@@ -1,7 +1,7 @@
/*
* net/tipc/discover.c
*
- * Copyright (c) 2003-2006, Ericsson AB
+ * Copyright (c) 2003-2006, 2014, Ericsson AB
* Copyright (c) 2005-2006, 2010-2011, Wind River Systems
* All rights reserved.
*
@@ -106,147 +106,150 @@ static void disc_dupl_alert(struct tipc_bearer *b_ptr, u32 node_addr,
}
/**
- * tipc_disc_rcv - handle incoming link setup message (request or response)
+ * tipc_disc_rcv - handle incoming discovery message (request or response)
* @buf: buffer containing message
- * @b_ptr: bearer that message arrived on
+ * @bearer: bearer that message arrived on
*/
-void tipc_disc_rcv(struct sk_buff *buf, struct tipc_bearer *b_ptr)
+void tipc_disc_rcv(struct sk_buff *buf, struct tipc_bearer *bearer)
{
- struct tipc_node *n_ptr;
+ struct tipc_node *node;
struct tipc_link *link;
- struct tipc_media_addr media_addr;
+ struct tipc_media_addr maddr;
struct sk_buff *rbuf;
struct tipc_msg *msg = buf_msg(buf);
- u32 dest = msg_dest_domain(msg);
- u32 orig = msg_prevnode(msg);
+ u32 ddom = msg_dest_domain(msg);
+ u32 onode = msg_prevnode(msg);
u32 net_id = msg_bc_netid(msg);
- u32 type = msg_type(msg);
+ u32 mtyp = msg_type(msg);
u32 signature = msg_node_sig(msg);
- int addr_mismatch;
- int link_fully_up;
-
- media_addr.broadcast = 1;
- b_ptr->media->msg2addr(b_ptr, &media_addr, msg_media_addr(msg));
+ bool addr_match = false;
+ bool sign_match = false;
+ bool link_up = false;
+ bool accept_addr = false;
+ bool accept_sign = false;
+ bool respond = false;
+
+ bearer->media->msg2addr(bearer, &maddr, msg_media_addr(msg));
kfree_skb(buf);
/* Ensure message from node is valid and communication is permitted */
if (net_id != tipc_net_id)
return;
- if (media_addr.broadcast)
+ if (maddr.broadcast)
return;
- if (!tipc_addr_domain_valid(dest))
+ if (!tipc_addr_domain_valid(ddom))
return;
- if (!tipc_addr_node_valid(orig))
+ if (!tipc_addr_node_valid(onode))
return;
- if (orig == tipc_own_addr) {
- if (memcmp(&media_addr, &b_ptr->addr, sizeof(media_addr)))
- disc_dupl_alert(b_ptr, tipc_own_addr, &media_addr);
+
+ if (in_own_node(onode)) {
+ if (memcmp(&maddr, &bearer->addr, sizeof(maddr)))
+ disc_dupl_alert(bearer, tipc_own_addr, &maddr);
return;
}
- if (!tipc_in_scope(dest, tipc_own_addr))
+ if (!tipc_in_scope(ddom, tipc_own_addr))
return;
- if (!tipc_in_scope(b_ptr->domain, orig))
+ if (!tipc_in_scope(bearer->domain, onode))
return;
- /* Locate structure corresponding to requesting node */
- n_ptr = tipc_node_find(orig);
- if (!n_ptr) {
- n_ptr = tipc_node_create(orig);
- if (!n_ptr)
- return;
- }
- tipc_node_lock(n_ptr);
+ /* Locate, or if necessary, create, node: */
+ node = tipc_node_find(onode);
+ if (!node)
+ node = tipc_node_create(onode);
+ if (!node)
+ return;
- /* Prepare to validate requesting node's signature and media address */
- link = n_ptr->links[b_ptr->identity];
- addr_mismatch = (link != NULL) &&
- memcmp(&link->media_addr, &media_addr, sizeof(media_addr));
+ tipc_node_lock(node);
+ link = node->links[bearer->identity];
- /*
- * Ensure discovery message's signature is correct
- *
- * If signature is incorrect and there is no working link to the node,
- * accept the new signature but invalidate all existing links to the
- * node so they won't re-activate without a new discovery message.
- *
- * If signature is incorrect and the requested link to the node is
- * working, accept the new signature. (This is an instance of delayed
- * rediscovery, where a link endpoint was able to re-establish contact
- * with its peer endpoint on a node that rebooted before receiving a
- * discovery message from that node.)
- *
- * If signature is incorrect and there is a working link to the node
- * that is not the requested link, reject the request (must be from
- * a duplicate node).
