support for "cross"-loading files/directories, i.e. downloading

from one SFTP server while simultaneously uploading to another.

feedback & ok markus@

2 files changed, 442 insertions, 2 deletions

diff --git a/usr.bin/ssh/sftp-client.c b/usr.bin/ssh/sftp-client.c
index a3dc88d4a9d..ac04489d9d2 100644
--- a/usr.bin/ssh/sftp-client.c
+++ b/usr.bin/ssh/sftp-client.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sftp-client.c,v 1.144 2021/08/07 00:01:29 djm Exp $ */
+/* $OpenBSD: sftp-client.c,v 1.145 2021/08/07 00:02:41 djm Exp $ */
 /*
  * Copyright (c) 2001-2004 Damien Miller <djm@openbsd.org>
  *
@@ -2029,6 +2029,429 @@ upload_dir(struct sftp_conn *conn, const char *src, const char *dst,
 	return ret;
 }
 
+static void
+handle_dest_replies(struct sftp_conn *to, const char *to_path, int synchronous,
+    u_int *nreqsp, u_int *write_errorp)
+{
+	struct sshbuf *msg;
+	u_char type;
+	u_int id, status;
+	int r;
+	struct pollfd pfd;
+
+	if ((msg = sshbuf_new()) == NULL)
+		fatal_f("sshbuf_new failed");
+
+	/* Try to eat replies from the upload side */
+	while (*nreqsp > 0) {
+		debug3_f("%u outstanding replies", *nreqsp);
+		if (!synchronous) {
+			/* Bail out if no data is ready to be read */
+			pfd.fd = to->fd_in;
+			pfd.events = POLLIN;
+			if ((r = poll(&pfd, 1, 0)) == -1) {
+				if (errno == EINTR)
+					break;
+				fatal_f("poll: %s", strerror(errno));
+			} else if (r == 0)
+				break; /* fd not ready */
+		}
+		sshbuf_reset(msg);
+		get_msg(to, msg);
+
+		if ((r = sshbuf_get_u8(msg, &type)) != 0 ||
+		    (r = sshbuf_get_u32(msg, &id)) != 0)
+			fatal_fr(r, "dest parse");
+		debug3("Received dest reply T:%u I:%u R:%u", type, id, *nreqsp);
+		if (type != SSH2_FXP_STATUS) {
+			fatal_f("Expected SSH2_FXP_STATUS(%d) packet, got %d",
+			    SSH2_FXP_STATUS, type);
+		}
+		if ((r = sshbuf_get_u32(msg, &status)) != 0)
+			fatal_fr(r, "parse dest status");
+		debug3("dest SSH2_FXP_STATUS %u", status);
+		if (status != SSH2_FX_OK) {
+			/* record first error */
+			if (*write_errorp == 0)
+				*write_errorp = status;
+		}
+		/*
+		 * XXX this doesn't do full reply matching like do_upload and
+		 * so cannot gracefully truncate terminated uploads at a
+		 * high-water mark. ATM the only caller of this function (scp)
+		 * doesn't support transfer resumption, so this doesn't matter
+		 * a whole lot.
+		 *
+		 * To be safe, do_crossload truncates the destination file to
+		 * zero length on upload failure, since we can't trust the
+		 * server not to have reordered replies that could have
+		 * inserted holes where none existed in the source file.
+		 *
+		 * XXX we could get a more accutate progress bar if we updated
+		 * the counter based on the reply from the destination...
+		 */
+		(*nreqsp)--;
+	}
+	debug3_f("done: %u outstanding replies", *nreqsp);
+}
+
+int
+do_crossload(struct sftp_conn *from, struct sftp_conn *to,
+    const char *from_path, const char *to_path,
+    Attrib *a, int preserve_flag)
+{
+	struct sshbuf *msg;
+	int write_error, read_error, lmodified = 0, r;
+	u_int64_t offset = 0, size;
+	u_int id, buflen, num_req, max_req, status = SSH2_FX_OK;
+	u_int num_upload_req;
+	off_t progress_counter;
+	u_char *from_handle, *to_handle;
+	size_t from_handle_len, to_handle_len;
+	struct request {
+		u_int id;
+		size_t len;
+		u_int64_t offset;
+		TAILQ_ENTRY(request) tq;
+	};
+	TAILQ_HEAD(reqhead, request) requests;
+	struct request *req;
+	u_char type;
+
+	TAILQ_INIT(&requests);
+
+	if (a == NULL && (a = do_stat(from, from_path, 0)) == NULL)
+		return -1;
+
+	if ((a->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) &&
+	    (!S_ISREG(a->perm))) {
+		error("Cannot download non-regular file: %s", from_path);
