Counters

Counters are elements of the miner. In the Go project layout, they must be located in the miner/counter sub-package.

Every counter is related to a network layer (or directly to a packet). It means that it will access only on its layer specific field (we do not recommend to parse further layers in counters logic). The following layers are currently available:

• PKT (raw packet)
• ARP
• IPv4
• ICMPv4
• TCP
• UDP

A counter must implement 3 simple functions given by the interface below.

type BaseCtrInterface interface {
    Name() string  // the name of the counter
    Value() uint64 // get back the value of the counter
    Reset()        // method to reset the counter
}

In addition, it must implement a Process function related to the layers it depends on. For instance, an IPv4 counter must have a method with the following signature

Process(ip *layers.IPv4)

You can have a look to the counters already implemented within netspot. As a general example, a counter is a simple file with the following content.

// <layer>_<counter_name>.go

package counters

import (
    "github.com/google/gopacket/layers"
)

func init() {
    // The counter is registered at the very beginning
    Register(&COUNTER{Counter: 0})
}

// COUNTER is a custom Counter I made
type COUNTER struct {
    BaseCtr
    Counter uint64
}

// Name returns the name of the counter
func (c *COUNTER) Name() string {

}

// Value returns the current value of the counter
func (c *COUNTER) Value() uint64 {

}

// Reset resets the counter
func (c *COUNTER) Reset() {

}

// Process update the counter according to data it receives
func (c *COUNTER) Process(*layers.IPv4) {

}

Obviously, you can create more complex counters with additonal structures but you should keep in mind that its operation should be rather atomic.

Atomic

We recall that several goroutines are likely to call the Process function. It means that the internal counter value access is under high concurrency. For this purpose, you may have a look to the atomic/sync package. You can also have a look to this example.