olsrd: add ubus ipc integration to olsrd

IPC integration of olsrd with OpenWrt. Allow dynamic adding and removing
of interfaces at run-time. We need to rename the avl-tree files, since
libubox also defines avl tree. Also add patch to allow meshing via
wireguard point-to-point links.

The ubus interface offers following functions:
  - add_inteface '{"ifname":"wg_51820"}'
  - del_inteface '{"ifname":"wg_51820"}'

Signed-off-by: Nick Hainke <vincent@systemli.org>

olsrd/Makefile

@@ -34,7 +34,7 @@ endef
 define Package/olsrd
   $(call Package/olsrd/template)
   MENU:=1
-  DEPENDS:=+libpthread
+  DEPENDS:=+libpthread +libubus
 endef
 
 define Package/olsrd/conffiles

olsrd/patches/101-unix-fix-meshing-with-wireguard-point-to-point-interfaces.patch

@@ -0,0 +1,38 @@
+From fcb30aa4da732d279527feba01cacc7dc996d137 Mon Sep 17 00:00:00 2001
+From: Nick Hainke <vincent@systemli.org>
+Date: Sun, 16 Jan 2022 00:08:56 +0100
+Subject: [PATCH] unix: fix meshing with wireguard/point-to-point interfaces
+
+Wireguard interfaces have no BROADCAST flag. We can also mesh on
+point-to-point links. That is why we mesh now also on interfaces with
+the IFF_POINTOPOINT flag enabled.
+
+Signed-off-by: Nick Hainke <vincent@systemli.org>
+---
+ src/unix/ifnet.c | 8 ++++----
+ 1 file changed, 4 insertions(+), 4 deletions(-)
+
+--- a/src/unix/ifnet.c
++++ b/src/unix/ifnet.c
+@@ -184,8 +184,8 @@ chk_if_changed(struct olsr_if *iface)
+ 
+   /* Check broadcast */
+   if ((olsr_cnf->ip_version == AF_INET) && !iface->cnf->ipv4_multicast.v4.s_addr &&     /* Skip if fixed bcast */
+-      (!(ifp->int_flags & IFF_BROADCAST))) {
+-    OLSR_PRINTF(3, "\tNo broadcast - removing\n");
++      ((!(ifp->int_flags & IFF_BROADCAST) && !(ifp->int_flags & IFF_POINTOPOINT)))) {
++    OLSR_PRINTF(3, "\tNo broadcast or point-to-point - removing\n");
+     goto remove_interface;
+   }
+ 
+@@ -552,8 +552,8 @@ chk_if_up(struct olsr_if *iface, int deb
+ 
+   /* Check broadcast */
+   if ((olsr_cnf->ip_version == AF_INET) && !iface->cnf->ipv4_multicast.v4.s_addr &&     /* Skip if fixed bcast */
+-      (!(ifs.int_flags & IFF_BROADCAST))) {
+-    OLSR_PRINTF(debuglvl, "\tNo broadcast - skipping\n");
++      (!(ifs.int_flags & IFF_BROADCAST) && !(ifs.int_flags & IFF_POINTOPOINT))) {
++    OLSR_PRINTF(debuglvl, "\tNo broadcast or point-to-point - skipping\n");
+     return 0;
+   }
+ 

olsrd/patches/600-add-ubus-support.patch

@@ -0,0 +1,60 @@
+--- a/src/scheduler.c
++++ b/src/scheduler.c
+@@ -59,6 +59,8 @@
+ #include <assert.h>
+ #include <time.h>
+ 
++#include "ubus.h"
++
+ #ifdef __MACH__
+ #include "mach/clock_gettime.h"
+ #endif
+@@ -363,6 +365,8 @@ poll_sockets(void)
+   }
+   OLSR_FOR_ALL_SOCKETS_END(entry);
+ 
++  hfd = olsrd_ubus_add_read_sock(&ibits, hfd);
++
+   /* Running select on the FD set */
+   do {
+     n = olsr_select(hfd, fdsets & SP_PR_READ ? &ibits : NULL, fdsets & SP_PR_WRITE ? &obits : NULL, NULL, &tvp);
+@@ -395,6 +399,7 @@ poll_sockets(void)
+     }
+   }
+   OLSR_FOR_ALL_SOCKETS_END(entry);
++  olsrd_ubus_receive(&ibits);
+ }
+ 
+ static void
+--- a/src/main.c
++++ b/src/main.c
+@@ -74,6 +74,8 @@
+ #include "lock_file.h"
+ #include "cli.h"
+ 
++#include "ubus.h"
++
+ #if defined(__GLIBC__) && defined(__linux__) && !defined(__ANDROID__) && !defined(__UCLIBC__)
+   #define OLSR_HAVE_EXECINFO_H
+ #endif
+@@ -771,6 +773,9 @@ int main(int argc, char *argv[]) {
+   signal(SIGUSR2, SIG_IGN);
+ #endif /* _WIN32 */
+ 
++  /* Adding ubus */
++  olsrd_add_ubus();
++
+   /* Starting scheduler */
+   olsr_scheduler();
+ 
+--- a/Makefile.inc
++++ b/Makefile.inc
+@@ -252,7 +252,7 @@ else
+ ifeq ($(OS),win32)
+   LDFLAGS +=	-Wl,-export-all-symbols
+ else 
+-  LDFLAGS +=	-Wl,-export-dynamic 
++  LDFLAGS +=	-Wl,-export-dynamic,-lubus,-lubox
+ endif
+ ifeq ($(NORPATH),0)
+ LDFLAGS +=	-Wl,-rpath,$(LIBDIR)

