/
kernel_netlink.c
1872 lines (1561 loc) · 50.4 KB
/
kernel_netlink.c
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/*
Copyright 2007-2010 by Grégoire Henry, Julien Cristau and Juliusz Chroboczek
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/
#include <stdlib.h>
#include <stdio.h>
#include <stddef.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <time.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <net/route.h>
#include <net/if.h>
#include <arpa/inet.h>
#include <asm/types.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <linux/if_bridge.h>
#include <linux/fib_rules.h>
#include <linux/filter.h>
#include <net/if_arp.h>
#include <sched.h>
#include "babeld.h"
#include "kernel.h"
#include "util.h"
#include "interface.h"
#include "configuration.h"
// enum only exported by linux 4.10+
#ifdef HAVE_EXPIRES
#ifndef RTA_EXPIRES
#define RTA_EXPIRES (RTA_ENCAP+1)
#endif
#endif
#ifndef MAX_INTERFACES
#define MAX_INTERFACES 20
#endif
#define GET_PLEN(p, v4) (v4) ? (p) + 96 : (p)
#define COPY_ADDR(d, rta, v4) \
do { \
if(UNLIKELY(RTA_PAYLOAD(rta) < (v4 ? 4 : 16))) { \
fprintf(stderr, "truncated message."); \
return -1; \
} \
if(v4) \
v4tov6(d, RTA_DATA(rta)); \
else \
memcpy(d, RTA_DATA(rta), 16); \
} while(0)
int export_table = -1, import_tables[MAX_IMPORT_TABLES], import_table_count = 0;
struct sysctl_setting {
char *name;
int want;
int was;
};
#define NUM_SYSCTLS 4
static struct sysctl_setting sysctl_settings[NUM_SYSCTLS] = {
{"/proc/sys/net/ipv6/conf/all/forwarding", 1, -1},
{"/proc/sys/net/ipv4/conf/all/forwarding", 1, -1},
{"/proc/sys/net/ipv6/conf/all/accept_redirects", 0, -1},
{"/proc/sys/net/ipv4/conf/all/rp_filter", 0, -1},
};
struct old_if {
char *ifname;
int rp_filter;
};
struct old_if old_if[MAX_INTERFACES];
int num_old_if = 0;
static int dgram_socket = -1;
#ifndef ARPHRD_ETHER
#warning ARPHRD_ETHER not defined, we might not support exotic link layers
#define ARPHRD_ETHER 1
#define NO_ARPHRD
#endif
static int filter_netlink(struct nlmsghdr *nh, struct kernel_filter *filter);
/* Determine an interface's hardware address, in modified EUI-64 format */
int
if_eui64(char *ifname, int ifindex, unsigned char *eui)
{
int s, rc;
struct ifreq ifr;
s = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
if(s < 0) return -1;
memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
rc = ioctl(s, SIOCGIFHWADDR, &ifr);
if(rc < 0) {
int saved_errno = errno;
close(s);
errno = saved_errno;
return -1;
}
close(s);
switch(ifr.ifr_hwaddr.sa_family) {
case ARPHRD_ETHER:
#ifndef NO_ARPHRD
case ARPHRD_FDDI:
case ARPHRD_IEEE802_TR:
case ARPHRD_IEEE802:
#endif
{
unsigned char *mac;
mac = (unsigned char *)ifr.ifr_hwaddr.sa_data;
/* Check for null address and group and global bits */
if(memcmp(mac, zeroes, 6) == 0 ||
(mac[0] & 1) != 0 || (mac[0] & 2) != 0) {
errno = ENOENT;
return -1;
}
memcpy(eui, mac, 3);
eui[3] = 0xFF;
eui[4] = 0xFE;
memcpy(eui + 5, mac + 3, 3);
eui[0] ^= 2;
return 1;
}
#ifndef NO_ARPHRD
case ARPHRD_EUI64:
case ARPHRD_IEEE1394:
