Commit b982b6db authored by Martin Mareš's avatar Martin Mareš

Implemented netlink protocol parsing functions. More to come tomorrow.

parent b4b3b39e
......@@ -21,8 +21,7 @@ Core
- broadcast/multicast echoing suppresion
- we need ifindex at least for PtP links
- kernel: RTM_F_NOTIFY seems to be unimplemented
- kernel: RTM_DELROUTE not announced for device routes
- kernel: RTM_DELROUTE not announced for device routes [confirmed by Alexey: it's a feature]
- netlink: import Linux route attributes to our rta's, so that they can be filtered?
......@@ -35,6 +34,7 @@ Cleanup
- check log calls for trailing newlines
- check if all protocols set proper packet priorities and TTL's.
- replace all NUM's by expr's
- try compiling with -Wunused
Various ideas
~~~~~~~~~~~~~
......
......@@ -10,6 +10,11 @@
#include <stdio.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <sys/uio.h>
#define LOCAL_DEBUG
#undef ASYNC_NETLINK /* Define if async notifications should be used (debug) */
#include "nest/bird.h"
#include "nest/route.h"
......@@ -18,6 +23,7 @@
#include "lib/timer.h"
#include "lib/unix.h"
#include "lib/krt.h"
#include "lib/socket.h"
/*
* We need to work around namespace conflicts between us and the kernel,
......@@ -35,10 +41,218 @@
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#define LOCAL_DEBUG
#ifndef MSG_TRUNC /* FIXME: Hack to circumvent omissions in glibc includes */
#define MSG_TRUNC 0x20
#endif
struct proto_config *cf_krt;
/*
* Synchronous Netlink interface
*/
static int nl_sync_fd; /* Unix socket for synchronous netlink actions */
static u32 nl_sync_seq; /* Sequence number of last request sent */
static byte *nl_rx_buffer; /* Receive buffer */
static int nl_rx_size = 8192;
static struct nlmsghdr *nl_last_hdr; /* Recently received packet */
static unsigned int nl_last_size;
static void
nl_send(void *rq, int size)
{
struct nlmsghdr *nh = rq;
struct sockaddr_nl sa;
memset(&sa, 0, sizeof(sa));
sa.nl_family = AF_NETLINK;
nh->nlmsg_len = size;
nh->nlmsg_pid = 0;
nh->nlmsg_seq = ++nl_sync_seq;
if (sendto(nl_sync_fd, rq, size, 0, (struct sockaddr *)&sa, sizeof(sa)) < 0)
die("rtnetlink sendto: %m");
nl_last_hdr = NULL;
}
static void
nl_request_dump(int cmd)
{
struct {
struct nlmsghdr nh;
struct rtgenmsg g;
} req;
req.nh.nlmsg_type = cmd;
req.nh.nlmsg_flags = NLM_F_REQUEST | NLM_F_DUMP;
req.g.rtgen_family = PF_INET;
nl_send(&req, sizeof(req));
}
static struct nlmsghdr *
nl_get_reply(void)
{
for(;;)
{
if (!nl_last_hdr)
{
struct iovec iov = { nl_rx_buffer, nl_rx_size };
struct sockaddr_nl sa;
struct msghdr m = { (struct sockaddr *) &sa, sizeof(sa), &iov, 1, NULL, 0, 0 };
int x = recvmsg(nl_sync_fd, &m, 0);
if (x < 0)
die("nl_get_reply: %m");
nl_last_size = x;
nl_last_hdr = (void *) nl_rx_buffer;
if (m.msg_flags & MSG_TRUNC)
bug("nl_get_reply: got truncated reply which should be impossible");
}
if (NLMSG_OK(nl_last_hdr, nl_last_size))
{
struct nlmsghdr *h = nl_last_hdr;
if (h->nlmsg_seq != nl_sync_seq)
{
log(L_WARN "nl_get_reply: Ignoring out of sequence netlink packet (%x != %x)",
h->nlmsg_seq, nl_sync_seq);
continue;
}
nl_last_hdr = NLMSG_NEXT(h, nl_last_size);
return h;
}
if (nl_last_size)
log(L_WARN "nl_get_reply: Found packet remnant of size %d", nl_last_size);
nl_last_hdr = NULL;
}
}
static char *
nl_error(struct nlmsghdr *h)
{
struct nlmsgerr *e = NLMSG_DATA(h);
if (h->nlmsg_len < NLMSG_LENGTH(sizeof(struct nlmsgerr)))
return "Error message truncated";
else
return strerror(-e->error);
}
