mib2c --生成标量数据对应c文件

 env MIBS="+/root/.snmp/mibs/TEST-MODULE.MIB" mib2c TEST-MODULE::testModule

在ubuntu终端输入上面的指令前 确保 MIB文件已经拷贝到了对应的目录 另外确保mib2c工具已经安装了 前面Ubuntu安装snmp的两种方式 通过apt安装的时候会已经安装了mib2c工具

回车后提示：

这里询问我们选择那种类型的代码分格 我们后面 需要用net-snmp所以这里选择2

这里检查到我们的MIb树中包含标量和表格对象，这里自动生成的net-snmp分格的处理器不能同生成两种分格代码 需要分开生成 然后在合并 ，我们先生成标量类型的选择1

这里提示我们可以选择选择标量 API 风格还是魔法绑定整数变量 

选择标量 API 风格（mib2c.scalar.conf）
自定义数据处理：需要手动实现标量值的获取/设置逻辑（如从硬件传感器读取数据或写入配置）。
复杂业务逻辑：标量值与其他系统组件（如数据库、外部 API）交互时需额外处理。
灵活性要求高：需完全控制标量对象的行为（如验证输入、触发事件）

代码框架：

  static int handle_myScalar(netsnmp_mib_handler *handler, ...) {
      switch (reqinfo->mode) {
          case MODE_GET:
              // 自定义获取逻辑（如读取系统时间）
              snmp_set_var_typed_value(...);
              break;
          case MODE_SET:
              // 自定义设置逻辑（如写入配置文件）
              break;
      }
      return SNMP_ERR_NOERROR;
  }

魔法绑定整数变量（mib2c.int_watch.conf）适用 
简单监控需求：标量值直接映射到内存中的整数变量（如计数器、状态标志）。
无需复杂逻辑：只需自动同步变量值与 SNMP 标量，无需额外处理。
快速原型开发：快速测试或临时监控某个整数值。

生成代码：自动创建变量与标量的绑定，例如

 static int myScalar_value = 0;  // 内存中的变量
  netsnmp_register_scalar(..., &myScalar_value);

这里我们选择1

询问是否需要为notifications生成代码 这里我们选择n 如果选择y的话会覆盖前面的标量代码

最终生成的.c文件 有中文注释修改的地方就是后面我们需要调整的地方

/*
 * Note: this file originally auto-generated by mib2c
 * using mib2c.scalar.conf
 */

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

/** Initializes the testModule module */
void
init_testModule(void)
{
    const oid objtype1_oid[] = { 1,3,6,1,4,1,2,1,1 };
    const oid objtype2_oid[] = { 1,3,6,1,4,1,2,1,2 };

  DEBUGMSGTL(("testModule", "Initializing\n"));

    netsnmp_register_scalar(
        netsnmp_create_handler_registration("objtype1", handle_objtype1,
                               objtype1_oid, OID_LENGTH(objtype1_oid),
                               HANDLER_CAN_RWRITE
        ));
    netsnmp_register_scalar(
        netsnmp_create_handler_registration("objtype2", handle_objtype2,
                               objtype2_oid, OID_LENGTH(objtype2_oid),
                               HANDLER_CAN_RWRITE
        ));
}

int
handle_objtype1(netsnmp_mib_handler *handler,
                          netsnmp_handler_registration *reginfo,
                          netsnmp_agent_request_info   *reqinfo,
                          netsnmp_request_info         *requests)
{
    int ret;
    /* We are never called for a GETNEXT if it's registered as a
       "instance", as it's "magically" handled for us.  */

    /* a instance handler also only hands us one request at a time, so
       we don't need to loop over a list of requests; we'll only get one. */
    
    switch(reqinfo->mode) {

        case MODE_GET:
            snmp_set_var_typed_value(requests->requestvb, ASN_INTEGER,
                                     /* XXX: a pointer to the scalar's data */,
                                     /* XXX: the length of the data in bytes */);
            //   snmp_set_var_typed_value(requests->requestvb, ASN_OCTET_STR,
            //                        "test", //定义的变量名称buff
            //                           strlen("test") //buff的长度
            //                        );
            break;

