dify-plugin-daemon/internal/server/middleware.go

package server

import (
	"bytes"
	"io"

	"github.com/gin-gonic/gin"
	"github.com/langgenius/dify-plugin-daemon/internal/server/constants"
	"github.com/langgenius/dify-plugin-daemon/internal/types/entities/plugin_entities"
	"github.com/langgenius/dify-plugin-daemon/internal/utils/log"
)

func CheckingKey(key string) gin.HandlerFunc {
	return func(c *gin.Context) {
		// get header X-Api-Key
		if c.GetHeader(constants.X_API_KEY) != key {
			c.JSON(401, gin.H{"error": "Unauthorized"})
			c.Abort()
			return
		}

		c.Next()
	}
}

type ginContextReader struct {
	reader *bytes.Reader
}

func (g *ginContextReader) Read(p []byte) (n int, err error) {
	return g.reader.Read(p)
}

func (g *ginContextReader) Close() error {
	return nil
}

// RedirectPluginInvoke redirects the request to the correct cluster node
func (app *App) RedirectPluginInvoke() gin.HandlerFunc {
	return func(ctx *gin.Context) {
		// get plugin identity
		raw, err := ctx.GetRawData()
		if err != nil {
			ctx.AbortWithStatusJSON(400, gin.H{"error": "Invalid request"})
			return
		}

		ctx.Request.Body = &ginContextReader{
			reader: bytes.NewReader(raw),
		}

		identity, err := plugin_entities.NewPluginUniqueIdentifier(ctx.Request.Header.Get(constants.X_PLUGIN_IDENTIFIER))
		if err != nil {
			ctx.AbortWithStatusJSON(400, gin.H{"error": "Invalid request, " + err.Error()})
			return
		}

		// check if plugin in current node
		if !app.cluster.IsPluginNoCurrentNode(
			identity,
		) {
			app.redirectPluginInvokeByPluginIdentifier(ctx, identity)
			ctx.Abort()
		} else {
			ctx.Next()
		}
	}
}

func (app *App) redirectPluginInvokeByPluginIdentifier(
	ctx *gin.Context,
	plugin_unique_identifier plugin_entities.PluginUniqueIdentifier,
) {
	// try find the correct node
	nodes, err := app.cluster.FetchPluginAvailableNodesById(plugin_unique_identifier.String())
	if err != nil {
		ctx.AbortWithStatusJSON(500, gin.H{"error": "Internal server error"})
		return
	} else if len(nodes) == 0 {
		ctx.AbortWithStatusJSON(404, gin.H{"error": "No available node"})
		return
	}

	// redirect to the correct node
	node_id := nodes[0]
	status_code, header, body, err := app.cluster.RedirectRequest(node_id, ctx.Request)
	if err != nil {
		log.Error("redirect request failed: %s", err.Error())
		ctx.AbortWithStatusJSON(500, gin.H{"error": "Internal server error"})
		return
	}

	// set status code
	ctx.Writer.WriteHeader(status_code)

	// set header
	for key, values := range header {
		for _, value := range values {
			ctx.Writer.Header().Set(key, value)
		}
	}

	for {
		buf := make([]byte, 1024)
		n, err := body.Read(buf)
		if err != nil && err != io.EOF {
			break
		} else if err != nil {
			ctx.Writer.Write(buf[:n])
			break
		}

		if n > 0 {
			ctx.Writer.Write(buf[:n])
		}
	}
}

func (app *App) InitClusterID() gin.HandlerFunc {
	return func(ctx *gin.Context) {
		ctx.Set("cluster_id", app.cluster.ID())
		ctx.Next()
	}
}