Infrastructure/imageproxy
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detect content type if response header is missing

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Some misconfigured servers will fail to properly set the content-type in
the response header.  In those cases, detect the content-type from the
response body.

Refs #132
This commit is contained in:
Will Norris 2019-03-26 16:38:37 +00:00
parent 6aca1e0b20
commit cf54b2cf2c
1 changed files with 17 additions and 0 deletions
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17
imageproxy.go
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@ -170,6 +170,7 @@ func (p *Proxy) serveImage(w http.ResponseWriter, r *http.Request) {
http.Error(w, msg, http.StatusInternalServerError) http.Error(w, msg, http.StatusInternalServerError)
return return
} }
// close the original resp.Body, even if we wrap it in a NopCloser below
defer resp.Body.Close() defer resp.Body.Close()
cached := resp.Header.Get(httpcache.XFromCache) cached := resp.Header.Get(httpcache.XFromCache)
@ -185,6 +186,12 @@ func (p *Proxy) serveImage(w http.ResponseWriter, r *http.Request) {
} }
contentType, _, _ := mime.ParseMediaType(resp.Header.Get("Content-Type")) contentType, _, _ := mime.ParseMediaType(resp.Header.Get("Content-Type"))
if contentType == "" {
// try to detect content type
b := bufio.NewReader(resp.Body)
resp.Body = ioutil.NopCloser(b)
contentType = peekContentType(b)
}
if resp.ContentLength != 0 && !contentTypeMatches(p.ContentTypes, contentType) { if resp.ContentLength != 0 && !contentTypeMatches(p.ContentTypes, contentType) {
log.Printf("content-type not allowed: %q", contentType) log.Printf("content-type not allowed: %q", contentType)
http.Error(w, msgNotAllowed, http.StatusForbidden) http.Error(w, msgNotAllowed, http.StatusForbidden)
@ -201,6 +208,16 @@ func (p *Proxy) serveImage(w http.ResponseWriter, r *http.Request) {
io.Copy(w, resp.Body) io.Copy(w, resp.Body)
} }
// peekContentType peeks at the first 512 bytes of p, and attempts to detect
// the content type. Returns empty string if error occurs.
func peekContentType(p *bufio.Reader) string {
byt, err := p.Peek(512)
if err != nil && err != bufio.ErrBufferFull {
return ""
}
return http.DetectContentType(byt)
}
// copyHeader copies header values from src to dst, adding to any existing // copyHeader copies header values from src to dst, adding to any existing
// values with the same header name. If keys is not empty, only those header // values with the same header name. If keys is not empty, only those header
// keys will be copied. // keys will be copied.