+		return(-1);
+	}
+	if (a->flags & SSH2_FILEXFER_ATTR_SIZE)
+		size = a->size;
+	else
+		size = 0;
+
+	buflen = from->download_buflen;
+	if (buflen > to->upload_buflen)
+		buflen = to->upload_buflen;
+
+	/* Send open request to read side */
+	if (send_open(from, from_path, "origin", SSH2_FXF_READ, NULL,
+	    &from_handle, &from_handle_len) != 0)
+		return -1;
+
+	/* Send open request to write side */
+	a->flags &= ~SSH2_FILEXFER_ATTR_SIZE;
+	a->flags &= ~SSH2_FILEXFER_ATTR_UIDGID;
+	a->perm &= 0777;
+	if (!preserve_flag)
+		a->flags &= ~SSH2_FILEXFER_ATTR_ACMODTIME;
+	if (send_open(to, to_path, "dest",
+	    SSH2_FXF_WRITE|SSH2_FXF_CREAT|SSH2_FXF_TRUNC, a,
+	    &to_handle, &to_handle_len) != 0) {
+		do_close(from, from_handle, from_handle_len);
+		return -1;
+	}
+
+	/* Read from remote "from" and write to remote "to" */
+	offset = 0;
+	write_error = read_error = num_req = num_upload_req = 0;
+	max_req = 1;
+	progress_counter = 0;
+
+	if (showprogress && size != 0)
+		start_progress_meter(from_path, size, &progress_counter);
+	if ((msg = sshbuf_new()) == NULL)
+		fatal_f("sshbuf_new failed");
+	while (num_req > 0 || max_req > 0) {
+		u_char *data;
+		size_t len;
+
+		/*
+		 * Simulate EOF on interrupt: stop sending new requests and
+		 * allow outstanding requests to drain gracefully
+		 */
+		if (interrupted) {
+			if (num_req == 0) /* If we haven't started yet... */
+				break;
+			max_req = 0;
+		}
+
+		/* Send some more requests */
+		while (num_req < max_req) {
+			debug3("Request range %llu -> %llu (%d/%d)",
+			    (unsigned long long)offset,
+			    (unsigned long long)offset + buflen - 1,
+			    num_req, max_req);
+			req = xcalloc(1, sizeof(*req));
+			req->id = from->msg_id++;
+			req->len = buflen;
+			req->offset = offset;
+			offset += buflen;
+			num_req++;
+			TAILQ_INSERT_TAIL(&requests, req, tq);
+			send_read_request(from, req->id, req->offset,
+			    req->len, from_handle, from_handle_len);
+		}
+
+		/* Try to eat replies from the upload side (nonblocking) */
+		handle_dest_replies(to, to_path, 0,
+		    &num_upload_req, &write_error);
+
+		sshbuf_reset(msg);
+		get_msg(from, msg);
+		if ((r = sshbuf_get_u8(msg, &type)) != 0 ||
+		    (r = sshbuf_get_u32(msg, &id)) != 0)
+			fatal_fr(r, "parse");
+		debug3("Received origin reply T:%u I:%u R:%d",
+		    type, id, max_req);
+
+		/* Find the request in our queue */
+		for (req = TAILQ_FIRST(&requests);
+		    req != NULL && req->id != id;
+		    req = TAILQ_NEXT(req, tq))
+			;
+		if (req == NULL)
+			fatal("Unexpected reply %u", id);
+
+		switch (type) {
+		case SSH2_FXP_STATUS:
+			if ((r = sshbuf_get_u32(msg, &status)) != 0)
+				fatal_fr(r, "parse status");
+			if (status != SSH2_FX_EOF)
+				read_error = 1;
+			max_req = 0;
+			TAILQ_REMOVE(&requests, req, tq);
+			free(req);
+			num_req--;
+			break;
+		case SSH2_FXP_DATA:
+			if ((r = sshbuf_get_string(msg, &data, &len)) != 0)
+				fatal_fr(r, "parse data");
+			debug3("Received data %llu -> %llu",
+			    (unsigned long long)req->offset,
+			    (unsigned long long)req->offset + len - 1);
+			if (len > req->len)
+				fatal("Received more data than asked for "
+				    "%zu > %zu", len, req->len);
+			lmodified = 1;
+
+			/* Write this chunk out to the destination */
+			sshbuf_reset(msg);
+			if ((r = sshbuf_put_u8(msg, SSH2_FXP_WRITE)) != 0 ||
+			    (r = sshbuf_put_u32(msg, to->msg_id++)) != 0 ||
+			    (r = sshbuf_put_string(msg, to_handle,
+			    to_handle_len)) != 0 ||
+			    (r = sshbuf_put_u64(msg, req->offset)) != 0 ||
+			    (r = sshbuf_put_string(msg, data, len)) != 0)
+				fatal_fr(r, "compose write");
+			send_msg(to, msg);
+			debug3("Sent message SSH2_FXP_WRITE I:%u O:%llu S:%zu",
