toys/other/ifconfig.c - third_party/toybox - Git at Google

 /* ifconfig.c - Configure network interface.
  *
  * Copyright 2012 Ranjan Kumar <ranjankumar.bth@gmail.com>
  * Copyright 2012 Kyungwan Han <asura321@gamil.com>
  * Reviewed by Kyungsu Kim <kaspyx@gmail.com>
  *
  * Not in SUSv4.

 USE_IFCONFIG(NEWTOY(ifconfig, "^?a", TOYFLAG_SBIN))

 config IFCONFIG
   bool "ifconfig"
   default y
   help
     usage: ifconfig [-a] [INTERFACE [ACTION...]]

     Display or configure network interface.

     With no arguments, display active interfaces. First argument is interface
     to operate on, one argument by itself displays that interface.

     -a	Show all interfaces, not just active ones

     Additional arguments are actions to perform on the interface:

     ADDRESS[/NETMASK] - set IPv4 address (1.2.3.4/5)
     default - unset ipv4 address
     add|del ADDRESS[/PREFIXLEN] - add/remove IPv6 address (1111::8888/128)
     up - enable interface
     down - disable interface

     netmask|broadcast|pointopoint ADDRESS - set more IPv4 characteristics
     hw ether|infiniband ADDRESS - set LAN hardware address (AA:BB:CC...)
     txqueuelen LEN - number of buffered packets before output blocks
     mtu LEN - size of outgoing packets (Maximum Transmission Unit)

     Flags you can set on an interface (or -remove by prefixing with -):
     arp - don't use Address Resolution Protocol to map LAN routes
     promisc - don't discard packets that aren't to this LAN hardware address
     multicast - force interface into multicast mode if the driver doesn't
     allmulti - promisc for multicast packets

     Obsolete fields included for historical purposes:
     irq|io_addr|mem_start ADDR - micromanage obsolete hardware
     outfill|keepalive INTEGER - SLIP analog dialup line quality monitoring
     metric INTEGER - added to Linux 0.9.10 with comment "never used", still true
 */

 #define FOR_ifconfig
 #include "toys.h"

 #include <net/if_arp.h>
 #include <net/ethernet.h>

 GLOBALS(
   int sockfd;
 )

 // Convert hostname to binary address for AF_INET or AF_INET6
 // return /prefix (or range max if none)
 int get_addrinfo(char *host, sa_family_t af, void *addr)
 {
   struct addrinfo hints, *result, *rp = 0;
   int status, len;
   char *from, *slash;

   memset(&hints, 0 , sizeof(struct addrinfo));
   hints.ai_family = af;
   hints.ai_socktype = SOCK_STREAM;

   slash = strchr(host, '/');
   if (slash) *slash = 0;

   status = getaddrinfo(host, NULL, &hints, &result);
   if (!status)
     for (rp = result; rp; rp = rp->ai_next)
       if (rp->ai_family == af) break;
   if (!rp) error_exit("bad address '%s' : %s", host, gai_strerror(status));

   // ai_addr isn't struct in_addr or in6_addr, it's struct sockaddr. Of course.
   // You'd think ipv4 and ipv6 would have some basic compatibility, but no.
   from = ((char *)rp->ai_addr) + 4;
   if (af == AF_INET6) {
     len = 16;
     from += 4;  // skip "flowinfo" field ipv6 puts before address
   } else len = 4;
   memcpy(addr, from, len);
   freeaddrinfo(result);

   len = -1;
   if (slash) len = atolx_range(slash+1, 0, (af == AF_INET) ? 32 : 128);

   return len;
 }

 static void display_ifconfig(char *name, int always, unsigned long long val[])
 {
   struct ifreq ifre;
   struct {
     int type;
     char *title;
   } types[] = {
     {ARPHRD_LOOPBACK, "Local Loopback"}, {ARPHRD_ETHER, "Ethernet"},
     {ARPHRD_PPP, "Point-to-Point Protocol"}, {ARPHRD_INFINIBAND, "InfiniBand"},
     {ARPHRD_SIT, "IPv6-in-IPv4"}, {-1, "UNSPEC"}
   };
   int i;
   char *pp;
   FILE *fp;
   short flags;

   xstrncpy(ifre.ifr_name, name, IFNAMSIZ);
   if (ioctl(TT.sockfd, SIOCGIFFLAGS, &ifre)<0) perror_exit("%s", name);
   flags = ifre.ifr_flags;
   if (!always && !(flags & IFF_UP)) return;

   // query hardware type and hardware address
   i = ioctl(TT.sockfd, SIOCGIFHWADDR, &ifre);

   for (i=0; i < (sizeof(types)/sizeof(*types))-1; i++)
     if (ifre.ifr_hwaddr.sa_family == types[i].type) break;

   xprintf("%-9s Link encap:%s  ", name, types[i].title);
   if(i >= 0 && ifre.ifr_hwaddr.sa_family == ARPHRD_ETHER) {
     xprintf("HWaddr ");
     for (i=0; i<6; i++) xprintf(":%02X"+!i, ifre.ifr_hwaddr.sa_data[i]);
   }
   xputc('\n');

   // If an address is assigned record that.

