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Replace scp transfer test with SFTP #52

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fac036b
transfer: replace scp upload with sftp
odeinjul Jul 3, 2026
9e72f71
transfer: replace scp download with sftp
odeinjul Jul 3, 2026
05908cc
docs: describe sftp transfer test
odeinjul Jul 3, 2026
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7 changes: 3 additions & 4 deletions README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -6,11 +6,11 @@ ssh-based ping: measure character-echo latency and bandwidth for an interactive
## Description

Use this utility to test the performance of interactive ssh sessions
or scp file transfers. It uses ssh to log into a remote system, then
or SFTP file transfers. It uses ssh to log into a remote system, then
runs two tests: the first test sends one character at a time, waiting
for each character to be returned while it records the latency time
for each. The second test sends a dummy file over scp to /dev/null
on the remote system.
for each. The second test writes and reads back a dummy file over SFTP
at a target file on the remote system.

For the echo test, you may specify a character count limit (-c) or a test
time limit (-t), and also the command (-e) used on the remote system that
Expand Down Expand Up @@ -147,4 +147,3 @@ Or you can directly install on the current system with:
sudo make install

Enjoy!

4 changes: 2 additions & 2 deletions doc/sshping.pod
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Expand Up @@ -74,7 +74,7 @@ Short and long forms of options take the same arguments as shown.
Run these tests e=echo s=speed; default es=both

-s, --size MB
For transfer speed test (the scp test), send/receive MB
For transfer speed test (the SFTP test), send/receive MB
megabytes; default=8 MB

-t, --time SECS
Expand Down Expand Up @@ -147,7 +147,7 @@ Echo-Count

The file transfer I<speed test> measures the upload and
download throughput rate, in bytes per second (Bps),
using the scp subsystem. This is the subsystem typically used
using the SFTP subsystem. This is a subsystem commonly used
when copying files over ssh.

For the upload test, a random 1MB file is copied to
Expand Down
209 changes: 144 additions & 65 deletions src/sshping.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -33,9 +33,11 @@
#endif

#include <algorithm>
#include <fcntl.h>
#include <inttypes.h>
#include <iostream>
#include <libssh/libssh.h>
#include <libssh/sftp.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
Expand Down Expand Up @@ -739,6 +741,73 @@ int run_echo_test(ssh_channel & chn) {
return SSH_OK;
}

// Start an SFTP session on the existing SSH connection
sftp_session begin_sftp_session(ssh_session ses) {
sftp_session sftp = sftp_new(ses);
if (sftp == NULL) {
fprintf(stderr, "*** Cannot allocate SFTP session: %s\n", ssh_get_error(ses));
return NULL;
}

int rc = sftp_init(sftp);
if (rc != SSH_OK) {
fprintf(stderr, "*** Cannot init SFTP session: %s (SFTP error %d)\n",
ssh_get_error(ses),
sftp_get_error(sftp));
sftp_free(sftp);
return NULL;
}
return sftp;
}

// Write exactly len bytes unless SFTP reports an error
int sftp_write_all(ssh_session ses,
sftp_session sftp,
sftp_file file,
const char* buf,
size_t len) {
size_t written = 0;
while (written < len) {
ssize_t nbytes = sftp_write(file, buf + written, len - written);
if (nbytes < 0) {
fprintf(stderr, "*** Can't write to remote file: %s (SFTP error %d)\n",
ssh_get_error(ses),
sftp_get_error(sftp));
return SSH_ERROR;
}
if (nbytes == 0) {
fprintf(stderr, "*** SFTP write made no progress\n");
return SSH_ERROR;
}
written += nbytes;
}
return SSH_OK;
}

// Read exactly len bytes unless SFTP reports an error or early EOF
int sftp_read_all(ssh_session ses,
sftp_session sftp,
sftp_file file,
char* buf,
size_t len) {
size_t read = 0;
while (read < len) {
ssize_t nbytes = sftp_read(file, buf + read, len - read);
if (nbytes < 0) {
fprintf(stderr, "*** Failed read on file download: %s (SFTP error %d)\n",
ssh_get_error(ses),
sftp_get_error(sftp));
return SSH_ERROR;
}
if (nbytes == 0) {
fprintf(stderr, "*** Remote file ended before expected download size\n");
return SSH_ERROR;
}
read += nbytes;
}
return SSH_OK;
}

// Run an upload speed test
int run_upload_test(ssh_session ses) {

Expand All @@ -748,48 +817,51 @@ int run_upload_test(ssh_session ses) {
}
printf("Upload-Size: %17s\n", fmtnum(size * MEGA, 0, "B").c_str());

ssh_scp scp = ssh_scp_new(ses, SSH_SCP_WRITE, remfile);
if (scp == NULL) {
fprintf(stderr, "*** Cannot allocate scp context: %s\n", ssh_get_error(ses));
sftp_session sftp = begin_sftp_session(ses);
if (sftp == NULL) {
return SSH_ERROR;
}

int rc = ssh_scp_init(scp);
if (rc != SSH_OK) {
fprintf(stderr, "*** Cannot init scp context: %s\n", ssh_get_error(ses));
ssh_scp_free(scp);
return rc;
}

uint64_t t2 = get_time();

