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provider_client.go
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provider_client.go
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package golangsdk
import (
"bytes"
"context"
"encoding/json"
"errors"
"io"
"io/ioutil"
"net/http"
"strings"
"sync"
"github.com/chnsz/golangsdk/auth"
)
// DefaultUserAgent is the default User-Agent string set in the request header.
const (
DefaultUserAgent = "golangsdk/2.0.0"
DefaultMaxBackoffRetries = 5
)
// UserAgent represents a User-Agent header.
type UserAgent struct {
// prepend is the slice of User-Agent strings to prepend to DefaultUserAgent.
// All the strings to prepend are accumulated and prepended in the Join method.
prepend []string
}
type RetryFunc func(context.Context, *ErrUnexpectedResponseCode, error, uint) error
// Prepend prepends a user-defined string to the default User-Agent string. Users
// may pass in one or more strings to prepend.
func (ua *UserAgent) Prepend(s ...string) {
ua.prepend = append(s, ua.prepend...)
}
// Join concatenates all the user-defined User-Agend strings with the default
// Gophercloud User-Agent string.
func (ua *UserAgent) Join() string {
uaSlice := append(ua.prepend, DefaultUserAgent)
return strings.Join(uaSlice, " ")
}
// ProviderClient stores details that are required to interact with any
// services within a specific provider's API.
//
// Generally, you acquire a ProviderClient by calling the NewClient method in
// the appropriate provider's child package, providing whatever authentication
// credentials are required.
type ProviderClient struct {
// IdentityBase is the base URL used for a particular provider's identity
// service - it will be used when issuing authenticatation requests. It
// should point to the root resource of the identity service, not a specific
// identity version.
IdentityBase string
// IdentityEndpoint is the identity endpoint. This may be a specific version
// of the identity service. If this is the case, this endpoint is used rather
// than querying versions first.
IdentityEndpoint string
// TokenID is the ID of the most recently issued valid token.
// NOTE: Aside from within a custom ReauthFunc, this field shouldn't be set by an application.
// To safely read or write this value, call `Token` or `SetToken`, respectively
TokenID string
// ProjectID is the ID of project to which User is authorized.
ProjectID string
// DomainID is the ID of project to which User is authorized.
DomainID string
// EndpointLocator describes how this provider discovers the endpoints for
// its constituent services.
EndpointLocator EndpointLocator
// HTTPClient allows users to interject arbitrary http, https, or other transit behaviors.
HTTPClient http.Client
// UserAgent represents the User-Agent header in the HTTP request.
UserAgent UserAgent
// ReauthFunc is the function used to re-authenticate the user if the request
// fails with a 401 HTTP response code. This a needed because there may be multiple
// authentication functions for different Identity service versions.
ReauthFunc func() error
// AKSKAuthOptions provides the value for AK/SK authentication, it should be nil if you use token authentication,
// Otherwise, it must have a value
AKSKAuthOptions AKSKAuthOptions
// Context is the context passed to the HTTP request.
Context context.Context
// Retry backoff func
RetryBackoffFunc RetryFunc
// MaxBackoffRetries set the maximum number of backoffs. When not set, defaults to DefaultMaxBackoffRetries
MaxBackoffRetries uint
// mut is a mutex for the client. It protects read and write access to client attributes such as getting
// and setting the TokenID.
mut *sync.RWMutex
// reauthmut is a mutex for reauthentication it attempts to ensure that only one reauthentication
// attempt happens at one time.
reauthmut *reauthlock
}
// reauthlock represents a set of attributes used to help in the reauthentication process.
type reauthlock struct {
sync.RWMutex
reauthing bool
}
// AuthenticatedHeaders returns a map of HTTP headers that are common for all
// authenticated service requests.
func (client *ProviderClient) AuthenticatedHeaders() (m map[string]string) {
if client.reauthmut != nil {
client.reauthmut.RLock()
if client.reauthmut.reauthing {
client.reauthmut.RUnlock()
return
}
client.reauthmut.RUnlock()
}
t := client.Token()
if t == "" {
return
}
return map[string]string{"X-Auth-Token": t}
}
// UseTokenLock creates a mutex that is used to allow safe concurrent access to the auth token.
// If the application's ProviderClient is not used concurrently, this doesn't need to be called.
func (client *ProviderClient) UseTokenLock() {
client.mut = new(sync.RWMutex)
client.reauthmut = new(reauthlock)
}
// Token safely reads the value of the auth token from the ProviderClient. Applications should
// call this method to access the token instead of the TokenID field
func (client *ProviderClient) Token() string {
if client.mut != nil {
client.mut.RLock()
defer client.mut.RUnlock()
}
return client.TokenID
}
// SetToken safely sets the value of the auth token in the ProviderClient. Applications may
// use this method in a custom ReauthFunc
func (client *ProviderClient) SetToken(t string) {
if client.mut != nil {
client.mut.Lock()
defer client.mut.Unlock()
}
client.TokenID = t
}
// Reauthenticate calls client.ReauthFunc in a thread-safe way. If this is
// called because of a 401 response, the caller may pass the previous token. In
// this case, the reauthentication can be skipped if another thread has already
// reauthenticated in the meantime. If no previous token is known, an empty
// string should be passed instead to force unconditional reauthentication.
