/*
 *  Template MIB group implementation - example.c
 *
 */

/* include important headers */
#include <config.h>
#if HAVE_STDLIB_H
#include <stdlib.h>
#endif
#if HAVE_STRING_H
#include <string.h>
#else
#include <strings.h>
#endif

/* needed by util_funcs.h */
#if TIME_WITH_SYS_TIME
# ifdef WIN32
#  include <sys/timeb.h>
# else
#  include <sys/time.h>
# endif
# include <time.h>
#else
# if HAVE_SYS_TIME_H
#  include <sys/time.h>
# else
#  include <time.h>
# endif
#endif

#if HAVE_WINSOCK_H
#include <winsock.h>
#endif
#if HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif

/* mibincl.h contains all the snmp specific headers to define the
   return types and various defines and structures. */
#include "mibincl.h"

/* header_generic() comes from here */
#include "util_funcs.h"

#include "agent_read_config.h"

/* include our .h file */
#include "example.h"


   /*
    *  Certain objects can be set via configuration file directives.
    *  These variables hold the values for such objects, as they need to
    *   be accessible to both the config handlers, and the callback routine.
    */
#define EXAMPLE_STR_LEN	300
#define EXAMPLE_STR_DEFAULT	"life the universe and everything"
int	example_int = 42;
char	example_str[ EXAMPLE_STR_LEN ];

	/* Forward declarations for the config handlers */
void example_parse_config_exampleint( const char *token, char *cptr );
void example_parse_config_examplestr( const char *token, char *cptr );
void example_free_config_exampleint( void );
void example_free_config_examplestr( void );


	/*********************
	 *
	 *  Initialisation & common implementation functions
	 *
	 *********************/

    /*
     * This array structure defines a representation of the
     *  MIB being implemented.
     *
     * The type of the array is 'struct variableN', where N is
     *  large enough to contain the longest OID sub-component
     *  being loaded.  This will normally be the maximum value
     *  of the fifth field in each line.  In this case, the second
     *  and third entries are both of size 2, so we're using
     *  'struct variable2'
     *
     * The supported values for N are listed in <agent/var_struct.h>
     *  If the value you need is not listed there, simply use the
     *  next largest that is.
     *
     * The format of each line is as follows
     *  (using the first entry as an example):
     *	    1: EXAMPLESTRING:
     *		The magic number defined in the example header file.
     *		This is passed to the callback routine and is used
     *		  to determine which object is being queried.
     *	    2: ASN_OCTET_STR:
     *		The type of the object.
     *		Valid types are listed in <snmp_impl.h>
     *	    3: RONLY (or RWRITE):
     *		Whether this object can be SET or not.
     *	    4: var_example:
     *		The callback routine, used when the object is queried.
     *		This will usually be the same for all objects in a module
     *		  and is typically defined later in this file.
     *	    5: 1:
     *		The length of the OID sub-component (the next field)
     *	    6: {1}:
     *		The OID sub-components of this entry.
     *		In other words, the bits of the full OID that differ
     *		  between the various entries of this array.
     *		This value is appended to the common prefix (defined later)
     *		  to obtain the full OID of each entry.
     */
struct variable2 example_variables[] = {
    { EXAMPLESTRING,    ASN_OCTET_STR, RONLY, var_example, 1, {1}},
    { EXAMPLEINTEGER,   ASN_INTEGER,   RWRITE, var_example, 2, {2,1}},
    { EXAMPLEOBJECTID,  ASN_OBJECT_ID, RONLY, var_example, 2, {2,2}},
    { EXAMPLETIMETICKS, ASN_TIMETICKS, RONLY, var_example, 1, {3}},
    { EXAMPLEIPADDRESS, ASN_IPADDRESS, RONLY, var_example, 1, {4}},
    { EXAMPLECOUNTER,   ASN_COUNTER,   RONLY, var_example, 1, {5}},
    { EXAMPLEGAUGE,     ASN_GAUGE,     RONLY, var_example, 1, {6}},
    { EXAMPLETRIGGERTRAP, ASN_INTEGER, RWRITE, var_example, 1, {7}},
    { EXAMPLETRIGGERTRAP2, ASN_INTEGER, RWRITE, var_example, 1, {8}}
  };

    /*
     * This array defines the OID of the top of the mib tree that we're
     *  registering underneath.
     * Note that this needs to be the correct size for the OID being 
     *  registered, so that the length of the OID can be calculated.
     *  The format given here is the simplest way to achieve this.
     */
  oid example_variables_oid[] = { 1,3,6,1,4,1,2021,254 };

