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import Foundation
struct EmailSecurityService {
/// Analyze email security records. SPF is parsed from existing TXT records;
/// DMARC and DKIM require additional DoH queries.
static func analyze(domain: String, txtRecords: [DNSRecord]) async -> EmailSecurityResult {
// SPF: extract from existing TXT records
let spfRecord = txtRecords.first(where: { $0.value.lowercased().hasPrefix("v=spf1") })
let spf = EmailSecurityRecord(found: spfRecord != nil, value: spfRecord?.value)
// DMARC and DKIM queries in parallel
async let dmarcResult = queryTXT(subdomain: "_dmarc.\(domain)")
async let dkimResult = queryDKIM(domain: domain)
let dmarcValue = await dmarcResult
let dkimValue = await dkimResult
let dmarc = EmailSecurityRecord(
found: dmarcValue != nil,
value: dmarcValue
)
let dkim = EmailSecurityRecord(
found: dkimValue != nil,
value: dkimValue
)
return EmailSecurityResult(spf: spf, dmarc: dmarc, dkim: dkim)
}
/// Query a TXT record for the given subdomain via DoH.
private static func queryTXT(subdomain: String) async -> String? {
do {
let records = try await DNSLookupService.lookup(domain: subdomain, recordType: .TXT)
return records.first?.value
} catch {
return nil
}
}
/// Try common DKIM selectors and return the first found.
private static func queryDKIM(domain: String) async -> String? {
let selectors = ["default", "google", "mail"]
return await withTaskGroup(of: (Int, String?).self, returning: String?.self) { group in
for (index, selector) in selectors.enumerated() {
group.addTask {
let value = await queryTXT(subdomain: "\(selector)._domainkey.\(domain)")
return (index, value)
}
}
var results: [(Int, String?)] = []
for await result in group {
results.append(result)
}
// Return the first (by selector order) that has a value
return results
.sorted { $0.0 < $1.0 }
.first(where: { $0.1 != nil })?.1
}
}
}
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