case ARPHRD_INFINIBAND: {
unsigned char *mac;
mac = (unsigned char *)ifr.ifr_hwaddr.sa_data;
if(memcmp(mac, zeroes, 8) == 0 ||
(mac[0] & 1) != 0 || (mac[0] & 2) != 0) {
errno = ENOENT;
return -1;
}
memcpy(eui, mac, 8);
eui[0] ^= 2;
return 1;
}
#endif
default:
errno = ENOENT;
return -1;
}
}
static int
read_proc(char *filename)
{
char buf[100];
int fd, rc;
fd = open(filename, O_RDONLY);
if(fd < 0)
return -1;
rc = read(fd, buf, 99);
if(rc < 0) {
int saved_errno = errno;
close(fd);
errno = saved_errno;
return -1;
}
close(fd);
if(rc == 0)
return -1;
buf[rc] = '\0';
return atoi(buf);
}
static int
write_proc(char *filename, int value)
{
char buf[100];
int fd, rc, n;
n = snprintf(buf, 100, "%d", value);
fd = open(filename, O_WRONLY);
if(fd < 0)
return -1;
rc = write(fd, buf, n);
if(rc < n) {
int saved_errno = errno;
close(fd);
errno = saved_errno;
return -1;
}
close(fd);
return 1;
}
struct netlink {
unsigned short seqno;
int sock;
struct sockaddr_nl sockaddr;
socklen_t socklen;
};
static struct netlink nl_command = { 0, -1, {0}, 0 };
static struct netlink nl_listen = { 0, -1, {0}, 0 };
static int nl_setup = 0;
static int
netlink_socket(struct netlink *nl, uint32_t groups)
{
int rc;
int rcvsize = 512 * 1024;
nl->sock = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
if(nl->sock < 0)
return -1;
memset(&nl->sockaddr, 0, sizeof(nl->sockaddr));
nl->sockaddr.nl_family = AF_NETLINK;
nl->sockaddr.nl_groups = groups;
nl->socklen = sizeof(nl->sockaddr);
nl->seqno = time(NULL);
rc = fcntl(nl->sock, F_GETFL, 0);
if(rc < 0)
goto fail;
rc = fcntl(nl->sock, F_SETFL, (rc | O_NONBLOCK));
if(rc < 0)
goto fail;
#ifdef SO_RCVBUFFORCE
rc = setsockopt(nl->sock, SOL_SOCKET, SO_RCVBUFFORCE,
&rcvsize, sizeof(rcvsize));
#else
rc = -1;
#endif
if(rc < 0) {
rc = setsockopt(nl->sock, SOL_SOCKET, SO_RCVBUF,
&rcvsize, sizeof(rcvsize));
if(rc < 0) {
perror("setsockopt(SO_RCVBUF)");
}
}
rc = setsockopt(nl->sock, SOL_SOCKET, SO_SNDBUF,
&rcvsize, sizeof(rcvsize));
if(rc < 0) {
perror("setsockopt(SO_SNDBUF)");
}
rc = bind(nl->sock, (struct sockaddr *)&nl->sockaddr, nl->socklen);
if(rc < 0)
goto fail;
rc = getsockname(nl->sock, (struct sockaddr *)&nl->sockaddr, &nl->socklen);
if(rc < 0)
goto fail;
return 0;
fail:
{
int saved_errno = errno;
close(nl->sock);
nl->sock = -1;
errno = saved_errno;
return -1;
}
}
static int
netlink_read(struct netlink *nl, struct netlink *nl_ignore, int answer,
struct kernel_filter *filter)
{
/* 'answer' must be true when we just have send a request on 'nl_socket' */
/* 'nl_ignore' is used in kernel_callback to ignore message originating */
/* from 'nl_command' while reading 'nl_listen' */
/* Return code : */
/* -1 : error */
/* 0 : success */
int err;
struct msghdr msg;
struct sockaddr_nl nladdr;
struct iovec iov;
struct nlmsghdr *nh;
int len;
int done = 0;
int skip = 0;
char buf[65536*2];
memset(&nladdr, 0, sizeof(nladdr));
nladdr.nl_family = AF_NETLINK;
memset(&msg, 0, sizeof(msg));
msg.msg_name = &nladdr;
msg.msg_namelen = sizeof(nladdr);
