route: service gateway (#70)

* route: service gateway

Signed-off-by: E99p1ant <i@github.red>

* remove debug log

Signed-off-by: E99p1ant <i@github.red>

---------

Signed-off-by: E99p1ant <i@github.red>

Author: wuhan005

internal/conf/conf.go

@@ -70,5 +70,18 @@ func Init() error {
 		return errors.Wrap(err, "map 'mail'")
 	}
 
+	serviceSections := File.Section("service").ChildSections()
+	for _, serviceSection := range serviceSections {
+		serviceSection := serviceSection
+		var backend struct {
+			Prefix     string `ini:"prefix"`
+			ForwardURL string `ini:"forward_url"`
+		}
+		if err := serviceSection.MapTo(&backend); err != nil {
+			return errors.Wrapf(err, "map 'service.%s'", serviceSection.Name())
+		}
+		Service.Backends = append(Service.Backends, backend)
+	}
+
 	return nil
 }

internal/conf/static.go

@@ -83,4 +83,11 @@ var (
 		Port     int    `ini:"port"`
 		SMTP     string `ini:"smtp"`
 	}
+
+	Service struct {
+		Backends []struct {
+			Prefix     string `ini:"prefix"`
+			ForwardURL string `ini:"forward_url"`
+		}
+	}
 )

internal/route/route.go

@@ -29,6 +29,7 @@ import (
 	"github.com/wuhan005/NekoBox/route/auth"
 	"github.com/wuhan005/NekoBox/route/pixel"
 	"github.com/wuhan005/NekoBox/route/question"
+	"github.com/wuhan005/NekoBox/route/service"
 	"github.com/wuhan005/NekoBox/route/user"
 	"github.com/wuhan005/NekoBox/static"
 	"github.com/wuhan005/NekoBox/templates"
@@ -141,6 +142,7 @@ func New() *flamego.Flame {
 			})
 
 			f.Any("/pixel/{**}", reqUserSignIn, pixel.Proxy)
+			f.Any("/service/{**}", service.Proxy)
 		}, context.APIEndpoint)
 	},
 		cache.Cacher(cache.Options{

route/service/proxy.go

@@ -0,0 +1,84 @@
+package service
+
+import (
+	"crypto/tls"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"strconv"
+	"strings"
+
+	"github.com/sirupsen/logrus"
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/trace"
+
+	"github.com/wuhan005/NekoBox/internal/conf"
+	"github.com/wuhan005/NekoBox/internal/context"
+)
+
+func Proxy(ctx context.Context) error {
+	span := trace.SpanFromContext(ctx.Request().Context())
+
+	var userID uint
+	if ctx.IsLogged {
+		userID = ctx.User.ID
+	}
+
+	if span.SpanContext().IsValid() {
+		span.SetAttributes(
+			attribute.Int("nekobox.service.user-id", int(userID)),
+		)
+	}
+
+	uri := ctx.Param("**")
+	basePath := strings.Split(uri, "/")[0]
+	forwardPath := strings.TrimPrefix(uri, basePath)
+
+	var forwardURLStr string
+	for _, backend := range conf.Service.Backends {
+		if backend.Prefix == basePath {
+			forwardURLStr = backend.ForwardURL
+			break
+		}
+	}
+	if len(forwardURLStr) == 0 {
+		return ctx.JSONError(http.StatusNotFound, "页面不存在")
+	}
+
+	forwardURL, err := url.Parse(forwardURLStr)
+	if err != nil {
+		logrus.WithContext(ctx.Request().Context()).WithError(err).Error("Failed to parse forward URL")
+		return ctx.JSONError(http.StatusInternalServerError, "服务网关内部错误")
+	}
+
+	reverseProxy := httputil.ReverseProxy{
+		Director: func(req *http.Request) {
+			req.URL = forwardURL
+			req.URL.Path = strings.TrimRight(req.URL.Path, "/") + forwardPath
+			req.Host = forwardURL.Host
+
+			traceHeaders := http.Header{}
+			otel.GetTextMapPropagator().Inject(ctx.Request().Context(), propagation.HeaderCarrier(traceHeaders))
+			for key := range traceHeaders {
+				req.Header.Set(key, traceHeaders.Get(key))
+			}
+
+			req.Header.Set("X-NekoBox-From", "nekobox-gateway")
+			req.Header.Set("X-NekoBox-User-ID", strconv.Itoa(int(userID)))
+		},
+		Transport: &http.Transport{
+			TLSClientConfig: &tls.Config{
+				InsecureSkipVerify: true,
+			},
+		},
+		ErrorHandler: func(writer http.ResponseWriter, request *http.Request, err error) {
+			logrus.WithContext(ctx.Request().Context()).WithError(err).Error("Failed to handle reverse proxy request")
+			_ = ctx.JSONError(http.StatusInternalServerError, "服务网关内部错误")
+		},
+	}
+
+	reverseProxy.ServeHTTP(ctx.ResponseWriter(), ctx.Request().Request)
+	return nil
+}