X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;ds=sidebyside;f=lib%2Fnetlink-socket.c;h=2d2aa29db9a4b253ae78394360b584e40d6240dc;hb=9ed3ba29b36ab99b75d6519660f58d6f5f9bd190;hp=f4bf864ad9df5146e12a9b8ae6962e4b87e08802;hpb=2ad204c8631635a0daf6bb58ece79f89e580e299;p=openvswitch

diff --git a/lib/netlink-socket.c b/lib/netlink-socket.c
index f4bf864a..2d2aa29d 100644
--- a/lib/netlink-socket.c
+++ b/lib/netlink-socket.c
@@ -38,7 +38,7 @@ VLOG_DEFINE_THIS_MODULE(netlink_socket);
 
 COVERAGE_DEFINE(netlink_overflow);
 COVERAGE_DEFINE(netlink_received);
-COVERAGE_DEFINE(netlink_recv_retry);
+COVERAGE_DEFINE(netlink_recv_jumbo);
 COVERAGE_DEFINE(netlink_send);
 COVERAGE_DEFINE(netlink_sent);
 
@@ -245,39 +245,6 @@ nl_sock_send(struct nl_sock *sock, const struct ofpbuf *msg, bool wait)
     return nl_sock_send__(sock, msg, wait);
 }
 
-/* Tries to send the 'n_iov' chunks of data in 'iov' to the kernel on 'sock' as
- * a single Netlink message.  (The message must be fully formed and not require
- * finalization of its nlmsg_len or nlmsg_pid fields.)
- *
- * Returns 0 if successful, otherwise a positive errno value.  If 'wait' is
- * true, then the send will wait until buffer space is ready; otherwise,
- * returns EAGAIN if the 'sock' send buffer is full. */
-int
-nl_sock_sendv(struct nl_sock *sock, const struct iovec iov[], size_t n_iov,
-              bool wait)
-{
-    struct msghdr msg;
-    int error;
-
-    COVERAGE_INC(netlink_send);
-    memset(&msg, 0, sizeof msg);
-    msg.msg_iov = (struct iovec *) iov;
-    msg.msg_iovlen = n_iov;
-    do {
-        int retval;
-        retval = sendmsg(sock->fd, &msg, wait ? 0 : MSG_DONTWAIT);
-        error = retval < 0 ? errno : 0;
-    } while (error == EINTR);
-    if (error != EAGAIN) {
-        log_nlmsg(__func__, error, iov[0].iov_base, iov[0].iov_len,
-                  sock->protocol);
-        if (!error) {
-            COVERAGE_INC(netlink_sent);
-        }
-    }
-    return error;
-}
-
 /* This stress option is useful for testing that OVS properly tolerates
  * -ENOBUFS on NetLink sockets.  Such errors are unavoidable because they can
  * occur if the kernel cannot temporarily allocate enough GFP_ATOMIC memory to
@@ -290,73 +257,68 @@ STRESS_OPTION(
 static int
 nl_sock_recv__(struct nl_sock *sock, struct ofpbuf **bufp, bool wait)
 {
-    uint8_t tmp;
-    ssize_t bufsize = 2048;
-    ssize_t nbytes, nbytes2;
-    struct ofpbuf *buf;
+    /* We can't accurately predict the size of the data to be received.  Most
+     * received data will fit in a 2 kB buffer, so we allocate that much space.
+     * In case the data is actually bigger than that, we make available enough
+     * additional space to allow Netlink messages to be up to 64 kB long (a
+     * reasonable figure since that's the maximum length of a Netlink
+     * attribute). */
+    enum { MAX_SIZE = 65536 };
+    enum { HEAD_SIZE = 2048 };
+    enum { TAIL_SIZE = MAX_SIZE - HEAD_SIZE };
+
     struct nlmsghdr *nlmsghdr;
-    struct iovec iov;
-    struct msghdr msg = {
-        .msg_name = NULL,
-        .msg_namelen = 0,
-        .msg_iov = &iov,
-        .msg_iovlen = 1,
-        .msg_control = NULL,
-        .msg_controllen = 0,
-        .msg_flags = 0
-    };
+    uint8_t tail[TAIL_SIZE];
+    struct iovec iov[2];
+    struct ofpbuf *buf;
+    struct msghdr msg;
+    ssize_t retval;
 
-    buf = ofpbuf_new(bufsize);
     *bufp = NULL;
 