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
iov.iov_base = &buf;
int errors = 0;
do {
iov.iov_len = sizeof(buf);
len = recvmsg(nl->sock, &msg, 0);
if(len < 0) {
errors++;
switch(errno) {
case EINTR: continue;
case ENOBUFS:
case ENOMEM:
case EAGAIN: sched_yield(); continue; // fixme, wait for fd again
default: fprintf(stderr,"EEEIEEE - got a netlink message %d we don't handle!\n", errno);
continue;
}
}
while(len < 0 && errors < 5);
if(len < 0) {
perror("netlink_read: recvmsg()");
return -1;
} else if(len == 0) {
fprintf(stderr, "netlink_read: EOF\n");
goto socket_error;
} else if(msg.msg_namelen != nl->socklen) {
fprintf(stderr,
"netlink_read: unexpected sender address length (%d)\n",
msg.msg_namelen);
goto socket_error;
} else if(nladdr.nl_pid != 0) {
kdebugf("netlink_read: message not sent by kernel.\n");
return -1;
}
kdebugf("Netlink message: ");
for(nh = (struct nlmsghdr *)buf;
NLMSG_OK(nh, len);
nh = NLMSG_NEXT(nh, len)) {
kdebugf("%s{seq:%d}", (nh->nlmsg_flags & NLM_F_MULTI) ? "[multi] " : "",
nh->nlmsg_seq);
if(!answer)
done = 1;
if(nl_ignore && nh->nlmsg_pid == nl_ignore->sockaddr.nl_pid) {
fprintf(stderr,"Message from self - we should not see this more than twice - ever\n");
kdebugf("(ignore), ");
continue;
} else if(answer && (nh->nlmsg_pid != nl->sockaddr.nl_pid ||
nh->nlmsg_seq != nl->seqno)) {
kdebugf("(wrong seqno %d %d /pid %d %d), ",
nh->nlmsg_seq, nl->seqno,
nh->nlmsg_pid, nl->sockaddr.nl_pid);
continue;
} else if(nh->nlmsg_type == NLMSG_DONE) {
kdebugf("(done)\n");
done = 1;
break;
} else if(nh->nlmsg_type == NLMSG_ERROR) {
struct nlmsgerr *err = (struct nlmsgerr *)NLMSG_DATA(nh);
if(err->error == 0) {
kdebugf("(ACK)\n");
return 0;
} else {
kdebugf("netlink_read: %s\n", strerror(-err->error));
errno = -err->error;
return -1;
}
} else if(skip) {
kdebugf("(skip)");
} if(filter) {
kdebugf("(msg -> \"");
err = filter_netlink(nh, filter);
kdebugf("\" %d), ", err);
if(err < 0) skip = 1;
continue;
}
kdebugf(", ");
}
kdebugf("\n");
if(msg.msg_flags & MSG_TRUNC)
fprintf(stderr, "netlink_read: message truncated\n");
} while(!done);
return 0;
socket_error:
close(nl->sock);
nl->sock = -1;
errno = EIO;
return -1;
}
static int
netlink_talk(struct nlmsghdr *nh)
{
int rc;
struct sockaddr_nl nladdr;
struct msghdr msg;
struct iovec iov;
memset(&nladdr, 0, sizeof(nladdr));
nladdr.nl_family = AF_NETLINK;
nladdr.nl_pid = 0;
memset(&msg, 0, sizeof(msg));
msg.msg_name = &nladdr;
msg.msg_namelen = sizeof(nladdr);
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
iov.iov_base = nh;
iov.iov_len = nh->nlmsg_len;
nh->nlmsg_flags |= NLM_F_ACK;
nh->nlmsg_seq = ++nl_command.seqno;
kdebugf("Sending seqno %d from address %p (talk)\n",
nl_command.seqno, &nl_command.seqno);
int errors = 0;
// formerly: 100ms timeout on kernel handling, setup of a select loop
// Not a bad idea - the blocking context switch from the select
// better accomplishes what I'm trying to do with yield - it's just
// that the 100ms timeout bothers me and something else may have gone
// Wrong elsewhere.