   ifre.ifr_addr.sa_family = AF_INET;
   memset(&ifre.ifr_addr, 0, sizeof(ifre.ifr_addr));
   ioctl(TT.sockfd, SIOCGIFADDR, &ifre);
   pp = (char *)&ifre.ifr_addr;
   for (i = 0; i<sizeof(ifre.ifr_addr); i++) if (pp[i]) break;

   if (i != sizeof(ifre.ifr_addr)) {
     struct sockaddr_in *si = (struct sockaddr_in *)&ifre.ifr_addr;
     struct {
       char *name;
       int flag, ioctl;
     } addr[] = {
       {"addr", 0, 0},
       {"P-t-P", IFF_POINTOPOINT, SIOCGIFDSTADDR},
       {"Bcast", IFF_BROADCAST, SIOCGIFBRDADDR},
       {"Mask", 0, SIOCGIFNETMASK}
     };

     xprintf("%10c%s", ' ', (si->sin_family == AF_INET) ? "inet" :
         (si->sin_family == AF_INET6) ? "inet6" : "unspec");

     for (i=0; i < sizeof(addr)/sizeof(*addr); i++) {
       if (!addr[i].flag || (flags & addr[i].flag)) {
         if (addr[i].ioctl && ioctl(TT.sockfd, addr[i].ioctl, &ifre))
           si->sin_family = 0;
         xprintf(" %s:%s ", addr[i].name,
           (si->sin_family == 0xFFFF || !si->sin_family)
             ? "[NOT SET]" : inet_ntoa(si->sin_addr));
       }
     }

     xputc('\n');
   }

   fp = fopen(pp = "/proc/net/if_inet6", "r");
   if (fp) {
     char iface_name[IFNAMSIZ];
     int plen, iscope;

     while (fgets(toybuf, sizeof(toybuf), fp)) {
       int nitems;
       char ipv6_addr[40];

       nitems = sscanf(toybuf, "%32s %*08x %02x %02x %*02x %15s\n",
                       ipv6_addr, &plen, &iscope, iface_name);
       if (nitems<0 && feof(fp)) break;
       if (nitems != 4) perror_exit("bad %s", pp);

       if (!strcmp(name, iface_name)) {
         struct sockaddr_in6 s6;
         char *ptr = ipv6_addr+sizeof(ipv6_addr)-1;

         // convert giant hex string into colon-spearated ipv6 address by
         // inserting ':' every 4 characters.
         for (i = 32; i; i--)
           if ((*(ptr--) = ipv6_addr[i])) if (!(i&3)) *(ptr--) = ':';

         // Convert to binary and back to get abbreviated :: version
         if (inet_pton(AF_INET6, ipv6_addr, (void *)&s6.sin6_addr) > 0) {
           if (inet_ntop(AF_INET6, &s6.sin6_addr, toybuf, sizeof(toybuf))) {
             char *scopes[] = {"Global","Host","Link","Site","Compat"},
                  *scope = "Unknown";

             for (i=0; i < sizeof(scopes)/sizeof(*scopes); i++)
               if (iscope == (!!i)<<(i+3)) scope = scopes[i];
             xprintf("%10cinet6 addr: %s/%d Scope: %s\n",
                     ' ', toybuf, plen, scope);
           }
         }
       }
     }
     fclose(fp);
   }

   xprintf("%10c", ' ');

   if (flags) {
     unsigned short mask = 1;
     char **s, *str[] = {
       "UP", "BROADCAST", "DEBUG", "LOOPBACK", "POINTOPOINT", "NOTRAILERS",
       "RUNNING", "NOARP", "PROMISC", "ALLMULTI", "MASTER", "SLAVE", "MULTICAST",
       "PORTSEL", "AUTOMEDIA", "DYNAMIC", NULL
     };

     for (s = str; *s; s++) {
       if (flags & mask) xprintf("%s ", *s);
       mask = mask << 1;
     }
   } else xprintf("[NO FLAGS] ");

   if (ioctl(TT.sockfd, SIOCGIFMTU, &ifre) < 0) ifre.ifr_mtu = 0;
   xprintf(" MTU:%d", ifre.ifr_mtu);
   if (ioctl(TT.sockfd, SIOCGIFMETRIC, &ifre) < 0) ifre.ifr_metric = 0;
   if (!ifre.ifr_metric) ifre.ifr_metric = 1;
   xprintf("  Metric:%d", ifre.ifr_metric);

   // non-virtual interface

   if (val) {
     char *label[] = {"RX bytes", "RX packets", "errors", "dropped", "overruns",
       "frame", 0, 0, "TX bytes", "TX packets", "errors", "dropped", "overruns",
       "collisions", "carrier", 0, "txqueuelen"};
     signed char order[] = {-1, 1, 2, 3, 4, 5, -1, 9, 10, 11, 12, 14, -1,
       13, 16, -1, 0, 8};
     int i;

