Use netlink for getting interface mac and index in ndhc instead of ioctl.

ndhc/CMakeLists.txt

@@ -11,6 +11,7 @@ set(NDHC_SRCS
   ifchange.c
   dhcpmsg.c
   arp.c
+  netlink.c
   ndhc.c
   )
 

ndhc/ndhc.c

@@ -52,6 +52,8 @@
 #include "ifchange.h"
 #include "socket.h"
 #include "arp.h"
+#include "netlink.h"
+
 #include "log.h"
 #include "chroot.h"
 #include "cap.h"
@@ -361,9 +363,14 @@ int main(int argc, char **argv)
         write_pid(pidfile);
     }
 
-    if (read_interface(client_config.interface, &client_config.ifindex,
-                       NULL, client_config.arp) < 0)
+    if (nl_open() < 0) {
+        log_line("FATAL - failed to open netlink socket");
         exit(EXIT_FAILURE);
+    }
+    if (nl_getifdata(client_config.interface) < 0) {
+        log_line("FATAL - failed to get interface MAC and index");
+        exit(EXIT_FAILURE);
+    }
 
     if (!client_config.clientid) {
         client_config.clientid = xmalloc(6 + 3);
@@ -391,5 +398,6 @@ int main(int argc, char **argv)
 
     do_work();
 