// rc = wait_for_fd(1, nl_command.sock, 100);
do {
rc = sendmsg(nl_command.sock, &msg, MSG_DONTWAIT);
if(rc < 0) {
errors++;
switch(errno) {
case EINTR: continue;
case EAGAIN: sched_yield();
rc = wait_for_fd(1, nl_command.sock, 5);
if( rc <=0 ) {
if(rc == 0) continue;
errors = 5;
}
continue; break; // hmm. When we overflow we get the rc from the waitfor
// This could possibly be a temporary error:
case ENETDOWN:
// Interface probably went down and flushed for us. It won't be
// be back any time soon:
case ESRCH:
// Pre-existing route (or a failure to update in time in
// the kernel) that trying harder to add won't help.
case EEXIST: errors = 5; break;
default: fprintf(stderr,"EEEIEEE - got a netlink message %d we don't handle!\n", errno);
continue;
}
}
} while(rc < 0 && errors < 5);
// FIXME: what if we get 0? Should never happen right? Well, 0 is now possible from
// the above and may have been possible before
if(rc == 0)fprintf(stderr, "netlink_talk returned 0!?\n");
// FIXME: There is a netlink bug I'm trying to track down involving the errno
// sometimes getting wedged into the return message.
if(rc < nh->nlmsg_len) {
int saved_errno = errno;
perror("sendmsg");
errno = saved_errno;
return -1;
}
// FIXME: Can this get out of sync?? I didn't manage to write it, so why should
// I read it?
rc = netlink_read(&nl_command, NULL, 1, NULL); /* FIXME: Do more robust checking of the ACK */
return rc;
}
static int
netlink_send_dump(int type, void *data, int len) {
struct sockaddr_nl nladdr;
struct msghdr msg;
struct iovec iov[2];
union {
char raw[NLMSG_ALIGN(sizeof(struct nlmsghdr))];
struct nlmsghdr nh;
} buf;
int rc;
/* At least we should send an 'struct rtgenmsg' */
if(data == NULL || len == 0) {
errno = EIO;
return -1;
}
/* And more : using anything else that 'struct rtgenmsg' is currently */
/* ignored by the linux kernel (today: 2.6.21) because NLM_F_MATCH is */
/* not yet implemented */
memset(&nladdr, 0, sizeof(nladdr));
nladdr.nl_family = AF_NETLINK;
memset(&msg, 0, sizeof(msg));
msg.msg_name = &nladdr;
msg.msg_namelen = sizeof(nladdr);
msg.msg_iov = iov;
msg.msg_iovlen = 2;
iov[0].iov_base = buf.raw;
iov[0].iov_len = sizeof(buf.raw);
iov[1].iov_base = data;
iov[1].iov_len = len;
memset(buf.raw, 0, sizeof(buf.raw));
buf.nh.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST;
buf.nh.nlmsg_type = type;
buf.nh.nlmsg_seq = ++nl_command.seqno;
buf.nh.nlmsg_len = NLMSG_LENGTH(len);
kdebugf("Sending seqno %d from address %p (dump)\n",
nl_command.seqno, &nl_command.seqno);
// FIXME - no decent error checking here
rc = sendmsg(nl_command.sock, &msg, 0);
if(rc < buf.nh.nlmsg_len) {
int saved_errno = errno;
perror("sendmsg");
errno = saved_errno;
return -1;
}
return 0;
}
int
