我是 Qt 新手，我想为我的软件实现 FTP 和 SFTP 支持。 当我用谷歌搜索时，我发现不存在 Qt 的 sftp 库，但使用 QNetworkAccessManager 应该是可能的。 然后我试图发现如何构建自定义协议或类似的东西，但没有弄清楚如何去做。
有人知道我该怎么做吗？
谢谢， 迈克尔
【问题讨论】：
标签： c++ qt sftp qnetworkaccessmanager
Qt SDK 中不支持 SFTP，但 Qt Creator 实现了 SFTP。
我已经隔离了包含 SSH 和 SFTP 的库，并在 Github 中创建了一个名为 QSsh 的新项目。该项目的目的是为任何 Qt 应用程序提供 SSH 和 SFTP 支持。
我写了一个关于如何使用 SFTP 上传文件的示例。看看examples/SecureUploader/
希望对你有帮助
【讨论】：
您需要为每个协议自定义实现。但是我们可以创建一个像 QHttp 这样的类来做到这一点。有几个协议具有相似的语义，但不是全部。所以，如果你想写，告诉我，我帮你。
【讨论】：
Qt SDK 中没有当前的 SSH 包装器实现。您有 3 个选择：
【讨论】：
我使用 libssh 执行此操作。非常直截了当。 https://api.libssh.org/stable/libssh_tutor_sftp.html
不要忘记将您的 sftp 服务器添加到系统中的已知主机中。
ssh-keyscan -H mysftpserver.com >> ~/.ssh/known_hosts
示例代码：
#include "sftpuploader.h"
#include <QtDebug>
#include <QFileInfo>
#include <libssh/libssh.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <libssh/sftp.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <QFile>
int verify_knownhost(ssh_session session)
{
int state, hlen;
unsigned char *hash = NULL;
char *hexa;
char buf[10];
state = ssh_is_server_known(session);
hlen = ssh_get_pubkey_hash(session, &hash);
if (hlen < 0)
return -1;
switch (state)
{
case SSH_SERVER_KNOWN_OK:
break; /* ok */
case SSH_SERVER_KNOWN_CHANGED:
fprintf(stderr, "Host key for server changed: it is now:\n");
ssh_print_hexa("Public key hash", hash, hlen);
fprintf(stderr, "For security reasons, connection will be stopped\n");
free(hash);
return -1;
case SSH_SERVER_FOUND_OTHER:
fprintf(stderr, "The host key for this server was not found but an other"
"type of key exists.\n");
fprintf(stderr, "An attacker might change the default server key to"
"confuse your client into thinking the key does not exist\n");
free(hash);
return -1;
case SSH_SERVER_FILE_NOT_FOUND:
fprintf(stderr, "Could not find known host file.\n");
fprintf(stderr, "If you accept the host key here, the file will be"
"automatically created.\n");
/* fallback to SSH_SERVER_NOT_KNOWN behavior */
case SSH_SERVER_NOT_KNOWN:
hexa = ssh_get_hexa(hash, hlen);
fprintf(stderr,"The server is unknown. Do you trust the host key?\n");
fprintf(stderr, "Public key hash: %s\n", hexa);
free(hexa);
if (fgets(buf, sizeof(buf), stdin) == NULL)
{
free(hash);
return -1;
}
if (strncasecmp(buf, "yes", 3) != 0)
{
free(hash);
return -1;
}
if (ssh_write_knownhost(session) < 0)
{
fprintf(stderr, "Error %s\n", strerror(errno));
free(hash);
return -1;
}
break;
case SSH_SERVER_ERROR:
fprintf(stderr, "Error %s", ssh_get_error(session));
free(hash);
return -1;
}
free(hash);
return 0;
}
bool upload(const QString &localFile,
const QString &dest,
const QString &host,
const QString &username,
const QString &passwd)
{
bool retVal = false;
QFileInfo info(localFile);
m_localFilename = info.canonicalFilePath();
m_remoteFilename = dest + "/" + info.fileName();
int verbosity = SSH_LOG_PROTOCOL;
int port = 22;
int rc;
sftp_session sftp;
sftp_file file;
int access_type;
int nwritten;
QByteArray dataToWrite;
ssh_session my_ssh_session;
QFile myfile(m_localFilename);
if(!myfile.exists())
{
qDebug() << "SFTPUploader: File doesn't exist " << m_localFilename;
return retVal;
}
my_ssh_session = ssh_new();
if(my_ssh_session == NULL)
{
return retVal;
}
ssh_options_set(my_ssh_session, SSH_OPTIONS_HOST, host.toUtf8());
ssh_options_set(my_ssh_session, SSH_OPTIONS_LOG_VERBOSITY, &verbosity);
ssh_options_set(my_ssh_session, SSH_OPTIONS_PORT, &port);
rc = ssh_connect(my_ssh_session);
if (rc != SSH_OK)
{
qDebug() << "SFTPUploader: Error connecting to localhost: " << ssh_get_error(my_ssh_session);
ssh_free(my_ssh_session);
return retVal;
}
else
{
qDebug() << "SFTPUploader: SSH connected";
}
// Verify the server's identity
// For the source code of verify_knowhost(), check previous example
if (verify_knownhost(my_ssh_session) < 0)
{
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
qDebug() << "SFTPUploader: verify_knownhost failed";
return retVal;
}
rc = ssh_userauth_password(my_ssh_session, username.toUtf8(), passwd.toUtf8());
if (rc != SSH_AUTH_SUCCESS)
{
qDebug() << "SFTPUploader: Error authenticating with password: " << ssh_get_error(my_ssh_session);
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
return retVal;
}
else
{
qDebug() << "SFTPUploader: Authentication sucess";
}
sftp = sftp_new(my_ssh_session);
if (sftp == NULL)
{
qDebug() << "SFTPUploader: Error allocating SFTP session:" << ssh_get_error(my_ssh_session);
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
return retVal;
}
rc = sftp_init(sftp);
if (rc != SSH_OK)
{
qDebug() << "SFTPUploader: Error initializing SFTP session:", sftp_get_error(sftp);
sftp_free(sftp);
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
return retVal;
}
access_type = O_WRONLY | O_CREAT | O_TRUNC;
file = sftp_open(sftp, dest.toUtf8(), access_type, S_IRWXU);
if (file == NULL)
{
qDebug() << "SFTPUploader: Can't open file for writing:", ssh_get_error(my_ssh_session);
sftp_free(sftp);
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
return retVal;
}
if(myfile.open(QFile::ReadOnly))
{
dataToWrite = myfile.readAll();
}
nwritten = sftp_write(file, dataToWrite, dataToWrite.size());
if (nwritten != dataToWrite.size())
{
qDebug() << "SFTPUploader: Can't write data to file: ", ssh_get_error(my_ssh_session);
sftp_close(file);
sftp_free(sftp);
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
return retVal;
}
rc = sftp_close(file);
if (rc != SSH_OK)
{
qDebug() << "SFTPUploader: Can't close the written file:" << ssh_get_error(my_ssh_session);
sftp_free(sftp);
ssh_disconnect(my_ssh_session);
ssh_free(my_ssh_session);
return retVal;
}
else
{
qDebug() << "SFTPUploader: Success";
retVal = true;
}
return retVal;
}
【讨论】：