-try_again:
-    /* Attempt to read the message.  We don't know the size of the data
-     * yet, so we take a guess at 2048.  If we're wrong, we keep trying
-     * and doubling the buffer size each time.
-     */
-    nlmsghdr = ofpbuf_put_uninit(buf, bufsize);
-    iov.iov_base = nlmsghdr;
-    iov.iov_len = bufsize;
+    buf = ofpbuf_new(HEAD_SIZE);
+    iov[0].iov_base = buf->data;
+    iov[0].iov_len = HEAD_SIZE;
+    iov[1].iov_base = tail;
+    iov[1].iov_len = TAIL_SIZE;
+
+    memset(&msg, 0, sizeof msg);
+    msg.msg_iov = iov;
+    msg.msg_iovlen = 2;
+
     do {
-        nbytes = recvmsg(sock->fd, &msg, (wait ? 0 : MSG_DONTWAIT) | MSG_PEEK);
-    } while (nbytes < 0 && errno == EINTR);
-    if (nbytes < 0) {
+        retval = recvmsg(sock->fd, &msg, wait ? 0 : MSG_DONTWAIT);
+    } while (retval < 0 && errno == EINTR);
+
+    if (retval < 0) {
+        int error = errno;
+        if (error == ENOBUFS) {
+            /* Socket receive buffer overflow dropped one or more messages that
+             * the kernel tried to send to us. */
+            COVERAGE_INC(netlink_overflow);
+        }
         ofpbuf_delete(buf);
-        return errno;
+        return error;
     }
+
     if (msg.msg_flags & MSG_TRUNC) {
-        COVERAGE_INC(netlink_recv_retry);
-        bufsize *= 2;
-        ofpbuf_reinit(buf, bufsize);
-        goto try_again;
+        VLOG_ERR_RL(&rl, "truncated message (longer than %d bytes)", MAX_SIZE);
+        ofpbuf_delete(buf);
+        return E2BIG;
     }
-    buf->size = nbytes;
 
-    /* We successfully read the message, so recv again to clear the queue */
-    iov.iov_base = &tmp;
-    iov.iov_len = 1;
-    do {
-        nbytes2 = recvmsg(sock->fd, &msg, MSG_DONTWAIT);
-    } while (nbytes2 < 0 && errno == EINTR);
-    if (nbytes2 < 0) {
-        if (errno == ENOBUFS) {
-            /* The kernel is notifying us that a message it tried to send to us
-             * was dropped.  We have to pass this along to the caller in case
-             * it wants to retry a request.  So kill the buffer, which we can
-             * re-read next time. */
-            COVERAGE_INC(netlink_overflow);
-            ofpbuf_delete(buf);
-            return ENOBUFS;
-        } else {
-            VLOG_ERR_RL(&rl, "failed to remove nlmsg from socket: %s\n",
-                        strerror(errno));
-        }
+    ofpbuf_put_uninit(buf, MIN(retval, HEAD_SIZE));
+    if (retval > HEAD_SIZE) {
+        COVERAGE_INC(netlink_recv_jumbo);
+        ofpbuf_put(buf, tail, retval - HEAD_SIZE);
     }
-    if (nbytes < sizeof *nlmsghdr
+
+    nlmsghdr = buf->data;
+    if (retval < sizeof *nlmsghdr
         || nlmsghdr->nlmsg_len < sizeof *nlmsghdr
-        || nlmsghdr->nlmsg_len > nbytes) {
+        || nlmsghdr->nlmsg_len > retval) {
         VLOG_ERR_RL(&rl, "received invalid nlmsg (%zd bytes < %d)",
-                    bufsize, NLMSG_HDRLEN);
+                    retval, NLMSG_HDRLEN);
         ofpbuf_delete(buf);
         return EPROTO;
     }
@@ -718,6 +680,7 @@ static struct hmap genl_families = HMAP_INITIALIZER(&genl_families);
 
 static const struct nl_policy family_policy[CTRL_ATTR_MAX + 1] = {
     [CTRL_ATTR_FAMILY_ID] = {.type = NL_A_U16},
+    [CTRL_ATTR_MCAST_GROUPS] = {.type = NL_A_NESTED},
 };
 
 static struct genl_family *
@@ -763,46 +726,92 @@ genl_family_to_name(uint16_t id)
     }
 }
 
-static int do_lookup_genl_family(const char *name)
+static int
+do_lookup_genl_family(const char *name, struct nlattr **attrs,
+                      struct ofpbuf **replyp)
 {
     struct nl_sock *sock;
     struct ofpbuf request, *reply;
-    struct nlattr *attrs[ARRAY_SIZE(family_policy)];
-    int retval;
+    int error;
 