kernel_setup(int setup)
{
struct sysctl_setting *s;
int i, rc;
if(setup) {
if(export_table < 0)
export_table = RT_TABLE_MAIN;
if(import_table_count < 1)
import_tables[import_table_count++] = RT_TABLE_MAIN;
dgram_socket = socket(PF_INET, SOCK_DGRAM, 0);
if(dgram_socket < 0)
return -1;
rc = netlink_socket(&nl_command, 0);
if(rc < 0) {
perror("netlink_socket(0)");
return -1;
}
nl_setup = 1;
if(skip_kernel_setup) return 1;
for(i=0; i<NUM_SYSCTLS; i++) {
s = &sysctl_settings[i];
s->was = read_proc(s->name);
if(s->was < 0) {
perror("Couldn't read sysctl");
return -1;
}
if(s->was != s->want) {
rc = write_proc(s->name, s->want);
if(rc < 0) {
perror("Couldn't write sysctl");
return -1;
}
}
}
return 1;
} else {
close(dgram_socket);
dgram_socket = -1;
close(nl_command.sock);
nl_command.sock = -1;
nl_setup = 0;
if(skip_kernel_setup) return 1;
for(i=0; i<NUM_SYSCTLS; i++) {
s = &sysctl_settings[i];
if(s->was >= 0 && s->was != s->want) {
rc = write_proc(s->name,s->was);
if(rc < 0) {
perror("Couldn't write sysctl");
return -1;
}
}
}
return 1;
}
}
static inline unsigned int
rtnlgrp_to_mask(unsigned int grp)
{
return grp ? 1 << (grp - 1) : 0;
}
#define array_size(ar) (sizeof(ar) / sizeof(ar[0]))
/* Filter out messages from self that occur on listener socket,
caused by our actions on the command socket
*/
// FIXME: We can do better here with the output of tcpdump at hand
// Can filter out everything we are listening to including interface
// Events.
static void netlink_install_filter (int sock, __u32 pid)
{
struct sock_filter filter[] = {
/* 0: ldh [4] */
BPF_STMT(BPF_LD|BPF_ABS|BPF_H, offsetof(struct nlmsghdr, nlmsg_type)),
/* 1: jeq 0x18 jt 3 jf 6 */
BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, htons(RTM_NEWROUTE), 1, 0),
/* 2: jeq 0x19 jt 3 jf 6 */
BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, htons(RTM_DELROUTE), 0, 3),
/* 3: ldw [12] */
BPF_STMT(BPF_LD|BPF_ABS|BPF_W, offsetof(struct nlmsghdr, nlmsg_pid)),
/* 4: jeq XX jt 5 jf 6 */
BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, htonl(pid), 0, 1),
/* 5: ret 0 (skip) */
BPF_STMT(BPF_RET|BPF_K, 0),
/* 6: ret 0xffff (keep) */
BPF_STMT(BPF_RET|BPF_K, 0xffff),
};
struct sock_fprog prog = {
.len = array_size(filter),
.filter = filter,
};
if (setsockopt(sock, SOL_SOCKET, SO_ATTACH_FILTER, &prog, sizeof(prog)) < 0)
fprintf(stderr,"Can't install socket filter for some reason - will see messages from self: %s\n",
strerror(errno));
}
int
kernel_setup_socket(int setup)
{
int rc;
if(setup) {
rc = netlink_socket(&nl_listen,
rtnlgrp_to_mask(RTNLGRP_IPV6_ROUTE)
| rtnlgrp_to_mask(RTNLGRP_IPV4_ROUTE)
| rtnlgrp_to_mask(RTNLGRP_LINK)
| rtnlgrp_to_mask(RTNLGRP_IPV4_IFADDR)
| rtnlgrp_to_mask(RTNLGRP_IPV6_IFADDR)
/* We monitor rules, because it can be change by third parties. For example