   

    /*
     * This function is called at the time the agent starts up
     *  to do any initializations that might be required.
     *
     * In theory it is optional and can be omitted if no
     *  initialization is needed.  In practise, every module
     *  will need to register itself (or the objects being
     *  implemented will not appear in the MIB tree), and this
     *  registration is typically done here.
     *
     * If this function is added or removed, you must re-run
     *  the configure script, to detect this change.
     */
void init_example(void)
{
    /*
     * Register ourselves with the agent to handle our mib tree.
     * The arguments are:
     *    descr:   A short description of the mib group being loaded.
     *    var:     The variable structure to load.
     *			(the name of the variable structure defined above)
     *    vartype: The type of this variable structure
     *    theoid:  The OID pointer this MIB is being registered underneath.
     */
  REGISTER_MIB("example", example_variables, variable2, example_variables_oid);


    /*
     *  Register config handlers for the two objects that can be set
     *   via configuration file directive.
     *  Also set a default value for the string object.  Note that the
     *   example integer variable was initialised above.
     */
  strcpy( example_str, EXAMPLE_STR_DEFAULT );

  snmpd_register_config_handler( "exampleint",
			example_parse_config_exampleint,
			example_free_config_exampleint,
			"exampleint value" );
  snmpd_register_config_handler( "examplestr",
			example_parse_config_examplestr,
			example_free_config_examplestr,
			"examplestr value" );
  snmpd_register_config_handler( "examplestring",
			example_parse_config_examplestr,
			example_free_config_examplestr,
			"examplestring value" );

    /*
     * One common requirement is to read values from the kernel.
     * This is usually initialised here, to speed up access when the
     *  information is read in, as a response to an incoming request.
     *
     * This module doesn't actually use this mechanism,
     * so this call is commented out here.
     */
  /* auto_nlist( "example_symbol", 0, 0 ); */
}

	/*********************
	 *
	 *  Configuration file handling functions
	 *
	 *********************/

void
example_parse_config_exampleint( const char *token, char *cptr )
{
    example_int = atoi( cptr );
}

void
example_parse_config_examplestr( const char *token, char *cptr )
{
		/*
		 * Make sure the string fits in the space allocated for it.
		 */
    if ( strlen( cptr ) < EXAMPLE_STR_LEN )
	strcpy( example_str, cptr );
    else {
		/*
		 * Truncate the string if necessary.
		 * An alternative approach would be to log an error,
		 *  and discard this value altogether.
		 */
	strncpy( example_str, cptr, EXAMPLE_STR_LEN-3 );
	example_str[ EXAMPLE_STR_LEN-3 ] = 0;
	strcat(  example_str, "..." );
    }
}

	/*  We don't need to do anything special when closing down */
void
example_free_config_exampleint( void ) {}

void
example_free_config_examplestr( void ) {}

	/*********************
	 *
	 *  System specific implementation functions
	 *
	 *********************/

    /*
     * Define the callback function used in the example_variables structure.
     * This is called whenever an incoming request refers to an object
     *  within this sub-tree.
     *
     * Four of the parameters are used to pass information in.
     * These are:
     *	  vp	  The entry from the 'example_variables' array for the
     *		   object being queried.
     *	  name	  The OID from the request.
     *	  length  The length of this OID.
     *	  exact	  A flag to indicate whether this is an 'exact' request
     *		   (GET/SET) or an 'inexact' one (GETNEXT/GETBULK).
     *
     * Four of the parameters are used to pass information back out.
     * These are:
     *	  name	   The OID being returned.
     *	  length   The length of this OID.
     *	  var_len  The length of the answer being returned.
     *    write_method   A pointer to the SET function for this object.
     *
     * Note that name & length serve a dual purpose in both roles.
     */

u_char	*
var_example(struct variable *vp,
	    oid *name,
	    size_t *length,
	    int exact,
	    size_t *var_len,
	    WriteMethod **write_method)
{
    /*
     *  The result returned from this function needs to be a pointer to
     *    static data (so that it can be accessed from outside).
     *  Define suitable variables for any type of data we may return.
     */
  static char string[EXAMPLE_STR_LEN];	/* for EXAMPLESTRING   */
  static oid  oid_ret[8];		/* for EXAMPLEOBJECTID */
  static long long_ret;			/* for everything else */
  
