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gosuv/vendor/github.com/gopherjs/gopherjs/compiler/natives/src/crypto/rand/rand.go

50 lines
1.1 KiB

// +build js
package rand
import (
"errors"
"github.com/gopherjs/gopherjs/js"
)
func init() {
Reader = &rngReader{}
}
type rngReader struct{}
func (r *rngReader) Read(b []byte) (n int, err error) {
array := js.InternalObject(b).Get("$array")
offset := js.InternalObject(b).Get("$offset").Int()
// browser
crypto := js.Global.Get("crypto")
if crypto == js.Undefined {
crypto = js.Global.Get("msCrypto")
}
if crypto != js.Undefined {
if crypto.Get("getRandomValues") != js.Undefined {
n = len(b)
if n > 65536 {
// Avoid QuotaExceededError thrown by getRandomValues
// when length is more than 65536, as specified in
// http://www.w3.org/TR/WebCryptoAPI/#Crypto-method-getRandomValues
n = 65536
}
crypto.Call("getRandomValues", array.Call("subarray", offset, offset+n))
return n, nil
}
}
// Node.js
if require := js.Global.Get("require"); require != js.Undefined {
if randomBytes := require.Invoke("crypto").Get("randomBytes"); randomBytes != js.Undefined {
array.Call("set", randomBytes.Invoke(len(b)), offset)
return len(b), nil
}
}
return 0, errors.New("crypto/rand not available in this environment")
}