Fixed file names.

google/internal/oauth/sts_exchange.go

@@ -0,0 +1,75 @@
+package externalaccount
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+)
+
+func ExchangeToken(endpoint string, request *STSTokenExchangeRequest, authentication ClientAuthentication, headers http.Header, options map[string]interface{}) (*STSTokenExchangeResponse, error) {
+
+	client := &http.Client{}
+
+	data := url.Values{}
+	data.Set("audience", request.Audience)
+	data.Set("grant_type", "urn:ietf:params:oauth:grant-type:token-exchange")
+	data.Set("requested_token_type", "urn:ietf:params:oauth:token-type:access_token")
+	data.Set("subject_token_type", request.SubjectTokenType)
+	data.Set("subject_token", request.SubjectToken)
+	data.Set("scope", strings.Join(request.Scope, " "))
+
+	authentication.InjectAuthentication(&data, &headers)
+	req, err := http.NewRequest("POST", endpoint, strings.NewReader(data.Encode()))
+	if err != nil {
+		fmt.Errorf("oauth2/google: failed to properly build http request")
+	}
+	for key, _ := range headers {
+		for _, val := range headers.Values(key) {
+			req.Header.Add(key, val)
+		}
+	}
+	req.Header.Add("Content-Length", strconv.Itoa(len(data.Encode())))
+
+	resp, err := client.Do(req)
+	if err != nil {
+		fmt.Errorf("oauth2/google: invalid response from Secure Token Server: #{err}")
+	}
+	defer resp.Body.Close()
+	body, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		fmt.Errorf("oauth2/google: invalid body in Secute Token Server response: #{err}")
+	}
+	var stsResp STSTokenExchangeResponse
+	err = json.Unmarshal(body, &stsResp)
+	if err != nil {
+		fmt.Println(err)
+	}
+	return &stsResp, nil
+}
+
+type STSTokenExchangeRequest struct {
+	ActingParty struct {
+		ActorToken     string
+		ActorTokenType string
+	}
+	GrantType          string
+	Resource           string
+	Audience           string
+	Scope              []string
+	RequestedTokenType string
+	SubjectToken       string
+	SubjectTokenType   string
+}
+
+type STSTokenExchangeResponse struct {
+	AccessToken     string `json:"access_token"`
+	IssuedTokenType string `json:"issued_token_type"`
+	TokenType       string `json:"token_type"`
+	ExpiresIn       int    `json:"expires_in"`
+	Scope           string `json:"scope"`
+	RefreshToken    string `json:"refresh_token"`
+}