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libssh2/example/sftp_RW_nonblock.c
Viktor Szakats 854cfa8292
build: prepare builds for clang-cl, add cmake ossfuzz support 
- cmake: add support to build ossfuzz.
  Enable with `-DBUILD_OSSFUZZ=ON`.
  Also supports `-DLIB_FUZZING_ENGINE=` like autotools does.
- check for `__clang__` when suppressing warnings in source. Necessary
  for clang-cl, which set `__clang__`, but doesn't set `__GNU__`.
- cmake: optimize out 4 picky warning option detections with gcc.
- cmake: bring `-pedantic-error`, `-Wall` use closer to curl's.
- cmake: set `-Wno-language-extension-token` for clang-cl.
- cmake: escape only the necessary `-W` options for clang-cl.
- cmake: apply picky warnings to C++.
- cmake: replace `unset(VAR)` with `set(VAR "")` for init.
- cmake: prefer dash-style MSVC options.
- cmake: simplify `MATCHES` expression.
- cmake: formatting/whitespace.
- ci/GHA: bump `actions/upload-artifact` to v4

Closes #1524
2025-01-30 22:01:49 +01:00

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/* Copyright (C) The libssh2 project and its contributors.
*
* Sample showing how to do SFTP transfers in a non-blocking manner.
*
* It will first download a given source file, store it locally and then
* upload the file again to a given destination file.
*
* Using the SFTP server running on 127.0.0.1
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include "libssh2_setup.h"
#include <libssh2.h>
#include <libssh2_sftp.h>
#ifdef _WIN32
#define write(f, b, c) write((f), (b), (unsigned int)(c))
#endif
#ifdef HAVE_SYS_SOCKET_H
#include <sys/socket.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#ifdef HAVE_SYS_TIME_H
#include <sys/time.h>
#endif
#include <stdio.h>
static const char *pubkey = "/home/username/.ssh/id_rsa.pub";
static const char *privkey = "/home/username/.ssh/id_rsa";
static const char *username = "username";
static const char *password = "password";
static const char *sftppath = "/tmp/TEST"; /* source path */
static const char *dest = "/tmp/TEST2"; /* destination path */
static const char *storage = "/tmp/sftp-storage"; /* local file name to store
the downloaded file in */
static int waitsocket(libssh2_socket_t socket_fd, LIBSSH2_SESSION *session)
{
struct timeval timeout;
int rc;
fd_set fd;
fd_set *writefd = NULL;
fd_set *readfd = NULL;
int dir;
timeout.tv_sec = 10;
timeout.tv_usec = 0;
FD_ZERO(&fd);
#if defined(__GNUC__) || defined(__clang__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wsign-conversion"
#endif
FD_SET(socket_fd, &fd);
#if defined(__GNUC__) || defined(__clang__)
#pragma GCC diagnostic pop
#endif
/* now make sure we wait in the correct direction */
dir = libssh2_session_block_directions(session);
if(dir & LIBSSH2_SESSION_BLOCK_INBOUND)
readfd = &fd;
if(dir & LIBSSH2_SESSION_BLOCK_OUTBOUND)
writefd = &fd;
rc = select((int)(socket_fd + 1), readfd, writefd, NULL, &timeout);
return rc;
}
int main(int argc, char *argv[])
{
libssh2_socket_t sock;
int i, auth_pw = 1;
struct sockaddr_in sin;
const char *fingerprint;
int rc;
LIBSSH2_SESSION *session = NULL;
LIBSSH2_SFTP *sftp_session;
LIBSSH2_SFTP_HANDLE *sftp_handle;
FILE *tempstorage = NULL;
