diff options
| -rw-r--r-- | net/tipc/discover.c | 219 |
1 files changed, 111 insertions, 108 deletions
diff --git a/net/tipc/discover.c b/net/tipc/discover.c index b15cbedfea13..aa722a42ef8b 100644 --- a/net/tipc/discover.c +++ b/net/tipc/discover.c @@ -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); } /** |