Re: [tcpdump-workers] LINKTYPE_LINUX_SLL2 implementation (libpcap & tcpdump)

2018-07-11 Thread Guy Harris
Note, by the way, that, for memory-mapped captures, the Linux kernel appears, in tpacket_rcv(), to reserve 16 octets of extra space, which is exactly enough to insert a DLT_LINUX_SLL header, but not enough for a DLT_LINUX_SLL2 header (and wouldn't even be enough if we *didn't* pad it to put the

Re: [tcpdump-workers] LINKTYPE_LINUX_SLL2 implementation (libpcap & tcpdump)

2018-07-11 Thread Guy Harris
On Jul 11, 2018, at 1:14 PM, Denis Ovsienko wrote: > Could the 4-octet field (ifindex) be at the beginning? Yes, but the padding would still be necessary. ___ tcpdump-workers mailing list tcpdump-workers@lists.tcpdump.org https://lists.sandelman.ca/mai

Re: [tcpdump-workers] LINKTYPE_LINUX_SLL2 implementation (libpcap & tcpdump)

2018-07-11 Thread Denis Ovsienko
On Wed, 11 Jul 2018 19:41:06 +0100 Guy Harris wrote > Currently > > https://www.tcpdump.org/linktypes/LINKTYPE_LINUX_SLL2.html > > has a 2-octet field followed immediately by a 4-octet field. > > This means the 4-octet field isn't aligned on a 4-octet boundary; I'm

Re: [tcpdump-workers] LINKTYPE_LINUX_SLL2 implementation (libpcap & tcpdump)

2018-07-11 Thread Guy Harris
Currently https://www.tcpdump.org/linktypes/LINKTYPE_LINUX_SLL2.html has a 2-octet field followed immediately by a 4-octet field. This means the 4-octet field isn't aligned on a 4-octet boundary; I'm going to update the LINKTYPE_LINUX_SLL2 specification to put a 2-byte reserved field a

Re: [tcpdump-workers] LINKTYPE_LINUX_SLL2 implementation (libpcap & tcpdump)

2018-07-11 Thread Guy Harris
On Jul 11, 2018, at 7:06 AM, Petr Vorel wrote: > It looks like 1) is impossible the need for both to define > pcap_create_interface(). Currently, the list isn't set in pcap_create(), it's set in pcap_activate(), so it'd be set in pcap_activate_linux(). You would then either 1) have th

Re: [tcpdump-workers] LINKTYPE_LINUX_SLL2 implementation (libpcap & tcpdump)

2018-07-11 Thread Petr Vorel
Hi, > > 1) Keeping LINKTYPE_LINUX_SLL [2] altogether with LINKTYPE_LINUX_SLL2, > > compile > > both (having one of them as default for linux, second allow to use with -y > > switch > > in tcpdump). > > 2) Keeping LINKTYPE_LINUX_SLL [2] altogether with LINKTYPE_LINUX_SLL2 but > > compile only one

Re: [tcpdump-workers] LINKTYPE_LINUX_SLL2 implementation (libpcap & tcpdump)

2018-07-11 Thread Denis Ovsienko
> [1] https://www.tcpdump.org/linktypes/LINKTYPE_LINUX_SLL2.html > [2] https://www.tcpdump.org/linktypes/LINKTYPE_LINUX_SLL.html > [3] https://github.com/the-tcpdump-group/libpcap/issues/127 JFYI, I remember the beginning of this story from January 2015 well. Paul Evans suggested the origi

Re: [tcpdump-workers] LINKTYPE_LINUX_SLL2 implementation (libpcap & tcpdump)

2018-07-11 Thread Petr Vorel
Hi, > > This requires a numerical value to be assigned to LINKTYPE_LINUX_SLL2 and > > DLT_LINUX_SLL2; no such value has yet been assigned. > It seems it should be 276 (next free number). > I've sent it as a pull request to github (I prefer using git format-patch && > git > send-email to ML as it

Re: [tcpdump-workers] LINKTYPE_LINUX_SLL2 implementation (libpcap & tcpdump)

2018-07-11 Thread Petr Vorel
Hi Guy, > (Re-sending, from my real e-mail address rather than my forwarding-for-life > e-mail address, because the latter had issues and required moderation.) I had some issues with not appearing messages as well :(. > On Jul 10, 2018, at 9:34 AM, Petr Vorel wrote: > > I'm playing with implem

Re: [tcpdump-workers] LINKTYPE_LINUX_SLL2 implementation (libpcap & tcpdump)

2018-07-10 Thread Guy Harris
(Re-sending, from my real e-mail address rather than my forwarding-for-life e-mail address, because the latter had issues and required moderation.) On Jul 10, 2018, at 9:34 AM, Petr Vorel wrote: > I'm playing with implementing LINKTYPE_LINUX_SLL2 [1] as a part of [3] > in libpcap and using it i

[tcpdump-workers] LINKTYPE_LINUX_SLL2 implementation (libpcap & tcpdump)

2018-07-10 Thread Petr Vorel
Hi, I've sent my first email into ML yesterday, but it's not in ML. I'm sorry to these who might read it twice. I'm playing with implementing LINKTYPE_LINUX_SLL2 [1] as a part of [3] in libpcap and using it in tcpdump. I wonder what is a correct solution for libpcap: 1) Keeping LINKTYPE_LINUX_SL