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024be3b009
This function was invented by the BSDs (it's not in POSIX.1). It provides a high-level interface into ioctl(SIOCGIFCONF) which is comparatively clumsy to use. We already made the ioctls portable across our entire support vector back in 2021, so this interface is portable too. See o//tool/viz/getifaddrs.com for our demo app
114 lines
4.6 KiB
C
114 lines
4.6 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2023 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/sock/ifaddrs.h"
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#include "libc/calls/calls.h"
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#include "libc/mem/mem.h"
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#include "libc/sock/sock.h"
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#include "libc/sock/struct/ifconf.h"
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#include "libc/sock/struct/ifreq.h"
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#include "libc/str/str.h"
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#include "libc/sysv/consts/af.h"
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#include "libc/sysv/consts/iff.h"
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#include "libc/sysv/consts/sio.h"
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#include "libc/sysv/consts/sock.h"
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struct IfAddr {
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struct ifaddrs ifaddrs;
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char name[IFNAMSIZ];
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struct sockaddr_in addr;
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struct sockaddr_in netmask;
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struct sockaddr_in bstaddr;
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};
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/**
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* Frees network interface address list.
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*/
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void freeifaddrs(struct ifaddrs *ifp) {
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struct ifaddrs *next;
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while (ifp) {
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next = ifp->ifa_next;
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free(ifp);
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ifp = next;
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}
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}
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/**
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* Gets network interface address list.
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*
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* @return 0 on success, or -1 w/ errno
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* @see tool/viz/getifaddrs.c for example code
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*/
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int getifaddrs(struct ifaddrs **out_ifpp) {
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int rc = -1;
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int fd;
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if ((fd = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0)) != -1) {
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char *data;
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size_t size;
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if ((data = malloc((size = 16384)))) {
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struct ifconf conf;
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conf.ifc_buf = data;
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conf.ifc_len = size;
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if (!ioctl(fd, SIOCGIFCONF, &conf)) {
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struct ifaddrs *res = 0;
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for (struct ifreq *ifr = (struct ifreq *)data;
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(char *)ifr < data + conf.ifc_len; ++ifr) {
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if (ifr->ifr_addr.sa_family != AF_INET) {
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continue; // TODO(jart): IPv6 support
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}
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struct IfAddr *addr;
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if ((addr = calloc(1, sizeof(struct IfAddr)))) {
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memcpy(addr->name, ifr->ifr_name, IFNAMSIZ);
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addr->ifaddrs.ifa_name = addr->name;
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memcpy(&addr->addr, &ifr->ifr_addr, sizeof(struct sockaddr_in));
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addr->ifaddrs.ifa_addr = (struct sockaddr *)&addr->addr;
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addr->ifaddrs.ifa_netmask = (struct sockaddr *)&addr->netmask;
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if (!ioctl(fd, SIOCGIFFLAGS, ifr)) {
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addr->ifaddrs.ifa_flags = ifr->ifr_flags;
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}
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if (!ioctl(fd, SIOCGIFNETMASK, ifr)) {
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memcpy(&addr->netmask, &ifr->ifr_addr,
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sizeof(struct sockaddr_in));
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}
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unsigned long op;
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if (addr->ifaddrs.ifa_flags & IFF_BROADCAST) {
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op = SIOCGIFBRDADDR;
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} else if (addr->ifaddrs.ifa_flags & IFF_POINTOPOINT) {
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op = SIOCGIFDSTADDR;
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} else {
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op = 0;
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}
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if (op && !ioctl(fd, op, ifr)) {
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memcpy(&addr->bstaddr, &ifr->ifr_addr,
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sizeof(struct sockaddr_in));
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addr->ifaddrs.ifa_broadaddr = // is union'd w/ ifu_dstaddr
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(struct sockaddr *)&addr->bstaddr;
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}
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addr->ifaddrs.ifa_next = res;
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res = (struct ifaddrs *)addr;
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}
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}
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*out_ifpp = res;
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rc = 0;
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}
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free(data);
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}
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close(fd);
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}
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return rc;
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}
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