net-snmp C语言API编程学习4--获取各个类型数据的返回值

通过net-snmp C语言API，得到agent端返回的数据，各种snmp类型的数据的解析方法

1. /* manipuate the information ourselves */
   
2.         for(vars = response->variables; vars; vars = vars->next_variable) //pdu is a snmp_pdu style variable
   
3.         {
   
4.             printf("var type is %d\n", vars->type);
   
5.             if (vars->type == ASN_OCTET_STR) //vars is a variable_list style variable
   
6.             {
   
7.                 //判断是字符串还是Hex-STRING
   
8.                 int hex = 0;
   
9.                 int x;
   
10.                 u_char * cp;
    
11.                 int allow_realloc = 1;
    
12.                 u_char *buf = NULL;
    
13.                 size_t buf_len = 256, out_len = 0;
    
14. 
    
15.                 for (cp = vars->val.string, x = 0; x < (int) vars->val_len; x++, cp++)
    
16.                 {
    
17.                     if (!isprint(*cp) && !isspace(*cp))
    
18.                     {
    
19.                         hex = 1;
    
20.                     }
    
21.                 }
    
22.                 if(!hex) //字符串
    
23.                 {
    
24.                     char *sp = (char *)malloc(1 + vars->val_len);
    
25.                     memcpy(sp, vars->val.string, vars->val_len); //netsnmp_vardata is a netsnmp_vardata style variable
    
26.      sp[vars->val_len] = '\0';
    
27.                     printf("value #%d is a string: %s\n", count++, sp);
    
28.                     free(sp);
    
29.                 }
    
30.                 else //Hex-STRING
    
31.                 {
    
32.                     buf = (u_char *) calloc(buf_len, 1);
    
33.                     snmp_cstrcat(&buf, &buf_len, &out_len, allow_realloc, "");
    
34.                     sprint_realloc_hexstring(&buf, &buf_len, &out_len, allow_realloc,vars->val.string, vars->val_len);
    
35.                     printf("value #%d is a hex-string: %s\n", count++, buf);
    
36.                     free(buf);
    
37.                 }
    
38.             }
    
39.             else if(vars->type == ASN_TIMETICKS)
    
40.             {
    
41.                 long timetick = *vars->val.integer;
    
42.                 printf("value #%d is a timetick: %d\n", count++, timetick);
    
43.             }
    
44.             else if(vars->type == ASN_OBJECT_ID)
    
45.             {
    
46.                  printf("value #%d is a oid: ", count++);
    
47.                  for(i=0; i<vars->name_length; i++)
    
48.                  {
    
49.                      if(*(vars->name_loc+i) == 0)
    
50.                          break;
    
51.                      printf(".%d", *(vars->name_loc+i));
    
52.                  }
    
53.                  printf(" and value is ");
    
54.                  for(i=0; i<(vars->val_len/sizeof(int)); i++)
    
55.                  {
    
56.                      printf(".%d", *(vars->val.objid+i));
    
57.                  }
    
58.                  printf("\n");
    
59.                 
    
60.             }
    
61.             else if(vars->type == ASN_INTEGER)
    
62.             {
    
63.                 printf("value #%d is a integer: %d\n", count++, *(vars->val.integer));
    
64.             }
    
65.             else if(vars->type == ASN_COUNTER)
    
66.             {
    
67.                 printf("value #%d is a count: %u\n", count++, (unsigned int)(*vars->val.integer & 0xffffffff));
    
68.             }
    
69.             else if(vars->type == ASN_GAUGE)
    
70.             {
    
71.                 printf("value #%d is a gauge: %u\n", count++, *(vars->val.integer));
    
72.             }
    
73.             else if(vars->type == ASN_IPADDRESS)
    
74.             {
    
75.                 u_char *ip = vars->val.string;
    
76.                 printf("value #%d is a ipaddress: %d.%d.%d.%d\n", count++, ip[0], ip[1], ip[2], ip[3]);
    
77.             }
    
78.             else if(vars->type == ASN_NULL)
    
79.             {
    
80.                 printf("value #%d is a null: \n", count++);
    
81.             }
    
82.             else
    
83.               printf("value #%d is NOT a string! Ack!\n", count++);
    
84.         }
    
85. 
    
86.     }