained to find it. > > > > I believe you can, from another program, bind() with the same name, and > > > > then getsockname() will return the complete sockaddr_can with SA filled > > > > in. > > > > > > > > > Also, in cases of a program crash or a power outage, the > > > > > claimed address is still saved. > > > > > > > > That is a true remark. > > > > Given a power outage (the program never crashes :-) ), > > > > and looking at the code, +10 years later, I would now write to a temp file, > > > > and rename() the file to make it an atomic operation. > > > > Doing that regularly, or upon change, would be an improvement. > > > > > > > > Kurt > > > > > > > > > > > > > > > Thanks in advance, > > > > > Elenita > > > > -- > Pengutronix e.K. | | > Steuerwalder Str. 21 | http://www.pengutronix.de/ | > 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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