I implemented a client/server communication over SSH with libssh. I also want to implement file upload from client to the server now and have been following the doc for it.
However, it hangs on the call sftp = sftp_new(session);
. Do I have to explicitly open another ssh_channel for it on the server side as well? I only added the sftp code on the client so far.
For all who are struggling as well, I finally found the solution.
I found on the thread of this question that libssh/sftp.h
does have separate functions for the server at the very end. To enable them, you have to use #define WITH_SERVER
.
Despite the comment on the doc that you don't have to handle channels yourself, you do have to open a new channel on the server side for the SFTP communication. Implementing this worked for me:
while ((msg = ssh_message_get(session)))
{
if (ssh_message_type(msg) == SSH_REQUEST_CHANNEL_OPEN && ssh_message_subtype(msg) == SSH_CHANNEL_SESSION)
{
printf("[+] Got channel open request, opening new channel for sftp\n");
sftpChannel = ssh_message_channel_request_open_reply_accept(msg);
ssh_message_free(msg);
}
if (ssh_message_type(msg) == SSH_REQUEST_CHANNEL && ssh_message_subtype(msg) == SSH_CHANNEL_REQUEST_SUBSYSTEM)
{
if (!strcmp(ssh_message_channel_request_subsystem(msg), "sftp"))
{
ssh_message_channel_request_reply_success(msg);
ssh_message_free(msg);
// setup SFTP session
sftp_session sftp = sftp_server_new(session, sftpChannel);
if (sftp == NULL)
{
fprintf(stderr, "Error allocating SFTP session: %s\n", ssh_get_error(session));
}
int rc = sftp_server_init(sftp);
if (rc != SSH_OK)
{
fprintf(stderr, "Error initializing SFTP session: %i.\n", sftp_get_error(sftp));
sftp_free(sftp);
}
// handle communication...
}
}
}