+    nl_close();
     return EXIT_SUCCESS;
 }

ndhc/netlink.c

@@ -0,0 +1,217 @@
+/*
+ * Copyright 2011 Nicholas J. Kain <njkain@gmail.com>
+ * Copyright 2006, 2007 Stefan Rompf <sux@loplof.de>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation
+ *
+ */
+
+#include <arpa/inet.h>
+#include <assert.h>
+#include <asm/types.h>
+#include <sys/socket.h>
+#include <linux/netlink.h>
+#include <linux/rtnetlink.h>
+#include <unistd.h>
+#include <net/if.h>
+#include <stdio.h>
+#include <strings.h>
+#include <string.h>
+#include <sys/select.h>
+#include <fcntl.h>
+
+#include "netlink.h"
+#include "config.h"
+#include "log.h"
+
+// OS_REMOVED -> exit
+// OS_SHUT -> exit
+// OS_DOWN -> action
+// OS_UP -> action
+
+#define NLMSG_RECVSIZE 8192
+
+static int nl_socket = -1;
+static unsigned int nl_seq;
+
+/* internal callback handling */
+static void (*nlcb_function)(struct nlmsghdr *msg, void **args);
+static void *nlcb_args[3];
+static __u32 nlcb_pid;
+static unsigned int nlcb_seq;
+static char nlcb_run;
+
+int nl_open() {
+    struct sockaddr_nl nlsock = {
+        .nl_family = AF_NETLINK,
+        .nl_pad = 0,
+        .nl_pid = getpid(),
+        .nl_groups = RTMGRP_LINK
+    };
+
+    nlcb_pid = nlsock.nl_pid;
+
+    assert(nl_socket == -1);
+
+    nl_socket = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_ROUTE);
+
+    if (nl_socket == -1) return -1;
+
+    if (bind(nl_socket, (const struct sockaddr *)&nlsock, sizeof(nlsock)))
+        goto err_close;
+
+    if (fcntl(nl_socket, F_SETFD, FD_CLOEXEC))
+        goto err_close;
+
+    return 0;
+
+  err_close:
+    nl_close();
+    return -1;
+}
+
+void nl_close() {
+    close(nl_socket);
+    nl_socket = -1;
+}
+
+void nl_queryifstatus(int ifidx) {
+    struct {
+        struct nlmsghdr hdr;
+        struct ifinfomsg ifinfo;
+    } req;
+
+    req.hdr.nlmsg_len = sizeof(req);
+    req.hdr.nlmsg_type = RTM_GETLINK;
+    req.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_ROOT;
+    req.hdr.nlmsg_seq = ++nl_seq;
+    req.hdr.nlmsg_pid = nlcb_pid;
+    req.ifinfo.ifi_family = AF_UNSPEC;
+    req.ifinfo.ifi_index = ifidx; /* Doesn't work... */
+    req.ifinfo.ifi_flags = IFF_UP;
+    req.ifinfo.ifi_change = 0xffffffff;
+
+    send(nl_socket, &req, sizeof(req),0);
+}
+
+
+static void nl_handlemsg(struct nlmsghdr *msg, unsigned int len) {
+    if (len < sizeof(*msg)) return;
+
+    while(NLMSG_OK(msg,len)) {
+        if (nlcb_run &&
+            nlcb_pid == msg->nlmsg_pid &&
+            nlcb_seq == msg->nlmsg_seq) {
+            nlcb_function(msg, nlcb_args);
+
+            if (msg->nlmsg_type == NLMSG_DONE ||
+                msg->nlmsg_type == NLMSG_ERROR) nlcb_run = 0;
+        }
+
+        if (NLMSG_PAYLOAD(msg, msg->nlmsg_len) >= sizeof(struct ifinfomsg)) {
+            struct ifinfomsg *ifinfo = NLMSG_DATA(msg);
+
+            switch(msg->nlmsg_type) {
+                case RTM_NEWLINK:
+                    if (ifinfo->ifi_index != client_config.ifindex)
+                        break;
+                    if (ifinfo->ifi_flags & IFF_UP) {
+                        if (ifinfo->ifi_flags & IFF_RUNNING)
+                            printf("XXX_OS_UP() NYI\n");
+                        else
+                            printf("XXX_OS_DOWN() NYI\n");
+                    } else
+                        printf("XXX_OS_SHUT() NYI\n");
+                    break;
+                case RTM_DELLINK:
+                    if (ifinfo->ifi_index != client_config.ifindex)
+                        break;
+                    printf("XXX_OS_REMOVED() NYI\n");
+                    break;
+                default:
+                    break;
+            }
+        }
+        msg = NLMSG_NEXT(msg,len);
+    }
+}
+
+static void nl_sync_dump() {
+    char c[NLMSG_RECVSIZE];
+    struct nlmsghdr *msg = (struct nlmsghdr *)c;
+    int n;
+
+    nlcb_seq = nl_seq;
+    for(nlcb_run = 1; nlcb_run;) {
+        n = recv(nl_socket, c, NLMSG_RECVSIZE, 0);
+        assert(n >= 0);
+        nl_handlemsg(msg,n);
+    }
+}
+
+// Callback function for getting interface mac address and index.
+static void copy_ifdata(struct nlmsghdr *msg, void **args) {
+    struct ifinfomsg *ifinfo = NLMSG_DATA(msg);
+    struct rtattr *rta = IFLA_RTA(ifinfo);
+    int len = NLMSG_PAYLOAD(msg, sizeof(*ifinfo));
+    int found = 0;
+
+    if (msg->nlmsg_type != RTM_NEWLINK)
+        return;
+    if (client_config.ifindex)
+        return;
+
+    for(; RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) {
+        switch(rta->rta_type) {
+            case IFLA_IFNAME:
+                if (!strncmp(client_config.interface,
+                             (char *)RTA_DATA(rta), RTA_PAYLOAD(rta))) {
+                    client_config.ifindex = ifinfo->ifi_index;
+                    log_line("adapter index %d", ifinfo->ifi_index);
+                    found |= 1;
+                }
+                break;
+            case IFLA_ADDRESS:
+                if (found != 1)
+                    break;
+                /* We can only handle ethernet like devices with 6 octet MAC */
+                if (RTA_PAYLOAD(rta) == 6) {
+                    memcpy(client_config.arp, RTA_DATA(rta), 6);
+                    log_line("adapter hardware address %02x:%02x:%02x:%02x:%02x:%02x",
+                             client_config.arp[0], client_config.arp[1],
+                             client_config.arp[2], client_config.arp[3],
+                             client_config.arp[4], client_config.arp[5]);
+                    found |= 2;
+                }
+                break;
+        }
+    }
+    if (found == 3)
+        nlcb_args[0] = (void *)1;
+}
+
+// Gets interface mac address and index (synchronous).
+int nl_getifdata(const char *ifname) {
+    struct {
+        struct nlmsghdr hdr;
+        struct ifinfomsg ifinfo;
+    } req;
+
+    req.hdr.nlmsg_len = sizeof(req);
+    req.hdr.nlmsg_type = RTM_GETLINK;
+    req.hdr.nlmsg_flags = NLM_F_REQUEST | NLM_F_ROOT;
+    req.hdr.nlmsg_seq = ++nl_seq;
+    req.hdr.nlmsg_pid = nlcb_pid;
+    req.ifinfo.ifi_family = AF_UNSPEC;
+
+    if (send(nl_socket, &req, sizeof(req), 0) != sizeof(req)) return -1;
+
+    nlcb_function = copy_ifdata;
+    nlcb_args[0] = NULL;
+
+    nl_sync_dump();
+
+    return nlcb_args[0]?0:-1;
+}

