/*
   * dccp_probe - Observe the DCCP flow with kprobes.
   *
   * The idea for this came from Werner Almesberger's umlsim
   * Copyright (C) 2004, Stephen Hemminger <shemminger@osdl.org>
   *
   * Modified for DCCP from Stephen Hemminger's code
   * Copyright (C) 2006, Ian McDonald <ian.mcdonald@jandi.co.nz>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   */
  
  #include <linux/kernel.h>
  #include <linux/kprobes.h>
  #include <linux/socket.h>
  #include <linux/dccp.h>
  #include <linux/proc_fs.h>
  #include <linux/module.h>
  #include <linux/kfifo.h>
  #include <linux/vmalloc.h>

  #include <linux/time64.h>

  #include <linux/gfp.h>

  #include <net/net_namespace.h>

  
  #include "dccp.h"
  #include "ccid.h"
  #include "ccids/ccid3.h"
  
  static int port;
  
  static int bufsize = 64 * 1024;
  
  static const char procname[] = "dccpprobe";

  static struct {

  	struct kfifo	  fifo;

  	spinlock_t	  lock;
  	wait_queue_head_t wait;

  	struct timespec64 tstart;

  } dccpw;
  
  static void printl(const char *fmt, ...)
  {
  	va_list args;
  	int len;

  	struct timespec64 now;

  	char tbuf[256];
  
  	va_start(args, fmt);

  	getnstimeofday64(&now);

  	now = timespec64_sub(now, dccpw.tstart);

  
  	len = sprintf(tbuf, "%lu.%06lu ",
  		      (unsigned long) now.tv_sec,

  		      (unsigned long) now.tv_nsec / NSEC_PER_USEC);

  	len += vscnprintf(tbuf+len, sizeof(tbuf)-len, fmt, args);
  	va_end(args);

  	kfifo_in_locked(&dccpw.fifo, tbuf, len, &dccpw.lock);

  	wake_up(&dccpw.wait);
  }

  static int jdccp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size)

  {

  	const struct inet_sock *inet = inet_sk(sk);

  	struct ccid3_hc_tx_sock *hc = NULL;

  	if (ccid_get_current_tx_ccid(dccp_sk(sk)) == DCCPC_CCID3)

  		hc = ccid3_hc_tx_sk(sk);

  	if (port == 0 || ntohs(inet->inet_dport) == port ||
  	    ntohs(inet->inet_sport) == port) {

  		if (hc)

  			printl("%pI4:%u %pI4:%u %d %d %d %d %u %llu %llu %d
  ",

  			       &inet->inet_saddr, ntohs(inet->inet_sport),
  			       &inet->inet_daddr, ntohs(inet->inet_dport), size,

  			       hc->tx_s, hc->tx_rtt, hc->tx_p,
  			       hc->tx_x_calc, hc->tx_x_recv >> 6,
  			       hc->tx_x >> 6, hc->tx_t_ipi);

  		else

  			printl("%pI4:%u %pI4:%u %d
  ",

  			       &inet->inet_saddr, ntohs(inet->inet_sport),
  			       &inet->inet_daddr, ntohs(inet->inet_dport),
  			       size);

  	}
  
  	jprobe_return();
  	return 0;
  }
  
  static struct jprobe dccp_send_probe = {

  	.kp	= {
  		.symbol_name = "dccp_sendmsg",
  	},

  	.entry	= jdccp_sendmsg,

  };
  
  static int dccpprobe_open(struct inode *inode, struct file *file)
  {

  	kfifo_reset(&dccpw.fifo);

  	getnstimeofday64(&dccpw.tstart);

  	return 0;
  }
  
  static ssize_t dccpprobe_read(struct file *file, char __user *buf,
  			      size_t len, loff_t *ppos)
  {
  	int error = 0, cnt = 0;
  	unsigned char *tbuf;

  	if (!buf)

  		return -EINVAL;
  
  	if (len == 0)
  		return 0;
  
  	tbuf = vmalloc(len);
  	if (!tbuf)
  		return -ENOMEM;
  
  	error = wait_event_interruptible(dccpw.wait,

  					 kfifo_len(&dccpw.fifo) != 0);

  	if (error)
  		goto out_free;

  	cnt = kfifo_out_locked(&dccpw.fifo, tbuf, len, &dccpw.lock);

  	error = copy_to_user(buf, tbuf, cnt) ? -EFAULT : 0;

  
  out_free:
  	vfree(tbuf);
  
  	return error ? error : cnt;
  }

  static const struct file_operations dccpprobe_fops = {

  	.owner	 = THIS_MODULE,
  	.open	 = dccpprobe_open,
  	.read    = dccpprobe_read,

  	.llseek  = noop_llseek,

  };
  
  static __init int dccpprobe_init(void)
  {
  	int ret = -ENOMEM;
  
  	init_waitqueue_head(&dccpw.wait);
  	spin_lock_init(&dccpw.lock);

  	if (kfifo_alloc(&dccpw.fifo, bufsize, GFP_KERNEL))

  		return ret;

  	if (!proc_create(procname, S_IRUSR, init_net.proc_net, &dccpprobe_fops))

  		goto err0;

  	ret = register_jprobe(&dccp_send_probe);
  	if (ret) {
  		ret = request_module("dccp");
  		if (!ret)
  			ret = register_jprobe(&dccp_send_probe);
  	}

  	if (ret)
  		goto err1;
  
  	pr_info("DCCP watch registered (port=%d)
  ", port);
  	return 0;
  err1:

  	remove_proc_entry(procname, init_net.proc_net);

  err0:

  	kfifo_free(&dccpw.fifo);

  	return ret;
  }
  module_init(dccpprobe_init);
  
  static __exit void dccpprobe_exit(void)
  {

  	kfifo_free(&dccpw.fifo);

  	remove_proc_entry(procname, init_net.proc_net);

  	unregister_jprobe(&dccp_send_probe);
  
  }
  module_exit(dccpprobe_exit);
  
  MODULE_PARM_DESC(port, "Port to match (0=all)");
  module_param(port, int, 0);
  
  MODULE_PARM_DESC(bufsize, "Log buffer size (default 64k)");
  module_param(bufsize, int, 0);
  
  MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>");
  MODULE_DESCRIPTION("DCCP snooper");
  MODULE_LICENSE("GPL");