84 lines
2 KiB
Go
84 lines
2 KiB
Go
package dbus
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import "net/url"
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// EscapeBusAddressValue implements a requirement to escape the values
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// in D-Bus server addresses, as defined by the D-Bus specification at
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// https://dbus.freedesktop.org/doc/dbus-specification.html#addresses.
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func EscapeBusAddressValue(val string) string {
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toEsc := strNeedsEscape(val)
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if toEsc == 0 {
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// Avoid unneeded allocation/copying.
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return val
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}
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// Avoid allocation for short paths.
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var buf [64]byte
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var out []byte
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// Every to-be-escaped byte needs 2 extra bytes.
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required := len(val) + 2*toEsc
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if required <= len(buf) {
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out = buf[:required]
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} else {
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out = make([]byte, required)
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}
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j := 0
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for i := 0; i < len(val); i++ {
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if ch := val[i]; needsEscape(ch) {
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// Convert ch to %xx, where xx is hex value.
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out[j] = '%'
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out[j+1] = hexchar(ch >> 4)
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out[j+2] = hexchar(ch & 0x0F)
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j += 3
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} else {
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out[j] = ch
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j++
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}
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}
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return string(out)
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}
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// UnescapeBusAddressValue unescapes values in D-Bus server addresses,
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// as defined by the D-Bus specification at
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// https://dbus.freedesktop.org/doc/dbus-specification.html#addresses.
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func UnescapeBusAddressValue(val string) (string, error) {
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// Looks like url.PathUnescape does exactly what is required.
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return url.PathUnescape(val)
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}
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// hexchar returns an octal representation of a n, where n < 16.
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// For invalid values of n, the function panics.
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func hexchar(n byte) byte {
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const hex = "0123456789abcdef"
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// For n >= len(hex), runtime will panic.
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return hex[n]
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}
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// needsEscape tells if a byte is NOT one of optionally-escaped bytes.
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func needsEscape(c byte) bool {
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if 'a' <= c && c <= 'z' || 'A' <= c && c <= 'Z' || '0' <= c && c <= '9' {
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return false
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}
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switch c {
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case '-', '_', '/', '\\', '.', '*':
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return false
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}
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return true
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}
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// strNeedsEscape tells how many bytes in the string need escaping.
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func strNeedsEscape(val string) int {
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count := 0
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for i := 0; i < len(val); i++ {
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if needsEscape(val[i]) {
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count++
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}
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}
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return count
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}
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