mirror of
https://gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake.git
synced 2025-10-13 11:11:30 -04:00
8343bbc336
Client timeouts are currently counted from when the client is matched with a proxy. Instead, count client timeouts from the moment when the request is received. Closes #40449
84 lines
2.8 KiB
Go
84 lines
2.8 KiB
Go
package main
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import (
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"context"
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"log"
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"net/http"
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"strings"
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"time"
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"gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/v2/common/amp"
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"gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/v2/common/messages"
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"gitlab.torproject.org/tpo/anti-censorship/pluggable-transports/snowflake/v2/common/util"
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)
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// ampClientOffers is the AMP-speaking endpoint for client poll messages,
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// intended for access via an AMP cache. In contrast to the other clientOffers,
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// the client's encoded poll message is stored in the URL path rather than the
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// HTTP request body (because an AMP cache does not support POST), and the
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// encoded client poll response is sent back as AMP-armored HTML.
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func ampClientOffers(i *IPC, w http.ResponseWriter, r *http.Request) {
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ctx, cancel := context.WithTimeout(r.Context(), ClientTimeout*time.Second)
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defer cancel()
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// The encoded client poll message immediately follows the /amp/client/
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// path prefix, so this function unfortunately needs to be aware of and
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// remote its own routing prefix.
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path := strings.TrimPrefix(r.URL.Path, "/amp/client/")
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if path == r.URL.Path {
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// The path didn't start with the expected prefix. This probably
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// indicates an internal bug.
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log.Println("ampClientOffers: unexpected prefix in path")
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w.WriteHeader(http.StatusInternalServerError)
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return
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}
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var encPollReq []byte
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var response []byte
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var err error
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encPollReq, err = amp.DecodePath(path)
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if err == nil {
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arg := messages.Arg{
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Body: encPollReq,
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RemoteAddr: util.GetClientIp(r),
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RendezvousMethod: messages.RendezvousAmpCache,
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Context: ctx,
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}
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err = i.ClientOffers(arg, &response)
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} else {
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response, err = (&messages.ClientPollResponse{
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Error: "cannot decode URL path",
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}).EncodePollResponse()
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}
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if err != nil {
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// We couldn't even construct a JSON object containing an error
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// message :( Nothing to do but signal an error at the HTTP
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// layer. The AMP cache will translate this 500 status into a
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// 404 status.
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// https://amp.dev/documentation/guides-and-tutorials/learn/amp-caches-and-cors/amp-cache-urls/#redirect-%26-error-handling
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log.Printf("ampClientOffers: %v", err)
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w.WriteHeader(http.StatusInternalServerError)
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return
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}
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w.Header().Set("Content-Type", "text/html")
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// Attempt to hint to an AMP cache not to waste resources caching this
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// document. "The Google AMP Cache considers any document fresh for at
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// least 15 seconds."
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// https://developers.google.com/amp/cache/overview#google-amp-cache-updates
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w.Header().Set("Cache-Control", "max-age=15")
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w.WriteHeader(http.StatusOK)
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enc, err := amp.NewArmorEncoder(w)
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if err != nil {
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log.Printf("amp.NewArmorEncoder: %v", err)
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return
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}
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defer enc.Close()
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if _, err := enc.Write(response); err != nil {
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log.Printf("ampClientOffers: unable to write answer: %v", err)
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}
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}
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