func (client *ProviderClient) Reauthenticate(previousToken string) (err error) {
if client.ReauthFunc == nil {
return nil
}
if client.mut == nil {
return client.ReauthFunc()
}
client.mut.Lock()
defer client.mut.Unlock()
client.reauthmut.Lock()
client.reauthmut.reauthing = true
client.reauthmut.Unlock()
if previousToken == "" || client.TokenID == previousToken {
err = client.ReauthFunc()
}
client.reauthmut.Lock()
client.reauthmut.reauthing = false
client.reauthmut.Unlock()
return
}
// RequestOpts customizes the behavior of the provider.Request() method.
type RequestOpts struct {
// JSONBody, if provided, will be encoded as JSON and used as the body of the HTTP request. The
// content type of the request will default to "application/json" unless overridden by MoreHeaders.
// It's an error to specify both a JSONBody and a RawBody.
JSONBody interface{}
// RawBody contains an io.Reader that will be consumed by the request directly. No content-type
// will be set unless one is provided explicitly by MoreHeaders.
RawBody io.Reader
// JSONResponse, if provided, will be populated with the contents of the response body parsed as
// JSON.
JSONResponse interface{}
// OkCodes contains a list of numeric HTTP status codes that should be interpreted as success. If
// the response has a different code, an error will be returned.
OkCodes []int
// MoreHeaders specifies additional HTTP headers to be provide on the request. If a header is
// provided with a blank value (""), that header will be *omitted* instead: use this to suppress
// the default Accept header or an inferred Content-Type, for example.
MoreHeaders map[string]string
// ErrorContext specifies the resource error type to return if an error is encountered.
// This lets resources override default error messages based on the response status code.
ErrorContext error
// KeepResponseBody specifies whether to keep the HTTP response body. Usually used, when the HTTP
// response body is considered for further use. Valid when JSONResponse is nil.
KeepResponseBody bool
}
// requestState contains temporary state for a single ProviderClient.Request() call.
type requestState struct {
// This flag indicates if we have reauthenticated during this request because of a 401 response.
// It ensures that we don't reauthenticate multiple times for a single request. If we
// reauthenticate, but keep getting 401 responses with the fresh token, reauthenticating some more
// will just get us into an infinite loop.
hasReauthenticated bool
// Retry-After backoff counter, increments during each backoff call
retries uint
}
var applicationJSON = "application/json"
func jsonMarshal(t interface{}) ([]byte, error) {
buffer := &bytes.Buffer{}
enc := json.NewEncoder(buffer)
enc.SetEscapeHTML(false)
err := enc.Encode(t)
return buffer.Bytes(), err
}
// Request performs an HTTP request using the ProviderClient's current HTTPClient. An authentication
// header will automatically be provided.
func (client *ProviderClient) Request(method, url string, options *RequestOpts) (*http.Response, error) {
return client.doRequest(method, url, options, &requestState{
hasReauthenticated: false,
})
}
func (client *ProviderClient) doRequest(method, url string, options *RequestOpts, state *requestState) (*http.Response, error) {
var body io.Reader
var contentType *string
// Derive the content body by either encoding an arbitrary object as JSON, or by taking a provided
// io.ReadSeeker as-is. Default the content-type to application/json.
if options.JSONBody != nil {
if options.RawBody != nil {
return nil, errors.New("Please provide only one of JSONBody or RawBody to golangsdk.Request()")
}
rendered, err := jsonMarshal(options.JSONBody)
if err != nil {
return nil, err
}
body = bytes.NewReader(rendered)
contentType = &applicationJSON
}
// Return an error, when "KeepResponseBody" is true and "JSONResponse" is not nil
if options.KeepResponseBody && options.JSONResponse != nil {
return nil, errors.New("cannot use KeepResponseBody when JSONResponse is not nil")
}
if options.RawBody != nil {
body = options.RawBody
}
// Construct the http.Request.
req, err := http.NewRequest(method, url, body)
if err != nil {
return nil, err
}
if client.Context != nil {
req = req.WithContext(client.Context)
}
// Populate the request headers. Apply options.MoreHeaders last, to give the caller the chance to
// modify or omit any header.
if contentType != nil {
req.Header.Set("Content-Type", *contentType)
}
req.Header.Set("Accept", applicationJSON)
// Set the User-Agent header
req.Header.Set("User-Agent", client.UserAgent.Join())
if options.MoreHeaders != nil {
for k, v := range options.MoreHeaders {
if v != "" {
req.Header.Set(k, v)
} else {
req.Header.Del(k)
}
}
}
// get latest token from client
for k, v := range client.AuthenticatedHeaders() {
req.Header.Set(k, v)
}
prereqtok := req.Header.Get("X-Auth-Token")
if client.AKSKAuthOptions.AccessKey != "" {
if err := auth.Sign(req, client.AKSKAuthOptions.AccessKey, client.AKSKAuthOptions.SecretKey); err != nil {
return nil, err
}
if client.AKSKAuthOptions.ProjectId != "" {
req.Header.Set("X-Project-Id", client.AKSKAuthOptions.ProjectId)
}
if client.AKSKAuthOptions.DomainID != "" {
req.Header.Set("X-Domain-Id", client.AKSKAuthOptions.DomainID)
}
if client.AKSKAuthOptions.SecurityToken != "" {
req.Header.Set("X-Security-Token", client.AKSKAuthOptions.SecurityToken)
}
}
// Issue the request.