     // Query txqueuelen
     if (ioctl(TT.sockfd, SIOCGIFTXQLEN, &ifre) >= 0) val[16] = ifre.ifr_qlen;
     else val[16] = -1;

     for (i = 0; i < sizeof(order); i++) {
       int j = order[i];

       if (j < 0) xprintf("\n%10c", ' ');
       else xprintf("%s:%llu ", label[j], val[j]);
     }
   }
   xputc('\n');

   if(!ioctl(TT.sockfd, SIOCGIFMAP, &ifre) && (ifre.ifr_map.irq ||
       ifre.ifr_map.mem_start || ifre.ifr_map.dma || ifre.ifr_map.base_addr))
   {
     xprintf("%10c", ' ');
     if(ifre.ifr_map.irq) xprintf("Interrupt:%d ", ifre.ifr_map.irq);
     if(ifre.ifr_map.base_addr >= 0x100) // IO_MAP_INDEX
       xprintf("Base address:0x%x ", ifre.ifr_map.base_addr);
     if(ifre.ifr_map.mem_start)
       xprintf("Memory:%lx-%lx ", ifre.ifr_map.mem_start, ifre.ifr_map.mem_end);
     if(ifre.ifr_map.dma) xprintf("DMA chan:%x ", ifre.ifr_map.dma);
     xputc('\n');
   }
   xputc('\n');
 }

 static void show_iface(char *iface_name)
 {
   char *name;
   struct string_list *ifaces = 0, *sl;
   int i, j;
   FILE *fp;

   fp = xfopen("/proc/net/dev", "r");

   for (i=0; fgets(toybuf, sizeof(toybuf), fp); i++) {
     char *buf = toybuf;
     unsigned long long val[17];

     if (i<2) continue;

     while (isspace(*buf)) buf++;
     name = strsep(&buf, ":");
     if(!buf) error_exit("bad name %s", name);

     errno = 0;
     for (j=0; j<16 && !errno; j++) val[j] = strtoll(buf, &buf, 0);
     if (errno) perror_exit("bad %s at %s", name, buf);

     if (iface_name) {
       if (!strcmp(iface_name, name)) {
         display_ifconfig(iface_name, 1, val);

         return;
       }
     } else {
       sl = xmalloc(sizeof(*sl)+strlen(name)+1);
       strcpy(sl->str, name);
       sl->next = ifaces;
       ifaces = sl;

       display_ifconfig(sl->str, toys.optflags & FLAG_a, val);
     }
   }
   fclose(fp);

   if (iface_name) display_ifconfig(iface_name, 1, 0);
   else {
     struct ifconf ifcon;
     struct ifreq *ifre;
     int num;

     // Loop until buffer's big enough
     ifcon.ifc_buf = NULL;
     for (num = 30;;num += 10) {
       ifcon.ifc_len = sizeof(struct ifreq)*num;
       ifcon.ifc_buf = xrealloc(ifcon.ifc_buf, ifcon.ifc_len);
       xioctl(TT.sockfd, SIOCGIFCONF, &ifcon);
       if (ifcon.ifc_len != sizeof(struct ifreq)*num) break;
     }

     ifre = ifcon.ifc_req;
     for(num = 0; num < ifcon.ifc_len && ifre; num += sizeof(struct ifreq), ifre++)
     {
       // Skip duplicates
       for(sl = ifaces; sl; sl = sl->next)
         if(!strcmp(sl->str, ifre->ifr_name)) break;

       if(!sl) display_ifconfig(ifre->ifr_name, toys.optflags & FLAG_a, 0);
     }

     free(ifcon.ifc_buf);
   }

   llist_traverse(ifaces, free);
 }

 // Encode offset and size of field into an int, and make result negative
 #define IFREQ_OFFSZ(x) -(int)((offsetof(struct ifreq, x)<<16) + sizeof(ifre.x))

 void ifconfig_main(void)
 {
   char **argv = toys.optargs;
   struct ifreq ifre;
   int i;

   TT.sockfd = xsocket(AF_INET, SOCK_DGRAM, 0);
   if(toys.optc < 2) {
     show_iface(*argv);
     return;
   }

   // Open interface
   memset(&ifre, 0, sizeof(struct ifreq));
   xstrncpy(ifre.ifr_name, *argv, IFNAMSIZ);

   // Perform operations on interface
   while(*++argv) {
     // Table of known operations
     struct argh {
       char *name;
       int on, off; // set, clear
     } try[] = {
       {0, IFF_UP|IFF_RUNNING, SIOCSIFADDR},
       {"up", IFF_UP|IFF_RUNNING, 0},
       {"down", 0, IFF_UP},
       {"arp", 0, IFF_NOARP},
       {"promisc", IFF_PROMISC, 0},
       {"allmulti", IFF_ALLMULTI, 0},
       {"multicast", IFF_MULTICAST, 0},
       {"pointopoint", IFF_POINTOPOINT, SIOCSIFDSTADDR},
       {"broadcast", IFF_BROADCAST, SIOCSIFBRDADDR},
       {"netmask", 0, SIOCSIFNETMASK},
       {"dstaddr", 0, SIOCSIFDSTADDR},
       {"mtu", IFREQ_OFFSZ(ifr_mtu), SIOCSIFMTU},
       {"keepalive", IFREQ_OFFSZ(ifr_data), SIOCDEVPRIVATE}, // SIOCSKEEPALIVE
       {"outfill", IFREQ_OFFSZ(ifr_data), SIOCDEVPRIVATE+2}, // SIOCSOUTFILL
       {"metric", IFREQ_OFFSZ(ifr_metric), SIOCSIFMETRIC},
       {"txqueuelen", IFREQ_OFFSZ(ifr_qlen), SIOCSIFTXQLEN},
       {"mem_start", IFREQ_OFFSZ(ifr_map.mem_start), SIOCSIFMAP},
       {"io_addr", IFREQ_OFFSZ(ifr_map.base_addr), SIOCSIFMAP},
       {"irq", IFREQ_OFFSZ(ifr_map.irq), SIOCSIFMAP},
       {"inet", 0, 0},
       {"inet6", 0, 0}
     };
     char *s = *argv;
     int rev = (*s == '-');

     s += rev;

