/* $Id: data.c,v 1.1 1998/04/10 19:53:32 rsmit06 Exp rsmit06 $
 * ------------------------------------------------------------------------
 * This file is part of xnetload, a program to monitor network traffic,
 * and display it in an X window.
 *
 * Copyright (C) 1997, 1998  R.F. Smith <rsmit06@ibm.net>
 *
 * You can contact the author at the following address:
 *      email: rsmit06@ibm.net
 * snail-mail: R.F. Smith
 *             Dr. Hermansweg 36
 *             5624 HR Eindhoven
 *             The Netherlands
 *
 * 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.
 * 
 * ------------------------------------------------------------------------
 * $Log: data.c,v $
 * Revision 1.1  1998/04/10 19:53:32  rsmit06
 * Initial revision
 *
 *
 */

#include <syslog.h> /* for error reporting */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "data.h"

/* size of buffer to copy /proc/net/xxx to */
#define BUFSIZE 1024

/********** Global variables **********/
count_t average;   /* average count */
count_t max;       /* maximum count */
int type = 0;      /* What kind of data is gathered */
int where = 0;     /* Where to gather data from. */


/********** Static variables **********/
static char *iface_name;       /* Name of the interface to be queried. */
static count_t last;           /* Previously read values. */
static float inarray[NUMAVG];  /* Array for receive counts. */
static float outarray[NUMAVG]; /* Array for transmit counts. */

/********** Function definitions **********/

/* return values for read_*  */
#define READ_VTYPE_ERR    -6   /* unknown accounting rule type */
#define READ_ALLOC_ERR    -5   /* Not enough memory on the stack */
#define READ_FOPEN_ERR    -4   /* Can't open file */
#define READ_FREAD_ERR    -3   /* Can't read file */
#define READ_IFACE_ERR    -2   /* Interface not found */
#define READ_SCAN_ERR     -1   /* Unknown file layout */
#define READ_BYTES         1   /* Function reads byte counts */
#define READ_PACKETS       2   /* Function reads packet counts */

/* Read the byte or packet count for the network interface  
   named in `iface' from /proc/net/dev, store it in the  
   variable pointed to by `pcnt', if `pcnt' is not NULL. */
static int read_dev(count_t *pcnt, char *iface);

/* Read the byte count for the network interface named in `iface'  
   from /proc/net/ip_acct, store it in the  
   variable pointed to by `pcnt', if `pcnt' is not NULL. */
static int read_ip_acct(count_t *pcnt, char *iface);

/********** Function implementations **********/

void 
report_error(char *msg)
{
  /* Open connection to system logfile. */
  openlog("xnetload", LOG_CONS|LOG_PERROR, LOG_USER);
  /* Write a log message. */
  syslog(LOG_ERR, "%s.\n", msg);
  /* Close the logfile. */
  closelog();
  /* Write the message to stderr. */
  fprintf(stderr, "xnetload: %s.\n", msg);
  /* Terminate the program. */
  exit(1);
}

int 
initialize(char *iface, int try_ip_acct)
{
  int r;
  /* Initialize global variables. */
  iface_name = iface;
  /* Check if an interface is specified. */
  if (iface == 0) {
    report_error("No network interface specified");
  }
  /* If we want to use ip_accounting, try it. */
  if (try_ip_acct) {
    r = read_ip_acct(&last, iface);
    where = IP_ACCT;
    switch (r) {
    case READ_VTYPE_ERR:
      report_error("Unknown accounting rule type");
      break;
    case READ_ALLOC_ERR:
      report_error("Memory allocation failed");
      break;
    case READ_FOPEN_ERR:
      report_error("Could not open /proc/net/ip_acct");
      break;
    case READ_IFACE_ERR:
      report_error("Interface not found in /proc/net/ip_acct");
      break;
    case READ_SCAN_ERR:
      report_error("Error scanning /proc/net/ip_acct");
      break;
    case READ_BYTES:
      type = BYTES_TYPE;
      break;
    default:
      report_error("Unknown return value from read_ip_acct");
    }
  } else {
    r = read_dev(&last, iface);
    where = DEV;
    switch (r) {
    case READ_FOPEN_ERR:
      report_error("Could not open /proc/net/dev");
      break;
    case READ_IFACE_ERR:
      report_error("Interface not found in /proc/net/dev");
      break;
    case READ_SCAN_ERR:
      report_error("Error scanning /proc/net/dev");
      break;
    case READ_BYTES:
      type = BYTES_TYPE;
      break;
    case READ_PACKETS:
      type = PACKETS_TYPE;
      break;
    default:
      report_error("Unknown return value from read_dev");
    }
  }
  return type;
}

void 
update_avg(void) 
{
  count_t current;
  count_t diff;
  int i;
  /* Read the data. */
  if (where == IP_ACCT) {
    i = read_ip_acct(&current, iface_name);
  } else {
    i = read_dev(&current, iface_name);
  }
  if (i < 0) {
    report_error("Terminating");
  }
  /* Calculate the difference with the last call */
  diff.in = current.in - last.in;
  diff.out = current.out - last.out;
  /* Update the arrays. */
  memmove(&inarray[1], &inarray[0], (NUMAVG-1)*sizeof(float));
  inarray[0] = diff.in;
  memmove(&outarray[1], &outarray[0], (NUMAVG-1)*sizeof(float));
  outarray[0] = diff.out;
  /* Calculate the average */
  average.in = average.out = 0;
  for (i=0; i<NUMAVG; i++) {
    average.in += inarray[i];
    average.out += outarray[i];
  }
  average.in /= NUMAVG;
  average.out /= NUMAVG;
  /* Update the maximum. */
  if (average.in > max.in) max.in = average.in;
  if (average.out > max.out) max.out = average.out;
  /* Store current count for further reference. */
  memcpy(&last, &current, sizeof(count_t));
}

int 
read_dev(count_t *pcnt, char *iface)
{
  FILE *f;
  char buf[BUFSIZE];
  int num, retval;
  char *pch;
  unsigned int values[16];