resp, err := client.HTTPClient.Do(req)
if err != nil {
return nil, err
}
// Allow default OkCodes if none explicitly set
okc := options.OkCodes
if okc == nil {
okc = defaultOkCodes(method)
}
// Validate the HTTP response status.
var ok bool
for _, code := range okc {
if resp.StatusCode == code {
ok = true
break
}
}
if !ok {
body, _ := ioutil.ReadAll(resp.Body)
resp.Body.Close()
respErr := ErrUnexpectedResponseCode{
URL: url,
Method: method,
Expected: okc,
Actual: resp.StatusCode,
RequestId: resp.Header.Get("X-Request-Id"),
Body: body,
}
errType := options.ErrorContext
switch resp.StatusCode {
case http.StatusBadRequest:
err = ErrDefault400{respErr}
if error400er, ok := errType.(Err400er); ok {
err = error400er.Error400(respErr)
}
case http.StatusUnauthorized:
if client.ReauthFunc != nil && !state.hasReauthenticated {
err = client.Reauthenticate(prereqtok)
if err != nil {
e := &ErrUnableToReauthenticate{}
e.ErrOriginal = respErr
return nil, e
}
if options.RawBody != nil {
if seeker, ok := options.RawBody.(io.Seeker); ok {
seeker.Seek(0, 0)
}
}
state.hasReauthenticated = true
resp, err = client.doRequest(method, url, options, state)
if err != nil {
switch err.(type) {
case *ErrUnexpectedResponseCode:
e := &ErrErrorAfterReauthentication{}
e.ErrOriginal = err.(*ErrUnexpectedResponseCode)
return nil, e
default:
e := &ErrErrorAfterReauthentication{}
e.ErrOriginal = err
return nil, e
}
}
return resp, nil
}
err = ErrDefault401{respErr}
if error401er, ok := errType.(Err401er); ok {
err = error401er.Error401(respErr)
}
case http.StatusForbidden:
err = ErrDefault403{respErr}
if error403er, ok := errType.(Err403er); ok {
err = error403er.Error403(respErr)
}
case http.StatusNotFound:
err = ErrDefault404{respErr}
if error404er, ok := errType.(Err404er); ok {
err = error404er.Error404(respErr)
}
case http.StatusMethodNotAllowed:
err = ErrDefault405{respErr}
if error405er, ok := errType.(Err405er); ok {
err = error405er.Error405(respErr)
}
case http.StatusRequestTimeout:
err = ErrDefault408{respErr}
if error408er, ok := errType.(Err408er); ok {
err = error408er.Error408(respErr)
}
case http.StatusTooManyRequests:
err = ErrDefault429{respErr}
if error429er, ok := errType.(Err429er); ok {
err = error429er.Error429(respErr)
}
maxTries := client.MaxBackoffRetries
if maxTries == 0 {
maxTries = DefaultMaxBackoffRetries
}
if f := client.RetryBackoffFunc; f != nil && state.retries < maxTries {
var e error
e = f(client.Context, &respErr, err, state.retries)
if e != nil {
return resp, e
}
state.retries = state.retries + 1
return client.doRequest(method, url, options, state)
}
case http.StatusInternalServerError:
err = ErrDefault500{respErr}
if error500er, ok := errType.(Err500er); ok {
err = error500er.Error500(respErr)
}
case http.StatusServiceUnavailable:
err = ErrDefault503{respErr}
if error503er, ok := errType.(Err503er); ok {
err = error503er.Error503(respErr)
}
}
if err == nil {
err = respErr
}
return resp, err
}
// Parse the response body as JSON, if requested to do so.
if options.JSONResponse != nil {
defer resp.Body.Close()
// Don't decode JSON when there is no content
if resp.StatusCode == http.StatusNoContent {
// read till EOF, otherwise the connection will be closed and cannot be reused
_, err = io.Copy(ioutil.Discard, resp.Body)
return resp, err
}
if err := json.NewDecoder(resp.Body).Decode(options.JSONResponse); err != nil {
return nil, err
}
}
// Close unused body to allow the HTTP connection to be reused
if !options.KeepResponseBody && options.JSONResponse == nil {
defer resp.Body.Close()
// read till EOF, otherwise the connection will be closed and cannot be reused
if _, err := io.Copy(ioutil.Discard, resp.Body); err != nil {
return nil, err
}
}
return resp, nil
}
func defaultOkCodes(method string) []int {
switch method {
case "GET", "HEAD":
return []int{200}
case "POST":
return []int{200, 201, 202}
case "PUT":
return []int{200, 201, 202}
case "PATCH":
return []int{200, 202, 204}
case "DELETE":
return []int{200, 202, 204}
}
return []int{}
}