     // "set hardware address" is oddball enough to special case
     if (!strcmp(*argv, "hw")) {
       char *hw_addr, *ptr, *p;
       struct sockaddr *sock = &ifre.ifr_hwaddr;
       int count = 6;

       ptr = p = (char *)sock->sa_data;
       memset(sock, 0, sizeof(struct sockaddr));
       if (argv[1]) {
         if (!strcmp("ether", *++argv)) sock->sa_family = ARPHRD_ETHER;
         else if (!strcmp("infiniband", *argv)) {
           sock->sa_family = ARPHRD_INFINIBAND;
           count = 20;
           p = ptr = toybuf;
         }
       }
       if (!sock->sa_family || !argv[1]) {
         toys.exithelp++;
         error_exit("bad hw '%s'", *argv);
       }
       hw_addr = *++argv;

       // Parse and verify address.
       while (*hw_addr && (p-ptr) < count) {
         int val, len = 0;

         if (*hw_addr == ':') hw_addr++;
         sscanf(hw_addr, "%2x%n", &val, &len);
         if (!len || len > 2) break; // 1 nibble can be set e.g. C2:79:38:95:D:A
         hw_addr += len;
         *p++ = val;
       }

       if ((p-ptr) != count || *hw_addr)
         error_exit("bad hw-addr '%s'", *argv);

       // the linux kernel's "struct sockaddr" (include/linux/socket.h in the
       // kernel source) only has 14 bytes of sa_data, and an infiniband address
       // is 20. So if we go through the ioctl, the kernel will truncate
       // infiniband addresses, meaning we have to go through sysfs instead.
       if (sock->sa_family == ARPHRD_INFINIBAND && !strchr(ifre.ifr_name, '/')) {
         int fd;

         sprintf(toybuf, "/sys/class/net/%s/address", ifre.ifr_name);
         fd = xopen(toybuf, O_RDWR);
         xwrite(fd, *argv, strlen(*argv));
         close(fd);
       } else xioctl(TT.sockfd, SIOCSIFHWADDR, &ifre);
       continue;

     // Add/remove ipv6 address to interface

     } else if (!strcmp(*argv, "add") || !strcmp(*argv, "del")) {
       struct ifreq_inet6 {
         struct in6_addr addr;
         unsigned prefix;
         int index;
       } ifre6;
       int plen, fd6 = xsocket(AF_INET6, SOCK_DGRAM, 0);

       if (!argv[1]) {
         toys.exithelp++;
         error_exit("%s", *argv);
       }

       plen = get_addrinfo(argv[1], AF_INET6, &ifre6.addr);
       if (plen < 0) plen = 128;
       xioctl(fd6, SIOCGIFINDEX, &ifre);
       ifre6.index = ifre.ifr_ifindex;
       ifre6.prefix = plen;
       xioctl(fd6, **(argv++)=='a' ? SIOCSIFADDR : SIOCDIFADDR, &ifre6);

       close(fd6);
       continue;
     // Iterate through table to find/perform operation
     } else for (i = 0; i < ARRAY_LEN(try); i++) {
       struct argh *t = try+i;
       int on = t->on, off = t->off;

       if (!t->name) {
         if (isdigit(**argv) || !strcmp(*argv, "default")) argv--;
         else continue;
       } else if (strcmp(t->name, s)) continue;

       // Is this an SIOCSI entry?
       if ((off|0xff) == 0x89ff) {
         if (!rev) {
           if (!*++argv) error_exit("%s needs argument", t->name);

           // Assign value to ifre field and call ioctl? (via IFREQ_OFFSZ.)
           if (on < 0) {
             long l = strtoul(*argv, 0, 0);

             if (off == SIOCSIFMAP) xioctl(TT.sockfd, SIOCGIFMAP, &ifre);
             on = -on;
             poke((on>>16) + (char *)&ifre, l, on&15);
             xioctl(TT.sockfd, off, &ifre);
             break;
           } else {
             struct sockaddr_in *si = (struct sockaddr_in *)&ifre.ifr_addr;
             int mask = -1;

             si->sin_family = AF_INET;

             if (!strcmp(*argv, "default")) si->sin_addr.s_addr = INADDR_ANY;
             else mask = get_addrinfo(*argv, AF_INET, &si->sin_addr);
             xioctl(TT.sockfd, off, &ifre);

             // Handle /netmask
             if (mask >= 0) {
               // sin_addr probably isn't unaligned, but just in case...
               mask = htonl((~0)<<(32-mask));
               memcpy(&si->sin_addr, &mask, 4);
               xioctl(TT.sockfd, SIOCSIFNETMASK, &ifre);
             }
           }
         }
         off = 0;
       }

       // Set flags
       if (on || off) {
         xioctl(TT.sockfd, SIOCGIFFLAGS, &ifre);
         ifre.ifr_flags &= ~(rev ? on : off);
         ifre.ifr_flags |= (rev ? off : on);
         xioctl(TT.sockfd, SIOCSIFFLAGS, &ifre);
       }

       break;
     }
     if (i == sizeof(try)/sizeof(*try)) {
       toys.exithelp++;
       error_exit("bad argument '%s'", *argv);
     }
   }
   close(TT.sockfd);
 }
	/* ifconfig.c - Configure network interface.
	*
	* Copyright 2012 Ranjan Kumar <ranjankumar.bth@gmail.com>
	* Copyright 2012 Kyungwan Han <asura321@gamil.com>
	* Reviewed by Kyungsu Kim <kaspyx@gmail.com>
	*
	* Not in SUSv4.

