careyjames/dns-scout

package dnsinformation

import (
    "fmt"
    "strings"

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

const (
    DMARCLookupString = "_dmarc."
    DMARCValid        = "v=DMARC1"
)

// getDMARC fetches the DMARC record for a given domain.
func getDMARC(domain string) (string, error) {
    txtRecords, err := GetTXT(DMARCLookupString + domain)
    if len(txtRecords) <= 0 {
        txtRecords, _ = GetDMARCRecordNSLookup(domain)
    }
    if err != nil {
        return "", err
    }
    for _, record := range txtRecords {
        if HasDMARCRecord(record) {
            return record, nil
        }
    }
    return "", nil
}

func HasDMARCRecord(record string) bool {
    return (len(record) > 8 && record[:8] == DMARCValid) || (len(record) > 6 && record[:6] == "vDMARC")
}

// GetDMARCPrompt fetches the DMARC record for a given domain.
func GetDMARCPrompt(input string) {
    dmarc, _ := getDMARC(input)
    if dmarc != "" {
        if isValidDMARC(dmarc) {
            formattedDMARC := formatLongText(dmarc, 80, " ")
            fmt.Printf(color.Blue(" DMARC ✅:") + color.Grey(" ") + color.Grey(formattedDMARC) + constants.Newline)
        } else {
            fmt.Printf(color.Blue(" DMARC ❌:") + color.Red(" ") + color.Red(dmarc[8:]) + constants.Newline)
        }
    } else {
        fmt.Printf(color.Blue(" DMARC ❌:") + color.Red(" None") + constants.Newline)
    }
}

func isValidDMARC(record string) bool {
    if len(record) > 8 && record[:8] == DMARCValid {
        return true
    }
    return false
}

// formatLongText formats long text strings for better readability.
func formatLongText(text string, threshold int, indent string) string {
    if len(text) <= threshold {
        return text
    }

    var result strings.Builder
    for len(text) > threshold {
        splitAt := strings.LastIndex(text[:threshold], " ")
        if splitAt == -1 {
            splitAt = threshold
        }
        result.WriteString(text[:splitAt] + "\n" + indent)
        text = text[splitAt+1:]
    }
    result.WriteString(text)
    return result.String()
}