a /etc/init.d/network restart on OpenWRT flush the rules. */
| rtnlgrp_to_mask(RTNLGRP_IPV4_RULE)
| rtnlgrp_to_mask(RTNLGRP_IPV6_RULE));
if(rc < 0) {
perror("netlink_socket(_ROUTE | _LINK | _IFADDR | _RULE)");
kernel_socket = -1;
return -1;
}
netlink_install_filter(nl_listen.sock,getpid());
kernel_socket = nl_listen.sock;
return 1;
} else {
close(nl_listen.sock);
nl_listen.sock = -1;
kernel_socket = -1;
return 1;
}
}
static int
get_old_if(const char *ifname)
{
int i;
for(i = 0; i < num_old_if; i++)
if(strcmp(old_if[i].ifname, ifname) == 0)
return i;
if(num_old_if >= MAX_INTERFACES)
return -1;
old_if[num_old_if].ifname = strdup(ifname);
if(old_if[num_old_if].ifname == NULL)
return -1;
old_if[num_old_if].rp_filter = -1;
return num_old_if++;
}
int
kernel_setup_interface(int setup, const char *ifname, int ifindex)
{
char buf[100];
int i, rc;
/* rp_filter has weird semantics: both all/rp_filter and ifname/rp_filter
must be set to 0 for the rp_filter to be disabled. Deal with it. */
rc = snprintf(buf, 100, "/proc/sys/net/ipv4/conf/%s/rp_filter", ifname);
if(rc < 0 || rc >= 100)
return -1;
i = get_old_if(ifname);
if(setup) {
if(i >= 0)
old_if[i].rp_filter = read_proc(buf);
if(i < 0 || old_if[i].rp_filter < 0)
fprintf(stderr,
"Warning: cannot save old configuration for %s.\n",
ifname);
rc = write_proc(buf, 0);
if(rc < 0)
return -1;
} else {
if(i >= 0 && old_if[i].rp_filter >= 0)
rc = write_proc(buf, old_if[i].rp_filter);
else
rc = -1;
if(rc < 0)
fprintf(stderr,
"Warning: cannot restore old configuration for %s.\n",
ifname);
}
return 1;
}
int
kernel_interface_operational(const char *ifname, int ifindex)
{
struct ifreq req;
int rc;
int flags = link_detect ? (IFF_UP | IFF_RUNNING) : IFF_UP;
memset(&req, 0, sizeof(req));
strncpy(req.ifr_name, ifname, sizeof(req.ifr_name));
rc = ioctl(dgram_socket, SIOCGIFFLAGS, &req);
if(rc < 0)
return -1;
return ((req.ifr_flags & flags) == flags);
}
int
kernel_interface_ipv4(const char *ifname, int ifindex, unsigned char *addr_r)
{
struct ifreq req;
int rc;
memset(&req, 0, sizeof(req));
strncpy(req.ifr_name, ifname, sizeof(req.ifr_name));
req.ifr_addr.sa_family = AF_INET;
rc = ioctl(dgram_socket, SIOCGIFADDR, &req);
if(rc < 0)
return -1;
memcpy(addr_r, &((struct sockaddr_in*)&req.ifr_addr)->sin_addr, 4);
return 1;
}
int
kernel_interface_mtu(const char *ifname, int ifindex)
{
struct ifreq req;
int rc;
memset(&req, 0, sizeof(req));
strncpy(req.ifr_name, ifname, sizeof(req.ifr_name));
rc = ioctl(dgram_socket, SIOCGIFMTU, &req);
if(rc < 0)
return -1;
return req.ifr_mtu;
}
static int
isbridge(const char *ifname, int ifindex)
{
char buf[256];
int rc, i;
unsigned long args[3];
int indices[256];
rc = snprintf(buf, 256, "/sys/class/net/%s", ifname);
