Quoting Mats Erik Andersson (2015-07-17 13:04:59) > Thursday den 16 July 2015 klockan 13:01 skrev Justus Winter detta: > > > > > * The hardware type of an adaper is encoded in the member > > > `ifr_hwaddr.sa_family' of `struct ifreq'. An ethernet > > > adapter will correctly state ARPHRD_ETHER (= 1), while > > > the loopback adapter `lo' will be in error with a value 4. > > > The correct value is ARPHRD_LOOPBACK (= 772), which is > > > in use by GNU/Linux. See the header <net/if_arp.h>. > > > The value 4 is ARPHRD_PRONET, the PROnet token ring! > > > > That is surprising indeed. A superficial look revealed that it should > > indeed be set to ARPHRD_LOOPBACK: > > > > % grep ARPHRD_LOOPBACK > > pfinet/linux-src/include/linux/if_arp.h:#define ARPHRD_LOOPBACK 772 > > /* Loopback device */ > > [...] > > pfinet/loopback.c: dev->type = ARPHRD_LOOPBACK; > > A possibly relevant observation: The obtained value 4 is > identical to ARPHRD_LOOPBACK & 0x00ff. Is 'dev->type' > of length 16 bits, i.e., a short integer like 'sa_family'?
Hmm, it is an `unsigned short' indeed, but that should be sufficient to hold the value 772. But it is plausible that the value is silently truncated to 8 bit somewhere. Justus -- To UNSUBSCRIBE, email to [email protected] with a subject of "unsubscribe". Trouble? Contact [email protected] Archive: https://lists.debian.org/[email protected]
