func()

in http2/transport.go [2224:2341]
102 lines of code
27 McCabe index (conditional complexity)

func (rl *clientConnReadLoop) handleResponse(cs *clientStream, f *MetaHeadersFrame) (*http.Response, error) {
	if f.Truncated {
		return nil, errResponseHeaderListSize
	}

	status := f.PseudoValue("status")
	if status == "" {
		return nil, errors.New("malformed response from server: missing status pseudo header")
	}
	statusCode, err := strconv.Atoi(status)
	if err != nil {
		return nil, errors.New("malformed response from server: malformed non-numeric status pseudo header")
	}

	regularFields := f.RegularFields()
	strs := make([]string, len(regularFields))
	header := make(http.Header, len(regularFields))
	res := &http.Response{
		Proto:      "HTTP/2.0",
		ProtoMajor: 2,
		Header:     header,
		StatusCode: statusCode,
		Status:     status + " " + http.StatusText(statusCode),
	}
	for _, hf := range regularFields {
		key := http.CanonicalHeaderKey(hf.Name)
		if key == "Trailer" {
			t := res.Trailer
			if t == nil {
				t = make(http.Header)
				res.Trailer = t
			}
			foreachHeaderElement(hf.Value, func(v string) {
				t[http.CanonicalHeaderKey(v)] = nil
			})
		} else {
			vv := header[key]
			if vv == nil && len(strs) > 0 {
				// More than likely this will be a single-element key.
				// Most headers aren't multi-valued.
				// Set the capacity on strs[0] to 1, so any future append
				// won't extend the slice into the other strings.
				vv, strs = strs[:1:1], strs[1:]
				vv[0] = hf.Value
				header[key] = vv
			} else {
				header[key] = append(vv, hf.Value)
			}
		}
	}

	if statusCode >= 100 && statusCode <= 199 {
		if f.StreamEnded() {
			return nil, errors.New("1xx informational response with END_STREAM flag")
		}
		cs.num1xx++
		const max1xxResponses = 5 // arbitrary bound on number of informational responses, same as net/http
		if cs.num1xx > max1xxResponses {
			return nil, errors.New("http2: too many 1xx informational responses")
		}
		if fn := cs.get1xxTraceFunc(); fn != nil {
			if err := fn(statusCode, textproto.MIMEHeader(header)); err != nil {
				return nil, err
			}
		}
		if statusCode == 100 {
			traceGot100Continue(cs.trace)
			select {
			case cs.on100 <- struct{}{}:
			default:
			}
		}
		cs.pastHeaders = false // do it all again
		return nil, nil
	}

	res.ContentLength = -1
	if clens := res.Header["Content-Length"]; len(clens) == 1 {
		if cl, err := strconv.ParseUint(clens[0], 10, 63); err == nil {
			res.ContentLength = int64(cl)
		} else {
			// TODO: care? unlike http/1, it won't mess up our framing, so it's
			// more safe smuggling-wise to ignore.
		}
	} else if len(clens) > 1 {
		// TODO: care? unlike http/1, it won't mess up our framing, so it's
		// more safe smuggling-wise to ignore.
	} else if f.StreamEnded() && !cs.isHead {
		res.ContentLength = 0
	}

	if cs.isHead {
		res.Body = noBody
		return res, nil
	}

	if f.StreamEnded() {
		if res.ContentLength > 0 {
			res.Body = missingBody{}
		} else {
			res.Body = noBody
		}
		return res, nil
	}

	cs.bufPipe.setBuffer(&dataBuffer{expected: res.ContentLength})
	cs.bytesRemain = res.ContentLength
	res.Body = transportResponseBody{cs}

	if cs.requestedGzip && asciiEqualFold(res.Header.Get("Content-Encoding"), "gzip") {
		res.Header.Del("Content-Encoding")
		res.Header.Del("Content-Length")
		res.ContentLength = -1
		res.Body = &gzipReader{body: res.Body}
		res.Uncompressed = true
	}
	return res, nil
}