Parse Netlink NEW/DELLINK and NEW/DELADDR messages.

Parse link and address information. Also send GETLINK and GETADDR
messages to the Netlink socket, so we get the current state of the
interfaces and addresses.

diff --git a/src/discovery.c b/src/discovery.c
index 5687cc351c50488ae940c34746e63a1a41c57ceb..34b49fa23d86bde1bb2bcf490d3c47499658f2dc 100644 (file)
--- a/src/discovery.c
+++ b/src/discovery.c
@@ -13,6 +13,8 @@
 #include <net/route.h>
 #elif defined(__linux)
 #include <asm/types.h>
+#include <net/if.h>
+#include <linux/if_link.h>
 #include <linux/netlink.h>
 #include <linux/rtnetlink.h>
 #endif
@@ -492,6 +494,100 @@ fail:
 }
 
 #if defined(__linux)
+static void netlink_getlink(int fd) {
+       static const struct {
+               struct nlmsghdr nlm;
+               struct ifinfomsg ifi;
+       } msg = {
+               .nlm.nlmsg_len = NLMSG_LENGTH(sizeof(msg.ifi)),
+               .nlm.nlmsg_type = RTM_GETLINK,
+               .nlm.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
+               .nlm.nlmsg_seq = 1,
+               .ifi.ifi_family = AF_UNSPEC,
+       };
+       send(fd, &msg, msg.nlm.nlmsg_len, 0);
+}
+
+static void netlink_getaddr(int fd) {
+       static const struct {
+               struct nlmsghdr nlm;
+               struct ifaddrmsg ifa;
+       } msg = {
+               .nlm.nlmsg_len = NLMSG_LENGTH(sizeof(msg.ifa)),
+               .nlm.nlmsg_type = RTM_GETADDR,
+               .nlm.nlmsg_flags = NLM_F_DUMP | NLM_F_REQUEST,
+               .nlm.nlmsg_seq = 2,
+               .ifa.ifa_family = AF_UNSPEC,
+       };
+       send(fd, &msg, msg.nlm.nlmsg_len, 0);
+}
+
+static void netlink_parse_link(meshlink_handle_t *mesh, const struct nlmsghdr *nlm) {
+       const struct ifinfomsg *ifi = (const struct ifinfomsg *)(nlm + 1);
+
+       if(ifi->ifi_flags & IFF_UP && ifi->ifi_flags & IFF_MULTICAST) {
+               logger(mesh, MESHLINK_INFO, "iface %d active\n", ifi->ifi_index);
+       } else {
+               logger(mesh, MESHLINK_INFO, "iface %d inactive\n", ifi->ifi_index);
+       }
+}
+
+static void netlink_parse_addr(meshlink_handle_t *mesh, const struct nlmsghdr *nlm) {
+       const struct ifaddrmsg *ifa = (const struct ifaddrmsg *)(nlm + 1);
+       const uint8_t *ptr = (const uint8_t *)(ifa + 1);
+       size_t len = nlm->nlmsg_len - (ptr - (const uint8_t *)nlm);
+
+       while(len >= sizeof(struct rtattr)) {
+               const struct rtattr *rta = (const struct rtattr *)ptr;
+
+               if(rta->rta_len <= 0 || rta->rta_len > len) {
+                       break;
+               }
+
+               if(rta->rta_type == IFA_ADDRESS) {
+                       char dest[40] = "?";
+
+                       if(rta->rta_len == 8) {
+                               inet_ntop(AF_INET, ptr + 4, dest, sizeof dest);
+                       } else if(rta->rta_len == 20) {
+                               inet_ntop(AF_INET6, ptr + 4, dest, sizeof dest);
+                       }
+
+                       logger(mesh, MESHLINK_INFO, "iface %d address %s %s\n", ifa->ifa_index, dest, nlm->nlmsg_type == RTM_NEWADDR ? "new" : "del");
+               }
+
+               unsigned short rta_len = (rta->rta_len + 3) & ~3;
+               ptr += rta_len;
+               len -= rta_len;
+       }
+}
+
+static void netlink_parse(meshlink_handle_t *mesh, const void *data, size_t len) {
+       const uint8_t *ptr = data;
+
+       while(len >= sizeof(struct nlmsghdr)) {
+               const struct nlmsghdr *nlm = (const struct nlmsghdr *)ptr;
+
+               if(nlm->nlmsg_len > len) {
+                       break;
+               }
+
+               switch(nlm->nlmsg_type) {
+               case RTM_NEWLINK:
+               case RTM_DELLINK:
+                       netlink_parse_link(mesh, nlm);
+                       break;
+
+               case RTM_NEWADDR:
+               case RTM_DELADDR:
+                       netlink_parse_addr(mesh, nlm);
+               }
+
+               ptr += nlm->nlmsg_len;
+               len -= nlm->nlmsg_len;
+       }
+}
+
 static void netlink_io_handler(event_loop_t *loop, void *data, int flags) {
        (void)flags;
        static time_t prev_update;
@@ -499,7 +595,7 @@ static void netlink_io_handler(event_loop_t *loop, void *data, int flags) {
 
        struct {
                struct nlmsghdr nlm;
-               char data[2048];
+               char data[16384];
        } msg;
 
        while(true) {
@@ -519,20 +615,18 @@ static void netlink_io_handler(event_loop_t *loop, void *data, int flags) {
                        break;
                }
 
-               switch(msg.nlm.nlmsg_type) {
-               case RTM_NEWLINK:
-               case RTM_DELLINK:
-               case RTM_NEWADDR:
-               case RTM_DELADDR:
+               if(msg.nlm.nlmsg_type == NLMSG_DONE) {
+                       if(msg.nlm.nlmsg_seq == 1) {
+                               // We just got the result of GETLINK, now send GETADDR.
+                               netlink_getaddr(mesh->pfroute_io.fd);
+                       }
+               } else {
+                       netlink_parse(mesh, &msg, result);
+
                        if(loop->now.tv_sec > prev_update + 5) {
                                prev_update = loop->now.tv_sec;
                                handle_network_change(mesh, 1);
                        }
-
-                       break;
-
-               default:
-                       break;
                }
        }
 }
@@ -621,6 +715,7 @@ bool discovery_start(meshlink_handle_t *mesh) {
 
                if(bind(sock, (struct sockaddr *)&sa, sizeof(sa)) != -1) {
                        io_add(&mesh->loop, &mesh->pfroute_io, netlink_io_handler, mesh, sock, IO_READ);
+                       netlink_getlink(sock);
                } else {
                        logger(mesh, MESHLINK_WARNING, "Could not bind AF_NETLINK socket: %s", strerror(errno));
                }