#ifdef _WIN32
const int mode = 448;
#else
const int mode = S_IRWXU;
#endif
char* buf = new char[MEGA];
srand(getpid());
for (size_t i=0; i < sizeof(buf); i++) {
for (size_t i=0; i < MEGA; i++) {
buf[i] = (rand() & 0x3f) + 32;
}
uint64_t t2 = get_time();

for (int i=0; i < size; i++) {
rc = ssh_scp_push_file(scp, remfile, MEGA, mode);
if (rc != SSH_OK) {
fprintf(stderr, "*** Can't open remote file: %s\n", ssh_get_error(ses));
sftp_file file = sftp_open(sftp, remfile, O_WRONLY | O_CREAT | O_TRUNC, mode);
if (file == NULL) {
fprintf(stderr, "*** Can't open remote file for upload: %s (SFTP error %d)\n",
ssh_get_error(ses),
sftp_get_error(sftp));
sftp_free(sftp);
delete[] buf;
return rc;
return SSH_ERROR;
}

rc = ssh_scp_write(scp, buf, MEGA);
int rc = sftp_write_all(ses, sftp, file, buf, MEGA);
int close_rc = sftp_close(file);
if (rc != SSH_OK) {
fprintf(stderr, "*** Can't write to remote file: %s\n", ssh_get_error(ses));
sftp_free(sftp);
delete[] buf;
return rc;
}
if (close_rc != SSH_OK) {
fprintf(stderr, "*** Can't close remote upload file: %s (SFTP error %d)\n",
ssh_get_error(ses),
sftp_get_error(sftp));
sftp_free(sftp);
delete[] buf;
return close_rc;
}
}
ssh_scp_close(scp);
ssh_scp_free(scp);
sftp_free(sftp);

uint64_t t3 = get_time();
double duration = double(nsec_diff(t3, t2)) / GIGAF;
Expand Down Expand Up @@ -818,65 +890,72 @@ int run_download_test(ssh_session ses) {
size_t avail = 0;
size_t remaining = size * MEGA;

sftp_session sftp = begin_sftp_session(ses);
if (sftp == NULL) {
delete[] buf;
return SSH_ERROR;
}

uint64_t t2 = get_time();
sftp_attributes attrs = sftp_stat(sftp, remfile);
if (attrs == NULL) {
fprintf(stderr, "*** Cannot stat download file: %s (SFTP error %d)\n",
ssh_get_error(ses),
sftp_get_error(sftp));
sftp_free(sftp);
delete[] buf;
return SSH_ERROR;
}
avail = attrs->size;
sftp_attributes_free(attrs);

if (verbosity) {
printf("+++ Available size of download: %lu Bytes\n", (unsigned long)avail);
if (remaining > avail) {
printf(" + (Will repeat download as needed)\n");
}
}
if (!avail) {
fprintf(stderr, "*** Remote file size must be non-zero\n");
sftp_free(sftp);
delete[] buf;
return SSH_ERROR;
}

while (remaining) {
ssh_scp scp = ssh_scp_new(ses, SSH_SCP_READ, remfile);
if (scp == NULL) {
fprintf(stderr, "*** Cannot allocate scp context: %s\n", ssh_get_error(ses));
size_t amount = avail;
if (amount > remaining) amount = remaining;
if (amount > DLBUF_SIZE) amount = DLBUF_SIZE;

sftp_file file = sftp_open(sftp, remfile, O_RDONLY, 0);
if (file == NULL) {
fprintf(stderr, "*** Can't open remote file for download: %s (SFTP error %d)\n",
ssh_get_error(ses),
sftp_get_error(sftp));
sftp_free(sftp);
delete[] buf;
return SSH_ERROR;
}

int rc = ssh_scp_init(scp);
int rc = sftp_read_all(ses, sftp, file, buf, amount);
int close_rc = sftp_close(file);
if (rc != SSH_OK) {
fprintf(stderr, "*** Cannot init scp context: %s\n", ssh_get_error(ses));
ssh_scp_free(scp);
sftp_free(sftp);
delete[] buf;
return rc;
}

rc = ssh_scp_pull_request(scp);
if (rc != SSH_SCP_REQUEST_NEWFILE) {
fprintf(stderr, "*** Cannot request download file - got %d: %s\n", rc, ssh_get_error(ses));
ssh_scp_close(scp);
ssh_scp_free(scp);
if (close_rc != SSH_OK) {
fprintf(stderr, "*** Can't close remote download file: %s (SFTP error %d)\n",
ssh_get_error(ses),
sftp_get_error(sftp));
sftp_free(sftp);
delete[] buf;
return rc;
}

if (!avail) {
avail = ssh_scp_request_get_size(scp);
if (verbosity) {
printf("+++ Available size of download: %lu Bytes\n", avail);
if (remaining > avail) {
printf(" + (Will repeat download as needed)\n");
}
}
if (!avail) {
fprintf(stderr, "*** Remote file size must be non-zero\n");
ssh_scp_close(scp);
ssh_scp_free(scp);
delete[] buf;
return rc;
}
}
size_t amount = avail;
if (amount > remaining) amount = remaining;
if (amount > DLBUF_SIZE) amount = DLBUF_SIZE;
ssh_scp_accept_request(scp);
rc = ssh_scp_read(scp, buf, amount);
if (rc == SSH_ERROR) {
fprintf(stderr, "*** Failed read on file download: %s\n", ssh_get_error(ses));
ssh_scp_close(scp);
ssh_scp_free(scp);
delete[] buf;
return rc;
return close_rc;
}

remaining -= amount;
ssh_scp_close(scp);
ssh_scp_free(scp);
}
sftp_free(sftp);

uint64_t t3 = get_time();
double duration = double(nsec_diff(t3, t2)) / GIGAF;
Expand Down