- */
- if (signature != n_ptr->signature) {
- if (n_ptr->working_links == 0) {
- struct tipc_link *curr_link;
- int i;
-
- for (i = 0; i < MAX_BEARERS; i++) {
- curr_link = n_ptr->links[i];
- if (curr_link) {
- memset(&curr_link->media_addr, 0,
- sizeof(media_addr));
- tipc_link_reset(curr_link);
- }
- }
- addr_mismatch = (link != NULL);
- } else if (tipc_link_is_up(link) && !addr_mismatch) {
- /* delayed rediscovery */
- } else {
- disc_dupl_alert(b_ptr, orig, &media_addr);
- tipc_node_unlock(n_ptr);
- return;
- }
- n_ptr->signature = signature;
+ /* Prepare to validate requesting node's signature and media address */
+ sign_match = (signature == node->signature);
+ addr_match = link && !memcmp(&link->media_addr, &maddr, sizeof(maddr));
+ link_up = link && tipc_link_is_up(link);
+
+
+ /* These three flags give us eight permutations: */
+
+ if (sign_match && addr_match && link_up) {
+ /* All is fine. Do nothing. */
+ } else if (sign_match && addr_match && !link_up) {
+ /* Respond. The link will come up in due time */
+ respond = true;
+ } else if (sign_match && !addr_match && link_up) {
+ /* Peer has changed i/f address without rebooting.
+ * If so, the link will reset soon, and the next
+ * discovery will be accepted. So we can ignore it.
+ * It may also be an cloned or malicious peer having
+ * chosen the same node address and signature as an
+ * existing one.
+ * Ignore requests until the link goes down, if ever.
+ */
+ disc_dupl_alert(bearer, onode, &maddr);
+ } else if (sign_match && !addr_match && !link_up) {
+ /* Peer link has changed i/f address without rebooting.
+ * It may also be a cloned or malicious peer; we can't
+ * distinguish between the two.
+ * The signature is correct, so we must accept.
+ */
+ accept_addr = true;
+ respond = true;
+ } else if (!sign_match && addr_match && link_up) {
+ /* Peer node rebooted. Two possibilities:
+ * - Delayed re-discovery; this link endpoint has already
+ * reset and re-established contact with the peer, before
+ * receiving a discovery message from that node.
+ * (The peer happened to receive one from this node first).
+ * - The peer came back so fast that our side has not
+ * discovered it yet. Probing from this side will soon
+ * reset the link, since there can be no working link
+ * endpoint at the peer end, and the link will re-establish.
+ * Accept the signature, since it comes from a known peer.
+ */
+ accept_sign = true;
+ } else if (!sign_match && addr_match && !link_up) {
+ /* The peer node has rebooted.
+ * Accept signature, since it is a known peer.
+ */
+ accept_sign = true;
+ respond = true;
+ } else if (!sign_match && !addr_match && link_up) {
+ /* Peer rebooted with new address, or a new/duplicate peer.
+ * Ignore until the link goes down, if ever.
+ */
+ disc_dupl_alert(bearer, onode, &maddr);
+ } else if (!sign_match && !addr_match && !link_up) {
+ /* Peer rebooted with new address, or it is a new peer.
+ * Accept signature and address.
+ */
+ accept_sign = true;
+ accept_addr = true;
+ respond = true;
}
- /*
- * Ensure requesting node's media address is correct
- *
- * If media address doesn't match and the link is working, reject the
- * request (must be from a duplicate node).
- *
- * If media address doesn't match and the link is not working, accept
- * the new media address and reset the link to ensure it starts up
- * cleanly.
- */
- if (addr_mismatch) {
- if (tipc_link_is_up(link)) {
- disc_dupl_alert(b_ptr, orig, &media_addr);
- tipc_node_unlock(n_ptr);
- return;
- } else {
- memcpy(&link->media_addr, &media_addr,
- sizeof(media_addr));
- tipc_link_reset(link);
- }
- }
+ if (accept_sign)
+ node->signature = signature;
- /* Create a link endpoint for this bearer, if necessary */
- if (!link) {
- link = tipc_link_create(n_ptr, b_ptr, &media_addr);
- if (!link) {
- tipc_node_unlock(n_ptr);
- return;
+ if (accept_addr) {
+ if (!link)
+ link = tipc_link_create(node, bearer, &maddr);
+ if (link) {
+ memcpy(&link->media_addr, &maddr, sizeof(maddr));
+ tipc_link_reset(link);
+ } else {
+ respond = false;
}
}
- /* Accept discovery message & send response, if necessary */
- link_fully_up = link_working_working(link);
-
- if ((type == DSC_REQ_MSG) && !link_fully_up) {
+ /* Send response, if necessary */
+ if (respond && (mtyp == DSC_REQ_MSG)) {
rbuf = tipc_buf_acquire(INT_H_SIZE);
if (rbuf) {
- tipc_disc_init_msg(rbuf, DSC_RESP_MSG, b_ptr);
- tipc_bearer_send(b_ptr->identity, rbuf, &media_addr);
+ tipc_disc_init_msg(rbuf, DSC_RESP_MSG, bearer);
+ tipc_bearer_send(bearer->identity, rbuf, &maddr);
kfree_skb(rbuf);
}
}
-
- tipc_node_unlock(n_ptr);
+ tipc_node_unlock(node);
}
/**