Implement support for upstream kernel "set_flags". (#116)

Implement support for the MPTCP_PM_CMD_SET_FLAGS command found in
recent versions of the upstream Linux kernel's MPTCP generic netlink
path management API.

Author: Ossama Othman

configure.ac

@@ -18,9 +18,9 @@ AC_INIT([mptcpd],
 # Interfaces changed:  CURRENT++ REVISION=0
 #            added:    CURRENT++ REVISION=0 AGE++
 #            removed:  CURRENT++ REVISION=0 AGE=0
-LIB_CURRENT=1
+LIB_CURRENT=2
 LIB_REVISION=0
-LIB_AGE=0
+LIB_AGE=1
 
 AC_SUBST([LIB_CURRENT])
 AC_SUBST([LIB_REVISION])

include/mptcpd/path_manager.h

@@ -207,6 +207,19 @@ MPTCPD_API int mptcpd_pm_set_limits(struct mptcpd_pm *pm,
                                     struct mptcpd_limit const *limits,
                                     size_t len);
 
+/**
+ * @brief Set MPTCP resource limits.
+ *
+ * @param[in] pm    The mptcpd path manager object.
+ * @param[in] addr  Local IP address.
+ * @param[in] flags Flags to be associated with @a addr.
+ *
+ * @return @c 0 if operation was successful. -1 or @c errno otherwise.
+ */
+MPTCPD_API int mptcpd_pm_set_flags(struct mptcpd_pm *pm,
+                                   struct sockaddr const *addr,
+                                   mptcpd_flags_t flags);
+
 /**
  * @brief Get MPTCP resource limits.
  *

include/mptcpd/private/path_manager.h

@@ -248,6 +248,17 @@ struct mptcpd_pm_cmd_ops
         int (*get_limits)(struct mptcpd_pm *pm,
                           mptcpd_pm_get_limits_cb callback,
                           void *data);
+
+        /**
+         * @brief
+         *
+         * @param[in] pm    The mptcpd path manager object.
+         * @param[in] addr  Local IP address information.
+         * @param[in] flags Flags to be associated with @a addr.
+         */
+        int (*set_flags)(struct mptcpd_pm *pm,
+                         struct sockaddr const *addr,
+                         mptcpd_flags_t flags);
         //@}
 
         /**

include/mptcpd/types.h

@@ -31,9 +31,35 @@ typedef uint8_t mptcpd_aid_t;
 /// MPTCP address ID format specifier.
 #define MPTCPD_PRIxAID PRIx8
 
-/// MPTCP flags type.
+/**
+ * @name MPTCP Address Flags
+ *
+ * Each MPTCP address flag is meant to be set as a bit in a
+ * @c mptcpd_flags_t variable as needed, e.g.:
+ *
+ * @code
+ * mptcpd_flags_t flags =
+ *     MPTCPD_ADDR_FLAG_SUBFLOW | MPTCPD_ADDR_FLAG_BACKUP;
+ * @endcode
+ */
+//@{
+/**
+ * @brief MPTCP flags type.
+ *
+ * MPTCP address flags integer type that contains set of flag bits.
+ */
 typedef uint32_t mptcpd_flags_t;
 
+/// 
+#define MPTCPD_ADDR_FLAG_SIGNAL  (1U << 0)
+
+/// 
+#define MPTCPD_ADDR_FLAG_SUBFLOW (1U << 1)
+
+/// 
+#define MPTCPD_ADDR_FLAG_BACKUP  (1U << 2)
+//@}
+
 /**
  * @enum mptcp_limit_types
  *

lib/path_manager.c

@@ -214,6 +214,25 @@ int mptcpd_pm_get_limits(struct mptcpd_pm *pm,
         return ops->get_limits(pm, callback, data);
 }
 
+int mptcpd_pm_set_flags(struct mptcpd_pm *pm,
+                        struct sockaddr const *addr,
+                        mptcpd_flags_t flags)
+{
+        if (pm == NULL || addr == NULL)
+                return EINVAL;
+
+        if (!is_pm_ready(pm, __func__))
+                return EAGAIN;
+
+        struct mptcpd_pm_cmd_ops const *const ops =
+                pm->netlink_pm->cmd_ops;
+
+        if (ops->set_flags == NULL)
+                return ENOTSUP;
+
+        return ops->set_flags(pm, addr, flags);
+}
+
 int mptcpd_pm_add_subflow(struct mptcpd_pm *pm,
                           mptcpd_token_t token,
                           mptcpd_aid_t local_address_id,

src/netlink_pm_upstream.c

@@ -30,6 +30,12 @@
 #include "commands.h"
 #include "path_manager.h"
 