	USE_IFCONFIG(NEWTOY(ifconfig, "^?a", TOYFLAG_SBIN))

	config IFCONFIG
	bool "ifconfig"
	default y
	help
	usage: ifconfig [-a] [INTERFACE [ACTION...]]

	Display or configure network interface.

	With no arguments, display active interfaces. First argument is interface
	to operate on, one argument by itself displays that interface.

	-a Show all interfaces, not just active ones

	Additional arguments are actions to perform on the interface:

	ADDRESS[/NETMASK] - set IPv4 address (1.2.3.4/5)
	default - unset ipv4 address
	add\|del ADDRESS[/PREFIXLEN] - add/remove IPv6 address (1111::8888/128)
	up - enable interface
	down - disable interface

	netmask\|broadcast\|pointopoint ADDRESS - set more IPv4 characteristics
	hw ether\|infiniband ADDRESS - set LAN hardware address (AA:BB:CC...)
	txqueuelen LEN - number of buffered packets before output blocks
	mtu LEN - size of outgoing packets (Maximum Transmission Unit)

	Flags you can set on an interface (or -remove by prefixing with -):
	arp - don't use Address Resolution Protocol to map LAN routes
	promisc - don't discard packets that aren't to this LAN hardware address
	multicast - force interface into multicast mode if the driver doesn't
	allmulti - promisc for multicast packets

	Obsolete fields included for historical purposes:
	irq\|io_addr\|mem_start ADDR - micromanage obsolete hardware
	outfill\|keepalive INTEGER - SLIP analog dialup line quality monitoring
	metric INTEGER - added to Linux 0.9.10 with comment "never used", still true
	*/

	#define FOR_ifconfig
	#include "toys.h"

	#include <net/if_arp.h>
	#include <net/ethernet.h>

	GLOBALS(
	int sockfd;
	)

	// Convert hostname to binary address for AF_INET or AF_INET6
	// return /prefix (or range max if none)
	int get_addrinfo(char host, sa_family_t af, void addr)
	{
	struct addrinfo hints, result, rp = 0;
	int status, len;
	char from, slash;

	memset(&hints, 0 , sizeof(struct addrinfo));
	hints.ai_family = af;
	hints.ai_socktype = SOCK_STREAM;

	slash = strchr(host, '/');
	if (slash) *slash = 0;

	status = getaddrinfo(host, NULL, &hints, &result);
	if (!status)
	for (rp = result; rp; rp = rp->ai_next)
	if (rp->ai_family == af) break;
	if (!rp) error_exit("bad address '%s' : %s", host, gai_strerror(status));

	// ai_addr isn't struct in_addr or in6_addr, it's struct sockaddr. Of course.
	// You'd think ipv4 and ipv6 would have some basic compatibility, but no.
	from = ((char *)rp->ai_addr) + 4;
	if (af == AF_INET6) {
	len = 16;
	from += 4; // skip "flowinfo" field ipv6 puts before address
	} else len = 4;
	memcpy(addr, from, len);
	freeaddrinfo(result);

	len = -1;
	if (slash) len = atolx_range(slash+1, 0, (af == AF_INET) ? 32 : 128);

	return len;
	}

	static void display_ifconfig(char *name, int always, unsigned long long val[])
	{
	struct ifreq ifre;
	struct {
	int type;
	char *title;
	} types[] = {
	{ARPHRD_LOOPBACK, "Local Loopback"}, {ARPHRD_ETHER, "Ethernet"},
	{ARPHRD_PPP, "Point-to-Point Protocol"}, {ARPHRD_INFINIBAND, "InfiniBand"},
	{ARPHRD_SIT, "IPv6-in-IPv4"}, {-1, "UNSPEC"}
	};
	int i;
	char *pp;
	FILE *fp;
	short flags;

	xstrncpy(ifre.ifr_name, name, IFNAMSIZ);
	if (ioctl(TT.sockfd, SIOCGIFFLAGS, &ifre)<0) perror_exit("%s", name);
	flags = ifre.ifr_flags;
	if (!always && !(flags & IFF_UP)) return;

	// query hardware type and hardware address
	i = ioctl(TT.sockfd, SIOCGIFHWADDR, &ifre);

	for (i=0; i < (sizeof(types)/sizeof(*types))-1; i++)
	if (ifre.ifr_hwaddr.sa_family == types[i].type) break;

	xprintf("%-9s Link encap:%s ", name, types[i].title);
	if(i >= 0 && ifre.ifr_hwaddr.sa_family == ARPHRD_ETHER) {
	xprintf("HWaddr ");
	for (i=0; i<6; i++) xprintf(":%02X"+!i, ifre.ifr_hwaddr.sa_data[i]);
	}
	xputc('\n');

	// If an address is assigned record that.

