From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263015AbUEWP1r (ORCPT ); Sun, 23 May 2004 11:27:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263000AbUEWP1r (ORCPT ); Sun, 23 May 2004 11:27:47 -0400 Received: from userel174.dsl.pipex.com ([62.188.199.174]:20356 "EHLO einstein.homenet") by vger.kernel.org with ESMTP id S263062AbUEWP1D (ORCPT ); Sun, 23 May 2004 11:27:03 -0400 Date: Sun, 23 May 2004 16:25:34 +0100 (BST) From: Tigran Aivazian X-X-Sender: tigran@einstein.homenet To: Joshua Kwan cc: linux-kernel@vger.kernel.org Subject: Re: consistent ioctl for getting all net interfaces? In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org I forgot to mention that I tested on some early 2.6 (pre) and it worked fine. If SIOCGIFCONF was broken in the more recent 2.6 kernels then I should re-test and revisit this function... Kind regards Tigran On Sun, 23 May 2004, Tigran Aivazian wrote: > On Sat, 22 May 2004, Joshua Kwan wrote: > > I'm interested in not having to parse /proc/net/dev to get a list of all > > available (not necessarily even up) interfaces on the system. I > > investigated the ioctl SIOCGIFCONF, but it seems to behave differently on > > 2.4 and 2.6 series kernels, e.g. sometimes it won't return all interfaces. > > > > Is there some end-all ioctl that does what I want, or am I forever doomed > > to process /proc/net/dev (in C, no less..)? > > > > Please CC me on replies, I don't read this list very often any more. > > Of course this is possible and here is the solution I wrote some time ago > (ioctl-based). > > Note that a more simple solution is also possible but is less portable > (because will depend on glibc version). > > /* TCPCAP endpoint, just an opaque handle for applications */ > struct tcpcap { > int fd; /* socket file descriptor */ > struct timeval *ts; /* user supplied addr of timestamp */ > struct sockaddr_ll *from; /* user supplied addr of extra info */ > int nports; /* number of bits set in ->ports */ > int maxport; /* highest port number set in ->ports */ > unsigned char *ports; /* ports currently set in ->lsf */ > unsigned char *setports; /* pending ports to be added */ > unsigned char *clrports; /* pending ports to be removed */ > int recv_buflen; /* socket receive buffer size */ > struct sock_fprog *lsf; /* compiled filter program */ > struct sock_filter *lsf_insns; /* the actual LSF instructions */ > int snaplen; /* length of part of each packet */ > int pkt_count; /* number of packets seen */ > int promisc; /* set interface(s) to promisc. mode */ > struct tcpcap_if *iface; /* list of network interfaces */ > int ifcount; /* number of elements in ->iface[] */ > }; > > > /* > * internal helper: get the list of all IPv4 up interfaces > * and record their name and IP address into pcap->iface[] > * array. Also set promiscuous mode as requested via pcap->promisc. > */ > static int walkiflist(struct tcpcap *pcap) > { > struct ifconf ifc; > struct ifreq *ifreqs, *ifr; > int fd, rq_len, nifs, i, ret = 0; > > /* this is a helper datagram socket which we must create > * because the actual packet socket is created later on, > * at tcpcap_start() time. > */ > fd = socket(PF_INET, SOCK_DGRAM, 0); > if (fd < 0) { > DPRINTF("socket(), errno=%d (%s)\n", > errno, strerror(errno)); > return TERR_SOCKET; > } > > ifc.ifc_buf = NULL; > rq_len = 4*sizeof(struct ifreq); > do { > ifc.ifc_len = rq_len; > ifc.ifc_buf = realloc(ifc.ifc_buf, ifc.ifc_len); > if (ifc.ifc_buf == NULL) { > DPRINTF("ifc.buf = realloc() failed\n"); > ret = TERR_REALLOC; > goto outclose; > } > if(ioctl(fd, SIOCGIFCONF, &ifc) < 0) { > DPRINTF("ioctl(SIOCGIFCONF), errno=%d (%s)\n", > errno, strerror(errno)); > if (ifc.ifc_buf) > free(ifc.ifc_buf); > ret = TERR_IOCTL; > goto outclose; > } > rq_len *= 2; > } while (rq_len < sizeof(struct ifreq) + ifc.ifc_len); > > nifs = ifc.ifc_len / sizeof(struct ifreq); > ifreqs = realloc(ifc.ifc_buf, nifs*sizeof(struct ifreq)); > if (ifreqs == NULL) { > DPRINTF("ifreqs = realloc()\n"); > ret = TERR_REALLOC; > free(ifc.ifc_buf); > goto outclose; > } > > /* allocate enough space for the maximum number of interfaces */ > pcap->iface = zalloc(nifs*sizeof(struct tcpcap_if)); > if (pcap->iface == NULL) { > DPRINTF("pcap->iface = zalloc() failed\n"); > ret = TERR_ZALLOC; > goto outfree; > } > > /* look through what we found and select only the 'interesting' ones */ > for (ifr = ifreqs, i=0; i struct sockaddr_in *addr; > > /* only interested in IPv4 */ > if (ifr->ifr_addr.sa_family != AF_INET) > continue; > > /* not interested in loopback */ > if (!strncmp(ifr->ifr_name, "lo", 2)) > continue; > > /* request flags because SIOCGIFCONF only > * initialized name, family and address > */ > if(ioctl(fd, SIOCGIFFLAGS, ifr) < 0) { > DPRINTF("ioctl(SIOCGIFFLAGS), errno=%d (%s)\n", > errno, strerror(errno)); > ret = TERR_IOCTL; > goto outfree; > } > > /* not interested in down interfaces */ > if (!(ifr->ifr_flags & IFF_UP)) > continue; > > /* OK, this interface passed all our criteria, so > * record it into pcap->iface[] array > */ > pcap->iface[pcap->ifcount].ifname =strdup(ifr->ifr_name); > addr = (struct sockaddr_in *)&(ifr->ifr_addr); > pcap->iface[pcap->ifcount].addr = htonl(addr->sin_addr.s_addr); > > /* if required set this interface into promisc. mode, > * unless it is already in promiscuous mode. > */ > if (pcap->promisc && !(ifr->ifr_flags & IFF_PROMISC)) { > > /* enable promiscuous mode */ > ifr->ifr_flags |= IFF_PROMISC; > > /* set interface flags */ > if (ioctl(fd, SIOCSIFFLAGS, ifr) == -1) { > DPRINTF("ioctl(SIOCSIFFLAGS), errno=%d (%s)\n", > errno, strerror(errno)); > ret = TERR_IOCTL; > goto outfree; > } > > /* record the fact that we modified this interface */ > pcap->iface[pcap->ifcount].promisc = 1; > DPRINTF("Enabled promisc. mode on %s (0x%x)\n", > pcap->iface[pcap->ifcount].ifname, > pcap->iface[pcap->ifcount].addr); > } > > pcap->ifcount++; > } > > outfree: > free(ifreqs); > > outclose: > close(fd); > > return ret; > } > > - > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ >