pancap/ethernet/dns/common.go

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package dns
import (
"fmt"
"github.com/google/gopacket/layers"
"net"
)
var (
privateBlocks = []net.IPNet{
{net.IPv4(10, 0, 0, 0), net.IPv4Mask(255, 0, 0, 0)}, // 10.0.0.0/8
{net.IPv4(172, 16, 0, 0), net.IPv4Mask(255, 240, 0, 0)}, // 172.16.0.0/12
{net.IPv4(192, 168, 0, 0), net.IPv4Mask(255, 255, 0, 0)}, // 192.168.0.0/24
{net.IPv4(100, 64, 0, 0), net.IPv4Mask(255, 192, 0, 0)}, // 100.64.0.0/10
{net.IPv4(169, 254, 0, 0), net.IPv4Mask(255, 255, 0, 0)}, // 169.254.0.0/16
}
)
// Processes the given dnstype and raises its stats in the given array
func processType(typearr map[layers.DNSType]int, dnstype layers.DNSType) {
typearr[dnstype]++
}
// Appends the appendee to the array if it does not contain appendee yet
func appendIfUnique(appendee string, array []string) []string {
// Iterate over all elements and check values
for _, elem := range array {
if elem == appendee {
// ... found. Stop here
return array
}
}
// None found, append
return append(array, appendee)
}
// Checks if the given IP is in a private range or not
func ipIsPrivate(ip net.IP) bool {
// check every private IP block for our IP
for _, block := range privateBlocks {
if block.Contains(ip) {
// found, is a private IP
return true
}
}
// Not in any of the private blocks, not private
return false
}
// Prints each element, along with a small ASCII tree
func printTree(strarr []string) {
// iterate over each element
for iter, elem := range strarr {
// check if we got the last element
if iter < len(strarr) - 1 {
fmt.Printf("|- %s\n", elem)
} else {
fmt.Printf("'- %s\n\n", elem)
}
}
}
// Generates a summary string for DNS types in the given array
func generateDNSTypeSummary(typearr map[layers.DNSType]int) string {
var answerarr []string
// Iterate over all possible DNS types
for iter, typeelem := range typearr {
// Read amount of type hits for this type
answerarr = append(answerarr, fmt.Sprintf("%d %s", typeelem, iter.String()))
}
// Check if we even processed a single type
if len(answerarr) == 0 {
// we didn't, strange.
return "(no types encountered)"
}
// now, glue all array elements together
answerstr := ""
for iter, elem := range answerarr {
// Check if we need to apply to proper sentence rules
if iter == 0 {
// We don't need to append yet
answerstr = elem
} else if iter == len(answerarr) - 1 {
// Last element, use "and" instead of a comma
answerstr = fmt.Sprintf("%s and %s", answerstr, elem)
} else {
// Some entry, just add it with a comma
answerstr = fmt.Sprintf("%s, %s", answerstr, elem)
}
}
return answerstr
}