        /*
         * SET REQUEST
         *
         * multiple states in the transaction.  See:
         * http://www.net-snmp.org/tutorial-5/toolkit/mib_module/set-actions.jpg
         */
        case MODE_SET_RESERVE1:
                /* or you could use netsnmp_check_vb_type_and_size instead */
            ret = netsnmp_check_vb_type(requests->requestvb, ASN_INTEGER);
            if ( ret != SNMP_ERR_NOERROR ) {
                netsnmp_set_request_error(reqinfo, requests, ret );
            }
            break;

        case MODE_SET_RESERVE2:
            /* XXX malloc "undo" storage buffer */
            if (/* XXX if malloc, or whatever, failed: */) {
                netsnmp_set_request_error(reqinfo, requests, SNMP_ERR_RESOURCEUNAVAILABLE);
            }
            break;

        case MODE_SET_FREE:
            /* XXX: free resources allocated in RESERVE1 and/or
               RESERVE2.  Something failed somewhere, and the states
               below won't be called. */
            break;

        case MODE_SET_ACTION:
            /* XXX: perform the value change here */
            if (/* XXX: error? */) {
                netsnmp_set_request_error(reqinfo, requests, /* some error */);
            }
            break;

        case MODE_SET_COMMIT:
            // static char buff[256]="";
            // /* XXX: delete temporary storage */
            //  memcpy(buff,requests->requestvb->buf,requests->requestvb->val_len); // 赋值
            //  buff[requests->requestvb->val_len] ='\0';   //字符串结束符
            if (/* XXX: error? */) {
                /* try _really_really_ hard to never get to this point */
                netsnmp_set_request_error(reqinfo, requests, SNMP_ERR_COMMITFAILED);
            }
            break;

        case MODE_SET_UNDO:
            /* XXX: UNDO and return to previous value for the object */
            if (/* XXX: error? */) {
                /* try _really_really_ hard to never get to this point */
                netsnmp_set_request_error(reqinfo, requests, SNMP_ERR_UNDOFAILED);
            }
            break;

        default:
            /* we should never get here, so this is a really bad error */
            snmp_log(LOG_ERR, "unknown mode (%d) in handle_objtype1\n", reqinfo->mode );
            return SNMP_ERR_GENERR;
    }

    return SNMP_ERR_NOERROR;
}
int
handle_objtype2(netsnmp_mib_handler *handler,
                          netsnmp_handler_registration *reginfo,
                          netsnmp_agent_request_info   *reqinfo,
                          netsnmp_request_info         *requests)
{
    int ret;
    /* We are never called for a GETNEXT if it's registered as a
       "instance", as it's "magically" handled for us.  */

    /* a instance handler also only hands us one request at a time, so
       we don't need to loop over a list of requests; we'll only get one. */
    
    switch(reqinfo->mode) {

        case MODE_GET:
            snmp_set_var_typed_value(requests->requestvb, ASN_INTEGER,
                                     /* XXX: a pointer to the scalar's data */,
                                     /* XXX: the length of the data in bytes */);
            break;

        /*
         * SET REQUEST
         *
         * multiple states in the transaction.  See:
         * http://www.net-snmp.org/tutorial-5/toolkit/mib_module/set-actions.jpg
         */
        case MODE_SET_RESERVE1:
                /* or you could use netsnmp_check_vb_type_and_size instead */
            ret = netsnmp_check_vb_type(requests->requestvb, ASN_INTEGER);
            if ( ret != SNMP_ERR_NOERROR ) {
                netsnmp_set_request_error(reqinfo, requests, ret );
            }
            break;

        case MODE_SET_RESERVE2:
            /* XXX malloc "undo" storage buffer */
            if (/* XXX if malloc, or whatever, failed: */) {
                netsnmp_set_request_error(reqinfo, requests, SNMP_ERR_RESOURCEUNAVAILABLE);
            }
            break;

        case MODE_SET_FREE:
            /* XXX: free resources allocated in RESERVE1 and/or
               RESERVE2.  Something failed somewhere, and the states
               below won't be called. */
            break;

        case MODE_SET_ACTION:
            /* XXX: perform the value change here */
            if (/* XXX: error? */) {
                netsnmp_set_request_error(reqinfo, requests, /* some error */);
            }
            break;

        case MODE_SET_COMMIT:
            /* XXX: delete temporary storage */
            if (/* XXX: error? */) {
                /* try _really_really_ hard to never get to this point */
                netsnmp_set_request_error(reqinfo, requests, SNMP_ERR_COMMITFAILED);
            }
            break;

        case MODE_SET_UNDO:
            /* XXX: UNDO and return to previous value for the object */
            if (/* XXX: error? */) {
                /* try _really_really_ hard to never get to this point */
                netsnmp_set_request_error(reqinfo, requests, SNMP_ERR_UNDOFAILED);
            }
            break;

        default:
            /* we should never get here, so this is a really bad error */
            snmp_log(LOG_ERR, "unknown mode (%d) in handle_objtype2\n", reqinfo->mode );
            return SNMP_ERR_GENERR;
    }

    return SNMP_ERR_NOERROR;
}