new: dns.spoof now supports a hosts file with multiple mappings (closes #344)

modules/dns_spoof_hosts.go

@@ -0,0 +1,83 @@
+package modules
+
+import (
+	"bufio"
+	"fmt"
+	"net"
+	"os"
+	"regexp"
+	"strings"
+
+	"github.com/bettercap/bettercap/core"
+
+	"github.com/gobwas/glob"
+)
+
+var hostsSplitter = regexp.MustCompile(`\s+`)
+
+type HostEntry struct {
+	Host    string
+	Suffix  string
+	Expr    glob.Glob
+	Address net.IP
+}
+
+func (e HostEntry) Matches(host string) bool {
+	return e.Host == host || strings.HasSuffix(host, e.Suffix) || (e.Expr != nil && e.Expr.Match(host))
+}
+
+type Hosts []HostEntry
+
+func NewHostEntry(host string, address net.IP) HostEntry {
+	entry := HostEntry{
+		Host:    host,
+		Address: address,
+	}
+
+	if host[0] == '.' {
+		entry.Suffix = host
+	} else {
+		entry.Suffix = "." + host
+	}
+
+	if expr, err := glob.Compile(host); err == nil {
+		entry.Expr = expr
+	}
+
+	return entry
+}
+
+func HostsFromFile(filename string) (err error, entries []HostEntry) {
+	input, err := os.Open(filename)
+	if err != nil {
+		return
+	}
+	defer input.Close()
+
+	scanner := bufio.NewScanner(input)
+	scanner.Split(bufio.ScanLines)
+	for scanner.Scan() {
+		line := core.Trim(scanner.Text())
+		if line == "" || line[0] == '#' {
+			continue
+		}
+		if parts := hostsSplitter.Split(line, 2); len(parts) == 2 {
+			address := net.ParseIP(parts[0])
+			domain := parts[1]
+			entries = append(entries, NewHostEntry(domain, address))
+		} else {
+			return fmt.Errorf("'%s' invalid hosts line", line), nil
+		}
+	}
+
+	return
+}
+
+func (h Hosts) Resolve(host string) net.IP {
+	for _, entry := range h {
+		if entry.Matches(host) {
+			return entry.Address
+		}
+	}
+	return nil
+}