在谷歌云存储中使用服务帐户获取OAuth令牌时'invalid_grant'错误

我写了一个小Qt/С++应用程序，使用谷歌云存储来保存图像文件。我在Google API控制台中创建了一个服务帐户客户端ID，并尝试与Google REST API进行交互。但在这之前，我需要得到一个OAuth授权令牌。

我一直试图得到令牌三天，但每次我得到相同的烦人的错误:｛"error": "invalid_grant"}

我试图调整时间，因为它是建议在这里:invalid_grant返回使用服务帐户和谷歌驱动器API。没用。

我在谷歌API控制台创建了另一个客户端ID，如本主题所建议的:Invalid_grant在谷歌分析。没有结果。

这是我的一个请求令牌的小类的代码。谁能告诉我哪里做错了吗?

#include "googlestorageuploader.h"
#include "openssl/evp.h"
#include "openssl/pem.h"
#include "openssl/bio.h"
#include "openssl/err.h"
#include "openssl/pkcs12.h"
#include <QFile>
#include <QDateTime>
#include <QNetworkAccessManager>
#include <QNetworkRequest>
#include <QSslConfiguration>
#include <QDebug>
// Just a wrapper that takes OpenSsl function 'a' and calls it.
// If 'a' returns zero the wrapper throws a string containg description
// of error occured
#define OPENSSL_FUNCTION_CALL(a) 
if (!a) 
{ 
    char buffer[120]; 
    ERR_error_string(ERR_get_error(), buffer); 
    char s[256]; 
    sprintf(s, ""#a" function call failed.n%s", buffer); 
    throw s; 
} 
// String template for standard JWT Header
const QString kJwtHeader = "{"alg":"RS256","typ":"JWT"}";
// String template for JWT claim set
// Contains two placeholders for "exp" and "iat" keys
const QString kJwtClaimSet = "{"
    ""iss":"XXXXXXXXXXXX-yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy@developer.gserviceaccount.com","
    ""scope":"https://www.googleapis.com/auth/devstorage.readonly","
    ""aud":"https://accounts.google.com/o/oauth2/token","
    ""exp":%1,"
    ""iat":%2"
    "}";
// This function computes JWT signature
// 'input' is an array of bytes passed as an input
// 'privateKey' is an array of bytes that contains a private key in PKCS12 format
//      (as it is in the file received from 'Google APIs Console->API Access')
// Uses OpenSSL API to create a signature using SHA256withRSA
QByteArray signWithRsaSha256(const QByteArray &input, const QByteArray &privateKey)
{
    EVP_PKEY *pkey = 0;
    BIO *bp = 0;
    EVP_MD_CTX *ctx = 0;
    const EVP_MD *sha256Md = 0;
    unsigned char sig[256];
    unsigned int s(0);
    QByteArray out;
    PKCS12 *p12 = 0;
    X509 *cert= 0;
    OpenSSL_add_all_ciphers();
    OpenSSL_add_all_digests();
    ctx = EVP_MD_CTX_create();
    EVP_MD_CTX_init(ctx);
    sha256Md = EVP_sha256(); // TODO: need to free
    bp = BIO_new_mem_buf((void*)privateKey.data(), privateKey.size());
    try {
        OPENSSL_FUNCTION_CALL(EVP_SignInit(ctx, sha256Md));
        OPENSSL_FUNCTION_CALL(EVP_SignUpdate(ctx, input.constData(), input.size()));
        OPENSSL_FUNCTION_CALL(d2i_PKCS12_bio(bp, &p12));
        OPENSSL_FUNCTION_CALL(PKCS12_parse(p12, "notasecret", &pkey, &cert, NULL));
        s = EVP_PKEY_size(pkey);
        OPENSSL_FUNCTION_CALL(EVP_SignFinal(ctx, sig, &s, pkey));
        out.setRawData((const char *)sig, s);
    }
    catch (const char *s)
    {
        qCritical() << s;
    }
    EVP_MD_CTX_destroy(ctx);
    BIO_free(bp);
    X509_free(cert);
    EVP_cleanup();
    return out;
}
CGoogleStorageUploader::CGoogleStorageUploader(QObject *parent) :
QObject(parent)
{
    nam_ = new QNetworkAccessManager(this);
}
// Creates and sends HTTP POST request to get an authorization token
void CGoogleStorageUploader::requestToken()
{
    QNetworkRequest req(QUrl("https://accounts.google.com/o/oauth2/token"));
    req.setRawHeader("Host", "accounts.google.com");
    req.setRawHeader("Content-Type", "application/x-www-form-urlencoded");
    req.setSslConfiguration(QSslConfiguration::defaultConfiguration());
    QByteArray assertion = formJWT();
    QByteArray data;
    data = "grant_type=urn%3Aietf%3Aparams%3Aoauth%3Agrant-type%3Ajwt-bearer&assertion=" + assertion;
    QNetworkReply *reply = nam_->post(req, data);
    connect(reply, SIGNAL(finished()), SLOT(onNetworkReplyFinished()));
    connect(reply, SIGNAL(sslErrors(QList<QSslError>)), SLOT(onNetworkReplySslErrors(QList<QSslError>)));
    connect(reply, SIGNAL(error(QNetworkReply::NetworkError)), SLOT(onNetworkReplyError(QNetworkReply::NetworkError)));
}
// Constructs JWT
QByteArray CGoogleStorageUploader::formJWT()
{
    QDateTime now = QDateTime::currentDateTime();
    QDateTime utcNow = now.toUTC();
    quint32 secs = utcNow.toTime_t() - 300; // adjust to Google Server time
    QString claimSet = kJwtClaimSet.arg(secs + 3600).arg(secs); // fill "exp" and "iat" fields
    QByteArray signature, privateKey, jwt;
    QFile file (":res/pk.p12"); // copy of file received from Google API Console
    if (file.open(QFile::ReadOnly))
    {
        privateKey = file.readAll();
        QByteArray encodedHeader = kJwtHeader.toUtf8().toBase64(); // serialize to UTF8 and Base64url safe encode (https://developers.google.com/accounts/docs/OAuth2ServiceAccount#formingclaimset)
        QByteArray encodedClaimSet = claimSet.toUtf8().toBase64(); // serialize to UTF8 and Base64url safe encode (https://developers.google.com/accounts/docs/OAuth2ServiceAccount#formingclaimset)
        // "Sign the UTF-8 representation of the input" (https://developers.google.com/accounts/docs/OAuth2ServiceAccount#computingsignature)
        signature = signWithRsaSha256(QString(encodedHeader + "." + encodedClaimSet).toUtf8(), privateKey);
        QByteArray encodedSignature = signature.toBase64();
        jwt = encodedHeader + "." + encodedClaimSet + "." + encodedSignature;
    }
    file.close();
    qDebug() << jwt;
    return jwt;
}
void CGoogleStorageUploader::onNetworkReplyFinished()
{
    QNetworkReply *r = static_cast<QNetworkReply*>(sender());
    qDebug() << "finished: " << r->readAll();
}
void CGoogleStorageUploader::onNetworkReplySslErrors(const QList<QSslError> &errs)
{
    QNetworkReply *r = static_cast<QNetworkReply*>(sender());
    qDebug() << "ssl errors: " << r->readAll();
    r->ignoreSslErrors(errs);
}
void CGoogleStorageUploader::onNetworkReplyError(QNetworkReply::NetworkError err)
{
    qDebug() << "network error:  " << err;
}