	ifre.ifr_addr.sa_family = AF_INET;
	memset(&ifre.ifr_addr, 0, sizeof(ifre.ifr_addr));
	ioctl(TT.sockfd, SIOCGIFADDR, &ifre);
	pp = (char *)&ifre.ifr_addr;
	for (i = 0; i<sizeof(ifre.ifr_addr); i++) if (pp[i]) break;

	if (i != sizeof(ifre.ifr_addr)) {
	struct sockaddr_in si = (struct sockaddr_in )&ifre.ifr_addr;
	struct {
	char *name;
	int flag, ioctl;
	} addr[] = {
	{"addr", 0, 0},
	{"P-t-P", IFF_POINTOPOINT, SIOCGIFDSTADDR},
	{"Bcast", IFF_BROADCAST, SIOCGIFBRDADDR},
	{"Mask", 0, SIOCGIFNETMASK}
	};

	xprintf("%10c%s", ' ', (si->sin_family == AF_INET) ? "inet" :
	(si->sin_family == AF_INET6) ? "inet6" : "unspec");

	for (i=0; i < sizeof(addr)/sizeof(*addr); i++) {
	if (!addr[i].flag \|\| (flags & addr[i].flag)) {
	if (addr[i].ioctl && ioctl(TT.sockfd, addr[i].ioctl, &ifre))
	si->sin_family = 0;
	xprintf(" %s:%s ", addr[i].name,
	(si->sin_family == 0xFFFF \|\| !si->sin_family)
	? "[NOT SET]" : inet_ntoa(si->sin_addr));
	}
	}

	xputc('\n');
	}

	fp = fopen(pp = "/proc/net/if_inet6", "r");
	if (fp) {
	char iface_name[IFNAMSIZ];
	int plen, iscope;

	while (fgets(toybuf, sizeof(toybuf), fp)) {
	int nitems;
	char ipv6_addr[40];

	nitems = sscanf(toybuf, "%32s %08x %02x %02x %02x %15s\n",
	ipv6_addr, &plen, &iscope, iface_name);
	if (nitems<0 && feof(fp)) break;
	if (nitems != 4) perror_exit("bad %s", pp);

	if (!strcmp(name, iface_name)) {
	struct sockaddr_in6 s6;
	char *ptr = ipv6_addr+sizeof(ipv6_addr)-1;

	// convert giant hex string into colon-spearated ipv6 address by
	// inserting ':' every 4 characters.
	for (i = 32; i; i--)
	if (((ptr--) = ipv6_addr[i])) if (!(i&3)) (ptr--) = ':';

	// Convert to binary and back to get abbreviated :: version
	if (inet_pton(AF_INET6, ipv6_addr, (void *)&s6.sin6_addr) > 0) {
	if (inet_ntop(AF_INET6, &s6.sin6_addr, toybuf, sizeof(toybuf))) {
	char *scopes[] = {"Global","Host","Link","Site","Compat"},
	*scope = "Unknown";

	for (i=0; i < sizeof(scopes)/sizeof(*scopes); i++)
	if (iscope == (!!i)<<(i+3)) scope = scopes[i];
	xprintf("%10cinet6 addr: %s/%d Scope: %s\n",
	' ', toybuf, plen, scope);
	}
	}
	}
	}
	fclose(fp);
	}

	xprintf("%10c", ' ');

	if (flags) {
	unsigned short mask = 1;
	char *s, str[] = {
	"UP", "BROADCAST", "DEBUG", "LOOPBACK", "POINTOPOINT", "NOTRAILERS",
	"RUNNING", "NOARP", "PROMISC", "ALLMULTI", "MASTER", "SLAVE", "MULTICAST",
	"PORTSEL", "AUTOMEDIA", "DYNAMIC", NULL
	};

	for (s = str; *s; s++) {
	if (flags & mask) xprintf("%s ", *s);
	mask = mask << 1;
	}
	} else xprintf("[NO FLAGS] ");

	if (ioctl(TT.sockfd, SIOCGIFMTU, &ifre) < 0) ifre.ifr_mtu = 0;
	xprintf(" MTU:%d", ifre.ifr_mtu);
	if (ioctl(TT.sockfd, SIOCGIFMETRIC, &ifre) < 0) ifre.ifr_metric = 0;
	if (!ifre.ifr_metric) ifre.ifr_metric = 1;
	xprintf(" Metric:%d", ifre.ifr_metric);

	// non-virtual interface

	if (val) {
	char *label[] = {"RX bytes", "RX packets", "errors", "dropped", "overruns",
	"frame", 0, 0, "TX bytes", "TX packets", "errors", "dropped", "overruns",
	"collisions", "carrier", 0, "txqueuelen"};
	signed char order[] = {-1, 1, 2, 3, 4, 5, -1, 9, 10, 11, 12, 14, -1,
	13, 16, -1, 0, 8};
	int i;

