diff --git a/osbase/net/dns/name.go b/osbase/net/dns/name.go
new file mode 100644
index 0000000..9769d7e
--- /dev/null
+++ b/osbase/net/dns/name.go
@@ -0,0 +1,157 @@
+package dns
+
+import (
+	"net/netip"
+	"strings"
+)
+
+// IsSubDomain returns true if child is the same as or a subdomain of parent.
+// Both names should be in canonical form.
+func IsSubDomain(parent, child string) bool {
+	offset := len(child) - len(parent)
+	if offset < 0 || child[offset:] != parent {
+		return false
+	}
+	if offset == 0 || parent == "." {
+		return true
+	}
+	if child[offset-1] != '.' {
+		return false
+	}
+	j := offset - 2
+	for j >= 0 && child[j] == '\\' {
+		j--
+	}
+	return (offset-j)%2 == 0
+}
+
+// SplitLastLabel splits off the last label of a domain name. For example,
+// "www.example.com." is split into "www.example." and "com".
+func SplitLastLabel(name string) (rest string, label string) {
+	labelEnd := len(name)
+	if labelEnd != 0 && name[labelEnd-1] == '.' {
+		labelEnd--
+	}
+	labelStart := labelEnd
+	for ; labelStart > 0; labelStart-- {
+		if name[labelStart-1] != '.' {
+			continue
+		}
+		j := labelStart - 2
+		for j >= 0 && name[j] == '\\' {
+			j--
+		}
+		if (labelStart-j)%2 != 0 {
+			continue
+		}
+		break
+	}
+	return name[:labelStart], name[labelStart:labelEnd]
+}
+
+// ParseReverse parses name as a reverse lookup name. If name is not a reverse
+// name, the returned IP is invalid. The second return value indicates how many
+// bits of the address are present. The third return value is true if there are
+// extra labels before the reverse name.
+func ParseReverse(name string) (ip netip.Addr, bits int, extra bool) {
+	if strings.HasSuffix(name, "in-addr.arpa.") {
+		var ip [4]uint8
+		field := 0
+		pos := len(name) - len("in-addr.arpa.") - 1
+		for pos >= 0 && field < 4 {
+			if name[pos] != '.' {
+				break
+			}
+			nextPos := pos - 1
+			for nextPos >= 0 && name[nextPos] >= '0' && name[nextPos] <= '9' {
+				nextPos--
+			}
+			val := 0
+			for valPos := nextPos + 1; valPos < pos; valPos++ {
+				val = val*10 + int(name[valPos]) - '0'
+			}
+			valLen := pos - nextPos - 1
+			if valLen == 0 || valLen > 3 || (valLen != 1 && name[nextPos+1] == '0') || val > 255 {
+				// Number is empty, or too long, or has leading zero, or is too large.
+				break
+			}
+			ip[field] = uint8(val)
+			field++
+			pos = nextPos
+		}
+		if pos >= 0 {
+			// We did not parse the entire name.
+			j := pos - 1
+			for j >= 0 && name[j] == '\\' {
+				j--
+			}
+			if name[pos] != '.' || (pos-j)%2 == 0 {
+				// The last label we parsed was not terminated by a non-escaped dot.
+				field--
+				if field < 0 {
+					return netip.Addr{}, 0, false
+				}
+				ip[field] = 0
+			}
+		}
+		return netip.AddrFrom4(ip), field * 8, pos >= 0
+	}
+
+	if strings.HasSuffix(name, "ip6.arpa.") {
+		var ip [16]uint8
+		field := 0
+		half := false
+
+		pos := len(name) - len("ip6.arpa.") - 1
+		for pos > 0 && field < 16 {
+			if name[pos] != '.' {
+				break
+			}
+			var nibble uint8
+			if name[pos-1] >= '0' && name[pos-1] <= '9' {
+				nibble = name[pos-1] - '0'
+			} else if name[pos-1] >= 'a' && name[pos-1] <= 'f' {
+				nibble = name[pos-1] - 'a' + 10
+			} else {
+				break
+			}
+			if half {
+				ip[field] |= nibble
+				field++
+				half = false
+			} else {
+				ip[field] = nibble << 4
+				half = true
+			}
+			pos -= 2
+		}
+		if pos >= 0 {
+			// We did not parse the entire name.
+			j := pos - 1
+			for j >= 0 && name[j] == '\\' {
+				j--
+			}
+			if name[pos] != '.' || (pos-j)%2 == 0 {
+				// The last label we parsed was not terminated by a non-escaped dot.
+				if half {
+					half = false
+					ip[field] = 0
+				} else {
+					half = true
+					field--
+					if field < 0 {
+						return netip.Addr{}, 0, false
+					}
+					ip[field] &= 0xf0
+				}
+			}
+		}
+		bits := field * 8
+		if half {
+			bits += 4
+		}
+		return netip.AddrFrom16(ip), bits, pos >= 0
+	}
+
+	return netip.Addr{}, 0, false
+}