/*
   * Copyright (c) 2010 Voltaire Inc.  All rights reserved.
   *
   * This software is available to you under a choice of one of two
   * licenses.  You may choose to be licensed under the terms of the GNU
   * General Public License (GPL) Version 2, available from the file
   * COPYING in the main directory of this source tree, or the
   * OpenIB.org BSD license below:
   *
   *     Redistribution and use in source and binary forms, with or
   *     without modification, are permitted provided that the following
   *     conditions are met:
   *
   *      - Redistributions of source code must retain the above
   *        copyright notice, this list of conditions and the following
   *        disclaimer.
   *
   *      - Redistributions in binary form must reproduce the above
   *        copyright notice, this list of conditions and the following
   *        disclaimer in the documentation and/or other materials
   *        provided with the distribution.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
   * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
   * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
   * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
   * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
   * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
   * SOFTWARE.
   */
  
  #define pr_fmt(fmt) "%s:%s: " fmt, KBUILD_MODNAME, __func__
  
  #include <linux/export.h>
  #include <net/netlink.h>
  #include <net/net_namespace.h>
  #include <net/sock.h>
  #include <rdma/rdma_netlink.h>
  
  struct ibnl_client {
  	struct list_head		list;
  	int				index;
  	int				nops;
  	const struct ibnl_client_cbs   *cb_table;
  };
  
  static DEFINE_MUTEX(ibnl_mutex);
  static struct sock *nls;
  static LIST_HEAD(client_list);
  
  int ibnl_chk_listeners(unsigned int group)
  {
  	if (netlink_has_listeners(nls, group) == 0)
  		return -1;
  	return 0;
  }
  EXPORT_SYMBOL(ibnl_chk_listeners);
  
  int ibnl_add_client(int index, int nops,
  		    const struct ibnl_client_cbs cb_table[])
  {
  	struct ibnl_client *cur;
  	struct ibnl_client *nl_client;
  
  	nl_client = kmalloc(sizeof *nl_client, GFP_KERNEL);
  	if (!nl_client)
  		return -ENOMEM;
  
  	nl_client->index	= index;
  	nl_client->nops		= nops;
  	nl_client->cb_table	= cb_table;
  
  	mutex_lock(&ibnl_mutex);
  
  	list_for_each_entry(cur, &client_list, list) {
  		if (cur->index == index) {
  			pr_warn("Client for %d already exists
  ", index);
  			mutex_unlock(&ibnl_mutex);
  			kfree(nl_client);
  			return -EINVAL;
  		}
  	}
  
  	list_add_tail(&nl_client->list, &client_list);
  
  	mutex_unlock(&ibnl_mutex);
  
  	return 0;
  }
  EXPORT_SYMBOL(ibnl_add_client);
  
  int ibnl_remove_client(int index)
  {
  	struct ibnl_client *cur, *next;
  
  	mutex_lock(&ibnl_mutex);
  	list_for_each_entry_safe(cur, next, &client_list, list) {
  		if (cur->index == index) {
  			list_del(&(cur->list));
  			mutex_unlock(&ibnl_mutex);
  			kfree(cur);
  			return 0;
  		}
  	}
  	pr_warn("Can't remove callback for client idx %d. Not found
  ", index);
  	mutex_unlock(&ibnl_mutex);
  
  	return -EINVAL;
  }
  EXPORT_SYMBOL(ibnl_remove_client);
  
  void *ibnl_put_msg(struct sk_buff *skb, struct nlmsghdr **nlh, int seq,
  		   int len, int client, int op, int flags)
  {
  	unsigned char *prev_tail;
  
  	prev_tail = skb_tail_pointer(skb);
  	*nlh = nlmsg_put(skb, 0, seq, RDMA_NL_GET_TYPE(client, op),
  			 len, flags);
  	if (!*nlh)
  		goto out_nlmsg_trim;
  	(*nlh)->nlmsg_len = skb_tail_pointer(skb) - prev_tail;
  	return nlmsg_data(*nlh);
  
  out_nlmsg_trim:
  	nlmsg_trim(skb, prev_tail);
  	return NULL;
  }
  EXPORT_SYMBOL(ibnl_put_msg);
  
  int ibnl_put_attr(struct sk_buff *skb, struct nlmsghdr *nlh,
  		  int len, void *data, int type)
  {
  	unsigned char *prev_tail;
  