char mem[1000];
struct timeval timeout;
fd_set fd;
fd_set fd2;
#ifdef _WIN32
WSADATA wsadata;
rc = WSAStartup(MAKEWORD(2, 0), &wsadata);
if(rc) {
fprintf(stderr, "WSAStartup failed with error: %d\n", rc);
return 1;
}
#endif
if(argc > 1) {
username = argv[1];
}
if(argc > 2) {
password = argv[2];
}
if(argc > 3) {
sftppath = argv[3];
}
if(argc > 4) {
dest = argv[4];
}
rc = libssh2_init(0);
if(rc) {
fprintf(stderr, "libssh2 initialization failed (%d)\n", rc);
return 1;
}
/* Ultra basic "connect to port 22 on localhost". Your code is
* responsible for creating the socket establishing the connection
*/
sock = socket(AF_INET, SOCK_STREAM, 0);
if(sock == LIBSSH2_INVALID_SOCKET) {
fprintf(stderr, "failed to create socket.\n");
goto shutdown;
}
sin.sin_family = AF_INET;
sin.sin_port = htons(22);
sin.sin_addr.s_addr = htonl(0x7F000001);
if(connect(sock, (struct sockaddr*)(&sin), sizeof(struct sockaddr_in))) {
fprintf(stderr, "failed to connect.\n");
goto shutdown;
}
/* Create a session instance */
session = libssh2_session_init();
if(!session) {
fprintf(stderr, "Could not initialize SSH session.\n");
goto shutdown;
}
/* ... start it up. This will trade welcome banners, exchange keys,
* and setup crypto, compression, and MAC layers
*/
rc = libssh2_session_handshake(session, sock);
if(rc) {
fprintf(stderr, "Failure establishing SSH session: %d\n", rc);
goto shutdown;
}
libssh2_session_set_blocking(session, 0);
/* At this point we have not yet authenticated. The first thing to do
* is check the hostkey's fingerprint against our known hosts Your app
* may have it hard coded, may go to a file, may present it to the
* user, that's your call
*/
fingerprint = libssh2_hostkey_hash(session, LIBSSH2_HOSTKEY_HASH_SHA1);
fprintf(stderr, "Fingerprint: ");
for(i = 0; i < 20; i++) {
fprintf(stderr, "%02X ", (unsigned char)fingerprint[i]);
}
fprintf(stderr, "\n");
tempstorage = fopen(storage, "wb");
if(!tempstorage) {
fprintf(stderr, "Cannot open temp storage file %s\n", storage);
goto shutdown;
}
if(auth_pw) {
/* We could authenticate via password */
while((rc = libssh2_userauth_password(session, username, password)) ==
LIBSSH2_ERROR_EAGAIN);
if(rc) {
fprintf(stderr, "Authentication by password failed.\n");
goto shutdown;
}
}
else {
/* Or by public key */
while((rc =
libssh2_userauth_publickey_fromfile(session, username,
pubkey, privkey,
password)) ==
LIBSSH2_ERROR_EAGAIN);
if(rc) {
fprintf(stderr, "Authentication by public key failed.\n");
goto shutdown;
}
}
do {
sftp_session = libssh2_sftp_init(session);
if(!sftp_session) {
if(libssh2_session_last_errno(session) == LIBSSH2_ERROR_EAGAIN) {
fprintf(stderr, "non-blocking init\n");
waitsocket(sock, session); /* now we wait */
}
else {
fprintf(stderr, "Unable to init SFTP session\n");
goto shutdown;
}
}
} while(!sftp_session);
/* Request a file via SFTP */
do {
sftp_handle = libssh2_sftp_open(sftp_session, sftppath,
LIBSSH2_FXF_READ, 0);
if(!sftp_handle) {
if(libssh2_session_last_errno(session) != LIBSSH2_ERROR_EAGAIN) {
fprintf(stderr, "Unable to open file with SFTP: %ld\n",
libssh2_sftp_last_error(sftp_session));
goto shutdown;
}
else {
fprintf(stderr, "non-blocking open\n");
