fix: limit anonymous request body (#5244)

* fix: limit anonymous request body (env ANONYMOUS_REQUEST_BODY_LIMIT_KB = 512)

* fix: allow disabling anonymous request body limit

common/request_body_limit.go

@@ -0,0 +1,13 @@
+package common
+
+import "github.com/QuantumNous/new-api/constant"
+
+const defaultAnonymousRequestBodyLimitKB = 512
+
+func GetAnonymousRequestBodyLimitBytes() int64 {
+	limitKB := constant.AnonymousRequestBodyLimitKB
+	if limitKB < 0 {
+		limitKB = defaultAnonymousRequestBodyLimitKB
+	}
+	return int64(limitKB) << 10
+}