208 lines
6.3 KiB
Go
208 lines
6.3 KiB
Go
package pub
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import (
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"bytes"
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"context"
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"crypto"
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"fmt"
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"io/ioutil"
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"net/http"
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"net/url"
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"strings"
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"sync"
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"github.com/go-fed/httpsig"
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)
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const (
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// acceptHeaderValue is the Accept header value indicating that the
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// response should contain an ActivityStreams object.
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acceptHeaderValue = "application/ld+json; profile=\"https://www.w3.org/ns/activitystreams\""
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)
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// isSuccess returns true if the HTTP status code is either OK, Created, or
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// Accepted.
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func isSuccess(code int) bool {
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return code == http.StatusOK ||
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code == http.StatusCreated ||
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code == http.StatusAccepted
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}
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// Transport makes ActivityStreams calls to other servers in order to send or
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// receive ActivityStreams data.
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//
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// It is responsible for setting the appropriate request headers, signing the
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// requests if needed, and facilitating the traffic between this server and
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// another.
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//
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// The transport is exclusively used to issue requests on behalf of an actor,
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// and is never sending requests on behalf of the server in general.
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//
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// It may be reused multiple times, but never concurrently.
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type Transport interface {
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// Dereference fetches the ActivityStreams object located at this IRI
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// with a GET request.
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Dereference(c context.Context, iri *url.URL) ([]byte, error)
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// Deliver sends an ActivityStreams object.
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Deliver(c context.Context, b []byte, to *url.URL) error
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// BatchDeliver sends an ActivityStreams object to multiple recipients.
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BatchDeliver(c context.Context, b []byte, recipients []*url.URL) error
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}
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// Transport must be implemented by HttpSigTransport.
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var _ Transport = &HttpSigTransport{}
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// HttpSigTransport makes a dereference call using HTTP signatures to
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// authenticate the request on behalf of a particular actor.
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//
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// No rate limiting is applied.
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//
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// Only one request is tried per call.
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type HttpSigTransport struct {
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client HttpClient
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appAgent string
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gofedAgent string
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clock Clock
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getSigner httpsig.Signer
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getSignerMu *sync.Mutex
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postSigner httpsig.Signer
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postSignerMu *sync.Mutex
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pubKeyId string
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privKey crypto.PrivateKey
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}
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// NewHttpSigTransport returns a new Transport.
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//
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// It sends requests specifically on behalf of a specific actor on this server.
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// The actor's credentials are used to add an HTTP Signature to requests, which
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// requires an actor's private key, a unique identifier for their public key,
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// and an HTTP Signature signing algorithm.
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//
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// The client lets users issue requests through any HTTP client, including the
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// standard library's HTTP client.
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//
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// The appAgent uniquely identifies the calling application's requests, so peers
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// may aid debugging the requests incoming from this server. Note that the
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// agent string will also include one for go-fed, so at minimum peer servers can
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// reach out to the go-fed library to aid in notifying implementors of malformed
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// or unsupported requests.
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func NewHttpSigTransport(
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client HttpClient,
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appAgent string,
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clock Clock,
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getSigner, postSigner httpsig.Signer,
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pubKeyId string,
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privKey crypto.PrivateKey) *HttpSigTransport {
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return &HttpSigTransport{
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client: client,
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appAgent: appAgent,
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gofedAgent: goFedUserAgent(),
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clock: clock,
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getSigner: getSigner,
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getSignerMu: &sync.Mutex{},
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postSigner: postSigner,
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postSignerMu: &sync.Mutex{},
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pubKeyId: pubKeyId,
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privKey: privKey,
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}
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}
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// Dereference sends a GET request signed with an HTTP Signature to obtain an
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// ActivityStreams value.
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func (h HttpSigTransport) Dereference(c context.Context, iri *url.URL) ([]byte, error) {
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req, err := http.NewRequest("GET", iri.String(), nil)
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if err != nil {
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return nil, err
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}
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req = req.WithContext(c)
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req.Header.Add(acceptHeader, acceptHeaderValue)
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req.Header.Add("Accept-Charset", "utf-8")
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req.Header.Add("Date", h.clock.Now().UTC().Format("Mon, 02 Jan 2006 15:04:05")+" GMT")
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req.Header.Add("User-Agent", fmt.Sprintf("%s %s", h.appAgent, h.gofedAgent))
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req.Header.Set("Host", iri.Host)
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h.getSignerMu.Lock()
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err = h.getSigner.SignRequest(h.privKey, h.pubKeyId, req, nil)
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h.getSignerMu.Unlock()
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if err != nil {
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return nil, err
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}
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resp, err := h.client.Do(req)
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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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if resp.StatusCode != http.StatusOK {
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return nil, fmt.Errorf("GET request to %s failed (%d): %s", iri.String(), resp.StatusCode, resp.Status)
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}
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return ioutil.ReadAll(resp.Body)
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}
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// Deliver sends a POST request with an HTTP Signature.
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func (h HttpSigTransport) Deliver(c context.Context, b []byte, to *url.URL) error {
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req, err := http.NewRequest("POST", to.String(), bytes.NewReader(b))
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if err != nil {
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return err
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}
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req = req.WithContext(c)
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req.Header.Add(contentTypeHeader, contentTypeHeaderValue)
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req.Header.Add("Accept-Charset", "utf-8")
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req.Header.Add("Date", h.clock.Now().UTC().Format("Mon, 02 Jan 2006 15:04:05")+" GMT")
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req.Header.Add("User-Agent", fmt.Sprintf("%s %s", h.appAgent, h.gofedAgent))
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req.Header.Set("Host", to.Host)
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h.postSignerMu.Lock()
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err = h.postSigner.SignRequest(h.privKey, h.pubKeyId, req, b)
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h.postSignerMu.Unlock()
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if err != nil {
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return err
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}
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resp, err := h.client.Do(req)
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if err != nil {
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return err
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}
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defer resp.Body.Close()
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if !isSuccess(resp.StatusCode) {
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return fmt.Errorf("POST request to %s failed (%d): %s", to.String(), resp.StatusCode, resp.Status)
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}
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return nil
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}
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// BatchDeliver sends concurrent POST requests. Returns an error if any of the
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// requests had an error.
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func (h HttpSigTransport) BatchDeliver(c context.Context, b []byte, recipients []*url.URL) error {
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var wg sync.WaitGroup
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errCh := make(chan error, len(recipients))
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for _, recipient := range recipients {
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wg.Add(1)
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go func(r *url.URL) {
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defer wg.Done()
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if err := h.Deliver(c, b, r); err != nil {
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errCh <- err
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}
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}(recipient)
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}
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wg.Wait()
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errs := make([]string, 0, len(recipients))
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outer:
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for {
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select {
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case e := <-errCh:
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errs = append(errs, e.Error())
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default:
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break outer
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}
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}
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if len(errs) > 0 {
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return fmt.Errorf("batch deliver had at least one failure: %s", strings.Join(errs, "; "))
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}
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return nil
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}
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// HttpClient sends http requests, and is an abstraction only needed by the
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// HttpSigTransport. The standard library's Client satisfies this interface.
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type HttpClient interface {
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Do(req *http.Request) (*http.Response, error)
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}
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// HttpClient must be implemented by http.Client.
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var _ HttpClient = &http.Client{}
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