refactor: 自定义业务错误 (#33)

* refactor: 自定义业务错误

* refactor: 隐藏服务器错误与统一 panic 响应

backend/internal/middleware/recovery.go

@@ -0,0 +1,64 @@
+package middleware
+
+import (
+	"errors"
+	"net"
+	"net/http"
+	"os"
+	"strings"
+
+	infraerrors "github.com/Wei-Shaw/sub2api/internal/infrastructure/errors"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/response"
+	"github.com/gin-gonic/gin"
+)
+
+// Recovery converts panics into the project's standard JSON error envelope.
+//
+// It preserves Gin's broken-pipe handling by not attempting to write a response
+// when the client connection is already gone.
+func Recovery() gin.HandlerFunc {
+	return gin.CustomRecoveryWithWriter(gin.DefaultErrorWriter, func(c *gin.Context, recovered any) {
+		recoveredErr, _ := recovered.(error)
+
+		if isBrokenPipe(recoveredErr) {
+			if recoveredErr != nil {
+				_ = c.Error(recoveredErr)
+			}
+			c.Abort()
+			return
+		}
+
+		if c.Writer.Written() {
+			c.Abort()
+			return
+		}
+
+		response.ErrorWithDetails(
+			c,
+			http.StatusInternalServerError,
+			infraerrors.UnknownMessage,
+			infraerrors.UnknownReason,
+			nil,
+		)
+		c.Abort()
+	})
+}
+
+func isBrokenPipe(err error) bool {
+	if err == nil {
+		return false
+	}
+
+	var opErr *net.OpError
+	if !errors.As(err, &opErr) {
+		return false
+	}
+
+	var syscallErr *os.SyscallError
+	if !errors.As(opErr.Err, &syscallErr) {
+		return false
+	}
+
+	msg := strings.ToLower(syscallErr.Error())
+	return strings.Contains(msg, "broken pipe") || strings.Contains(msg, "connection reset by peer")
+}

backend/internal/middleware/recovery_test.go

@@ -0,0 +1,81 @@
+//go:build unit
+
+package middleware
+
+import (
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	infraerrors "github.com/Wei-Shaw/sub2api/internal/infrastructure/errors"
+	"github.com/Wei-Shaw/sub2api/internal/pkg/response"
+	"github.com/gin-gonic/gin"
+	"github.com/stretchr/testify/require"
+)
+
+func TestRecovery(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+
+	tests := []struct {
+		name         string
+		handler      gin.HandlerFunc
+		wantHTTPCode int
+		wantBody     response.Response
+	}{
+		{
+			name: "panic_returns_standard_json_500",
+			handler: func(c *gin.Context) {
+				panic("boom")
+			},
+			wantHTTPCode: http.StatusInternalServerError,
+			wantBody: response.Response{
+				Code:    http.StatusInternalServerError,
+				Message: infraerrors.UnknownMessage,
+			},
+		},
+		{
+			name: "no_panic_passthrough",
+			handler: func(c *gin.Context) {
+				response.Success(c, gin.H{"ok": true})
+			},
+			wantHTTPCode: http.StatusOK,
+			wantBody: response.Response{
+				Code:    0,
+				Message: "success",
+				Data:    map[string]any{"ok": true},
+			},
+		},
+		{
+			name: "panic_after_write_does_not_override_body",
+			handler: func(c *gin.Context) {
+				response.Success(c, gin.H{"ok": true})
+				panic("boom")
+			},
+			wantHTTPCode: http.StatusOK,
+			wantBody: response.Response{
+				Code:    0,
+				Message: "success",
+				Data:    map[string]any{"ok": true},
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r := gin.New()
+			r.Use(Recovery())
+			r.GET("/t", tt.handler)
+
+			w := httptest.NewRecorder()
+			req := httptest.NewRequest(http.MethodGet, "/t", nil)
+			r.ServeHTTP(w, req)
+
+			require.Equal(t, tt.wantHTTPCode, w.Code)
+
+			var got response.Response
+			require.NoError(t, json.Unmarshal(w.Body.Bytes(), &got))
+			require.Equal(t, tt.wantBody, got)
+		})
+	}
+}