I had a problem a while ago writing a program in C which utilizes scp to transfer and download files to a server. The program had to be written for windows. Initially I attempted to use the libCurl library which then I encountered different problems and it didn't work well. After switching to libssh and the issue was fixed.
I'm posting a segment of my sample code which downloads a file from a remote server. hopefully this could be helpful to anyone who lands here.
int scp_recv_file(ssh_session in_session,
char * in_remotefile, char * in_localfile)
{
ssh_scp t_scp = NULL;
int t_rc, t_filesize, t_filemode = -1;
char *t_filename, *t_buffer;
t_scp = ssh_scp_new
(in_session, SSH_SCP_READ | SSH_SCP_RECURSIVE, in_remotefile);
if (t_scp == NULL)
{
fprintf(stderr, "Error allocating scp session: %s\n",
ssh_get_error(in_session));
return SSH_ERROR;
}
t_rc = ssh_scp_init(t_scp);
if (t_rc != SSH_OK)
{
fprintf(stderr, "Error initializing scp session: %s\n",
ssh_get_error(in_session));
ssh_scp_free(t_scp);
return t_rc;
}
//create ssh pull a file request
t_rc = ssh_scp_pull_request(t_scp);
if (t_rc != SSH_SCP_REQUEST_NEWFILE)
{
fprintf(stderr, "Error receiving information about file: %s\n",
ssh_get_error(in_session));
return SSH_ERROR;
}
t_filesize = ssh_scp_request_get_size(t_scp);
t_filename = strdup(ssh_scp_request_get_filename(t_scp));
t_filemode = ssh_scp_request_get_permissions(t_scp);
printf("Receiving file %s, size %d, permisssions 0%o\n",
t_filename, t_filesize, t_filemode);
t_buffer = malloc(t_filesize);
if (t_buffer == NULL)
{
fprintf(stderr, "Memory allocation error\n");
return SSH_ERROR;
}
ssh_scp_accept_request(t_scp);
t_rc = ssh_scp_read(t_scp, t_buffer, t_filesize);
if (t_rc == SSH_ERROR)
{
fprintf(stderr, "Error receiving file data: %s\n",
ssh_get_error(in_session));
free(t_buffer);
return t_rc;
}
printf("Done\n");
//write buffer to file
writeToFile(in_localfile, t_buffer, t_filesize);
//write(1, buffer, size);
//free allocated memory
free(t_buffer);
free(t_filename);
t_rc = ssh_scp_pull_request(t_scp);
if (t_rc != SSH_SCP_REQUEST_EOF)
{
fprintf(stderr, "Unexpected request: %s\n",
ssh_get_error(in_session));
return SSH_ERROR;
}
//close scp and free
ssh_scp_close(t_scp);
ssh_scp_free(t_scp);
return SSH_OK;
}
Switched to lilbssh. You can manage the scp stages manually and works ok. However, I don't know if libssh2 is better or not. Any comments?