clawbot
f8ce8cef83
The template's files at a77fd30, without its history or LICENSE, after script/rename simplexcalc. Model: opus-5-5
60 lines
1.9 KiB
Go
60 lines
1.9 KiB
Go
package middleware
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import (
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"net/http"
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"runtime/debug"
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)
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// panicBody is the entire response a recovered panic produces. No
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// template, no detail: the client learns that the request failed, and
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// everything about why goes to the log and to Sentry, where it is not
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// attacker-readable.
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const panicBody = "internal server error"
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// Recoverer turns a panicking handler into a 500 rather than a dropped
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// connection.
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//
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// net/http already recovers panics, but what it does is close the
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// connection without a response, so the client sees a transport error
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// and no status. Answering 500 is the difference between "the service
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// is broken" and "the network is broken" for everyone downstream.
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//
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// A panic after the response has started cannot be turned into a 500 —
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// the status is already on the wire — so in that case the connection is
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// deliberately dropped by re-panicking to net/http, which is the only
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// honest signal left that the body is truncated. A truncated 200 that
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// looks complete is worse than a broken connection.
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func (m *Middleware) Recoverer() func(http.Handler) http.Handler {
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return func(next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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rec := newResponseRecorder(w)
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defer func() {
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v := recover()
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if v == nil {
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return
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}
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// http.ErrAbortHandler is net/http's documented way for
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// a handler to abandon a response on purpose. It is not
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// a bug, so it is not reported; it is re-raised for
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// net/http to handle as it always does.
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//nolint:errorlint,err113 // a sentinel value, compared as net/http documents.
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if v == http.ErrAbortHandler {
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panic(v)
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}
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m.params.Sentry.CapturePanic(v, debug.Stack())
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if rec.Written() {
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panic(v)
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}
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http.Error(rec, panicBody, http.StatusInternalServerError)
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}()
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next.ServeHTTP(rec, r)
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})
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}
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}
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