if(rc < 0 || rc >= 256)
goto fallback;
if(access(buf, R_OK) < 0)
goto fallback;
rc = snprintf(buf, 256, "/sys/class/net/%s/bridge", ifname);
if(rc < 0 || rc >= 256)
goto fallback;
if(access(buf, F_OK) >= 0)
return 1;
else if(errno == ENOENT)
return 0;
fallback:
args[0] = BRCTL_GET_BRIDGES;
args[1] = (unsigned long)indices;
args[2] = 256;
rc = ioctl(dgram_socket, SIOCGIFBR, args);
if(rc < 0) {
if(errno == ENOPKG)
return 0;
else
return -1;
}
for(i = 0; i < rc; i++) {
if(indices[i] == ifindex)
return 1;
}
return 0;
}
static int
isbatman(const char *ifname, int ifindex)
{
char buf[256];
int rc;
rc = snprintf(buf, 256, "/sys/devices/virtual/net/%s/mesh", ifname);
if(rc < 0 || rc >= 256)
return -1;
if(access(buf, F_OK) >= 0)
return 1;
if(errno != ENOENT)
return -1;
return 0;
}
// FIXME: Wifi channel detection has been borken for a very, very long time.
int
kernel_interface_wireless(const char *ifname, int ifindex)
{
#ifndef SIOCGIWNAME
#define SIOCGIWNAME 0x8B01
#endif
struct ifreq req;
int rc;
if(isbridge(ifname, ifindex) != 0 || isbatman(ifname, ifindex) != 0)
return -1;
memset(&req, 0, sizeof(req));
strncpy(req.ifr_name, ifname, sizeof(req.ifr_name));
rc = ioctl(dgram_socket, SIOCGIWNAME, &req);
if(rc < 0) {
if(errno == EOPNOTSUPP || errno == EINVAL)
rc = 0;
else {
perror("ioctl(SIOCGIWNAME)");
rc = -1;
}
} else {
rc = 1;
}
return rc;
}
/* Sorry for that, but I haven't managed to get <linux/wireless.h>
to include cleanly. */
#define SIOCGIWFREQ 0x8B05
struct iw_freq {
int m;
short e;
unsigned char i;
unsigned char flags;
};
struct iwreq_subset {
union {
char ifrn_name[IFNAMSIZ];
} ifr_ifrn;
union {
struct iw_freq freq;
} u;
};
static int
freq_to_chan(struct iw_freq *freq)
{
int m = freq->m, e = freq->e;
/* If exponent is 0, assume the channel is encoded directly in m. */
if(e == 0 && m > 0 && m < 254)
return m;
if(e <= 6) {
int mega, step, c, i;
/* This encodes 1 MHz */
mega = 1000000;
for(i = 0; i < e; i++)
mega /= 10;
/* Channels 1 through 13 are 5 MHz apart, with channel 1 at 2412. */
step = 5 * mega;
c = 1 + (m - 2412 * mega + step / 2) / step;
if(c >= 1 && c <= 13)
return c;
/* Channel 14 is at 2484 MHz */
if(c >= 14 && m < 2484 * mega + step / 2)
return 14;
/* 802.11a channel 36 is at 5180 MHz */
c = 36 + (m - 5180 * mega + step / 2) / step;
if(c >= 34 && c <= 165)
return c;
}
errno = ENOENT;
return -1;
}
int
kernel_interface_channel(const char *ifname, int ifindex)
{
struct iwreq_subset iwreq;
int rc;
memset(&iwreq, 0, sizeof(iwreq));
strncpy(iwreq.ifr_ifrn.ifrn_name, ifname, IFNAMSIZ);
rc = ioctl(dgram_socket, SIOCGIWFREQ, &iwreq);
if(rc >= 0)
return freq_to_chan(&iwreq.u.freq);
else
return -1;
}
/* Return true if we cannot handle disambiguation ourselves. */