+// Sanity check
+#if MPTCPD_ADDR_FLAG_SIGNAL != MPTCP_PM_ADDR_FLAG_SIGNAL                \
+        || MPTCPD_ADDR_FLAG_SUBFLOW != MPTCP_PM_ADDR_FLAG_SUBFLOW       \
+        || MPTCPD_ADDR_FLAG_BACKUP != MPTCP_PM_ADDR_FLAG_BACKUP
+# error Mismatch between mptcpd and upstream kernel addr flags.
+#endif
 
 /**
  * @struct get_addr_user_callback
@@ -622,6 +628,58 @@ static int upstream_get_limits(struct mptcpd_pm *pm,
                                   l_free  /* destroy */) == 0;
 }
 
+static int upstream_set_flags(struct mptcpd_pm *pm,
+                              struct sockaddr const *addr,
+                              mptcpd_flags_t flags)
+{
+        /*
+          Payload (nested):
+              Local address family
+              Local address
+              Flags
+         */
+
+        // Types chosen to match MPTCP genl API.
+        uint16_t const family = mptcpd_get_addr_family(addr);
+
+        size_t const payload_size =
+                MPTCPD_NLA_ALIGN(family)
+                + MPTCPD_NLA_ALIGN_ADDR(addr)
+                + MPTCPD_NLA_ALIGN(flags);
+
+        struct l_genl_msg *const msg =
+                l_genl_msg_new_sized(MPTCP_PM_CMD_SET_FLAGS,
+                                     payload_size);
+
+        bool const appended =
+                l_genl_msg_enter_nested(msg,
+                                        NLA_F_NESTED | MPTCP_PM_ATTR_ADDR)
+                && l_genl_msg_append_attr(
+                        msg,
+                        MPTCP_PM_ADDR_ATTR_FAMILY,
+                        sizeof(family),  // sizeof(uint16_t)
+                        &family)
+                && append_addr_attr(msg, addr)
+                && l_genl_msg_append_attr(
+                        msg,
+                        MPTCP_PM_ADDR_ATTR_FLAGS,
+                        sizeof(flags),  // sizeof(uint32_t)
+                        &flags)
+                && l_genl_msg_leave_nested(msg);
+
+        if (!appended) {
+                l_genl_msg_unref(msg);
+
+                return ENOMEM;
+        }
+
+        return l_genl_family_send(pm->family,
+                                  msg,
+                                  mptcpd_family_send_callback,
+                                  "set_flags", /* user data */
+                                  NULL  /* destroy */) == 0;
+}
+
 static struct mptcpd_pm_cmd_ops const cmd_ops =
 {
         .add_addr    = upstream_add_addr,
@@ -630,7 +688,8 @@ static struct mptcpd_pm_cmd_ops const cmd_ops =
         .dump_addrs  = upstream_dump_addrs,
         .flush_addrs = upstream_flush_addrs,
         .set_limits  = upstream_set_limits,
-        .get_limits  = upstream_get_limits
+        .get_limits  = upstream_get_limits,
+        .set_flags   = upstream_set_flags,
 };
 
 static struct mptcpd_netlink_pm const npm = {

tests/test-commands.c

@@ -261,6 +261,20 @@ static void test_get_limits(void const *test_data)
         assert(result == 0 || result == ENOTSUP);
 }
 
+static void test_set_flags(void const *test_data)
+{
+        struct mptcpd_pm *const pm = (struct mptcpd_pm *) test_data;
+
+        if (!is_pm_ready(pm, __func__))
+                return;
+
+        static mptcpd_flags_t const flags = MPTCPD_ADDR_FLAG_BACKUP;
+
+        int const result = mptcpd_pm_set_flags(pm, laddr1, flags);
+
+        assert(result == 0 || result == ENOTSUP);
+}
+
 static void test_add_subflow(void const *test_data)
 {
         struct mptcpd_pm *const pm = (struct mptcpd_pm *) test_data;
@@ -412,6 +426,7 @@ int main(void)
         l_test_add("remove_addr",    test_remove_addr,    pm);
         l_test_add("set_limits",     test_set_limits,     pm);
         l_test_add("get_limits",     test_get_limits,     pm);
+        l_test_add("set_flags",      test_set_flags,      pm);
         l_test_add("add_subflow",    test_add_subflow,    pm);
         l_test_add("set_backup",     test_set_backup,     pm);
         l_test_add("remove_subflow", test_remove_subflow, pm);