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package utils
import (
"net"
)
var hexTable = [256]byte{
'0': 0, '1': 1, '2': 2, '3': 3, '4': 4, '5': 5, '6': 6, '7': 7, '8': 8, '9': 9,
'a': 10, 'b': 11, 'c': 12, 'd': 13, 'e': 14, 'f': 15,
'A': 10, 'B': 11, 'C': 12, 'D': 13, 'E': 14, 'F': 15,
}
// IsIPv4 works the same way as net.ParseIP,
// but without check for IPv6 case and without returning net.IP slice, whereby IsIPv4 makes no allocations.
func IsIPv4(s string) bool {
for i := range net.IPv4len {
if len(s) == 0 {
return false
}
if i > 0 {
if s[0] != '.' {
return false
}
s = s[1:]
}
n, ci := 0, 0
for ci = 0; ci < len(s) && '0' <= s[ci] && s[ci] <= '9'; ci++ {
n = n*10 + int(s[ci]-'0')
if n > 0xFF {
return false
}
}
if ci == 0 || (ci > 1 && s[0] == '0') {
return false
}
s = s[ci:]
}
return len(s) == 0
}
// IsIPv6 works the same way as net.ParseIP,
// but without check for IPv4 case and without returning net.IP slice, whereby IsIPv6 makes no allocations.
func IsIPv6(s string) bool {
ellipsis := -1 // position of ellipsis in ip
// Might have leading ellipsis
if len(s) >= 2 && s[0] == ':' && s[1] == ':' {
ellipsis = 0
s = s[2:]
// Might be only ellipsis
if len(s) == 0 {
return true
}
}
// Loop, parsing hex numbers followed by colon.
i := 0
for i < net.IPv6len {
// Hex number.
n, ci := 0, 0
for ci = 0; ci < len(s); ci++ {
if (s[ci] < '0' || s[ci] > '9') && (s[ci] < 'a' || s[ci] > 'f') && (s[ci] < 'A' || s[ci] > 'F') {
break
}
n *= 16
n += int(hexTable[s[ci]])
if n > 0xFFFF {
return false
}
}
if ci == 0 || n > 0xFFFF {
return false
}
if ci < len(s) && s[ci] == '.' {
if ellipsis < 0 && i != net.IPv6len-net.IPv4len {
return false
}
if i+net.IPv4len > net.IPv6len {
return false
}
if !IsIPv4(s) {
return false
}
s = ""
i += net.IPv4len
break
}
// Save this 16-bit chunk.
i += 2
// Stop at end of string.
s = s[ci:]
if len(s) == 0 {
break
}
// Otherwise must be followed by colon and more.
if s[0] != ':' || len(s) == 1 {
return false
}
s = s[1:]
// Look for ellipsis.
if s[0] == ':' {
if ellipsis >= 0 { // already have one
return false
}
ellipsis = i
s = s[1:]
if len(s) == 0 { // can be at end
break
}
}
}
// Must have used entire string.
if len(s) != 0 {
return false
}
// If didn't parse enough, expand ellipsis.
if i < net.IPv6len {
if ellipsis < 0 {
return false
}
} else if ellipsis >= 0 {
// Ellipsis must represent at least one 0 group.
return false
}
return true
}
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