	// Query txqueuelen
	if (ioctl(TT.sockfd, SIOCGIFTXQLEN, &ifre) >= 0) val[16] = ifre.ifr_qlen;
	else val[16] = -1;

	for (i = 0; i < sizeof(order); i++) {
	int j = order[i];

	if (j < 0) xprintf("\n%10c", ' ');
	else xprintf("%s:%llu ", label[j], val[j]);
	}
	}
	xputc('\n');

	if(!ioctl(TT.sockfd, SIOCGIFMAP, &ifre) && (ifre.ifr_map.irq \|\|
	ifre.ifr_map.mem_start \|\| ifre.ifr_map.dma \|\| ifre.ifr_map.base_addr))
	{
	xprintf("%10c", ' ');
	if(ifre.ifr_map.irq) xprintf("Interrupt:%d ", ifre.ifr_map.irq);
	if(ifre.ifr_map.base_addr >= 0x100) // IO_MAP_INDEX
	xprintf("Base address:0x%x ", ifre.ifr_map.base_addr);
	if(ifre.ifr_map.mem_start)
	xprintf("Memory:%lx-%lx ", ifre.ifr_map.mem_start, ifre.ifr_map.mem_end);
	if(ifre.ifr_map.dma) xprintf("DMA chan:%x ", ifre.ifr_map.dma);
	xputc('\n');
	}
	xputc('\n');
	}

	static void show_iface(char *iface_name)
	{
	char *name;
	struct string_list ifaces = 0, sl;
	int i, j;
	FILE *fp;

	fp = xfopen("/proc/net/dev", "r");

	for (i=0; fgets(toybuf, sizeof(toybuf), fp); i++) {
	char *buf = toybuf;
	unsigned long long val[17];

	if (i<2) continue;

	while (isspace(*buf)) buf++;
	name = strsep(&buf, ":");
	if(!buf) error_exit("bad name %s", name);

	errno = 0;
	for (j=0; j<16 && !errno; j++) val[j] = strtoll(buf, &buf, 0);
	if (errno) perror_exit("bad %s at %s", name, buf);

	if (iface_name) {
	if (!strcmp(iface_name, name)) {
	display_ifconfig(iface_name, 1, val);

	return;
	}
	} else {
	sl = xmalloc(sizeof(*sl)+strlen(name)+1);
	strcpy(sl->str, name);
	sl->next = ifaces;
	ifaces = sl;

	display_ifconfig(sl->str, toys.optflags & FLAG_a, val);
	}
	}
	fclose(fp);

	if (iface_name) display_ifconfig(iface_name, 1, 0);
	else {
	struct ifconf ifcon;
	struct ifreq *ifre;
	int num;

	// Loop until buffer's big enough
	ifcon.ifc_buf = NULL;
	for (num = 30;;num += 10) {
	ifcon.ifc_len = sizeof(struct ifreq)*num;
	ifcon.ifc_buf = xrealloc(ifcon.ifc_buf, ifcon.ifc_len);
	xioctl(TT.sockfd, SIOCGIFCONF, &ifcon);
	if (ifcon.ifc_len != sizeof(struct ifreq)*num) break;
	}

	ifre = ifcon.ifc_req;
	for(num = 0; num < ifcon.ifc_len && ifre; num += sizeof(struct ifreq), ifre++)
	{
	// Skip duplicates
	for(sl = ifaces; sl; sl = sl->next)
	if(!strcmp(sl->str, ifre->ifr_name)) break;

	if(!sl) display_ifconfig(ifre->ifr_name, toys.optflags & FLAG_a, 0);
	}

	free(ifcon.ifc_buf);
	}

	llist_traverse(ifaces, free);
	}

	// Encode offset and size of field into an int, and make result negative
	#define IFREQ_OFFSZ(x) -(int)((offsetof(struct ifreq, x)<<16) + sizeof(ifre.x))

	void ifconfig_main(void)
	{
	char **argv = toys.optargs;
	struct ifreq ifre;
	int i;

	TT.sockfd = xsocket(AF_INET, SOCK_DGRAM, 0);
	if(toys.optc < 2) {
	show_iface(*argv);
	return;
	}

	// Open interface
	memset(&ifre, 0, sizeof(struct ifreq));
	xstrncpy(ifre.ifr_name, *argv, IFNAMSIZ);

	// Perform operations on interface
	while(*++argv) {
	// Table of known operations
	struct argh {
	char *name;
	int on, off; // set, clear
	} try[] = {
	{0, IFF_UP\|IFF_RUNNING, SIOCSIFADDR},
	{"up", IFF_UP\|IFF_RUNNING, 0},
	{"down", 0, IFF_UP},
	{"arp", 0, IFF_NOARP},
	{"promisc", IFF_PROMISC, 0},
	{"allmulti", IFF_ALLMULTI, 0},
	{"multicast", IFF_MULTICAST, 0},
	{"pointopoint", IFF_POINTOPOINT, SIOCSIFDSTADDR},
	{"broadcast", IFF_BROADCAST, SIOCSIFBRDADDR},
	{"netmask", 0, SIOCSIFNETMASK},
	{"dstaddr", 0, SIOCSIFDSTADDR},
	{"mtu", IFREQ_OFFSZ(ifr_mtu), SIOCSIFMTU},
	{"keepalive", IFREQ_OFFSZ(ifr_data), SIOCDEVPRIVATE}, // SIOCSKEEPALIVE
	{"outfill", IFREQ_OFFSZ(ifr_data), SIOCDEVPRIVATE+2}, // SIOCSOUTFILL
	{"metric", IFREQ_OFFSZ(ifr_metric), SIOCSIFMETRIC},
	{"txqueuelen", IFREQ_OFFSZ(ifr_qlen), SIOCSIFTXQLEN},
	{"mem_start", IFREQ_OFFSZ(ifr_map.mem_start), SIOCSIFMAP},
	{"io_addr", IFREQ_OFFSZ(ifr_map.base_addr), SIOCSIFMAP},
	{"irq", IFREQ_OFFSZ(ifr_map.irq), SIOCSIFMAP},
	{"inet", 0, 0},
	{"inet6", 0, 0}
	};
	char s = argv;
	int rev = (*s == '-');

	s += rev;