+			    id, (unsigned long long)offset, len);
+			num_upload_req++;
+			progress_counter += len;
+			free(data);
+
+			if (len == req->len) {
+				TAILQ_REMOVE(&requests, req, tq);
+				free(req);
+				num_req--;
+			} else {
+				/* Resend the request for the missing data */
+				debug3("Short data block, re-requesting "
+				    "%llu -> %llu (%2d)",
+				    (unsigned long long)req->offset + len,
+				    (unsigned long long)req->offset +
+				    req->len - 1, num_req);
+				req->id = from->msg_id++;
+				req->len -= len;
+				req->offset += len;
+				send_read_request(from, req->id,
+				    req->offset, req->len,
+				    from_handle, from_handle_len);
+				/* Reduce the request size */
+				if (len < buflen)
+					buflen = MAXIMUM(MIN_READ_SIZE, len);
+			}
+			if (max_req > 0) { /* max_req = 0 iff EOF received */
+				if (size > 0 && offset > size) {
+					/* Only one request at a time
+					 * after the expected EOF */
+					debug3("Finish at %llu (%2d)",
+					    (unsigned long long)offset,
+					    num_req);
+					max_req = 1;
+				} else if (max_req < from->num_requests) {
+					++max_req;
+				}
+			}
+			break;
+		default:
+			fatal("Expected SSH2_FXP_DATA(%u) packet, got %u",
+			    SSH2_FXP_DATA, type);
+		}
+	}
+
+	if (showprogress && size)
+		stop_progress_meter();
+
+	/* Drain replies from the server (blocking) */
+	debug3_f("waiting for %u replies from destination", num_upload_req);
+	handle_dest_replies(to, to_path, 1, &num_upload_req, &write_error);
+
+	/* Sanity check */
+	if (TAILQ_FIRST(&requests) != NULL)
+		fatal("Transfer complete, but requests still in queue");
+	/* Truncate at 0 length on interrupt or error to avoid holes at dest */
+	if (read_error || write_error || interrupted) {
+		debug("truncating \"%s\" at 0", to_path);
+		do_close(to, to_handle, to_handle_len);
+		free(to_handle);
+		if (send_open(to, to_path, "dest",
+		    SSH2_FXF_WRITE|SSH2_FXF_CREAT|SSH2_FXF_TRUNC, a,
+		    &to_handle, &to_handle_len) != 0) {
+			error("truncation failed for \"%s\"", to_path);
+			to_handle = NULL;
+		}
+	}
+	if (read_error) {
+		error("Couldn't read from origin file \"%s\" : %s",
+		    from_path, fx2txt(status));
+		status = -1;
+		do_close(from, from_handle, from_handle_len);
+		if (to_handle != NULL)
+			do_close(to, to_handle, to_handle_len);
+	} else if (write_error) {
+		error("Couldn't write to \"%s\": %s",
+		    to_path, fx2txt(write_error));
+		status = SSH2_FX_FAILURE;
+		do_close(from, from_handle, from_handle_len);
+		if (to_handle != NULL)
+			do_close(to, to_handle, to_handle_len);
+	} else {
+		if (do_close(from, from_handle, from_handle_len) != 0 ||
+		    interrupted)
+			status = -1;
+		else
+			status = SSH2_FX_OK;
+		if (to_handle != NULL) {
+			/* Need to resend utimes after write */
+			if (preserve_flag)
+				do_fsetstat(to, to_handle, to_handle_len, a);
+			do_close(to, to_handle, to_handle_len);
+		}
+	}
+	sshbuf_free(msg);
+	free(from_handle);
+	free(to_handle);
+
+	return status == SSH2_FX_OK ? 0 : -1;
+}
+
+static int
+crossload_dir_internal(struct sftp_conn *from, struct sftp_conn *to,
+    const char *from_path, const char *to_path,
+    int depth, Attrib *dirattrib, int preserve_flag, int print_flag)
+{
+	int i, ret = 0;
+	SFTP_DIRENT **dir_entries;
+	char *filename, *new_from_path = NULL, *new_to_path = NULL;
+	mode_t mode = 0777;
+
+	if (depth >= MAX_DIR_DEPTH) {
+		error("Maximum directory depth exceeded: %d levels", depth);
+		return -1;
+	}
+
+	if (dirattrib == NULL &&
+	    (dirattrib = do_stat(from, from_path, 1)) == NULL) {
+		error("Unable to stat remote directory \"%s\"", from_path);
+		return -1;
+	}
