C#简单实现SNMP的方法

/**C# Network Programming by Richard BlumPublisher: Sybex ISBN: 0782141765*/using System;using System.Text;using System.Net;using System.Net.Sockets;public class SimpleSNMP{  public static void Main(string[] argv)  {   int commlength, miblength, datatype, datalength, datastart;   int uptime = 0;   string output;   SNMP conn = new SNMP();   byte[] response = new byte[1024];   Console.WriteLine("Device SNMP information:");   // Send sysName SNMP request   response = conn.get("get", argv[0], argv[1], "1.3.6.1.2.1.1.5.0");   if (response[0] == 0xff)   {     Console.WriteLine("No response from {0}", argv[0]);     return;   }   // If response, get the community name and MIB lengths   commlength = Convert.ToInt16(response[6]);   miblength = Convert.ToInt16(response[23 + commlength]);   // Extract the MIB data from the SNMP response   datatype = Convert.ToInt16(response[24 + commlength + miblength]);   datalength = Convert.ToInt16(response[25 + commlength + miblength]);   datastart = 26 + commlength + miblength;   output = Encoding.ASCII.GetString(response, datastart, datalength);   Console.WriteLine(" sysName - Datatype: {0}, Value: {1}",       datatype, output);   // Send a sysLocation SNMP request   response = conn.get("get", argv[0], argv[1], "1.3.6.1.2.1.1.6.0");   if (response[0] == 0xff)   {     Console.WriteLine("No response from {0}", argv[0]);     return;   }   // If response, get the community name and MIB lengths   commlength = Convert.ToInt16(response[6]);   miblength = Convert.ToInt16(response[23 + commlength]);   // Extract the MIB data from the SNMP response   datatype = Convert.ToInt16(response[24 + commlength + miblength]);   datalength = Convert.ToInt16(response[25 + commlength + miblength]);   datastart = 26 + commlength + miblength;   output = Encoding.ASCII.GetString(response, datastart, datalength);   Console.WriteLine(" sysLocation - Datatype: {0}, Value: {1}", datatype, output);   // Send a sysContact SNMP request   response = conn.get("get", argv[0], argv[1], "1.3.6.1.2.1.1.4.0");   if (response[0] == 0xff)   {     Console.WriteLine("No response from {0}", argv[0]);     return;   }   // Get the community and MIB lengths   commlength = Convert.ToInt16(response[6]);   miblength = Convert.ToInt16(response[23 + commlength]);   // Extract the MIB data from the SNMP response   datatype = Convert.ToInt16(response[24 + commlength + miblength]);   datalength = Convert.ToInt16(response[25 + commlength + miblength]);   datastart = 26 + commlength + miblength;   output = Encoding.ASCII.GetString(response, datastart, datalength);   Console.WriteLine(" sysContact - Datatype: {0}, Value: {1}",       datatype, output);   // Send a SysUptime SNMP request   response = conn.get("get", argv[0], argv[1], "1.3.6.1.2.1.1.3.0");   if (response[0] == 0xff)   {     Console.WriteLine("No response from {0}", argv[0]);     return;   }   // Get the community and MIB lengths of the response   commlength = Convert.ToInt16(response[6]);   miblength = Convert.ToInt16(response[23 + commlength]);   // Extract the MIB data from the SNMp response   datatype = Convert.ToInt16(response[24 + commlength + miblength]);   datalength = Convert.ToInt16(response[25 + commlength + miblength]);   datastart = 26 + commlength + miblength;   // The sysUptime value may by a multi-byte integer   // Each byte read must be shifted to the higher byte order   while(datalength > 0)   {     uptime = (uptime << 8) + response[datastart++];     datalength--;   }   Console.WriteLine(" sysUptime - Datatype: {0}, Value: {1}",       datatype, uptime);  }}class SNMP{  public SNMP()  {  }  public byte[] get(string request, string host, string community, string mibstring)  {   byte[] packet = new byte[1024];   byte[] mib = new byte[1024];   int snmplen;   int comlen = community.Length;   string[] mibvals = mibstring.Split('.');   int miblen = mibvals.Length;   int cnt = 0, temp, i;   int orgmiblen = miblen;   int pos = 0;   // Convert the string MIB into a byte array of integer values   // Unfortunately, values over 128 require multiple bytes   // which also increases the MIB length   for (i = 0; i < orgmiblen; i++)   {     temp = Convert.ToInt16(mibvals[i]);     if (temp > 127)     {      mib[cnt] = Convert.ToByte(128 + (temp / 128));      mib[cnt + 1] = Convert.ToByte(temp - ((temp / 128) * 128));      cnt += 2;      miblen++;     } else     {      mib[cnt] = Convert.ToByte(temp);      cnt++;     }   }   snmplen = 29 + comlen + miblen - 1; //Length of entire SNMP packet   //The SNMP sequence start   packet[pos++] = 0x30; //Sequence start   packet[pos++] = Convert.ToByte(snmplen - 2); //sequence size   //SNMP version   packet[pos++] = 0x02; //Integer type   packet[pos++] = 0x01; //length   packet[pos++] = 0x00; //SNMP version 1   //Community name   packet[pos++] = 0x04; // String type   packet[pos++] = Convert.ToByte(comlen); //length   //Convert community name to byte array   byte[] data = Encoding.ASCII.GetBytes(community);   for (i = 0; i < data.Length; i++)   {     packet[pos++] = data[i];   }   //Add GetRequest or GetNextRequest value   if (request == "get")     packet[pos++] = 0xA0;   else     packet[pos++] = 0xA1;   packet[pos++] = Convert.ToByte(20 + miblen - 1); //Size of total MIB   //Request ID   packet[pos++] = 0x02; //Integer type   packet[pos++] = 0x04; //length   packet[pos++] = 0x00; //SNMP request ID   packet[pos++] = 0x00;   packet[pos++] = 0x00;   packet[pos++] = 0x01;   //Error status   packet[pos++] = 0x02; //Integer type   packet[pos++] = 0x01; //length   packet[pos++] = 0x00; //SNMP error status   //Error index   packet[pos++] = 0x02; //Integer type   packet[pos++] = 0x01; //length   packet[pos++] = 0x00; //SNMP error index   //Start of variable bindings   packet[pos++] = 0x30; //Start of variable bindings sequence   packet[pos++] = Convert.ToByte(6 + miblen - 1); // Size of variable binding   packet[pos++] = 0x30; //Start of first variable bindings sequence   packet[pos++] = Convert.ToByte(6 + miblen - 1 - 2); // size   packet[pos++] = 0x06; //Object type   packet[pos++] = Convert.ToByte(miblen - 1); //length   //Start of MIB   packet[pos++] = 0x2b;   //Place MIB array in packet   for(i = 2; i < miblen; i++)     packet[pos++] = Convert.ToByte(mib[i]);   packet[pos++] = 0x05; //Null object value   packet[pos++] = 0x00; //Null   //Send packet to destination   Socket sock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram,            ProtocolType.Udp);   sock.SetSocketOption(SocketOptionLevel.Socket,           SocketOptionName.ReceiveTimeout, 5000);   IPHostEntry ihe = Dns.Resolve(host);   IPEndPoint iep = new IPEndPoint(ihe.AddressList[0], 161);   EndPoint ep = (EndPoint)iep;   sock.SendTo(packet, snmplen, SocketFlags.None, iep);   //Receive response from packet   try   {     int recv = sock.ReceiveFrom(packet, ref ep);   } catch (SocketException)   {     packet[0] = 0xff;   }   return packet;  }  public string getnextMIB(byte[] mibin)  {   string output = "1.3";   int commlength = mibin[6];   int mibstart = 6 + commlength + 17; //find the start of the mib section   //The MIB length is the length defined in the SNMP packet   // minus 1 to remove the ending .0, which is not used   int miblength = mibin[mibstart] - 1;   mibstart += 2; //skip over the length and 0x2b values   int mibvalue;   for(int i = mibstart; i < mibstart + miblength; i++)   {     mibvalue = Convert.ToInt16(mibin[i]);     if (mibvalue > 128)     {      mibvalue = (mibvalue/128)*128 + Convert.ToInt16(mibin[i+1]);      //ERROR here, it should be mibvalue = (mibvalue-128)*128 + Convert.ToInt16(mibin[i+1]);      //for mib values greater than 128, the math is not adding up correctly        i++;     }     output += "." + mibvalue;   }   return output;  }}