Normalize URL query string before executing HTTP requests

- Make sure query strings parameters are encoded
- As opposed to the standard library, do not append equal sign
for query parameters with empty value
- Strip URL fragments like Web browsers

url/url.go

@@ -4,9 +4,12 @@
 
 package url // import "miniflux.app/url"
 
-import "net/url"
-import "fmt"
-import "strings"
+import (
+	"fmt"
+	"net/url"
+	"sort"
+	"strings"
+)
 
 // AbsoluteURL converts the input URL as absolute URL if necessary.
 func AbsoluteURL(baseURL, input string) (string, error) {
@@ -69,3 +72,51 @@ func Domain(websiteURL string) string {
 
 	return parsedURL.Host
 }
+
+// RequestURI returns the encoded URI to be used in HTTP requests.
+func RequestURI(websiteURL string) string {
+	u, err := url.Parse(websiteURL)
+	if err != nil {
+		return websiteURL
+	}
+
+	queryValues := u.Query()
+	u.RawQuery = "" // Clear RawQuery to make sure it's encoded properly.
+	u.Fragment = "" // Clear fragment because Web browsers strip #fragment before sending the URL to a web server.
+
+	var buf strings.Builder
+	buf.WriteString(u.String())
+
+	if len(queryValues) > 0 {
+		buf.WriteByte('?')
+
+		// Sort keys.
+		keys := make([]string, 0, len(queryValues))
+		for k := range queryValues {
+			keys = append(keys, k)
+		}
+		sort.Strings(keys)
+
+		i := 0
+		for _, key := range keys {
+			keyEscaped := url.QueryEscape(key)
+			values := queryValues[key]
+			for _, value := range values {
+				if i > 0 {
+					buf.WriteByte('&')
+				}
+				buf.WriteString(keyEscaped)
+
+				// As opposed to the standard library, we append the = only if the value is not empty.
+				if value != "" {
+					buf.WriteByte('=')
+					buf.WriteString(url.QueryEscape(value))
+				}
+
+				i++
+			}
+		}
+	}
+
+	return buf.String()
+}