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middleware.go
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middleware.go
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package server
import (
"context"
"net/http"
"github.com/fnproject/fn/api/common"
"github.com/gin-gonic/gin"
)
// Middleware just takes a http.Handler and returns one. So the next middle ware must be called
// within the returned handler or it would be ignored.
type Middleware interface {
Chain(next http.Handler) http.Handler
}
// MiddlewareFunc is a here to allow a plain function to be a middleware.
type MiddlewareFunc func(next http.Handler) http.Handler
// Chain used to allow middlewarefuncs to be middleware.
func (m MiddlewareFunc) Chain(next http.Handler) http.Handler {
return m(next)
}
func (s *Server) middlewareWrapperFunc(ctx context.Context) gin.HandlerFunc {
return func(c *gin.Context) {
if len(s.middlewares) > 0 {
defer func() {
//This is so that if the server errors or panics on a middleware the server will still respond and not send eof to client.
err := recover()
if err != nil {
common.Logger(c.Request.Context()).WithField("MiddleWarePanicRecovery:", err).Errorln("A panic occurred during middleware.")
handleErrorResponse(c, ErrInternalServerError)
}
}()
var h http.Handler
keepgoing := false
h = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
c.Request = c.Request.WithContext(r.Context())
keepgoing = true
})
s.chainAndServe(c.Writer, c.Request, h)
if !keepgoing {
c.Abort()
}
}
}
}
func (s *Server) chainAndServe(w http.ResponseWriter, r *http.Request, h http.Handler) {
for _, m := range s.middlewares {
h = m.Chain(h)
}
h.ServeHTTP(w, r)
}
// AddMiddleware add middleware
func (s *Server) AddMiddleware(m Middleware) {
//Prepend to array so that we can do first,second,third,last,third,second,first
//and not third,second,first,last,first,second,third
s.middlewares = append([]Middleware{m}, s.middlewares...)
}
// AddMiddlewareFunc add middlewarefunc
func (s *Server) AddMiddlewareFunc(m MiddlewareFunc) {
s.AddMiddleware(m)
}