  /* Try to open /proc/net/dev for reading. */
  f = fopen("/proc/net/dev", "r");
  if (f == 0) {
    /* Unable to open file. */
    return READ_FOPEN_ERR;
  }
  /* Read the file into a buffer. */
  num = fread(buf, 1, BUFSIZE-1, f);
  /* Check for read errors. */
  if (ferror(f)) {
    fclose(f);
    return READ_FREAD_ERR;
  }
  /* Terminate the buffer with 0. */
  buf[num] = 0;
  /* Close the file. */
  fclose(f);

  /* Seek the interface we're looking for. */
  pch = strstr(buf, iface);
  if (pch == 0) {
    /* Interface not found. */
    return READ_IFACE_ERR;
  }
  /* Skip the interface name. */
  pch += strlen(iface);
  /* Skip the ":" after the interface name. */
  pch++;

  /* There are different layouts for /proc/net/dev:
   * there are several fields for received and transmitted bytes
   * on 2.0.32:          on 2.1.90+            on 2.1.<90
   *              RECEIVE          
   *  > 1 packets         >  1 bytes          > 1 bytes
   *    2 errs               2 packets          2 packets
   *    3 drop               3 errs             3 errs
   *    4 fifo               4 drop             4 drop
   *    5 frame              5 fifo             5 fifo
   *                         6 frame            6 frame
   *                         7 compressed
   *                         8  multicast
   *              TRANSMIT
   *  > 6 packets         >  9 bytes          > 7 bytes
   *    7 errs              10 packets          8 packets
   *    8 drop              11 errs             9 errs
   *    9 fifo              12 drop            10 drop
   *   10 colls             13 fifo            11 fifo
   *   11 carrier           14 colls           12 colls
   *                        15 carrier         13 carrier
   *                        16 compressed      14 multicast
   */
  num = sscanf(pch, "%u %u %u %u %u %u %u %u %u %u %u %u %u %u %u %u",
               &values[0],  &values[1],  &values[2],  &values[3], 
               &values[4],  &values[5],  &values[6],  &values[7], 
               &values[8],  &values[9],  &values[10], &values[11], 
               &values[12], &values[13], &values[14], &values[15]);
  switch (num) {
  case 11: /* 2.0.xx kernel, can only read packets. */
    retval = READ_PACKETS;
    if (pcnt) {
      pcnt->in = (float) values[0];
      pcnt->out = (float) values[5];
    }
    break;
  case 14: /* 2.1.<90 kernel, can read byte counts. */
    retval = READ_BYTES;
    if (pcnt) {
      pcnt->in = (float) values[0];
      pcnt->out = (float) values[6];
    }
    break;
  case 16: /* 2.1.90+ kernel, can read byte counts. */
    retval = READ_BYTES;
    if (pcnt) {
      pcnt->in = (float) values[0];
      pcnt->out = (float) values[8];
    }
    break;
  default:
    /* Unknown layout/scan error. */
    return READ_SCAN_ERR;
  }

  /* probe went OK */
  return retval;
}

int 
read_ip_acct(count_t *pcnt, char *iface)
{
  FILE *f;
  char buf[BUFSIZE];
  int num, t, len;
  char *pch;
  char *iface2;
  /* Try to open /proc/net/ip_acct for reading. */
  f = fopen("/proc/net/ip_acct", "r");
  if (f == 0) {
    /* Unable to open file. */
    return READ_FOPEN_ERR;
  }
  /* Read the file into a buffer. */
  num = fread(buf, 1, BUFSIZE-1, f);
  /* Check for read errors. */
  if (ferror(f)) {
    fclose(f);
    return READ_FREAD_ERR;
  }
  /* Terminate the buffer with 0. */
  buf[num] = 0;
  /* Close the file. */
  fclose(f);
  /* Add a space to the `iface' string, so we can detect the difference
     between e.g. "eth1" and "eth11" */
  len = strlen(iface);
  iface2 = alloca(len+2);
  if (iface2 == 0)
    return READ_ALLOC_ERR;
  strcpy(iface2, iface);
  iface[len] = ' ';
  iface[len+1] = 0;
  /* Set pointer to start of buffer. */
  pch = &buf[0];
  /* There should be two accounting rules for our interface. */
  for (t=0; t<2; t++) {
    unsigned int vtype, v1, v2;
    /* Seek interface string. */
    pch = strstr(pch, iface2);
    if (pch == 0) {
      /* Maybe the accounting rules are not installed? */
      return READ_IFACE_ERR;
    }
    /* Skip interface string and space. */
    pch += len+1;
    /* Scan for data. */
    num = sscanf(pch, "%*u %u %*u %*u %u %u", &vtype, &v1, &v2);
    if (num != 3) {
      /* Error scanning the string. */
      return READ_SCAN_ERR;
    }
    switch(vtype) {
    case 1000: /* v1 = in count, v2 = in bytes */
      if (pcnt) {
        pcnt->in = (float) v2;
      }
      break;
    case 2000: /* v1 = out count; v2 = out bytes */
      if (pcnt) {
        pcnt->out = (float) v2;
      }
      break;
    default:
      return READ_VTYPE_ERR;
    }
  }
  return READ_BYTES;
}