SNMP查询以获取UPS信息

Question

我正在尝试从winapi获取apc的信息，但是我的代码SnmpMgrRequest失败了，当检查错误代码时，它会将其作为40，这在用于winapi的SNMP错误代码列表中没有提到。我已经张贴了下面的代码。如果能帮上忙，那就太好了。

#include <stdio.h>
#include <windows.h>
#include <WINSNMP.H>
#include <tchar.h>
#include <Strsafe.h>
#include <WinNT.h>
#include <Mgmtapi.h>
#include <Snmp.h>

#pragma comment (lib, "WSNMP32.LIB")
#pragma comment (lib, "Mgmtapi.lib")
#pragma comment (lib, "Snmpapi.lib")    

int main()
{
    int choice;
    LPSNMP_MGR_SESSION MgrSession;     
    INT nRetries = 1;
    AsnObjectIdentifier oid;
    RFC1157VarBindList variableBindings;
    AsnInteger errorStatus = 0;
    AsnInteger errorIndex = 0;
    char lpAgentAddress[50] ;

    LPSTR lpAgentCommunity ="public";
    variableBindings.list = NULL;
    variableBindings.len = 0;
    SNMPAPI MgrStatus;

    printf("\n SNMP Program \n ");
    printf("\n What You want to know ? \n ");
    printf("1---UPS Type \n");
    printf("2---Battery capacity \n");
    printf("3---Battery Temperature \n ");
    printf("4---Battery runtime remain \n ");
    printf("Enter your choice : ");
    scanf("%d",&choice);
    printf("\n Enter the ip address : ");
    scanf_s(" %s",lpAgentAddress);

    switch(choice)
    {
        case 1 :
            variableBindings.len++;
            SnmpMgrStrToOid(".1.3.6.1.4.1.318.1.1.1.1.1.1.0", &oid); // oid for apc ups 
            variableBindings.list = (SnmpVarBind *)SNMP_realloc(variableBindings.list, sizeof(SnmpVarBind) *variableBindings.len);
            SnmpUtilOidCpy(&variableBindings.list[0].name,&oid);
            variableBindings.list->value.asnType = ASN_NULL;
            MgrSession = SnmpMgrOpen((LPSTR)lpAgentAddress,lpAgentCommunity,1500,2);
            if (MgrSession == NULL)
            {
                printf("\n Session has failed ");
                SnmpUtilVarBindListFree(&variableBindings);
                return false;
            }
            MgrStatus = SnmpMgrRequest(MgrSession,SNMP_PDU_GET,&variableBindings,&errorStatus,&errorIndex);
            if (MgrStatus == NULL)
            {
                printf("\n Could not query the device ");
                printf("\n Error1 = %d",GetLastError());

                SnmpUtilVarBindListFree(&variableBindings);
                return false;
            } 
            else
            {
                if (errorStatus > 0){
                    printf("Error Returned from the agent ");

                    SnmpUtilVarBindListFree(&variableBindings);
                    return false;
                } 
                else
                {
                    for(unsigned int i=0;i<variableBindings.len;i++)
                    {
                        int infolen;
                        char systeminfo[2048];
                        char *snmpstring;
                        infolen = variableBindings.list[i].value.asnValue.string.length;
                        snmpstring =(char *) variableBindings.list[i].value.asnValue.string.stream;

                        memcpy(systeminfo, snmpstring,infolen);  //get the system information and copy in the array systeminfo 
                        systeminfo[infolen] = '\0'; 
                        printf("%s",systeminfo);
                    }
                }
            }
            break;
    }
}

Answer 1

它给出的错误代码为40，这在winapi的SNMP错误代码列表中没有提到。

如果SnmpMgrRequest()返回0，GetLastError()返回40，那么这就是SNMP_MGMTAPI_TIMEOUT，它在Mgmtaci.h中定义：

#define SNMP_MGMTAPI_TIMEOUT                40

SNMP_MGMTAPI_TIMEOUT 被证明为来自SnmpMgrRequest()的可能的错误代码。

如果函数失败，则返回值为NULL。若要获得扩展错误信息，请调用GetLastError，它可能返回下列错误代码之一。 SNMP_MGMTAPI_TIMEOUT请求超时.