waitsocket(sock, session); /* now we wait */
}
}
} while(!sftp_handle);
fprintf(stderr, "libssh2_sftp_open() is done, now receive data.\n");
do {
ssize_t nread;
do {
/* read in a loop until we block */
nread = libssh2_sftp_read(sftp_handle, mem, sizeof(mem));
fprintf(stderr, "libssh2_sftp_read returned %ld\n",
(long)nread);
if(nread > 0) {
/* write to stderr */
write(2, mem, (size_t)nread);
/* write to temporary storage area */
fwrite(mem, (size_t)nread, 1, tempstorage);
}
} while(nread > 0);
if(nread != LIBSSH2_ERROR_EAGAIN) {
/* error or end of file */
break;
}
timeout.tv_sec = 10;
timeout.tv_usec = 0;
FD_ZERO(&fd);
FD_ZERO(&fd2);
#if defined(__GNUC__) || defined(__clang__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wsign-conversion"
#endif
FD_SET(sock, &fd);
FD_SET(sock, &fd2);
#if defined(__GNUC__) || defined(__clang__)
#pragma GCC diagnostic pop
#endif
/* wait for readable or writeable */
rc = select((int)(sock + 1), &fd, &fd2, NULL, &timeout);
if(rc <= 0) {
/* negative is error
0 is timeout */
fprintf(stderr, "SFTP download timed out: %d\n", rc);
break;
}
} while(1);
libssh2_sftp_close(sftp_handle);
fclose(tempstorage);
tempstorage = fopen(storage, "rb");
if(!tempstorage) {
/* weird, we cannot read the file we just wrote to... */
fprintf(stderr, "Cannot open %s for reading\n", storage);
goto shutdown;
}
/* we're done downloading, now reverse the process and upload the
temporarily stored data to the destination path */
sftp_handle = libssh2_sftp_open(sftp_session, dest,
LIBSSH2_FXF_WRITE |
LIBSSH2_FXF_CREAT,
LIBSSH2_SFTP_S_IRUSR |
LIBSSH2_SFTP_S_IWUSR |
LIBSSH2_SFTP_S_IRGRP |
LIBSSH2_SFTP_S_IROTH);
if(sftp_handle) {
size_t nread;
char *ptr;
do {
ssize_t nwritten;
nread = fread(mem, 1, sizeof(mem), tempstorage);
if(nread <= 0) {
/* end of file */
break;
}
ptr = mem;
do {
/* write data in a loop until we block */
nwritten = libssh2_sftp_write(sftp_handle, ptr,
nread);
if(nwritten < 0)
break;
ptr += nwritten;
nread -= (size_t)nwritten;
} while(nwritten >= 0);
if(nwritten != LIBSSH2_ERROR_EAGAIN) {
/* error or end of file */
break;
}
timeout.tv_sec = 10;
timeout.tv_usec = 0;
FD_ZERO(&fd);
FD_ZERO(&fd2);
#if defined(__GNUC__) || defined(__clang__)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wsign-conversion"
#endif
FD_SET(sock, &fd);
FD_SET(sock, &fd2);
#if defined(__GNUC__) || defined(__clang__)
#pragma GCC diagnostic pop
#endif
/* wait for readable or writeable */
rc = select((int)(sock + 1), &fd, &fd2, NULL, &timeout);
if(rc <= 0) {
/* negative is error
0 is timeout */
fprintf(stderr, "SFTP upload timed out: %d\n", rc);
break;
}
} while(1);
fprintf(stderr, "SFTP upload done.\n");
}
else {
fprintf(stderr, "SFTP failed to open destination path: %s\n",
dest);
}
libssh2_sftp_shutdown(sftp_session);
shutdown:
if(session) {
libssh2_session_disconnect(session, "Normal Shutdown");
libssh2_session_free(session);
}
if(sock != LIBSSH2_INVALID_SOCKET) {
shutdown(sock, 2);
LIBSSH2_SOCKET_CLOSE(sock);
}
if(tempstorage)
fclose(tempstorage);
fprintf(stderr, "all done\n");
libssh2_exit();
#ifdef _WIN32
WSACleanup();
#endif
return 0;
}
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