Sub2API v1.0 - AI API 网关（二开初始版本，基于上游 Wei-Shaw/sub2api）

backend/internal/handler/request_body_parse_log.go

@@ -0,0 +1,54 @@
+package handler
+
+import (
+	"strconv"
+
+	"github.com/Wei-Shaw/sub2api/internal/service"
+	"go.uber.org/zap"
+)
+
+// parseFailureSnippetLen bounds the head/tail snippets logged on body parse
+// failure. 256 bytes is enough to see the structural context (model field,
+// first content block / trailing brace) without dumping user payloads.
+const parseFailureSnippetLen = 256
+
+// logRequestBodyParseFailure records the real reason a request body failed
+// JSON parsing/validation. The client keeps receiving the generic
+// "Failed to parse request body"; the sanitized diagnostics (underlying
+// error with byte offset, body length, escaped head/tail snippets) land in
+// the server log only, so operators can distinguish genuinely invalid JSON
+// from a truncated or partially consumed body.
+//
+// err may be nil for call sites that validate with gjson.ValidBytes directly;
+// the diagnostic error is derived from the body in that case.
+func logRequestBodyParseFailure(reqLog *zap.Logger, body []byte, err error) {
+	if reqLog == nil {
+		return
+	}
+	if err == nil {
+		err = service.DescribeInvalidJSON(body)
+	}
+
+	head := body
+	var tail []byte
+	if len(body) > parseFailureSnippetLen {
+		head = body[:parseFailureSnippetLen]
+		tail = body[len(body)-parseFailureSnippetLen:]
+	}
+
+	fields := []zap.Field{
+		zap.Error(err),
+		zap.Int("body_len", len(body)),
+		zap.String("body_head", sanitizeBodySnippet(head)),
+	}
+	if len(tail) > 0 {
+		fields = append(fields, zap.String("body_tail", sanitizeBodySnippet(tail)))
+	}
+	reqLog.Warn("parse request body failed", fields...)
+}
+
+// sanitizeBodySnippet escapes control characters and invalid UTF-8 so the
+// snippet is always a single printable log line.
+func sanitizeBodySnippet(b []byte) string {
+	return strconv.Quote(string(b))
+}