careyjames/dns-scout

package dnsinformation

import (
    "fmt"
    "net"
    "strings"

    "github.com/careyjames/dns-scout/color"
    constants "github.com/careyjames/dns-scout/constant"
)

// getPTR fetches the PTR records for a given domain.
func getPTR(domain string) ([]string, error) {
    // mx - ptr (AND OPERATION)
    // TRUE - TRUE : TRUE
    // FALSE - TRUE : FALSE
    // TRUE - PTR : FALSE
    // FALSE - FALSE : FALSE

    ips, err := net.LookupIP(domain)
    if err != nil {
        return nil, err
    }

    var ptrRecords []string
    for _, ip := range ips {
        ptrs, err := net.LookupAddr(ip.String())
        if err != nil {
            continue
        }
        ptrRecords = append(ptrRecords, ptrs...)
    }
    return ptrRecords, nil
}

// GetPTRPrompt prompt
func GetPTRPrompt(input string, isIp bool) {
    ptr, _ := getPTR(input)
    if len(ptr) > 0 {
        // Remove the trailing period from each PTR record
        for i, record := range ptr {
            if strings.HasSuffix(record, ".") {
                ptr[i] = record[:len(record)-1]
            }
        }
        // Join the records with a comma and a space, then replace ", " at the end of each line with a line break followed by a space
        ptrStr := strings.Join(ptr, ", ")
        ptrStr = strings.ReplaceAll(ptrStr, ", ", ",\n ")
        if isIp && isMx(input) {
            fmt.Printf(color.Blue(" PTR   ✅: ") + color.Grey(ptrStr))
        } else {
            // we might need to delete this
            fmt.Printf(color.Blue(" PTR   ✅: ") + color.Grey(ptrStr) + constants.Newline)
        }
    } else {
        if isAllowlisted(input) {
                // FIXME: add mapping for google microsoft for their service
            fmt.Printf(color.Blue(" PTR   🟢: ") + color.Grey("None, Google and Microsoft 365 use shared IPs, this is ok.")  + constants.Newline)
        } else {
            fmt.Printf(color.Blue(" PTR   ❌: ") + color.Red("None") + constants.Newline)
        }
    }
}

func isMx(input string) bool {
    mx, _ := getMX(input)
    return len(mx) > 0
}

func isAllowlisted(input string) bool {
    mx, _ := getMX(input)
    domains := []string{"google.com", "outlook.com"}
    if len(mx) == 0 {
        return false
    }
    return containsString(domains, mx[0])
}

func containsString(arr []string, str string) bool {
    for _, a := range arr {
        if strings.Contains(str, a) {
            return true
        }
    }
    return false;
}