    /*
     * Before returning an answer, we need to check that the request
     *  refers to a valid instance of this object.  The utility routine
     *  'header_generic' can be used to do this for scalar objects.
     *
     * This routine 'header_simple_table' does the same thing for "simple"
     *  tables. (See the AGENT.txt file for the definition of a simple table).
     *
     * Both these utility routines also set up default values for the
     *  return arguments (assuming the check succeeded).
     * The name and length are set suitably for the current object,
     *  var_len assumes that the result is an integer of some form,
     *  and write_method assumes that the object cannot be set.
     *
     * If these assumptions are correct, this callback routine simply
     * needs to return a pointer to the appropriate value (using 'long_ret').
     * Otherwise, 'var_len' and/or 'write_method' should be set suitably.
     */
  DEBUGMSGTL(("example","var_example entered\n"));
  if (header_generic(vp, name, length, exact, var_len, write_method) == MATCH_FAILED)
    return NULL;


    /*
     * Many object will need to obtain data from the operating system in
     *  order to return the appropriate value.  Typically, this is done
     *  here - immediately following the 'header' call, and before the
     *  switch statement. This is particularly appropriate if a single 
     *  interface call can return data for all the objects supported.
     *
     * This example module does not rely on external data, so no such
     *  calls are needed in this case.  
     */

    /*
     * Now use the magic number from the variable pointer 'vp' to
     *  select the particular object being queried.
     * In each case, one of the static objects is set up with the
     *  appropriate information, and returned mapped to a 'u_char *'
     */
  switch (vp->magic){
    case EXAMPLESTRING:
      sprintf(string, example_str);
		/*
		 * Note that the assumption that the answer will be an
		 *  integer does not hold true in this case, so the length
		 *  of the answer needs to be set explicitly.		
		 */
      *var_len = strlen(string);
      return (u_char *) string;

    case EXAMPLEINTEGER:
		/*
		 * Here the length assumption is correct, but the
		 *  object is writeable, so we need to set the
		 *  write_method pointer as well as the current value.
		 */
      long_ret = example_int;
      *write_method = write_exampleint;
      return (u_char *) &long_ret;
      
    case EXAMPLEOBJECTID:
      oid_ret[0] = 1;
      oid_ret[1] = 3;
      oid_ret[2] = 6;
      oid_ret[3] = 1;
      oid_ret[4] = 4;
      oid_ret[5] = oid_ret[6] = oid_ret[7] = 42;
		/*
		 * Again, the assumption regarding the answer length is wrong.
		 */
      *var_len = 8*sizeof(oid);
      return (u_char *) oid_ret;
      
    case EXAMPLETIMETICKS:
		/*
		 * Here both assumptions are correct,
		 *  so we just need to set up the answer.
		 */
      long_ret = 363136200;	/* 42 days, 42 minutes and 42.0 seconds */
      return (u_char *) &long_ret;
      
    case EXAMPLEIPADDRESS:
      /* ipaddresses get returned as a long.  ick */
      /* we're returning 127.0.0.1 */
      long_ret = ntohl(INADDR_LOOPBACK);
      return (u_char *) &long_ret;
      
    case EXAMPLECOUNTER:
      long_ret = 42;
      return (u_char *) &long_ret;
      
    case EXAMPLEGAUGE:
      long_ret = 42;	/* Do we detect a theme running through these answers? */
      return (u_char *) &long_ret;

    case EXAMPLETRIGGERTRAP:
		/*
		 * This object is essentially "write-only".
		 * It only exists to trigger the sending of a trap.
		 * Reading it will always return 0.
		 */
      long_ret = 0;
      *write_method = write_exampletrap;
      return (u_char *) &long_ret;

      case EXAMPLETRIGGERTRAP2:
		/*
		 * This object is essentially "write-only".
		 * It only exists to trigger the sending of a v2 trap.
		 * Reading it will always return 0.
		 */
      long_ret = 0;
      *write_method = write_exampletrap2;
      return (u_char *) &long_ret;

    default:
		/*
		 *  This will only be triggered if there's a problem with
		 *   the coding of the module.  SNMP requests that reference
		 *   a non-existant OID will be directed elsewhere.
		 *  If this branch is reached, log an error, so that
		 *   the problem can be investigated.
		 */
      DEBUGMSGTL(("snmpd", "unknown sub-id %d in examples/var_example\n", vp->magic));
  }
  /*
   * If we fall through to here, fail by returning NULL.
   * This is essentially a continuation of the 'default' case above.
   */
  return NULL;
}