static struct nlmsghdr *
nl_get_scan(void)
{
struct nlmsghdr *h = nl_get_reply();
if (h->nlmsg_type == NLMSG_DONE)
return NULL;
if (h->nlmsg_type == NLMSG_ERROR)
{
log(L_ERR "Netlink error: %s", nl_error(h));
return NULL;
}
return h;
}
/*
* Parsing of Netlink attributes
*/
static int nl_attr_len;
static void *
nl_checkin(struct nlmsghdr *h, int lsize)
{
nl_attr_len = h->nlmsg_len - NLMSG_LENGTH(lsize);
if (nl_attr_len < 0)
{
log(L_ERR "nl_checkin: underrun by %d bytes", -nl_attr_len);
return NULL;
}
return NLMSG_DATA(h);
}
static int
nl_parse_attrs(struct rtattr *a, struct rtattr **k, int ksize)
{
int max = ksize / sizeof(struct rtattr *);
bzero(k, ksize);
while (RTA_OK(a, nl_attr_len))
{
if (a->rta_type < max)
k[a->rta_type] = a;
a = RTA_NEXT(a, nl_attr_len);
}
if (nl_attr_len)
{
log(L_ERR "nl_parse_attrs: remnant of size %d", nl_attr_len);
return 0;
}
else
return 1;
}
/*
* Scanning of interfaces
*/
static void
nl_parse_link(struct nlmsghdr *h)
{
struct ifinfomsg *i;
struct rtattr *a[IFLA_STATS+1];
if (!(i = nl_checkin(h, sizeof(*i))) || !nl_parse_attrs(IFLA_RTA(i), a, sizeof(a)))
return;
DBG("NEWLINK %d\n", i->ifi_index);
}
static void
nl_parse_addr(struct nlmsghdr *h)
{
struct ifaddrmsg *i;
struct rtattr *a[IFA_ANYCAST+1];
if (!(i = nl_checkin(h, sizeof(*i))) || !nl_parse_attrs(IFA_RTA(i), a, sizeof(a)))
return;
DBG("NEWADDR %d\n", i->ifa_index);
}
static void
nl_scan_ifaces(void)
{
struct nlmsghdr *h;
nl_request_dump(RTM_GETLINK);
while (h = nl_get_scan())
if (h->nlmsg_type == RTM_NEWLINK || h->nlmsg_type == RTM_DELLINK)
nl_parse_link(h);
else
log(L_DEBUG "nl_scan_ifaces: Unknown packet received (type=%d)", h->nlmsg_type);
nl_request_dump(RTM_GETADDR);
while (h = nl_get_scan())
if (h->nlmsg_type == RTM_NEWADDR || h->nlmsg_type == RTM_DELADDR)
nl_parse_addr(h);
else
log(L_DEBUG "nl_scan_ifaces: Unknown packet received (type=%d)", h->nlmsg_type);
bug("NIIDW");
}
/*
* Asynchronous Netlink interface
*/
static sock *nl_async_sk; /* BIRD socket for asynchronous notifications */
static int
nl_async_hook(sock *sk, int size)
{
DBG("nl_async_hook\n");
return 0;
}
/*
* Protocol core
*/
static void
krt_preconfig(struct protocol *x, struct config *c)
{
......@@ -56,9 +270,33 @@ krt_init(struct proto_config *c)
return &p->p;
}
static void
nl_open_async(struct proto *p)
{
sock *sk;
struct sockaddr_nl sa;
sk = nl_async_sk = sk_new(p->pool);
sk->type = SK_MAGIC;
sk->rx_hook = nl_async_hook;
sk->fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
if (sk->fd < 0 || sk_open(sk))
die("Unable to open secondary rtnetlink socket: %m");
bzero(&sa, sizeof(sa));
sa.nl_family = AF_NETLINK;
sa.nl_groups = RTMGRP_LINK | RTMGRP_IPV4_IFADDR | RTMGRP_IPV4_ROUTE;
if (bind(sk->fd, (struct sockaddr *) &sa, sizeof(sa)) < 0)
die("Unable to bind secondary rtnetlink socket: %m");
}
static int
krt_start(struct proto *p)
{
#ifdef ASYNC_NETLINK
nl_open_async(p);
#endif
/* FIXME: Filter kernel routing table etc. */
return PS_UP;
......@@ -75,7 +313,14 @@ krt_shutdown(struct proto *p)
void
scan_if_init(void)
{
/* FIXME: What to do here? */
nl_sync_fd = socket(PF_NETLINK, SOCK_RAW, NETLINK_ROUTE);
if (nl_sync_fd < 0)
die("Unable to open rtnetlink socket: %m");
nl_sync_seq = now;
nl_rx_buffer = xmalloc(nl_rx_size);
/* FIXME: Should we fetch our local address and compare it with addresses of all incoming messages? */
nl_scan_ifaces();
}
struct protocol proto_unix_kernel = {
......
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