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When setting the MTU via netlink, we must be careful to preserve the link

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flags or bad things will happen (such as the link being set down).
This commit is contained in:
Nicholas J. Kain 2014-03-17 03:16:02 -04:00
parent 6fcc43d169
commit 03bd10ed88
1 changed files with 38 additions and 29 deletions
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67
ndhc/ifset.c
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@ -182,35 +182,6 @@ static ssize_t rtnl_if_flags_send(int fd, int type, int ifi_flags)
return rtnl_do_send(fd, request, header->nlmsg_len, __func__);
}
static ssize_t rtnl_if_mtu_set(int fd, unsigned int mtu)
{
uint8_t request[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
NLMSG_ALIGN(sizeof(struct ifinfomsg)) +
RTA_LENGTH(sizeof(unsigned int))];
struct nlmsghdr *header;
struct ifinfomsg *ifinfomsg;
memset(&request, 0, sizeof request);
header = (struct nlmsghdr *)request;
header->nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
header->nlmsg_type = RTM_SETLINK;
header->nlmsg_flags = NLM_F_ACK | NLM_F_REQUEST;
header->nlmsg_seq = ifset_nl_seq++;
ifinfomsg = NLMSG_DATA(header);
ifinfomsg->ifi_index = client_config.ifindex;
ifinfomsg->ifi_change = 0xffffffff;
if (nl_add_rtattr(header, sizeof request, IFLA_MTU,
&mtu, sizeof mtu) < 0) {
log_line("%s: (%s) couldn't add IFLA_MTU to nlmsg",
client_config.interface, __func__);
return -1;
}
return rtnl_do_send(fd, request, header->nlmsg_len, __func__);
}
static ssize_t rtnl_addr_broadcast_send(int fd, int type, int ifa_flags,
int ifa_scope, uint32_t *ipaddr,
uint32_t *bcast, uint8_t prefixlen)
@ -468,6 +439,44 @@ static int ipbcpfx_clear_others(int fd, uint32_t ipaddr, uint32_t bcast,
return ipx.already_ok ? 1 : 0;
}
static ssize_t rtnl_if_mtu_set(int fd, unsigned int mtu)
{
uint8_t request[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
NLMSG_ALIGN(sizeof(struct ifinfomsg)) +
RTA_LENGTH(sizeof(unsigned int))];
struct nlmsghdr *header;
struct ifinfomsg *ifinfomsg;
uint32_t oldflags;
int r = link_flags_get(fd, &oldflags);
if (r < 0) {
log_line("%s: (%s) failed to get old link flags: %u",
client_config.interface, __func__, r);
return -1;
}
memset(&request, 0, sizeof request);
header = (struct nlmsghdr *)request;
header->nlmsg_len = NLMSG_LENGTH(sizeof(struct ifinfomsg));
header->nlmsg_type = RTM_SETLINK;
header->nlmsg_flags = NLM_F_ACK | NLM_F_REQUEST;
header->nlmsg_seq = ifset_nl_seq++;
ifinfomsg = NLMSG_DATA(header);
ifinfomsg->ifi_flags = oldflags;
ifinfomsg->ifi_index = client_config.ifindex;
ifinfomsg->ifi_change = 0xffffffff;
if (nl_add_rtattr(header, sizeof request, IFLA_MTU,
&mtu, sizeof mtu) < 0) {
log_line("%s: (%s) couldn't add IFLA_MTU to nlmsg",
client_config.interface, __func__);
return -1;
}
return rtnl_do_send(fd, request, header->nlmsg_len, __func__);
}
// str_bcast is optional.
void perform_ip_subnet_bcast(const char *str_ipaddr,
const char *str_subnet, const char *str_bcast)