95 lines
2.5 KiB
Go
95 lines
2.5 KiB
Go
// Copyright 2017 CoreOS, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package client
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import (
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"bytes"
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"encoding/xml"
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"fmt"
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"io"
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"net"
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"net/http"
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"time"
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"github.com/coreos/go-omaha/omaha"
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)
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const (
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defaultTimeout = 90 * time.Second
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defaultTries = 7
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)
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// httpClient extends the standard http.Client to support xml encoding
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// and decoding as well as automatic retries on transient failures.
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type httpClient struct {
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http.Client
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}
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func newHTTPClient() *httpClient {
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return &httpClient{http.Client{
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Timeout: defaultTimeout,
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}}
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}
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// doPost sends a single HTTP POST, returning a parsed omaha response.
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func (hc *httpClient) doPost(url string, reqBody []byte) (*omaha.Response, error) {
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resp, err := hc.Post(url, "text/xml; charset=utf-8", bytes.NewReader(reqBody))
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if err != nil {
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return nil, err
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}
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defer resp.Body.Close()
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// A response over 1M in size is certainly bogus.
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respBody := &io.LimitedReader{R: resp.Body, N: 1024 * 1024}
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contentType := resp.Header.Get("Content-Type")
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omahaResp, err := omaha.ParseResponse(contentType, respBody)
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// Report a more sensible error if we truncated the body.
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if isUnexpectedEOF(err) && respBody.N <= 0 {
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err = bodySizeError
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} else if err == io.EOF {
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err = bodyEmptyError
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}
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// Prefer reporting HTTP errors over XML parsing errors.
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if resp.StatusCode != http.StatusOK {
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err = &httpError{resp}
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}
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return omahaResp, err
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}
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// Omaha encodes and sends an omaha request, retrying on any transient errors.
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func (hc *httpClient) Omaha(url string, req *omaha.Request) (resp *omaha.Response, err error) {
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buf := bytes.NewBufferString(xml.Header)
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enc := xml.NewEncoder(buf)
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if err := enc.Encode(req); err != nil {
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return nil, fmt.Errorf("omaha: failed to encode request: %v", err)
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}
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for i := 0; i < defaultTries; i++ {
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resp, err = hc.doPost(url, buf.Bytes())
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if neterr, ok := err.(net.Error); ok && neterr.Temporary() {
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// TODO(marineam): add exponential backoff
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continue
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}
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break
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}
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if err != nil {
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return nil, fmt.Errorf("omaha: request failed: %v", err)
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}
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return resp, nil
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}
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