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package valid
import (
"bytes"
)
var URIs = [][]byte{
[]byte("http://"),
[]byte("https://"),
[]byte("ftp://"),
[]byte("mailto:"),
}
var Paths = [][]byte{
[]byte("/"),
[]byte("./"),
[]byte("../"),
}
// TODO: documentation
func IsSafeURL(url []byte) bool {
nLink := len(url)
for _, path := range Paths {
nPath := len(path)
linkPrefix := url[:nPath]
if nLink >= nPath && bytes.Equal(linkPrefix, path) {
if nLink == nPath {
return true
} else if isAlnum(url[nPath]) {
return true
}
}
}
for _, prefix := range URIs {
// TODO: handle unicode here
// case-insensitive prefix test
nPrefix := len(prefix)
if nLink > nPrefix {
linkPrefix := bytes.ToLower(url[:nPrefix])
if bytes.Equal(linkPrefix, prefix) && isAlnum(url[nPrefix]) {
return true
}
}
}
return false
}
// isAlnum returns true if c is a digit or letter
// TODO: check when this is looking for ASCII alnum and when it should use unicode
func isAlnum(c byte) bool {
return (c >= '0' && c <= '9') || isLetter(c)
}
// isLetter returns true if c is ascii letter
func isLetter(c byte) bool {
return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')
}
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