Add a perform_ip_subnet_bcast() function that uses Linux netlink sockets
to set the interface ip, subnet, and broadcast address simultaneously. The advantage of this approach is that a single netlink notification will be sent rather than multiple messages as the ip, subnet, and broadcast address are set one at a time. Currently this function is not used, as it will require a wire format change that will be introduced in a subsequent commit.
This commit is contained in:
Nicholas J. Kain
parent
81a9fe1c8e
commit
06b65de08c
188
ifchd/linux.c
188
ifchd/linux.c
@ -40,6 +40,8 @@
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#include <net/route.h>
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#include <net/if.h>
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#include <netpacket/packet.h>
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#include <linux/netlink.h>
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#include <linux/rtnetlink.h>
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#include <pwd.h>
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#include <grp.h>
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@ -151,6 +153,192 @@ static int set_if_flag(struct ifchd_client *cl, short flag)
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return ret;
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}
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#define NLMSG_TAIL(nmsg) \
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((struct rtattr *) (((uint8_t*) (nmsg)) + \
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NLMSG_ALIGN((nmsg)->nlmsg_len)))
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static int add_rtattr(struct nlmsghdr *n, size_t max_length, int type,
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const void *data, size_t data_length)
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{
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size_t length;
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struct rtattr *rta;
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length = RTA_LENGTH(data_length);
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if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(length) > max_length)
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return -E2BIG;
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rta = NLMSG_TAIL(n);
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rta->rta_type = type;
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rta->rta_len = length;
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memcpy(RTA_DATA(rta), data, data_length);
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n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(length);
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return 0;
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}
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static int get_ifindex(const char *name)
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{
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struct ifreq ifr;
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int sk, err;
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if (!name)
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return -1;
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sk = socket(PF_INET, SOCK_DGRAM, 0);
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if (sk < 0)
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return -1;
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memset(&ifr, 0, sizeof ifr);
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strnkcpy(ifr.ifr_name, name, sizeof ifr.ifr_name);
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err = ioctl(sk, SIOCGIFINDEX, &ifr);
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close(sk);
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if (err < 0)
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return -1;
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return ifr.ifr_ifindex;
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}
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// 32-bit position values are relatively prime to 37, so the residue mod37
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// gives a unique mapping for each value. Gives correct result for v=0.
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static int trailz(uint32_t v)
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{
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static const int bpm37[] = {
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32, 0, 1, 26, 2, 23, 27, 0, 3, 16, 24, 30, 28, 11, 0, 13, 4, 7, 17,
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0, 25, 22, 31, 15, 29, 10, 12, 6, 0, 21, 14, 9, 5, 20, 8, 19, 18
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};
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return bpm37[(-v & v) % 37];
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}
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// sn must be in network order
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static inline int subnet4_to_prefixlen(uint32_t sn)
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{
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return 32 - trailz(sn);
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}
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// str_bcast is optional.
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void perform_ip_subnet_bcast(struct ifchd_client *cl,
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const char *str_ipaddr,
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const char *str_subnet,
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const char *str_bcast)
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{
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uint8_t request[NLMSG_ALIGN(sizeof(struct nlmsghdr)) +
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NLMSG_ALIGN(sizeof(struct ifaddrmsg)) +
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RTA_LENGTH(sizeof(struct in6_addr))];
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struct in_addr ipaddr, subnet, bcast;
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struct sockaddr_nl nl_addr;
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struct nlmsghdr *header;
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struct ifaddrmsg *ifaddrmsg;
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int nls, ifidx, r;
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uint8_t prefixlen;
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if (!str_ipaddr) {
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log_line("%s: (%s) interface ip address is NULL",
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cl->ifnam, __func__);
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return;
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}
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if (!str_subnet) {
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log_line("%s: (%s) interface subnet address is NULL",
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cl->ifnam, __func__);
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return;
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}
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if (!is_permitted(cl->ifnam))
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return;
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ifidx = get_ifindex(cl->ifnam);
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if (ifidx < 0) {
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log_line("%s: (%s) can't get interface index",
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cl->ifnam, __func__);
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return;
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}
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if (inet_pton(AF_INET, str_ipaddr, &ipaddr) <= 0) {
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log_line("%s: (%s) bad interface ip address: '%s'",
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cl->ifnam, __func__, str_ipaddr);
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return;
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}
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if (inet_pton(AF_INET, str_subnet, &subnet) <= 0) {
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log_line("%s: (%s) bad interface subnet address: '%s'",
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cl->ifnam, __func__, str_subnet);
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return;
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}
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prefixlen = subnet4_to_prefixlen(subnet.s_addr);
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if (str_bcast) {
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if (inet_pton(AF_INET, str_bcast, &bcast) <= 0) {
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log_line("%s: (%s) bad interface broadcast address: '%s'",
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cl->ifnam, __func__, str_bcast);
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return;
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}
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} else {
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// Generate the standard broadcast address if unspecified.
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bcast.s_addr = ipaddr.s_addr | htonl(0xfffffffflu >> prefixlen);
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}
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memset(&request, 0, sizeof request);
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header = (struct nlmsghdr *)request;
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header->nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));
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header->nlmsg_type = RTM_NEWADDR;
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header->nlmsg_flags = NLM_F_REPLACE | NLM_F_ACK | NLM_F_REQUEST;
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header->nlmsg_seq = 1;
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ifaddrmsg = NLMSG_DATA(header);
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ifaddrmsg->ifa_family = AF_INET;
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ifaddrmsg->ifa_prefixlen = prefixlen;
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ifaddrmsg->ifa_flags = IFA_F_PERMANENT;
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ifaddrmsg->ifa_scope = RT_SCOPE_UNIVERSE;
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ifaddrmsg->ifa_index = ifidx;
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if (add_rtattr(header, sizeof request, IFA_LOCAL,
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&ipaddr, sizeof ipaddr) < 0) {
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log_line("%s: (%s) couldn't add IFA_LOCAL to nlmsg",
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cl->ifnam, __func__);
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return;
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}
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if (add_rtattr(header, sizeof request, IFA_BROADCAST,
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&bcast, sizeof bcast) < 0) {
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log_line("%s: (%s) couldn't add IFA_BROADCAST to nlmsg",
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cl->ifnam, __func__);
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return;
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}
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nls = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
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if (nls < 0) {
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log_line("%s: (%s) netlink socket open failed: %s",
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cl->ifnam, __func__, strerror(errno));
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return;
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}
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memset(&nl_addr, 0, sizeof nl_addr);
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nl_addr.nl_family = AF_NETLINK;
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retry_sendto:
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r = sendto(nls, request, header->nlmsg_len, 0,
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(struct sockaddr *)&nl_addr, sizeof nl_addr);
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if (r < 0) {
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if (errno == EINTR)
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goto retry_sendto;
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else {
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log_line("%s: (%s) netlink sendto socket failed: %s",
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cl->ifnam, __func__, strerror(errno));
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close(nls);
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return;
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}
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}
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close(nls);
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log_line("Interface IP set to: '%s'", str_ipaddr);
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log_line("Interface subnet set to: '%s'", str_subnet);
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if (str_bcast)
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log_line("Broadcast address set to: '%s'", str_bcast);
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// XXX: Would be nice to do this via netlink, too.
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if (set_if_flag(cl, (IFF_UP | IFF_RUNNING)))
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return;
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}
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/* Sets IP address on an interface and brings it up. */
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void perform_ip(struct ifchd_client *cl, const char *str, size_t len)
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{
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