ofpbuf_delete(reply);
goto recv;
}
- if (nl_msg_nlmsgerr(reply, &retval)) {
+
+ /* If the reply is an error, discard the reply and return the error code.
+ *
+ * Except: if the reply is just an acknowledgement (error code of 0), and
+ * the caller is interested in the reply (replyp != NULL), pass the reply
+ * up to the caller. Otherwise the caller will get a return value of 0
+ * and null '*replyp', which makes unwary callers likely to segfault. */
+ if (nl_msg_nlmsgerr(reply, &retval) && (retval || !replyp)) {
ofpbuf_delete(reply);
if (retval) {
VLOG_DBG_RL(&rl, "received NAK error=%d (%s)",
return 0;
}
+/* Starts a Netlink "dump" operation, by sending 'request' to the kernel via
+ * 'sock', and initializes 'dump' to reflect the state of the operation.
+ *
+ * nlmsg_len in 'msg' will be finalized to match msg->size, and nlmsg_pid will
+ * be set to 'sock''s pid, before the message is sent. NLM_F_DUMP and
+ * NLM_F_ACK will be set in nlmsg_flags.
+ *
+ * The properties of Netlink make dump operations reliable as long as all of
+ * the following are true:
+ *
+ * - At most a single dump is in progress at a time on a given nl_sock.
+ *
+ * - The nl_sock is not subscribed to any multicast groups.
+ *
+ * - The nl_sock is not used to send any other messages before the dump
+ * operation is complete.
+ *
+ * This function provides no status indication. An error status for the entire
+ * dump operation is provided when it is completed by calling nl_dump_done().
+ *
+ * The caller is responsible for destroying 'request'. The caller must not
+ * close 'sock' before it completes the dump operation (by calling
+ * nl_dump_done()).
+ */
+void
+nl_dump_start(struct nl_dump *dump,
+ struct nl_sock *sock, const struct ofpbuf *request)
+{
+ struct nlmsghdr *nlmsghdr = nl_msg_nlmsghdr(request);
+ nlmsghdr->nlmsg_flags |= NLM_F_DUMP | NLM_F_ACK;
+ dump->seq = nlmsghdr->nlmsg_seq;
+ dump->sock = sock;
+ dump->status = nl_sock_send(sock, request, true);
+ dump->buffer = NULL;
+}
+
+/* Helper function for nl_dump_next(). */
+static int
+nl_dump_recv(struct nl_dump *dump, struct ofpbuf **bufferp)
+{
+ struct nlmsghdr *nlmsghdr;
+ struct ofpbuf *buffer;
+ int retval;
+
+ retval = nl_sock_recv(dump->sock, bufferp, true);
+ if (retval) {
+ return retval == EINTR ? EAGAIN : retval;
+ }
+ buffer = *bufferp;
+
+ nlmsghdr = nl_msg_nlmsghdr(buffer);
+ if (dump->seq != nlmsghdr->nlmsg_seq) {
+ VLOG_DBG_RL(&rl, "ignoring seq %"PRIu32" != expected %"PRIu32,
+ nlmsghdr->nlmsg_seq, dump->seq);
+ return EAGAIN;
+ }
+
+ if (nl_msg_nlmsgerr(buffer, &retval)) {
+ VLOG_INFO_RL(&rl, "netlink dump request error (%s)",
+ strerror(retval));
+ return retval && retval != EAGAIN ? retval : EPROTO;
+ }
+
+ return 0;
+}
+
+/* Attempts to retrieve another reply from 'dump', which must have been
+ * initialized with nl_dump_start().
+ *
+ * If successful, returns true and points 'reply->data' and 'reply->size' to
+ * the message that was retrieved. The caller must not modify 'reply' (because
+ * it points into the middle of a larger buffer).
+ *
+ * On failure, returns false and sets 'reply->data' to NULL and 'reply->size'
+ * to 0. Failure might indicate an actual error or merely the end of replies.
+ * An error status for the entire dump operation is provided when it is
+ * completed by calling nl_dump_done().