ndhc/netlink.h

@@ -0,0 +1,9 @@
+#ifndef NK_NETLINK_H_
+#define NK_NETLINK_H_
+
+int nl_open();
+void nl_close();
+void nl_queryifstatus(int ifidx);
+int nl_getifdata(const char *ifname);
+
+#endif /* NK_NETLINK_H_ */

ndhc/socket.c

@@ -47,57 +47,6 @@ int set_sock_nonblock(int fd)
     return ret;
 }
 
-/* Given an interface name in @interface, return its index number,
- * IPv4 address, and MAC in @ifindex, @addr (optional), and @mac.*/
-int read_interface(char *interface, int *ifindex, uint32_t *addr, uint8_t *mac)
-{
-    int fd, ret = -1;
-    struct ifreq ifr;
-    struct sockaddr_in *our_ip;
-
-    memset(&ifr, 0, sizeof(struct ifreq));
-    if((fd = socket(AF_INET, SOCK_RAW, IPPROTO_RAW)) == -1) {
-        log_error("socket failed!: %s", strerror(errno));
-        goto out;
-    }
-
-    ifr.ifr_addr.sa_family = AF_INET;
-    strlcpy(ifr.ifr_name, interface, IFNAMSIZ);
-
-    if (addr) {
-        if (ioctl(fd, SIOCGIFADDR, &ifr)) {
-            log_error("Couldn't get IP for %s.", strerror(errno));
-            goto out_fd;
-        }
-        our_ip = (struct sockaddr_in *) &ifr.ifr_addr;
-        *addr = our_ip->sin_addr.s_addr;
-        log_line("%s (our ip) = %s", ifr.ifr_name,
-                 inet_ntoa(our_ip->sin_addr));
-    }
-
-    if (ioctl(fd, SIOCGIFINDEX, &ifr)) {
-        log_error("SIOCGIFINDEX failed!: %s", strerror(errno));
-        goto out_fd;
-    }
-
-    log_line("adapter index %d", ifr.ifr_ifindex);
-    *ifindex = ifr.ifr_ifindex;
-
-    if (ioctl(fd, SIOCGIFHWADDR, &ifr)) {
-        log_error("Couldn't get MAC for %s", strerror(errno));
-        goto out_fd;
-    }
-
-    memcpy(mac, ifr.ifr_hwaddr.sa_data, 6);
-    log_line("adapter hardware address %02x:%02x:%02x:%02x:%02x:%02x",
-             mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
-    ret = 0;
-  out_fd:
-    close(fd);
-  out:
-    return ret;
-}
-
 /* Returns fd of new listen socket bound to @ip:@port on interface @inf
  * on success, or -1 on failure. */
 int listen_socket(unsigned int ip, int port, char *inf)

ndhc/socket.h

@@ -4,8 +4,6 @@
 #include <stdint.h>
 
 int set_sock_nonblock(int fd);
-int read_interface(char *interface, int *ifindex, uint32_t *addr,
-                   uint8_t *mac);
 int listen_socket(unsigned int ip, int port, char *inf);
 int raw_socket(int ifindex);