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Netlink is pickier than the ioctl interfaces and requires the link to

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manually be set to an 'up' state before much of anything can be changed.
Ensure that this is done very early in ndhc's lifetime, and record the
link status at startup time so that the hardware link status monitoring
will not get confused.  A perform_ifup() function is added to faciliate
this need.

Handle nl_getifdata() and get_if_index_and_mac() separately from the
hardware link status monitoring; don't call get_if_index_and_mac() from
nl_process_msgs().

Create the permanent ndhc-master cs.nlFd socket for hardware link status
monitoring after forking subprocesses.
This commit is contained in:
Nicholas J. Kain
2014-03-17 05:56:30 -04:00
parent 13aa5e6403
commit 22fede861f
5 changed files with 117 additions and 45 deletions
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119
ndhc/netlink.c
View File

@ -26,6 +26,7 @@
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <unistd.h>
#include <arpa/inet.h>
#include <assert.h>
#include <asm/types.h>
@ -51,33 +52,6 @@ static int nlattr_assign(struct nlattr *attr, int type, void *data)
return 0;
}
static void get_if_index_and_mac(const struct nlmsghdr *nlh,
struct ifinfomsg *ifm)
{
struct nlattr *tb[IFLA_MAX] = {0};
nl_attr_parse(nlh, sizeof *ifm, nlattr_assign, tb);
if (!tb[IFLA_IFNAME])
return;
if (!strncmp(client_config.interface,
nlattr_get_data(tb[IFLA_IFNAME]),
sizeof client_config.interface)) {
client_config.ifindex = ifm->ifi_index;
if (!tb[IFLA_ADDRESS])
suicide("FATAL: Adapter %s lacks a hardware address.");
int maclen = nlattr_get_len(tb[IFLA_ADDRESS]) - 4;
if (maclen != 6)
suicide("FATAL: Adapter hardware address length should be 6, but is %u.",
maclen);
const unsigned char *mac =
(unsigned char *)nlattr_get_data(tb[IFLA_ADDRESS]);
log_line("%s hardware address %x:%x:%x:%x:%x:%x",
client_config.interface,
mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
memcpy(client_config.arp, mac, 6);
}
}
static void nl_process_msgs(const struct nlmsghdr *nlh, void *data)
{
struct ifinfomsg *ifm = nlmsg_get_data(nlh);
@ -85,8 +59,6 @@ static void nl_process_msgs(const struct nlmsghdr *nlh, void *data)
switch(nlh->nlmsg_type) {
case RTM_NEWLINK:
if (!client_config.ifindex)
get_if_index_and_mac(nlh, ifm);
if (ifm->ifi_index != client_config.ifindex)
break;
// IFF_UP corresponds to ifconfig down or ifconfig up.
@ -137,18 +109,89 @@ void handle_nl_message(struct client_state_t *cs)
} while (ret > 0);
}
int nl_getifdata(struct client_state_t *cs)
static int get_if_index_and_mac(const struct nlmsghdr *nlh,
struct ifinfomsg *ifm)
{
if (nl_sendgetlinks(cs->nlFd, time(NULL)))
return -1;
struct nlattr *tb[IFLA_MAX] = {0};
nl_attr_parse(nlh, sizeof *ifm, nlattr_assign, tb);
if (tb[IFLA_IFNAME] && !strncmp(client_config.interface,
nlattr_get_data(tb[IFLA_IFNAME]),
sizeof client_config.interface)) {
client_config.ifindex = ifm->ifi_index;
if (!tb[IFLA_ADDRESS])
suicide("FATAL: Adapter %s lacks a hardware address.");
int maclen = nlattr_get_len(tb[IFLA_ADDRESS]) - 4;
if (maclen != 6)
suicide("FATAL: Adapter hardware address length should be 6, but is %u.",
maclen);
for (int pr = 0; !pr;) {
pr = poll(&((struct pollfd){.fd=cs->nlFd,.events=POLLIN}), 1, -1);
if (pr == 1)
handle_nl_message(cs);
else if (pr == -1)
suicide("nl: poll failed");
const unsigned char *mac =
(unsigned char *)nlattr_get_data(tb[IFLA_ADDRESS]);
log_line("%s hardware address %x:%x:%x:%x:%x:%x",
client_config.interface,
mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
memcpy(client_config.arp, mac, 6);
return 1;
}
return 0;
}
static void do_handle_getifdata(const struct nlmsghdr *nlh, void *data)
{
int *got_ifdata = (int *)data;
struct ifinfomsg *ifm = nlmsg_get_data(nlh);
switch(nlh->nlmsg_type) {
case RTM_NEWLINK:
*got_ifdata |= get_if_index_and_mac(nlh, ifm);
break;
default:
break;
}
}
static int handle_getifdata(int fd)
{
char nlbuf[8192];
ssize_t ret;
int got_ifdata = 0;
do {
ret = nl_recv_buf(fd, nlbuf, sizeof nlbuf);
if (ret == -1)
return -1;
if (nl_foreach_nlmsg(nlbuf, ret, 0, 0,
do_handle_getifdata, &got_ifdata) == -1)
return -1;
} while (ret > 0);
return got_ifdata ? 0 : -1;
}
int nl_getifdata(void)
{
int ret = -1;
int fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
if (fd < 0) {
log_line("%s: (%s) netlink socket open failed: %s",
client_config.interface, __func__, strerror(errno));
goto fail;
}
if (nl_sendgetlinks(fd, time(NULL))) {
log_line("%s: (%s) nl_sendgetlinks failed",
client_config.interface, __func__);
goto fail_fd;
}
for (int pr = 0; !pr;) {
pr = poll(&((struct pollfd){.fd=fd,.events=POLLIN}), 1, -1);
if (pr == 1)
ret = handle_getifdata(fd);
else if (pr == -1 && errno != EINTR)
goto fail_fd;
}
fail_fd:
close(fd);
fail:
return ret;
}