Function signV4

pkg/signer/request-signature-v4.go:308–381

Internal function called for different service types.

(req http.Request, accessKeyID, secretAccessKey, sessionToken, location, serviceType string, trailer http.Header)

// Internal function called for different service types.
func signV4(req http.Request, accessKeyID, secretAccessKey, sessionToken, location, serviceType string, trailer http.Header) *http.Request {
	// Signature calculation is not needed for anonymous credentials.
	if accessKeyID == "" || secretAccessKey == "" {
		return &req
	}

	// Initial time.
	t := time.Now().UTC()

	// Set x-amz-date.
	req.Header.Set("X-Amz-Date", t.Format(iso8601DateFormat))

	// Set session token if available.
	if sessionToken != "" {
		// S3 Express token if not set then set sessionToken
		// with older x-amz-security-token header.
		if v := req.Header.Get("x-amz-s3session-token"); v == "" {
			req.Header.Set("X-Amz-Security-Token", sessionToken)
		}
	}

	if len(trailer) > 0 {
		for k := range trailer {
			req.Header.Add("X-Amz-Trailer", strings.ToLower(k))
		}

		req.Header.Set("Content-Encoding", "aws-chunked")
		req.Header.Set("x-amz-decoded-content-length", strconv.FormatInt(req.ContentLength, 10))
	}

	hashedPayload := getHashedPayload(req)
	if serviceType == ServiceTypeSTS {
		// Content sha256 header is not sent with the request
		// but it is expected to have sha256 of payload for signature
		// in STS service type request.
		req.Header.Del("X-Amz-Content-Sha256")
	}

	// Get canonical request.
	canonicalRequest := getCanonicalRequest(req, v4IgnoredHeaders, hashedPayload)

	// Get string to sign from canonical request.
	stringToSign := getStringToSignV4(t, location, canonicalRequest, serviceType)

	// Get hmac signing key.
	signingKey := getSigningKey(secretAccessKey, location, t, serviceType)

	// Get credential string.
	credential := GetCredential(accessKeyID, location, t, serviceType)

	// Get all signed headers.
	signedHeaders := getSignedHeaders(req, v4IgnoredHeaders)

	// Calculate signature.
	signature := getSignature(signingKey, stringToSign)

	// If regular request, construct the final authorization header.
	parts := []string{