edge/pkg/http/fetch.go

package http

import (
	"io"
	"net/http"
	"net/url"

	"forge.cadoles.com/arcad/edge/pkg/module"
	"forge.cadoles.com/arcad/edge/pkg/module/fetch"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"
)

func (h *Handler) handleAppFetch(w http.ResponseWriter, r *http.Request) {
	h.mutex.RLock()
	defer h.mutex.RUnlock()

	ctx := r.Context()

	ctx = module.WithContext(ctx, map[module.ContextKey]any{
		ContextKeyOriginRequest: r,
	})

	rawURL := r.URL.Query().Get("url")

	url, err := url.Parse(rawURL)
	if err != nil {
		jsonError(w, http.StatusBadRequest, errorCodeBadRequest)

		return
	}

	requestMsg := fetch.NewMessageFetchRequest(ctx, r.RemoteAddr, url)

	reply, err := h.bus.Request(ctx, requestMsg)
	if err != nil {
		logger.Error(ctx, "could not retrieve fetch request reply", logger.E(errors.WithStack(err)))
		jsonError(w, http.StatusInternalServerError, errorCodeInternalError)

		return
	}

	logger.Debug(ctx, "fetch reply", logger.F("reply", reply))

	responseMsg, ok := reply.(*fetch.MessageFetchResponse)
	if !ok {
		logger.Error(
			ctx, "unexpected fetch response message",
			logger.F("message", reply),
		)
		jsonError(w, http.StatusInternalServerError, errorCodeInternalError)

		return
	}

	if !responseMsg.Allow {
		jsonError(w, http.StatusForbidden, errorCodeForbidden)

		return
	}

	proxyReq, err := http.NewRequest(http.MethodGet, url.String(), nil)
	if err != nil {
		logger.Error(
			ctx, "could not create proxy request",
			logger.E(errors.WithStack(err)),
		)
		jsonError(w, http.StatusInternalServerError, errorCodeInternalError)

		return
	}

	for header, values := range r.Header {
		for _, value := range values {
			proxyReq.Header.Add(header, value)
		}
	}

	proxyReq.Header.Add("X-Forwarded-From", r.RemoteAddr)

	res, err := h.httpClient.Do(proxyReq)
	if err != nil {
		logger.Error(
			ctx, "could not execute proxy request",
			logger.E(errors.WithStack(err)),
		)
		jsonError(w, http.StatusInternalServerError, errorCodeInternalError)

		return
	}

	defer func() {
		if err := res.Body.Close(); err != nil {
			logger.Error(
				ctx, "could not close response body",
				logger.E(errors.WithStack(err)),
			)
		}
	}()

	for header, values := range res.Header {
		for _, value := range values {
			w.Header().Add(header, value)
		}
	}

	w.WriteHeader(res.StatusCode)

	if _, err := io.Copy(w, res.Body); err != nil {
		panic(errors.WithStack(err))
	}
}