feat: support form array in three notations (#4498)

Signed-off-by: kevin <wanjunfeng@gmail.com>

rest/httpx/util.go

@@ -2,12 +2,23 @@ package httpx
 
 import (
 	"errors"
+	"fmt"
 	"net/http"
+	"strings"
 )
 
-const xForwardedFor = "X-Forwarded-For"
+const (
+	xForwardedFor = "X-Forwarded-For"
+	arraySuffix   = "[]"
+	// most servers and clients have a limit of 8192 bytes (8 KB)
+	// one parameter at least take 4 chars, for example `?a=b&c=d`
+	maxFormParamCount = 2048
+)
 
-// GetFormValues returns the form values.
+// GetFormValues returns the form values supporting three array notation formats:
+//  1. Standard notation: /api?names=alice&names=bob
+//  2. Comma notation: /api?names=alice,bob
+//  3. Bracket notation: /api?names[]=alice&names[]=bob
 func GetFormValues(r *http.Request) (map[string]any, error) {
 	if err := r.ParseForm(); err != nil {
 		return nil, err
@@ -19,16 +30,23 @@ func GetFormValues(r *http.Request) (map[string]any, error) {
 		}
 	}
 
+	var n int
 	params := make(map[string]any, len(r.Form))
 	for name, values := range r.Form {
 		filtered := make([]string, 0, len(values))
 		for _, v := range values {
-			if len(v) > 0 {
+			if n < maxFormParamCount {
 				filtered = append(filtered, v)
+				n++
+			} else {
+				return nil, fmt.Errorf("too many form values, error: %s", r.Form.Encode())
 			}
 		}
 
 		if len(filtered) > 0 {
+			if strings.HasSuffix(name, arraySuffix) {
+				name = name[:len(name)-2]
+			}
 			params[name] = filtered
 		}
 	}