	/*********************
	 *
	 *  Writeable object SET handling routines
	 *
	 *********************/
int
write_exampleint(int	action,
		 u_char	*var_val,
		 u_char	var_val_type,
		 size_t	var_val_len,
		 u_char	*statP,
		 oid	*name,
		 size_t	name_len)
{
		/* Define an arbitrary maximum permissible value */
#define MAX_EXAMPLE_INT	100
    static long intval;
    static long old_intval;

    switch ( action ) {
	case RESERVE1:
			/*
			 *  Check that the value being set is acceptable
			 */
	    if (var_val_type != ASN_INTEGER ) {
		DEBUGMSGTL(("example", "%x not integer type", var_val_type));
		return SNMP_ERR_WRONGTYPE;
	    }
	    if (var_val_len > sizeof(long)) {
		DEBUGMSGTL(("example", "wrong length %x", var_val_len));
		return SNMP_ERR_WRONGLENGTH;
	    }

	    intval = *((long *) var_val);
	    if (intval > MAX_EXAMPLE_INT) {
		DEBUGMSGTL(("example", "wrong value %x", intval));
		return SNMP_ERR_WRONGVALUE;
	    }
	    break;

	case RESERVE2:
			/*
			 *  This is conventially where any necesary
			 *   resources are allocated (e.g. calls to malloc)
			 *  Here, we are using static variables
			 *   so don't need to worry about this.
			 */
	    break;

	case FREE:
			/*
			 *  This is where any of the above resources
			 *   are freed again (because one of the other
			 *   values being SET failed for some reason).
			 *  Again, since we are using static variables
			 *   we don't need to worry about this either.
			 */
	    break;

	case ACTION:
			/*
			 *  Set the variable as requested.
			 *   Note that this may need to be reversed,
			 *   so save any information needed to do this.
			 */
	    old_intval	= example_int;
	    example_int	= intval;
	    break;

	case UNDO:
			/*
			 *  Something failed, so re-set the
			 *   variable to its previous value
			 *  (and free any allocated resources).
			 */
	    example_int	= old_intval;
	    break;

	case COMMIT:
			/*
			 *  Everything worked, so we can discard any
			 *   saved information, and make the change
			 *   permanent (e.g. write to the config file).
			 *  We also free any allocated resources.
			 *
			 *  In this case, there's nothing to do.
			 */
	    break;

    }
    return SNMP_ERR_NOERROR;
}

int
write_exampletrap(int	action,
		 u_char	*var_val,
		 u_char	var_val_type,
		 size_t	var_val_len,
		 u_char	*statP,
		 oid	*name,
		 size_t	name_len)
{
    long intval;

    DEBUGMSGTL(("example","write_exampletrap entered: action=%d\n",action));
    switch ( action ) {
	case RESERVE1:
			/*
			 *  The only acceptable value is the integer 1
			 */
	    if (var_val_type != ASN_INTEGER ) {
		DEBUGMSGTL(("example", "%x not integer type", var_val_type));
		return SNMP_ERR_WRONGTYPE;
	    }
	    if (var_val_len > sizeof(long)) {
		DEBUGMSGTL(("example", "wrong length %x", var_val_len));
		return SNMP_ERR_WRONGLENGTH;
	    }

	    intval = *((long *) var_val);
	    if  ( intval != 1 ) {
		DEBUGMSGTL(("example", "wrong value %x", intval));
		return SNMP_ERR_WRONGVALUE;
	    }
	    break;

	case RESERVE2:
			/* No resources are required.... */
	    break;

	case FREE:
			/* ... so no resources need be freed */
	    break;

	case ACTION:
			/*
			 *  Having triggered the sending of a trap,
			 *   it would be impossible to revoke this,
			 *   so we can't actually invoke the action here.
			 */
	    break;

	case UNDO:
			/*  We haven't done anything yet,
				so there's nothing to undo */
	    break;

	case COMMIT:
			/*
			 *  Everything else worked, so it's now safe
			 *   to trigger the trap.
			 *  Note that this is *only* acceptable since
			 *   the trap sending routines are "failsafe".
			 *  (In fact, they can fail, but they return no
			 *   indication of this, which is the next best thing!)
			 */
            DEBUGMSGTL(("example","write_exampletrap sending the trap\n",
                        action));
	    send_easy_trap( SNMP_TRAP_ENTERPRISESPECIFIC, 99 );
            DEBUGMSGTL(("example","write_exampletrap trap sent\n",action));
	    break;

    }
    return SNMP_ERR_NOERROR;
}

/* this documents how to send a SNMPv2 (and higher) trap via the
   send_v2trap() API.

