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|
package fasthttp
import (
"bytes"
"errors"
)
var (
errInvalidIPv6Host = errors.New("invalid IPv6 host")
errInvalidIPv6Zone = errors.New("invalid IPv6 zone")
errInvalidIPv6Address = errors.New("invalid IPv6 address")
)
func validateIPv6Literal(host []byte) error {
if len(host) == 0 || host[0] != '[' {
return nil
}
end := bytes.IndexByte(host, ']')
if end < 0 || end == 1 {
return errInvalidIPv6Host
}
addr := host[1:end]
// Optional zone.
if zi := bytes.IndexByte(addr, '%'); zi >= 0 {
if zi == len(addr)-1 {
return errInvalidIPv6Zone
}
addr = addr[:zi]
}
// Must have a colon to be IPv6.
if bytes.IndexByte(addr, ':') < 0 {
return errInvalidIPv6Address
}
// IPv4-embedded?
if bytes.IndexByte(addr, '.') >= 0 {
lastColon := bytes.LastIndexByte(addr, ':')
if lastColon < 0 || lastColon == len(addr)-1 {
return errInvalidIPv6Address
}
ipv4 := addr[lastColon+1:]
if !validIPv4(ipv4) {
return errInvalidIPv6Address
}
head := addr[:lastColon]
seenDoubleAtSplit := lastColon > 0 && addr[lastColon-1] == ':'
if seenDoubleAtSplit {
head = addr[:lastColon-1]
}
hextets, seenDoubleHead, ok := parseIPv6Hextets(head, false)
if !ok {
return errInvalidIPv6Address
}
if seenDoubleHead && seenDoubleAtSplit {
return errInvalidIPv6Address
}
hextets += 2 // IPv4 tail = 2 hextets
seenDouble := seenDoubleHead || seenDoubleAtSplit
// '::' must compress at least one hextet.
if (!seenDouble && hextets != 8) || (seenDouble && hextets >= 8) {
return errInvalidIPv6Address
}
return nil
}
// Pure IPv6
hextets, seenDouble, ok := parseIPv6Hextets(addr, false)
if !ok {
return errInvalidIPv6Address
}
if (!seenDouble && hextets != 8) || (seenDouble && hextets >= 8) {
return errInvalidIPv6Address
}
return nil
}
func parseIPv6Hextets(s []byte, allowTrailingColon bool) (groups int, seenDouble, ok bool) {
n := len(s)
if n == 0 {
return 0, false, true
}
i := 0
justSawDouble := false
for i < n {
if s[i] == ':' {
if i+1 < n && s[i+1] == ':' {
if seenDouble || justSawDouble {
return 0, false, false
}
seenDouble = true
justSawDouble = true
i += 2
if i == n {
break
}
continue
}
if i == 0 {
return 0, false, false
}
if justSawDouble {
return 0, false, false
}
if i == n-1 {
if allowTrailingColon {
break
}
return 0, false, false
}
if !ishex(s[i+1]) {
return 0, false, false
}
i++
continue
}
justSawDouble = false
cnt := 0
for cnt < 4 && i < n && ishex(s[i]) {
i++
cnt++
}
if cnt == 0 {
return 0, false, false
}
groups++
if i < n && s[i] != ':' {
return 0, false, false
}
}
return groups, seenDouble, true
}
// validIPv4 validates a dotted-quad (exactly 4 parts, 0..255) with no leading zeros
// unless the octet is exactly "0".
func validIPv4(s []byte) bool {
parts := 0
i := 0
n := len(s)
for parts < 4 {
if i >= n {
return false
}
start := i
val := 0
digits := 0
for i < n {
c := s[i]
if c < '0' || c > '9' {
break
}
val = val*10 + int(c-'0')
if val > 255 {
return false
}
i++
digits++
if digits > 3 {
return false
}
}
if digits == 0 {
return false
}
// Disallow leading zeros like "00", "01", "001".
// Allowed: exactly "0" or any number that doesn't start with '0'.
if digits > 1 && s[start] == '0' {
return false
}
parts++
if parts == 4 {
return i == n // must consume all input
}
if i >= n || s[i] != '.' {
return false
}
i++ // skip dot
}
return false
}
|
