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package falcore
import (
"fmt"
"io"
"net/http"
)
// Implements a RequestFilter using a http.Handler to produce the response
// This will always return a response due to the requirements of the http.Handler
// interface so it should be placed at the end of the Upstream pipeline.
type HandlerFilter struct {
handler http.Handler
}
func NewHandlerFilter(handler http.Handler) *HandlerFilter {
return &HandlerFilter{handler: handler}
}
func (h *HandlerFilter) FilterRequest(req *Request) *http.Response {
rw, respc := newPopulateResponseWriter(req.HttpRequest)
// this must be done concurrently so that the HandlerFunc can write the response
// while falcore is copying it to the socket
go func() {
h.handler.ServeHTTP(rw, req.HttpRequest)
rw.finish()
}()
return <-respc
}
// copied from net/http/filetransport.go
func newPopulateResponseWriter(req *http.Request) (*populateResponse, <-chan *http.Response) {
pr, pw := io.Pipe()
rw := &populateResponse{
ch: make(chan *http.Response),
pw: pw,
res: &http.Response{
Proto: "HTTP/1.0",
ProtoMajor: 1,
Header: make(http.Header),
Close: true,
Body: pr,
Request: req,
},
}
return rw, rw.ch
}
// populateResponse is a ResponseWriter that populates the *Response
// in res, and writes its body to a pipe connected to the response
// body. Once writes begin or finish() is called, the response is sent
// on ch.
type populateResponse struct {
res *http.Response
ch chan *http.Response
wroteHeader bool
hasContent bool
sentResponse bool
pw *io.PipeWriter
}
func (pr *populateResponse) finish() {
if !pr.wroteHeader {
pr.WriteHeader(500)
}
if !pr.sentResponse {
pr.sendResponse()
}
pr.pw.Close()
}
func (pr *populateResponse) sendResponse() {
if pr.sentResponse {
return
}
pr.sentResponse = true
if pr.hasContent {
pr.res.ContentLength = -1
}
pr.ch <- pr.res
}
func (pr *populateResponse) Header() http.Header {
return pr.res.Header
}
func (pr *populateResponse) WriteHeader(code int) {
if pr.wroteHeader {
return
}
pr.wroteHeader = true
pr.res.StatusCode = code
pr.res.Status = fmt.Sprintf("%d %s", code, http.StatusText(code))
}
func (pr *populateResponse) Write(p []byte) (n int, err error) {
if !pr.wroteHeader {
pr.WriteHeader(http.StatusOK)
}
pr.hasContent = true
if !pr.sentResponse {
pr.sendResponse()
}
return pr.pw.Write(p)
}