   Coding SNMP-v2 Trap:

   The SNMPv2-Trap PDU contains at least a pair of object names and
   values: - sysUpTime.0 whose value is the time in hundredths of a
   second since the netwok management portion of system was last
   reinitialized.  - snmpTrapOID.0 which is part of the trap group SNMPv2
   MIB whose value is the object-id of the specific trap you have defined
   in your own MIB.  Other variables can be added to caracterize the
   trap.

   The function send_v2trap adds automaticallys the two objects but the
   value of snmpTrapOID.0 is 0.0 by default. If you want to add your trap
   name, you have to reconstruct this object and to add your own
   variable.

*/


   
int
write_exampletrap2(int	action,
		 u_char	*var_val,
		 u_char	var_val_type,
		 size_t	var_val_len,
		 u_char	*statP,
		 oid	*name,
		 size_t	name_len)
{
    long intval;

    /* these variales will be used when we send the trap */
    oid objid_snmptrap[] = { 1,3,6,1,6,3,1,1,4,1,0}; /* snmpTrapOID.0 */
    oid demo_trap[] = { 1,3,6,1,4,1,2021,13,990}; /*demo-trap */
    oid example_string_oid[] = { 1,3,6,1,4,1,2021,254,1,0 };
    static struct variable_list var_trap;
    static struct variable_list var_obj;
    
    DEBUGMSGTL(("example","write_exampletrap2 entered: action=%d\n",action));
    switch ( action ) {
	case RESERVE1:
			/*
			 *  The only acceptable value is the integer 1
			 */
	    if (var_val_type != ASN_INTEGER ) {
		DEBUGMSGTL(("example", "%x not integer type", var_val_type));
		return SNMP_ERR_WRONGTYPE;
	    }
	    if (var_val_len > sizeof(long)) {
		DEBUGMSGTL(("example", "wrong length %x", var_val_len));
		return SNMP_ERR_WRONGLENGTH;
	    }

	    intval = *((long *) var_val);
	    if  ( intval != 1 ) {
		DEBUGMSGTL(("example", "wrong value %x", intval));
		return SNMP_ERR_WRONGVALUE;
	    }
	    break;

	case RESERVE2:
			/* No resources are required.... */
	    break;

	case FREE:
			/* ... so no resources need be freed */
	    break;

	case ACTION:
			/*
			 *  Having triggered the sending of a trap,
			 *   it would be impossible to revoke this,
			 *   so we can't actually invoke the action here.
			 */
	    break;

	case UNDO:
			/*  We haven't done anything yet,
				so there's nothing to undo */
	    break;

	case COMMIT:
			/*
			 *  Everything else worked, so it's now safe
			 *   to trigger the trap.
			 *  Note that this is *only* acceptable since
			 *   the trap sending routines are "failsafe".
			 *  (In fact, they can fail, but they return no
			 *   indication of this, which is the next best thing!)
			 */

/* trap definition objects */

            var_trap.next_variable = &var_obj; /* next variable */
            var_trap.name = objid_snmptrap; /* snmpTrapOID.0 */
            var_trap.name_length = sizeof(objid_snmptrap)/sizeof(oid); /* number of sub-ids */
            var_trap.type = ASN_OBJECT_ID;
            var_trap.val.objid = demo_trap; /* demo-trap objid */
            var_trap.val_len = sizeof(demo_trap); /* length in bytes (not number of subids!) */


/* additional objects */


            var_obj.next_variable = NULL; /* No more variables after this one */
            var_obj.name = example_string_oid;
            var_obj.name_length = sizeof(example_string_oid)/sizeof(oid); /* number of sub-ids */
            var_obj.type = ASN_OCTET_STR; /* type of variable */
            var_obj.val.string = example_str; /* value */
            var_obj.val_len = strlen(example_str);
            DEBUGMSGTL(("example","write_exampletrap2 sending the v2 trap\n",
                        action));
            send_v2trap(&var_trap);
            DEBUGMSGTL(("example","write_exampletrap2 v2 trap sent\n",action));

	    break;

    }
    return SNMP_ERR_NOERROR;
}

