// De-facto standard header keys.
	xForwardedFor    = http.CanonicalHeaderKey("X-Forwarded-For")
	xForwardedHost   = http.CanonicalHeaderKey("X-Forwarded-Host")
	xForwardedPort   = http.CanonicalHeaderKey("X-Forwarded-Port")
	xForwardedProto  = http.CanonicalHeaderKey("X-Forwarded-Proto")
	xForwardedScheme = http.CanonicalHeaderKey("X-Forwarded-Scheme")
	xRealIP          = http.CanonicalHeaderKey("X-Real-IP")
)

var (

	xhttp.AmzSignature:    true,
	xhttp.ContentEncoding: true,
	http.CanonicalHeaderKey(xhttp.AmzChecksumAlgo):   true,
	http.CanonicalHeaderKey(xhttp.AmzChecksumCRC32):  true,
	http.CanonicalHeaderKey(xhttp.AmzChecksumCRC32C): true,
	http.CanonicalHeaderKey(xhttp.AmzChecksumSHA1):   true,
	http.CanonicalHeaderKey(xhttp.AmzChecksumSHA256): true,
	http.CanonicalHeaderKey(xhttp.AmzChecksumMode):   true,
}

// Add policy conditionals.
const (

		// but its always necessary that the list of signed headers containing host in it.
		val, ok := reqHeaders[http.CanonicalHeaderKey(header)]
		if !ok {
			// try to set headers from Query String
			val, ok = reqQueries[header]
		}
		if ok {
			extractedSignedHeaders[http.CanonicalHeaderKey(header)] = val
			continue
		}
		switch header {
		case "expect":

	nv := make(textproto.MIMEHeader, len(v))
	for k, kv := range v {
		// Canonicalize all headers, to remove any duplicates.
		nv[http.CanonicalHeaderKey(k)] = kv
	}

	// Save all supported headers.
	for _, supportedHeader := range supportedHeaders {
		value, ok := nv[http.CanonicalHeaderKey(supportedHeader)]
		if ok {
			if v, ok := replicationToInternalHeaders[supportedHeader]; ok {
				m[v] = strings.Join(value, ",")

			writeErrorResponse(ctx, w, apiErr, r.URL)
			return
		}

		headerLen += int64(len(name)) + int64(len(fileName))
		if name != "file" {
			if http.CanonicalHeaderKey(name) == http.CanonicalHeaderKey("x-minio-fanout-list") {
				dec := json.NewDecoder(part)

				// while the array contains values
				for dec.More() {
					var m minio.PutObjectFanOutEntry

	// Get header map.
	headerMap := make(map[string][]string)
	for k, vv := range req.Header {
		// If request header key is not in ignored headers, then add it.
		if _, ok := ignoredStreamingHeaders[http.CanonicalHeaderKey(k)]; !ok {
			headerMap[strings.ToLower(k)] = vv
		}
	}

	// Get header keys.
	headers := []string{"host"}
	for k := range headerMap {
		headers = append(headers, k)
	}

func (m caseInsensitiveMap) Lookup(key string) (string, bool) {
	if len(m) == 0 {
		return "", false
	}
	for _, k := range []string{
		key,
		strings.ToLower(key),
		http.CanonicalHeaderKey(key),
	} {
		v, ok := m[k]
		if ok {
			return v, ok
		}
	}
	return "", false
}