module/network: break out message parsing code

This also allows us to actually handle errors (by aborting run())

modules/network.c

@@ -33,6 +33,10 @@ struct private {
     char *iface;
     struct particle *label;
 
+    int nl_sock;
+
+    bool get_addresses;
+
     int ifindex;
     uint8_t mac[6];
     bool carrier;
@@ -47,6 +51,8 @@ destroy(struct module *mod)
 {
     struct private *m = mod->private;
 
+    assert(m->nl_sock == -1);
+
     m->label->destroy(m->label);
 
     tll_free(m->addrs);
@@ -304,8 +310,10 @@ handle_address(struct module *mod, uint16_t type,
             const void *raw_addr = RTA_DATA(attr);
             size_t addr_len = RTA_PAYLOAD(attr);
 
+#if defined(LOG_ENABLE_DBG) && LOG_ENABLE_DBG
             char s[INET6_ADDRSTRLEN];
             inet_ntop(msg->ifa_family, raw_addr, s, sizeof(s));
+#endif
             LOG_DBG("%s: IFA_ADDRESS: %s", m->iface, s);
 
             mtx_lock(&mod->lock);
@@ -379,63 +387,24 @@ netlink_receive_messages(int sock, void **reply, size_t *len)
     return true;
 }
 
-static int
+static bool
-run(struct module_run_context *ctx)
+process_reply(struct module *mod, const struct nlmsghdr *hdr, size_t len)
 {
-    struct module *mod = ctx->module;
     struct private *m = mod->private;
 
-    module_signal_ready(ctx);
-
-    int nl_sock = netlink_connect();
-    if (nl_sock == -1)
-        return 1;
-
-    if (!send_rt_request(nl_sock, RTM_GETLINK)) {
-        close(nl_sock);
-        return 1;
-    }
-
-    /* We must wait for NLMSG_DONE from the first request, before
-     * sending another one... */
-    bool get_addresses = true;
-
-    /* Main loop */
-    while (true) {
-        struct pollfd fds[] = {
-            {.fd = ctx->abort_fd, .events = POLLIN},
-            {.fd = nl_sock, .events = POLLIN}
-        };
-
-        poll(fds, 2, -1);
-
-        if (fds[0].revents & POLLIN)
-            break;
-
-        if (fds[1].revents & POLLHUP) {
-            LOG_ERR("disconnected from netlink socket");
-            break;
-        }
-
-        assert(fds[1].revents & POLLIN);
-
-        /* Read one (or more) messages */
-        void *reply;
-        size_t len;
-        if (!netlink_receive_messages(nl_sock, &reply, &len))
-            break;
-
     /* Process response */
-        for (const struct nlmsghdr *hdr = (const struct nlmsghdr *)reply;
+    for (; NLMSG_OK(hdr, len); hdr = NLMSG_NEXT(hdr, len)) {
-             NLMSG_OK(hdr, len);
-             hdr = NLMSG_NEXT(hdr, len))
-        {
         switch (hdr->nlmsg_type) {
         case NLMSG_DONE:
+            if (m->ifindex == -1) {
+                LOG_ERR("%s: failed to find interface", m->iface);
+                return false;
+            }
+
             /* Request initial list of IPv4/6 addresses */
-                if (get_addresses && m->ifindex != -1) {
+            if (m->get_addresses && m->ifindex != -1) {
-                    get_addresses = false;
+                m->get_addresses = false;
-                    send_rt_request(nl_sock, RTM_GETADDR);
+                send_rt_request(m->nl_sock, RTM_GETADDR);
             }
             break;
 
@@ -460,7 +429,7 @@ run(struct module_run_context *ctx)
         case NLMSG_ERROR:{
             const struct nlmsgerr *err = NLMSG_DATA(hdr);
             LOG_ERRNO_P("netlink", err->error);
-                break;
+            return false;
         }
 
         default:
@@ -470,10 +439,62 @@ run(struct module_run_context *ctx)
         }
     }
 
+    return true;
+}
+
+static int
+run(struct module_run_context *ctx)
+{
+    struct module *mod = ctx->module;
+    struct private *m = mod->private;
+
+    module_signal_ready(ctx);
+
+    m->nl_sock = netlink_connect();
+    if (m->nl_sock == -1)
+        return 1;
+
+    if (!send_rt_request(m->nl_sock, RTM_GETLINK)) {
+        close(m->nl_sock);
+        m->nl_sock = -1;
+        return 1;
+    }
+
+    /* Main loop */
+    while (true) {
+        struct pollfd fds[] = {
+            {.fd = ctx->abort_fd, .events = POLLIN},
+            {.fd = m->nl_sock, .events = POLLIN}
+        };
+
+        poll(fds, 2, -1);
+
+        if (fds[0].revents & POLLIN)
+            break;
+
+        if (fds[1].revents & POLLHUP) {
+            LOG_ERR("disconnected from netlink socket");
+            break;
+        }
+
+        assert(fds[1].revents & POLLIN);
+
+        /* Read one (or more) messages */
+        void *reply;
+        size_t len;
+        if (!netlink_receive_messages(m->nl_sock, &reply, &len))
+            break;
+
+        if (!process_reply(mod, (const struct nlmsghdr *)reply, len)) {
+            free(reply);
+            break;
+        }
+
         free(reply);
     }
 
-    close(nl_sock);
+    close(m->nl_sock);
+    m->nl_sock = -1;
     return 0;
 }
 
@@ -484,6 +505,8 @@ module_network(const char *iface, struct particle *label)
     priv->iface = strdup(iface);
     priv->label = label;
 
+    priv->nl_sock = -1;
+    priv->get_addresses = true;
     priv->ifindex = -1;
     priv->carrier = false;
     priv->state = IF_OPER_DOWN;