+ */
+bool
+nl_dump_next(struct nl_dump *dump, struct ofpbuf *reply)
+{
+ struct nlmsghdr *nlmsghdr;
+
+ reply->data = NULL;
+ reply->size = 0;
+ if (dump->status) {
+ return false;
+ }
+
+ if (dump->buffer && !dump->buffer->size) {
+ ofpbuf_delete(dump->buffer);
+ dump->buffer = NULL;
+ }
+ while (!dump->buffer) {
+ int retval = nl_dump_recv(dump, &dump->buffer);
+ if (retval) {
+ ofpbuf_delete(dump->buffer);
+ dump->buffer = NULL;
+ if (retval != EAGAIN) {
+ dump->status = retval;
+ return false;
+ }
+ }
+ }
+
+ nlmsghdr = nl_msg_next(dump->buffer, reply);
+ if (!nlmsghdr) {
+ VLOG_WARN_RL(&rl, "netlink dump reply contains message fragment");
+ dump->status = EPROTO;
+ return false;
+ } else if (nlmsghdr->nlmsg_type == NLMSG_DONE) {
+ dump->status = EOF;
+ return false;
+ }
+
+ return true;
+}
+
+/* Completes Netlink dump operation 'dump', which must have been initialized
+ * with nl_dump_start(). Returns 0 if the dump operation was error-free,
+ * otherwise a positive errno value describing the problem. */
+int
+nl_dump_done(struct nl_dump *dump)
+{
+ /* Drain any remaining messages that the client didn't read. Otherwise the
+ * kernel will continue to queue them up and waste buffer space. */
+ while (!dump->status) {
+ struct ofpbuf reply;
+ if (!nl_dump_next(dump, &reply)) {
+ assert(dump->status);
+ }
+ }
+
+ ofpbuf_delete(dump->buffer);
+ return dump->status == EOF ? 0 : dump->status;
+}
+
/* Causes poll_block() to wake up when any of the specified 'events' (which is
* a OR'd combination of POLLIN, POLLOUT, etc.) occur on 'sock'. */
void
nl_msg_put_unspec(msg, type, value, strlen(value) + 1);
}
-/* Appends a Netlink attribute of the given 'type' and the given buffered
- * netlink message in 'nested_msg' to 'msg'. The nlmsg_len field in
- * 'nested_msg' is finalized to match 'nested_msg->size'. */
+/* Adds the header for nested Netlink attributes to 'msg', with the specified
+ * 'type', and returns the header's offset within 'msg'. The caller should add
+ * the content for the nested Netlink attribute to 'msg' (e.g. using the other
+ * nl_msg_*() functions), and then pass the returned offset to
+ * nl_msg_end_nested() to finish up the nested attributes. */
+size_t
+nl_msg_start_nested(struct ofpbuf *msg, uint16_t type)
+{
+ size_t offset = msg->size;
+ nl_msg_put_unspec(msg, type, NULL, 0);
+ return offset;
+}
+
+/* Finalizes a nested Netlink attribute in 'msg'. 'offset' should be the value
+ * returned by nl_msg_start_nested(). */
+void
+nl_msg_end_nested(struct ofpbuf *msg, size_t offset)
+{
+ struct nlattr *attr = ofpbuf_at_assert(msg, offset, sizeof *attr);
+ attr->nla_len = msg->size - offset;
+}
+
+/* Appends a nested Netlink attribute of the given 'type', with the 'size'
+ * bytes of content starting at 'data', to 'msg'. */
void
nl_msg_put_nested(struct ofpbuf *msg,
- uint16_t type, struct ofpbuf *nested_msg)
+ uint16_t type, const void *data, size_t size)
{
- nl_msg_nlmsghdr(nested_msg)->nlmsg_len = nested_msg->size;
- nl_msg_put_unspec(msg, type, nested_msg->data, nested_msg->size);
+ size_t offset = nl_msg_start_nested(msg, type);
+ nl_msg_put(msg, data, size);
+ nl_msg_end_nested(msg, offset);
+}
+
+/* If 'buffer' begins with a valid "struct nlmsghdr", pulls the header and its
+ * payload off 'buffer', stores header and payload in 'msg->data' and
+ * 'msg->size', and returns a pointer to the header.
+ *
+ * If 'buffer' does not begin with a "struct nlmsghdr" or begins with one that
+ * is invalid, returns NULL without modifying 'buffer'. */
+struct nlmsghdr *
+nl_msg_next(struct ofpbuf *buffer, struct ofpbuf *msg)
+{
+ if (buffer->size >= sizeof(struct nlmsghdr)) {
+ struct nlmsghdr *nlmsghdr = nl_msg_nlmsghdr(buffer);
+ size_t len = nlmsghdr->nlmsg_len;
+ if (len >= sizeof *nlmsghdr && len <= buffer->size) {
+ msg->data = nlmsghdr;
+ msg->size = len;
+ ofpbuf_pull(buffer, len);
+ return nlmsghdr;
+ }
+ }
+
+ msg->data = NULL;
+ msg->size = 0;
+ return NULL;
}
+\f
+/* Attributes. */
/* Returns the first byte in the payload of attribute 'nla'. */
const void *
return nl_attr_get(nla);
}
+/* Initializes 'nested' to the payload of 'nla'. Doesn't initialize every
+ * field in 'nested', but enough to poke around with it in a read-only way. */
+void
+nl_attr_get_nested(const struct nlattr *nla, struct ofpbuf *nested)
+{
+ nested->data = (void *) nl_attr_get(nla);
+ nested->size = nl_attr_get_size(nla);
+}
+
/* Default minimum and maximum payload sizes for each type of attribute. */
static const size_t attr_len_range[][2] = {
[0 ... N_NL_ATTR_TYPES - 1] = { 0, SIZE_MAX },
[NL_A_U64] = { 8, 8 },
[NL_A_STRING] = { 1, SIZE_MAX },
[NL_A_FLAG] = { 0, SIZE_MAX },
- [NL_A_NESTED] = { NLMSG_HDRLEN, SIZE_MAX },
+ [NL_A_NESTED] = { 0, SIZE_MAX },
};
/* Parses the 'msg' starting at the given 'nla_offset' as a sequence of Netlink
}
return true;
}
+
+/* Parses the Netlink attributes within 'nla'. 'policy[i]', for 0 <= i <
+ * n_attrs, specifies how the attribute with nla_type == i is parsed; a pointer
+ * to attribute i is stored in attrs[i]. Returns true if successful, false on
+ * failure. */
+bool
+nl_parse_nested(const struct nlattr *nla, const struct nl_policy policy[],
+ struct nlattr *attrs[], size_t n_attrs)
+{
+ struct ofpbuf buf;
+
+ nl_attr_get_nested(nla, &buf);
+ return nl_policy_parse(&buf, 0, policy, attrs, n_attrs);
+}
\f
/* Miscellaneous. */
git://git.onelab.eu / sliver-openvswitch.git / blobdiff