-    retval = nl_sock_create(NETLINK_GENERIC, &sock);
-    if (retval) {
-        return -retval;
+    *replyp = NULL;
+    error = nl_sock_create(NETLINK_GENERIC, &sock);
+    if (error) {
+        return error;
     }
 
     ofpbuf_init(&request, 0);
     nl_msg_put_genlmsghdr(&request, 0, GENL_ID_CTRL, NLM_F_REQUEST,
                           CTRL_CMD_GETFAMILY, 1);
     nl_msg_put_string(&request, CTRL_ATTR_FAMILY_NAME, name);
-    retval = nl_sock_transact(sock, &request, &reply);
+    error = nl_sock_transact(sock, &request, &reply);
     ofpbuf_uninit(&request);
-    if (retval) {
+    if (error) {
         nl_sock_destroy(sock);
-        return -retval;
+        return error;
     }
 
     if (!nl_policy_parse(reply, NLMSG_HDRLEN + GENL_HDRLEN,
-                         family_policy, attrs, ARRAY_SIZE(family_policy))) {
+                         family_policy, attrs, ARRAY_SIZE(family_policy))
+        || nl_attr_get_u16(attrs[CTRL_ATTR_FAMILY_ID]) == 0) {
         nl_sock_destroy(sock);
         ofpbuf_delete(reply);
-        return -EPROTO;
+        return EPROTO;
     }
 
-    retval = nl_attr_get_u16(attrs[CTRL_ATTR_FAMILY_ID]);
-    if (retval == 0) {
-        retval = -EPROTO;
-    } else {
-        define_genl_family(retval, name);
-    }
     nl_sock_destroy(sock);
-    ofpbuf_delete(reply);
+    *replyp = reply;
+    return 0;
+}
 
-    return retval;
+/* Finds the multicast group called 'group_name' in genl family 'family_name'.
+ * When successful, writes its result to 'multicast_group' and returns 0.
+ * Otherwise, clears 'multicast_group' and returns a positive error code. */
+int
+nl_lookup_genl_mcgroup(const char *family_name, const char *group_name,
+                       unsigned int *multicast_group)
+{
+    struct nlattr *family_attrs[ARRAY_SIZE(family_policy)];
+    struct ofpbuf all_mcs;
+    struct ofpbuf *reply;
+    struct nlattr *mc;
+    unsigned int left;
+    int error;
+
+    *multicast_group = 0;
+    error = do_lookup_genl_family(family_name, family_attrs, &reply);
+    if (error) {
+        return error;
+    }
+
+    nl_attr_get_nested(family_attrs[CTRL_ATTR_MCAST_GROUPS], &all_mcs);
+    NL_ATTR_FOR_EACH (mc, left, all_mcs.data, all_mcs.size) {
+        static const struct nl_policy mc_policy[] = {
+            [CTRL_ATTR_MCAST_GRP_ID] = {.type = NL_A_U32},
+            [CTRL_ATTR_MCAST_GRP_NAME] = {.type = NL_A_STRING},
+        };
+
+        struct nlattr *mc_attrs[ARRAY_SIZE(mc_policy)];
+        const char *mc_name;
+
+        if (!nl_parse_nested(mc, mc_policy, mc_attrs, ARRAY_SIZE(mc_policy))) {
+            error = EPROTO;
+            goto exit;
+        }
+
+        mc_name = nl_attr_get_string(mc_attrs[CTRL_ATTR_MCAST_GRP_NAME]);
+        if (!strcmp(group_name, mc_name)) {
+            *multicast_group =
+                nl_attr_get_u32(mc_attrs[CTRL_ATTR_MCAST_GRP_ID]);
+            error = 0;
+            goto exit;
+        }
+    }
+    error = EPROTO;
+
+exit:
+    ofpbuf_delete(reply);
+    return error;
 }
 
 /* If '*number' is 0, translates the given Generic Netlink family 'name' to a
@@ -813,7 +822,19 @@ int
 nl_lookup_genl_family(const char *name, int *number)
 {
     if (*number == 0) {
-        *number = do_lookup_genl_family(name);
+        struct nlattr *attrs[ARRAY_SIZE(family_policy)];
+        struct ofpbuf *reply;
+        int error;
+
+        error = do_lookup_genl_family(name, attrs, &reply);
+        if (!error) {
+            *number = nl_attr_get_u16(attrs[CTRL_ATTR_FAMILY_ID]);
+            define_genl_family(*number, name);
+        } else {
+            *number = -error;
+        }
+        ofpbuf_delete(reply);
+
         assert(*number != 0);
     }
     return *number > 0 ? 0 : -*number;