防止遗忘,实现一个snmp agent,基于ucd-netsnmp,可以无需netsnmp单独运行,加了点获取其他信息的代码。

struct.h
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
#ifndef UCD_SNMP_STRUCT
#define UCD_SNMP_STRUCT

#define STRMAX 1024
#define SHPROC 1
#define EXECPROC 2
#define PASSTHRU 3
#define PASSTHRU_PERSIST 4
#define MIBMAX 30

struct extensible {
    char            name[STRMAX];
    char            command[STRMAX];
    char            fixcmd[STRMAX];
    int             type;
    int             result;
    char            output[STRMAX];
    struct extensible *next;
    unsigned long   miboid[MIBMAX];
    size_t          miblen;
    int             pid;
};

struct myproc {
    char            name[STRMAX];
    char            fixcmd[STRMAX];
    int             min;
    int             max;
    struct myproc  *next;
};

/*
 * struct mibinfo 
 * {
 * int numid;
 * unsigned long mibid[10];
 * char *name;
 * void (*handle) ();
 * };
 */

#endif
example.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
```c
/*
 *  Template MIB group interface - example.h
 *
 */

/*
 * Don't include ourselves twice 
 */
#ifndef _MIBGROUP_EXAMPLE_H
#define _MIBGROUP_EXAMPLE_H

#ifdef __cplusplus
extern "C" {
#endif

    /*
     * We use 'header_generic' from the util_funcs module,
     *  so make sure this module is included in the agent.
     */
config_require(util_funcs)


    /*
     * Declare our publically-visible functions.
     * Typically, these will include the initialization and shutdown functions,
     *  the main request callback routine and any writeable object methods.
     *
     * Function prototypes are provided for the callback routine ('FindVarMethod')
     *  and writeable object methods ('WriteMethod').
     */
     void     init_example(void);
     FindVarMethod var_example;
     WriteMethod write_exampleint;
     WriteMethod write_exampletrap;
     WriteMethod write_exampletrap2;


    /*
     * Magic number definitions.
     * These must be unique for each object implemented within a
     *  single mib module callback routine.
     *
     * Typically, these will be the last OID sub-component for
     *  each entry, or integers incrementing from 1.
     *  (which may well result in the same values anyway).
     *
     * Here, the second and third objects are form a 'sub-table' and
     *   the magic numbers are chosen to match these OID sub-components.
     * This is purely for programmer convenience.
     * All that really matters is that the numbers are unique.
     */

#define	EXAMPLESTRING		1
#define EXAMPLEINTEGER		21
#define	EXAMPLEOBJECTID         22
#define EXAMPLETIMETICKS	3
#define	EXAMPLEIPADDRESS        4
#define EXAMPLECOUNTER		5
#define	EXAMPLEGAUGE            6
#define	EXAMPLETRIGGERTRAP      7
#define	EXAMPLETRIGGERTRAP2     8

#ifdef __cplusplus
}
#endif

#endif                          /* _MIBGROUP_EXAMPLE_H */
example.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
/*
 *  Template MIB group implementation - example.c
 *
 */

/*
 * include important headers 
 */
#include <net-snmp/net-snmp-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

#include <net-snmp/net-snmp-includes.h>
#include <net-snmp/agent/net-snmp-agent-includes.h>

/*
 * header_generic() comes from here 
 */
#include "/usr/include/net-snmp/agent/util_funcs.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.
     */
    strncpy(example_str, EXAMPLE_STR_DEFAULT, EXAMPLE_STR_LEN);

    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 - 4);
        example_str[EXAMPLE_STR_LEN - 4] = 0;
        strcat(example_str, "...");
        example_str[EXAMPLE_STR_LEN - 1] = 0;
    }
}

        /*
         * 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);
		printf("you have set the value :%ld",intval);
        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"));
        send_easy_trap(SNMP_TRAP_ENTERPRISESPECIFIC, 99);
        DEBUGMSGTL(("example", "write_exampletrap trap sent\n"));
        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 netsnmp_variable_list var_trap;
    static netsnmp_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"));
        send_v2trap(&var_trap);
        DEBUGMSGTL(("example", "write_exampletrap2 v2 trap sent\n"));

        break;

    }
    return SNMP_ERR_NOERROR;
}
example-demon.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
/*主函数:foxmail_new.c */