	// "set hardware address" is oddball enough to special case
	if (!strcmp(*argv, "hw")) {
	char hw_addr, ptr, *p;
	struct sockaddr *sock = &ifre.ifr_hwaddr;
	int count = 6;

	ptr = p = (char *)sock->sa_data;
	memset(sock, 0, sizeof(struct sockaddr));
	if (argv[1]) {
	if (!strcmp("ether", *++argv)) sock->sa_family = ARPHRD_ETHER;
	else if (!strcmp("infiniband", *argv)) {
	sock->sa_family = ARPHRD_INFINIBAND;
	count = 20;
	p = ptr = toybuf;
	}
	}
	if (!sock->sa_family \|\| !argv[1]) {
	toys.exithelp++;
	error_exit("bad hw '%s'", *argv);
	}
	hw_addr = *++argv;

	// Parse and verify address.
	while (*hw_addr && (p-ptr) < count) {
	int val, len = 0;

	if (*hw_addr == ':') hw_addr++;
	sscanf(hw_addr, "%2x%n", &val, &len);
	if (!len \|\| len > 2) break; // 1 nibble can be set e.g. C2:79:38:95:D:A
	hw_addr += len;
	*p++ = val;
	}

	if ((p-ptr) != count \|\| *hw_addr)
	error_exit("bad hw-addr '%s'", *argv);

	// the linux kernel's "struct sockaddr" (include/linux/socket.h in the
	// kernel source) only has 14 bytes of sa_data, and an infiniband address
	// is 20. So if we go through the ioctl, the kernel will truncate
	// infiniband addresses, meaning we have to go through sysfs instead.
	if (sock->sa_family == ARPHRD_INFINIBAND && !strchr(ifre.ifr_name, '/')) {
	int fd;

	sprintf(toybuf, "/sys/class/net/%s/address", ifre.ifr_name);
	fd = xopen(toybuf, O_RDWR);
	xwrite(fd, argv, strlen(argv));
	close(fd);
	} else xioctl(TT.sockfd, SIOCSIFHWADDR, &ifre);
	continue;

	// Add/remove ipv6 address to interface

	} else if (!strcmp(argv, "add") \|\| !strcmp(argv, "del")) {
	struct ifreq_inet6 {
	struct in6_addr addr;
	unsigned prefix;
	int index;
	} ifre6;
	int plen, fd6 = xsocket(AF_INET6, SOCK_DGRAM, 0);

	if (!argv[1]) {
	toys.exithelp++;
	error_exit("%s", *argv);
	}

	plen = get_addrinfo(argv[1], AF_INET6, &ifre6.addr);
	if (plen < 0) plen = 128;
	xioctl(fd6, SIOCGIFINDEX, &ifre);
	ifre6.index = ifre.ifr_ifindex;
	ifre6.prefix = plen;
	xioctl(fd6, **(argv++)=='a' ? SIOCSIFADDR : SIOCDIFADDR, &ifre6);

	close(fd6);
	continue;
	// Iterate through table to find/perform operation
	} else for (i = 0; i < ARRAY_LEN(try); i++) {
	struct argh *t = try+i;
	int on = t->on, off = t->off;

	if (!t->name) {
	if (isdigit(*argv) \|\| !strcmp(argv, "default")) argv--;
	else continue;
	} else if (strcmp(t->name, s)) continue;

	// Is this an SIOCSI entry?
	if ((off\|0xff) == 0x89ff) {
	if (!rev) {
	if (!*++argv) error_exit("%s needs argument", t->name);

	// Assign value to ifre field and call ioctl? (via IFREQ_OFFSZ.)
	if (on < 0) {
	long l = strtoul(*argv, 0, 0);

	if (off == SIOCSIFMAP) xioctl(TT.sockfd, SIOCGIFMAP, &ifre);
	on = -on;
	poke((on>>16) + (char *)&ifre, l, on&15);
	xioctl(TT.sockfd, off, &ifre);
	break;
	} else {
	struct sockaddr_in si = (struct sockaddr_in )&ifre.ifr_addr;
	int mask = -1;

	si->sin_family = AF_INET;

	if (!strcmp(*argv, "default")) si->sin_addr.s_addr = INADDR_ANY;
	else mask = get_addrinfo(*argv, AF_INET, &si->sin_addr);
	xioctl(TT.sockfd, off, &ifre);

	// Handle /netmask
	if (mask >= 0) {
	// sin_addr probably isn't unaligned, but just in case...
	mask = htonl((~0)<<(32-mask));
	memcpy(&si->sin_addr, &mask, 4);
	xioctl(TT.sockfd, SIOCSIFNETMASK, &ifre);
	}
	}
	}
	off = 0;
	}

	// Set flags
	if (on \|\| off) {
	xioctl(TT.sockfd, SIOCGIFFLAGS, &ifre);
	ifre.ifr_flags &= ~(rev ? on : off);
	ifre.ifr_flags \|= (rev ? off : on);
	xioctl(TT.sockfd, SIOCSIFFLAGS, &ifre);
	}

	break;
	}
	if (i == sizeof(try)/sizeof(*try)) {
	toys.exithelp++;
	error_exit("bad argument '%s'", *argv);
	}
	}
	close(TT.sockfd);
	}