olsrd/src/src/ubus.c

@@ -0,0 +1,210 @@
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sys/select.h>
+
+#include <libubox/blob.h>
+#include <libubox/blobmsg.h>
+#include <libubus.h>
+
+#include <arpa/inet.h>
+#include <net/if.h>
+#include <netinet/in.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+
+#include "ifnet.h"
+#include "interfaces.h"
+#include "log.h"
+#include "olsr.h"
+#include "olsr_cfg.h"
+
+#include "ubus.h"
+
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+
+// Shared state maintained throughout calls to handle ubus messages.
+static struct ubus_context *shared_ctx;
+
+enum { INTERFACE_IFNAME, __INTERFACE_MAX };
+
+static const struct blobmsg_policy interface_policy[__INTERFACE_MAX] = {
+    [INTERFACE_IFNAME] = {"ifname", BLOBMSG_TYPE_STRING},
+};
+
+static int olsrd_ubus_add_interface(struct ubus_context *ctx_local,
+                                    struct ubus_object *obj,
+                                    struct ubus_request_data *req,
+                                    const char *method, struct blob_attr *msg) {
+  struct blob_attr *tb[__INTERFACE_MAX];
+  struct blob_buf b = {0};
+  int ret;
+  char *ifname;
+
+  blobmsg_parse(interface_policy, __INTERFACE_MAX, tb, blob_data(msg),
+                blob_len(msg));
+
+  if (!tb[INTERFACE_IFNAME])
+    return UBUS_STATUS_INVALID_ARGUMENT;
+
+  ifname = blobmsg_get_string(tb[INTERFACE_IFNAME]);
+
+  struct interface_olsr *tmp = if_ifwithname(ifname);
+  if (tmp != NULL) {
+    return UBUS_STATUS_PERMISSION_DENIED;
+  }
+
+  struct olsr_if *temp;
+  for (temp = olsr_cnf->interfaces; temp != NULL; temp = temp->next) {
+    if (strcmp(temp->name, ifname) == 0)
+      return UBUS_STATUS_PERMISSION_DENIED;
+  }
+
+  struct olsr_if *tmp_ifs = olsr_create_olsrif(ifname, false);
+  struct if_config_options *default_ifcnf = get_default_if_config();
+  tmp_ifs->cnf = default_ifcnf;
+
+  blob_buf_init(&b, 0);
+  blobmsg_add_string(&b, "adding", ifname);
+
+  ret = ubus_send_reply(ctx_local, req, b.head);
+  if (ret)
+    olsr_syslog(OLSR_LOG_ERR, "Failed to send reply: %s\n",
+                ubus_strerror(ret));
+
+  blob_buf_free(&b);
+
+  return ret;
+}
+
+static int olsrd_ubus_del_interface(struct ubus_context *ctx_local,
+                                    struct ubus_object *obj,
+                                    struct ubus_request_data *req,
+                                    const char *method, struct blob_attr *msg) {
+  struct blob_attr *tb[__INTERFACE_MAX];
+  struct blob_buf b = {0};
+  int ret;
+  char *ifname;
+  struct olsr_if *tmp_if, *del_if;
+
+  blobmsg_parse(interface_policy, __INTERFACE_MAX, tb, blob_data(msg),
+                blob_len(msg));
+
+  if (!tb[INTERFACE_IFNAME])
+    return UBUS_STATUS_INVALID_ARGUMENT;
+
+  ifname = blobmsg_get_string(tb[INTERFACE_IFNAME]);
+
+  struct interface_olsr *tmp = if_ifwithname(ifname);
+
+  if (tmp != NULL) {
+
+    struct olsr_if *temp = olsr_cnf->interfaces, *prev;
+    if (temp != NULL && (strcmp(temp->name, ifname) == 0)) {
+      olsr_cnf->interfaces = temp->next;
+      olsr_remove_interface(temp);
+      goto send_reply;
+    }
+
+    while (temp != NULL && (strcmp(temp->name, ifname) != 0)) {
+      prev = temp;
+      temp = temp->next;
+    }
+
+    if (temp == NULL) {
+      goto send_reply;
+    }
+
+    prev->next = temp->next;
+    olsr_remove_interface(temp);
+  } else {
+    return UBUS_STATUS_PERMISSION_DENIED;
+  }
+
+send_reply:
+
+  blob_buf_init(&b, 0);
+  blobmsg_add_string(&b, "deleting", ifname);
+
+  ret = ubus_send_reply(ctx_local, req, b.head);
+  if (ret)
+    olsr_syslog(OLSR_LOG_ERR, "Failed to send reply: %s\n",
+                ubus_strerror(ret));
+
+  blob_buf_free(&b);
+
+  return ret;
+}
+
+// List of functions we expose via the ubus bus.
+static const struct ubus_method olsrd_methods[] = {
+    UBUS_METHOD("add_interface", olsrd_ubus_add_interface, interface_policy),
+    UBUS_METHOD("del_interface", olsrd_ubus_del_interface, interface_policy),
+};
+
+// Definition of the ubus object type.
+static struct ubus_object_type olsrd_object_type =
+    UBUS_OBJECT_TYPE("olsrd", olsrd_methods);
+
+// Object we announce via the ubus bus.
+static struct ubus_object olsrd_object = {
+    .name = "olsrd",
+    .type = &olsrd_object_type,
+    .methods = olsrd_methods,
+    .n_methods = ARRAY_SIZE(olsrd_methods),
+};
+
+// Registers handlers for olsrd methods in the global ubus context.
+static bool ubus_init_object() {
+  int ret;
+
+  ret = ubus_add_object(shared_ctx, &olsrd_object);
+  if (ret) {
+    olsr_syslog(OLSR_LOG_ERR, "Failed to add object: %s\n",
+                ubus_strerror(ret));
+    return false;
+  }
+
+  return true;
+}
+
+// Initializes the global ubus context, connecting to the bus to be able to
+// receive and send messages.
+static bool olsrd_ubus_init(void) {
+  if (shared_ctx)
+    return true;
+
+  shared_ctx = ubus_connect(NULL);
+  if (!shared_ctx)
+    return false;
+
+  return true;
+}
+
+void olsrd_ubus_receive(fd_set *readfds) {
+  if (!shared_ctx)
+    return;
+  if (FD_ISSET(shared_ctx->sock.fd, readfds))
+    ubus_handle_event(shared_ctx);
+}
+
+int olsrd_ubus_add_read_sock(fd_set *readfds, int maxfd) {
+  if (!shared_ctx)
+    return maxfd;
+
+  FD_SET(shared_ctx->sock.fd, readfds);
+  return MAX(maxfd, shared_ctx->sock.fd + 1);
+}
+
+bool olsrd_add_ubus() {
+  if (!olsrd_ubus_init()) {
+    olsr_syslog(OLSR_LOG_ERR, "Failed to initialize ubus!\n");
+    return false;
+  }
+  if (!ubus_init_object()) {
+    olsr_syslog(OLSR_LOG_ERR, "Failed to add objects to ubus!\n");
+    return false;
+  }
+  return true;
+}