#include <net-snmp/net-snmp-config.h>

#include <net-snmp/net-snmp-includes.h>

#include <net-snmp/agent/net-snmp-agent-includes.h>

#include <signal.h>

#include "example.h"

#define MYDEBUG 
#ifdef MYDEBUG
	#define myprintf(fmt, a...)  printf("%s,%s(),%d:" fmt "\n", __FILE__,__FUNCTION__,__LINE__, ##a)
#else
	#define myprintf(fmt, a...)
#endif

static int keep_running;

RETSIGTYPE

stop_server(int a) {
    keep_running = 0;
}

int main ()
{
  int agentx_subagent=0; /* change this if you want to be a SNMP master agent */
  int background = 0; /* change this if you want to run in the background */
  int syslog = 0; /* change this if you want to use syslog */

myprintf("it is ok\n");
  /* print log errors to syslog or stderr */

  if (syslog)
    snmp_enable_calllog();
  else
    snmp_enable_stderrlog();

	//myprintf("it is ok \n");
  /* we're an agentx subagent? */

  if (agentx_subagent) {

    /* make us a agentx client. */

    netsnmp_ds_set_boolean(NETSNMP_DS_APPLICATION_ID, NETSNMP_DS_AGENT_ROLE, 1);

  }

  /* run in background, if requested */

  if (background && netsnmp_daemonize(1, !syslog))

      exit(1);

  /* Initialize tcpip, if necessary */

  SOCK_STARTUP;

  /* Initialize the agent library */

  init_agent("example-demon");
init_system_mib();
init_sysORTable();
init_at();
init_snmp_mib();
init_tcp();
init_icmp();
init_ip();
init_udp();
init_vacm_vars();
init_memory();
init_proc();
init_versioninfo();
init_pass();
init_pass_persist();
init_disk();
init_loadave();
init_extensible();
init_errormib();
init_file();
init_snmpEngine();
init_snmpMPDStats();
init_usmStats();
init_usmUser();
init_var_route();




  /* Initialize our mib code here */

init_example();


  /* initialize vacm/usm access control  */

  if (!agentx_subagent) {

    void  init_vacm_vars();

    void  init_usmUser();

  }


  /* Example-demon will be used to read example-demon.conf files. */

  init_snmp("example-demon");

  /* If we're going to be a snmp master agent, initial the ports */

  if (!agentx_subagent)

    init_master_agent();  /* open the port to listen on (defaults to udp:161) */

  /* In case we recevie a request to stop (kill -TERM or kill -INT) */

  keep_running = 1;

  signal(SIGTERM, stop_server);

  signal(SIGINT, stop_server);

  snmp_log(LOG_INFO,"example-demon is up and running.\n");



  /* your main loop here... */

  while(keep_running) {

    /* if you use select(), see snmp_select_info() in snmp_api(3) */

    /*     --- OR ---  */

    agent_check_and_process(1); /* 0 == don't block */

  }

  /* at shutdown time */

  snmp_shutdown("example-demon");

  SOCK_CLEANUP;

  return 0;

}
example-demon.conf
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
###############################################################################
# Access Control
###############################################################################

# sec.name source community
rocommunity public
rwcommunity 223323
####
# Second, map the security names into group names:

# sec.model sec.name
group MyRWGroup v1 local
group MyRWGroup v2c local
group MyRWGroup usm local
group MyROGroup v1 mynetwork
group MyROGroup v2c mynetwork
group MyROGroup usm mynetwork

####
# Third, create a view for us to let the groups have rights to:

# incl/excl subtree mask
view all included .1 80

####
# Finally, grant the 2 groups access to the 1 view with different
# write permissions:

# context sec.model sec.level match read write notif
access MyROGroup "" any noauth exact all none none
access MyRWGroup "" any noauth exact all all none

agentaddress 161
makefile
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
CC=gcc
OBJS2=example-demon.o example.o
TARGETS=example-demon

CFLAGS=-I. `net-snmp-config --cflags`
BUILDLIBS=`net-snmp-config --libs`
BUILDAGENTLIBS=`net-snmp-config --agent-libs`

# shared library flags (assumes gcc)
DLFLAGS=-fPIC –shared

all: $(TARGETS)

example-demon: $(OBJS2)
	$(CC) -o example-demon $(OBJS2) $(BUILDAGENTLIBS)

clean:
	rm $(OBJS2) $(OBJS2) $(TARGETS)

目前无法获取到系统load,以后用到再深入。

参考文章 《Snmp Agent开发流程》 http://blog.csdn.net/ytz_linuxer/article/details/5985534

《网管SNMP Agent的快速开发》 http://www.wangchao.net.cn/bbsdetail_53491.html

《SNMP监控一些常用OID的总结》 http://www.cnblogs.com/aspx-net/p/3554044.html

《与大家分享uclinux上的ucd-snmp开发过程》 http://bbs.chinaunix.net/thread-2112856-1-1.html

发表评论