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package httpbinding
import (
"bytes"
"fmt"
)
const (
uriTokenStart = '{'
uriTokenStop = '}'
uriTokenSkip = '+'
)
func bufCap(b []byte, n int) []byte {
if cap(b) < n {
return make([]byte, 0, n)
}
return b[0:0]
}
// replacePathElement replaces a single element in the path []byte.
// Escape is used to control whether the value will be escaped using Amazon path escape style.
func replacePathElement(path, fieldBuf []byte, key, val string, escape bool) ([]byte, []byte, error) {
fieldBuf = bufCap(fieldBuf, len(key)+3) // { <key> [+] }
fieldBuf = append(fieldBuf, uriTokenStart)
fieldBuf = append(fieldBuf, key...)
start := bytes.Index(path, fieldBuf)
end := start + len(fieldBuf)
if start < 0 || len(path[end:]) == 0 {
// TODO what to do about error?
return path, fieldBuf, fmt.Errorf("invalid path index, start=%d,end=%d. %s", start, end, path)
}
encodeSep := true
if path[end] == uriTokenSkip {
// '+' token means do not escape slashes
encodeSep = false
end++
}
if escape {
val = EscapePath(val, encodeSep)
}
if path[end] != uriTokenStop {
return path, fieldBuf, fmt.Errorf("invalid path element, does not contain token stop, %s", path)
}
end++
fieldBuf = bufCap(fieldBuf, len(val))
fieldBuf = append(fieldBuf, val...)
keyLen := end - start
valLen := len(fieldBuf)
if keyLen == valLen {
copy(path[start:], fieldBuf)
return path, fieldBuf, nil
}
newLen := len(path) + (valLen - keyLen)
if len(path) < newLen {
path = path[:cap(path)]
}
if cap(path) < newLen {
newURI := make([]byte, newLen)
copy(newURI, path)
path = newURI
}
// shift
copy(path[start+valLen:], path[end:])
path = path[:newLen]
copy(path[start:], fieldBuf)
return path, fieldBuf, nil
}
// EscapePath escapes part of a URL path in Amazon style.
func EscapePath(path string, encodeSep bool) string {
var buf bytes.Buffer
for i := 0; i < len(path); i++ {
c := path[i]
if noEscape[c] || (c == '/' && !encodeSep) {
buf.WriteByte(c)
} else {
fmt.Fprintf(&buf, "%%%02X", c)
}
}
return buf.String()
}
var noEscape [256]bool
func init() {
for i := 0; i < len(noEscape); i++ {
// AWS expects every character except these to be escaped
noEscape[i] = (i >= 'A' && i <= 'Z') ||
(i >= 'a' && i <= 'z') ||
(i >= '0' && i <= '9') ||
i == '-' ||
i == '.' ||
i == '_' ||
i == '~'
}
}
|