  	prev_tail = skb_tail_pointer(skb);
  	if (nla_put(skb, type, len, data))
  		goto nla_put_failure;
  	nlh->nlmsg_len += skb_tail_pointer(skb) - prev_tail;
  	return 0;
  
  nla_put_failure:
  	nlmsg_trim(skb, prev_tail - nlh->nlmsg_len);
  	return -EMSGSIZE;
  }
  EXPORT_SYMBOL(ibnl_put_attr);
  
  static int ibnl_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
  {
  	struct ibnl_client *client;
  	int type = nlh->nlmsg_type;
  	int index = RDMA_NL_GET_CLIENT(type);
  	int op = RDMA_NL_GET_OP(type);
  
  	list_for_each_entry(client, &client_list, list) {
  		if (client->index == index) {
  			if (op < 0 || op >= client->nops ||
  			    !client->cb_table[op].dump)
  				return -EINVAL;
  
  			/*
  			 * For response or local service set_timeout request,
  			 * there is no need to use netlink_dump_start.
  			 */
  			if (!(nlh->nlmsg_flags & NLM_F_REQUEST) ||
  			    (index == RDMA_NL_LS &&
  			     op == RDMA_NL_LS_OP_SET_TIMEOUT)) {
  				struct netlink_callback cb = {
  					.skb = skb,
  					.nlh = nlh,
  					.dump = client->cb_table[op].dump,
  					.module = client->cb_table[op].module,
  				};
  
  				return cb.dump(skb, &cb);
  			}
  
  			{
  				struct netlink_dump_control c = {
  					.dump = client->cb_table[op].dump,
  					.module = client->cb_table[op].module,
  				};
  				return netlink_dump_start(nls, skb, nlh, &c);
  			}
  		}
  	}
  
  	pr_info("Index %d wasn't found in client list
  ", index);
  	return -EINVAL;
  }
  
  static void ibnl_rcv_reply_skb(struct sk_buff *skb)
  {
  	struct nlmsghdr *nlh;
  	int msglen;
  
  	/*
  	 * Process responses until there is no more message or the first
  	 * request. Generally speaking, it is not recommended to mix responses
  	 * with requests.
  	 */
  	while (skb->len >= nlmsg_total_size(0)) {
  		nlh = nlmsg_hdr(skb);
  
  		if (nlh->nlmsg_len < NLMSG_HDRLEN || skb->len < nlh->nlmsg_len)
  			return;
  
  		/* Handle response only */
  		if (nlh->nlmsg_flags & NLM_F_REQUEST)
  			return;
  
  		ibnl_rcv_msg(skb, nlh);
  
  		msglen = NLMSG_ALIGN(nlh->nlmsg_len);
  		if (msglen > skb->len)
  			msglen = skb->len;
  		skb_pull(skb, msglen);
  	}
  }
  
  static void ibnl_rcv(struct sk_buff *skb)
  {
  	mutex_lock(&ibnl_mutex);
  	ibnl_rcv_reply_skb(skb);
  	netlink_rcv_skb(skb, &ibnl_rcv_msg);
  	mutex_unlock(&ibnl_mutex);
  }
  
  int ibnl_unicast(struct sk_buff *skb, struct nlmsghdr *nlh,
  			__u32 pid)
  {
  	return nlmsg_unicast(nls, skb, pid);
  }
  EXPORT_SYMBOL(ibnl_unicast);
  
  int ibnl_multicast(struct sk_buff *skb, struct nlmsghdr *nlh,
  			unsigned int group, gfp_t flags)
  {
  	return nlmsg_multicast(nls, skb, 0, group, flags);
  }
  EXPORT_SYMBOL(ibnl_multicast);
  
  int __init ibnl_init(void)
  {
  	struct netlink_kernel_cfg cfg = {
  		.input	= ibnl_rcv,
  	};
  
  	nls = netlink_kernel_create(&init_net, NETLINK_RDMA, &cfg);
  	if (!nls) {
  		pr_warn("Failed to create netlink socket
  ");
  		return -ENOMEM;
  	}
  
  	return 0;
  }
  
  void ibnl_cleanup(void)
  {
  	struct ibnl_client *cur, *next;
  
  	mutex_lock(&ibnl_mutex);
  	list_for_each_entry_safe(cur, next, &client_list, list) {
  		list_del(&(cur->list));
  		kfree(cur);
  	}
  	mutex_unlock(&ibnl_mutex);
  
  	netlink_kernel_release(nls);
  }