Add back infinity mode (default for single address)

scanner.go

@@ -3,13 +3,44 @@ package main
 import (
 	"crypto/tls"
 	"log/slog"
+	"math/big"
 	"net"
 	"strconv"
 	"strings"
+	"sync"
 	"time"
 )
 
-func ScanTLS(host Host, out chan<- string) {
+type Scanner struct {
+	mu   *sync.Mutex
+	high net.IP
+	low  net.IP
+}
+
+func (s *Scanner) Scan(host Host, out chan<- string, increment bool) {
+	if host.Infinity && host.IP != nil {
+		s.mu.Lock()
+		if s.high == nil {
+			s.high = host.IP
+			s.low = host.IP
+			host.Origin = ""
+			host.Type = HostTypeIP
+		} else if increment {
+			s.high = nextIP(s.high, increment)
+			host.IP = s.high
+		} else {
+			s.low = nextIP(s.low, increment)
+			host.IP = s.low
+		}
+		s.mu.Unlock()
+	}
+	ScanTLS(host, out, increment)
+	if host.Infinity && host.IP != nil {
+		go s.Scan(host, out, increment)
+	}
+}
+
+func ScanTLS(host Host, out chan<- string, increment bool) {
 	if host.IP == nil {
 		ips, err := net.LookupIP(host.Origin)
 		if err != nil {
@@ -71,3 +102,18 @@ func ScanTLS(host Host, out chan<- string) {
 		"origin", host.Origin,
 		"tls", tls.VersionName(state.Version), "alpn", alpn, "cert-domain", domain, "cert-issuer", issuers)
 }
+
+func nextIP(ip net.IP, increment bool) net.IP {
+	// Convert to big.Int and increment
+	ipb := big.NewInt(0).SetBytes([]byte(ip))
+	if increment {
+		ipb.Add(ipb, big.NewInt(1))
+	} else {
+		ipb.Sub(ipb, big.NewInt(1))
+	}
+
+	// Add leading zeros
+	b := ipb.Bytes()
+	b = append(make([]byte, len(ip)-len(b)), b...)
+	return net.IP(b)
+}