[#451] Support Location in CompleteMultipart response

Signed-off-by: Denis Kirillov <d.kirillov@yadro.com>

api/middleware/reqinfo.go

@@ -69,8 +69,10 @@ var deploymentID = uuid.Must(uuid.NewRandom())
 
 var (
 	// De-facto standard header keys.
-	xForwardedFor = http.CanonicalHeaderKey("X-Forwarded-For")
-	xRealIP       = http.CanonicalHeaderKey("X-Real-IP")
+	xForwardedFor    = http.CanonicalHeaderKey("X-Forwarded-For")
+	xRealIP          = http.CanonicalHeaderKey("X-Real-IP")
+	xForwardedProto  = http.CanonicalHeaderKey("X-Forwarded-Proto")
+	xForwardedScheme = http.CanonicalHeaderKey("X-Forwarded-Scheme")
 
 	// RFC7239 defines a new "Forwarded: " header designed to replace the
 	// existing use of X-Forwarded-* headers.
@@ -79,6 +81,9 @@ var (
 	// Allows for a sub-match of the first value after 'for=' to the next
 	// comma, semi-colon or space. The match is case-insensitive.
 	forRegex = regexp.MustCompile(`(?i)(?:for=)([^(;|, )]+)(.*)`)
+	// Allows for a sub-match for the first instance of scheme (http|https)
+	// prefixed by 'proto='. The match is case-insensitive.
+	protoRegex = regexp.MustCompile(`(?i)^(;|,| )+(?:proto=)(https|http)`)
 )
 
 // NewReqInfo returns new ReqInfo based on parameters.
@@ -291,3 +296,31 @@ func getSourceIP(r *http.Request) string {
 	}
 	return raddr
 }
+
+// GetSourceScheme retrieves the scheme from the X-Forwarded-Proto and RFC7239
+// Forwarded headers (in that order).
+func GetSourceScheme(r *http.Request) string {
+	var scheme string
+
+	// Retrieve the scheme from X-Forwarded-Proto.
+	if proto := r.Header.Get(xForwardedProto); proto != "" {
+		scheme = strings.ToLower(proto)
+	} else if proto = r.Header.Get(xForwardedScheme); proto != "" {
+		scheme = strings.ToLower(proto)
+	} else if proto := r.Header.Get(forwarded); proto != "" {
+		// match should contain at least two elements if the protocol was
+		// specified in the Forwarded header. The first element will always be
+		// the 'for=', which we ignore, subsequently we proceed to look for
+		// 'proto=' which should precede right after `for=` if not
+		// we simply ignore the values and return empty. This is in line
+		// with the approach we took for returning first ip from multiple
+		// params.
+		if match := forRegex.FindStringSubmatch(proto); len(match) > 1 {
+			if match = protoRegex.FindStringSubmatch(match[2]); len(match) > 1 {
+				scheme = strings.ToLower(match[2])
+			}
+		}
+	}
+
+	return scheme
+}