olsrd/src/src/ubus.h

@@ -0,0 +1,40 @@
+/*
+    IPC integration of olsrd with OpenWrt.
+
+    The ubus interface offers following functions:
+    - add_inteface '{"ifname":"wg_51820"}'
+    - del_inteface '{"ifname":"wg_51820"}'
+*/
+
+#include <stdbool.h>
+#include <sys/select.h>
+
+/**
+ * Initialize ubus interface.
+ *
+ * Connect to the ubus daemon and expose the ubus functions.
+ *
+ * @return if initializing ubus was successful
+ */
+bool olsrd_add_ubus();
+
+/**
+ * Add ubus socket to given filedescriptor set.
+ *
+ * We need to check repeatedly if the ubus socket has something to read.
+ * The functions allows to add the ubus socket to the normal while(1)-loop of
+ * olsrd.
+ *
+ * @param readfs: the filedescriptor set
+ * @param maxfd: the current maximum file descriptor
+ * @return the maximum file descriptor
+ */
+int olsrd_ubus_add_read_sock(fd_set *readfds, int maxfd);
+
+/**
+ * Check and process ubus socket.
+ *
+ * If the ubus-socket signals that data is available, the ubus_handle_event is
+ * called.
+ */
+void olsrd_ubus_receive(fd_set *readfds);