+	if (!S_ISDIR(dirattrib->perm)) {
+		error("\"%s\" is not a directory", from_path);
+		return -1;
+	}
+	if (print_flag)
+		mprintf("Retrieving %s\n", from_path);
+
+	dirattrib->flags &= ~SSH2_FILEXFER_ATTR_SIZE;
+	dirattrib->flags &= ~SSH2_FILEXFER_ATTR_UIDGID;
+	if (dirattrib->flags & SSH2_FILEXFER_ATTR_PERMISSIONS) {
+		mode = dirattrib->perm & 01777;
+		dirattrib->perm = mode | (S_IWUSR|S_IXUSR); /* temp */
+	} else {
+		debug("Server did not send permissions for "
+		    "directory \"%s\"", to_path);
+	}
+	if (do_mkdir(to, to_path, dirattrib, print_flag) != 0)
+		return -1;
+
+	if (do_readdir(from, from_path, &dir_entries) == -1) {
+		error("%s: Failed to get directory contents", from_path);
+		return -1;
+	}
+
+	for (i = 0; dir_entries[i] != NULL && !interrupted; i++) {
+		free(new_from_path);
+		free(new_to_path);
+
+		filename = dir_entries[i]->filename;
+		new_from_path = path_append(from_path, filename);
+		new_to_path = path_append(to_path, filename);
+
+		if (S_ISDIR(dir_entries[i]->a.perm)) {
+			if (strcmp(filename, ".") == 0 ||
+			    strcmp(filename, "..") == 0)
+				continue;
+			if (crossload_dir_internal(from, to,
+			    new_from_path, new_to_path,
+			    depth + 1, &(dir_entries[i]->a), preserve_flag,
+			    print_flag) == -1)
+				ret = -1;
+		} else if (S_ISREG(dir_entries[i]->a.perm) ) {
+			if (do_crossload(from, to, new_from_path, new_to_path,
+			    &(dir_entries[i]->a), preserve_flag) == -1) {
+				error("Transfer of file %s to %s failed",
+				    new_from_path, new_to_path);
+				ret = -1;
+			}
+		} else
+			logit("%s: not a regular file\n", new_from_path);
+
+	}
+	free(new_to_path);
+	free(new_from_path);
+
+	dirattrib->perm = mode; /* original mode */
+	do_setstat(to, to_path, dirattrib);
+
+	free_sftp_dirents(dir_entries);
+
+	return ret;
+}
+
+int
+crossload_dir(struct sftp_conn *from, struct sftp_conn *to,
+    const char *from_path, const char *to_path,
+    Attrib *dirattrib, int preserve_flag, int print_flag)
+{
+	char *from_path_canon;
+	int ret;
+
+	if ((from_path_canon = do_realpath(from, from_path)) == NULL) {
+		error("Unable to canonicalize path \"%s\"", from_path);
+		return -1;
+	}
+
+	ret = crossload_dir_internal(from, to, from_path_canon, to_path, 0,
+	    dirattrib, preserve_flag, print_flag);
+	free(from_path_canon);
+	return ret;
+}
+
 char *
 path_append(const char *p1, const char *p2)
 {
diff --git a/usr.bin/ssh/sftp-client.h b/usr.bin/ssh/sftp-client.h
index 5dc6b782bd3..5b94d86a2f2 100644
--- a/usr.bin/ssh/sftp-client.h
+++ b/usr.bin/ssh/sftp-client.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: sftp-client.h,v 1.30 2021/03/31 22:16:34 djm Exp $ */
+/* $OpenBSD: sftp-client.h,v 1.31 2021/08/07 00:02:41 djm Exp $ */
 
 /*
  * Copyright (c) 2001-2004 Damien Miller <djm@openbsd.org>
@@ -144,6 +144,23 @@ int do_upload(struct sftp_conn *, const char *, const char *, int, int, int);
 int upload_dir(struct sftp_conn *, const char *, const char *, int, int, int,
     int);
 
+/*
+ * Download a 'from_path' from the 'from' connection and upload it to
+ * to 'to' connection at 'to_path'.
+ */
+int
+do_crossload(struct sftp_conn *from, struct sftp_conn *to,
+    const char *from_path, const char *to_path,
+    Attrib *a, int preserve_flag);
+
+/*
+ * Recursively download a directory from 'from_path' from the 'from'
+ * connection and upload it to 'to' connection at 'to_path'.
+ */
+int crossload_dir(struct sftp_conn *from, struct sftp_conn *to,
+    const char *from_path, const char *to_path,
+    Attrib *dirattrib, int preserve_flag, int print_flag);
+
 /* Concatenate paths, taking care of slashes. Caller must free result. */
 char *path_append(const char *, const char *);