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Add SNMP manager functions #2

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4a6a61c
Initial commit
Niich May 20, 2018
55efeab
Example of Get-request
Niich May 20, 2018
3725152
Updated example for SNMP Strings
Niich Jun 13, 2019
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560 changes: 346 additions & 214 deletions Arduino_SNMP.h
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101 changes: 92 additions & 9 deletions BER.h
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Original file line number Diff line number Diff line change
Expand Up @@ -16,6 +16,7 @@ typedef enum ASN_TYPE_WITH_VALUE {
// Complex
STRUCTURE = 0x30,
NETWORK_ADDRESS = 0x40,
COUNTER32 = 0x41,
TIMESTAMP = 0x43,

GetRequestPDU = 0xA0,
Expand Down Expand Up @@ -94,6 +95,8 @@ class IntegerType: public BER_CONTAINER {
*ptr = _type;
ptr++;
unsigned char* lengthPtr = ptr++;
//Serial.print("INTEGER length: ");
//Serial.println(*lengthPtr);
if(_value != 0){
_length = 4; // FIXME: need to give this dynamic length
// while(_length > 1){
Expand All @@ -120,22 +123,87 @@ class IntegerType: public BER_CONTAINER {
bool fromBuffer(unsigned char* buf){
buf++;// skip Type
_length = *buf;
buf++;

buf++;

unsigned short tempLength = _length;
// _value = *buf; // TODO: make work for integers more than 255
_value = *buf; // TODO: make work for integers more than 255

_value = 0;
while(tempLength > 0){
_value = _value << 8;
_value = _value | *buf++;
tempLength--;
}
//Serial.print("Counter Value: "); Serial.println(_value);
return true;
}
int getLength(){
return _length;
}
};

class Counter32 : public BER_CONTAINER {
public:
Counter32() : BER_CONTAINER(true, INTEGER) {};
Counter32(unsigned long value) : _value(value), BER_CONTAINER(true, INTEGER) {};
~Counter32() {};
unsigned long _value;
int serialise(unsigned char* buf) {
// here we print out the BER encoded ASN.1 bytes, which includes type, length and value. we return the length of the entire block (TL&V) ni bytes;
unsigned char* ptr = buf;
*ptr = _type;
ptr++;
unsigned char* lengthPtr = ptr++;
Serial.print("INTEGER length: ");
Serial.println(*lengthPtr);
if (_value != 0) {
_length = 4; // FIXME: need to give this dynamic length
// while(_length > 1){
// if(_value >> 24 == 0){
// _length--;
// _value = _value << 8;
// } else {
// break;
// }
// }
*ptr++ = _value >> 24 & 0xFF;
*ptr++ = _value >> 16 & 0xFF;
*ptr++ = _value >> 8 & 0xFF;
*ptr++ = _value & 0xFF;


}
else {
_length = 1;
*ptr = 0;
}
*lengthPtr = _length;
return _length + 2;
}
bool fromBuffer(unsigned char* buf) {
buf++;// skip Type
_length = *buf;

buf++;

unsigned short tempLength = _length;
_value = *buf; // TODO: make work for integers more than 255

_value = 0;
while (tempLength > 0) {
_value = _value << 8;
_value = _value | *buf++;
tempLength--;
}
//Serial.print("Counter Value: "); Serial.println(_value);
return true;
}
int getLength() {
return _length;
}
};

class TimestampType: public IntegerType {
public:
TimestampType(): IntegerType(){
Expand Down Expand Up @@ -270,11 +338,10 @@ class OIDType: public BER_CONTAINER {
}
delay(1);
}
Serial.print("OID: " );Serial.println(_value);
//Serial.print("OID: " );Serial.println(_value);
// memcpy(_value, buf, _length);
return true;
}

int getLength(){
return _length;
}
Expand Down Expand Up @@ -318,9 +385,13 @@ class ComplexType: public BER_CONTAINER {
ComplexType(ASN_TYPE type): BER_CONTAINER(false, type){};
~ComplexType(){
delete _values;

}
ValuesList* _values = 0;

// buf is an unsigned char pointer to an array that lists the bytes we got from the UDP packet
bool fromBuffer(unsigned char* buf){

// the buffer we get passed in is the complete ASN Container, including the type header.
buf++; // Skip our own type
_length = *buf;
Expand All @@ -334,7 +405,10 @@ class ComplexType: public BER_CONTAINER {
// now we are at the front of a list of one or many other types, lets do our loop
unsigned char i = 0;
while(i < _length){
ASN_TYPE valueType = (ASN_TYPE)*buf;



ASN_TYPE valueType = (ASN_TYPE)*buf;
buf++; i++;
unsigned short valueLength = *buf;
if(valueLength > 127){
Expand All @@ -346,7 +420,7 @@ class ComplexType: public BER_CONTAINER {
}
buf++; i++;
// Serial.println("SUP");
// char* newValue = (char*)malloc(sizeof(char) * valueLength + 2);
// char* Value = (char*)malloc(sizeof(char) * valueLength + 2);
// memset(newValue, 0, valueLength + 2);
// memcpy(newValue, buf - 2, valueLength + 2);
// buf += valueLength; i+= valueLength;
Expand All @@ -363,12 +437,17 @@ class ComplexType: public BER_CONTAINER {
break;
// primitive
case INTEGER:
newObj = new IntegerType();
newObj = new IntegerType();
break;
case STRING:
newObj = new OctetType();
break;
case COUNTER32:
//Serial.println("valueType is counter32");
newObj = new Counter32();
break;
case OID:
// Serial.println("valueType is OID");
newObj = new OIDType();
break;
case NULLTYPE:
Expand All @@ -381,14 +460,17 @@ class ComplexType: public BER_CONTAINER {
case TIMESTAMP:
newObj = new TimestampType();
break;

}

newObj->fromBuffer(buf - 2);
buf += valueLength; i+= valueLength;
//newObj->fromBuffer(newValue);
// free(newValue);
addValueToList(newObj);

}
return true;
return true;
}

int serialise(unsigned char* buf){
Expand All @@ -400,7 +482,7 @@ class ComplexType: public BER_CONTAINER {
*lengthPtr = 0;
ValuesList* conductor = _values;
while(conductor){
// Serial.print("about to serialise something of type: ");Serial.println(conductor->value->_type, HEX);
//Serial.print("about to serialise something of type: ");Serial.println(conductor->value->_type, HEX);
delay(0);

int length = conductor->value->serialise(ptr);
Expand All @@ -425,6 +507,7 @@ class ComplexType: public BER_CONTAINER {
} else {
*lengthPtr = actualLength;
}
delete conductor;
return actualLength + 2;
}

Expand Down
16 changes: 9 additions & 7 deletions README.md
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Original file line number Diff line number Diff line change
@@ -1,10 +1,12 @@
# Arduino_SNMP
SNMP Agent built with Arduino
# Arduino_SNMP_manager
This adds some SNMP manager functions. Allowing you to send get requests and parse the response.

This is a very rough-around-the-edges SNMP Agent library I created for personal use.
Originally designed on the ESP8266 Arduino Core, it is very Heap-Intensive and is not nice to memory.
Not sure how it will work on basic Arduinos.
This is my first time programing so the code is probably a disaster but it works for the task I needed.

It does let you pass in any UDP Client though, so it theoretically will work in any network environment.
I have only tested it for my use case.

generate and send get-requests.
parse response formated in int32.

Other response types like Char and Counter should would but I have not tested any of them.

Pull requests/comments are welcome
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