[git commit] tftp: on download, open local file only when first bit of data arrived
Denys Vlasenko
vda.linux at googlemail.com
Thu Feb 13 14:27:23 UTC 2020
commit: https://git.busybox.net/busybox/commit/?id=adc540f0dbcd640b37f39364aa4a1c6857a96a96
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master
No reason to potentially clobber existing file before absolutely necessary.
function old new delta
tftp_protocol 1947 2020 +73
tftp_main 393 376 -17
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 1/1 up/down: 73/-17) Total: 56 bytes
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
networking/tftp.c | 61 ++++++++++++++++++++++++++++++-------------------------
1 file changed, 33 insertions(+), 28 deletions(-)
diff --git a/networking/tftp.c b/networking/tftp.c
index 043747d0d..60fdff232 100644
--- a/networking/tftp.c
+++ b/networking/tftp.c
@@ -319,7 +319,7 @@ static int tftp_protocol(
uint16_t opcode;
uint16_t block_nr;
uint16_t recv_blk;
- int open_mode, local_fd;
+ int local_fd = -1;
int retries, waittime_ms;
int io_bufsize = blksize + 4;
char *cp;
@@ -354,19 +354,6 @@ static int tftp_protocol(
}
}
- /* Prepare open mode */
- if (CMD_PUT(option_mask32)) {
- open_mode = O_RDONLY;
- } else {
- open_mode = O_WRONLY | O_TRUNC | O_CREAT;
-#if ENABLE_TFTPD
- if ((option_mask32 & (TFTPD_OPT+TFTPD_OPT_c)) == TFTPD_OPT) {
- /* tftpd without -c */
- open_mode = O_WRONLY | O_TRUNC;
- }
-#endif
- }
-
/* Examples of network traffic.
* Note two cases when ACKs with block# of 0 are sent.
*
@@ -400,6 +387,14 @@ static int tftp_protocol(
if (!ENABLE_TFTP || our_lsa) { /* tftpd */
/* Open file (must be after changing user) */
+ int open_mode = O_RDONLY;
+ if (CMD_GET(option_mask32)) {
+ open_mode = O_WRONLY | O_TRUNC | O_CREAT;
+ if ((option_mask32 & (TFTPD_OPT+TFTPD_OPT_c)) == TFTPD_OPT) {
+ /* tftpd without -c */
+ open_mode = O_WRONLY | O_TRUNC;
+ }
+ }
local_fd = open(local_file, open_mode, 0666);
if (local_fd < 0) {
/* sanitize name, it came from untrusted remote side */
@@ -414,6 +409,7 @@ static int tftp_protocol(
strcpy(G_error_pkt_str, "can't open file");
goto send_err_pkt_nomsg;
}
+
/* gcc 4.3.1 would NOT optimize it out as it should! */
#if ENABLE_FEATURE_TFTP_BLOCKSIZE
if (blksize != TFTP_BLKSIZE_DEFAULT || want_transfer_size) {
@@ -432,10 +428,11 @@ static int tftp_protocol(
block_nr = 0;
}
} else { /* tftp */
- /* Open file (must be after changing user) */
- local_fd = CMD_GET(option_mask32) ? STDOUT_FILENO : STDIN_FILENO;
- if (NOT_LONE_DASH(local_file))
- local_fd = xopen(local_file, open_mode);
+ if (CMD_PUT(option_mask32)) {
+ local_fd = STDIN_FILENO;
+ if (local_file)
+ local_fd = xopen(local_file, O_RDONLY);
+ }
/* Removing #if, or using if() statement instead of #if may lead to
* "warning: null argument where non-null required": */
#if ENABLE_TFTP
@@ -491,7 +488,7 @@ static int tftp_protocol(
}
if (want_transfer_size) {
/* add "tsize", <nul>, size, <nul> (see RFC2349) */
- /* if tftp and downloading, we send "0" (since we opened local_fd with O_TRUNC)
+ /* if tftp and downloading, we send "0" (local_fd is not open yet)
* and this makes server to send "tsize" option with the size */
/* if tftp and uploading, we send file size (maybe dont, to not confuse old servers???) */
/* if tftpd and downloading, we are answering to client's request */
@@ -500,7 +497,8 @@ static int tftp_protocol(
strcpy(cp, "tsize");
cp += sizeof("tsize");
st.st_size = 0;
- fstat(local_fd, &st);
+ if (local_fd >= 0)
+ fstat(local_fd, &st);
cp += sprintf(cp, "%"OFF_FMT"u", (off_t)st.st_size) + 1;
# if ENABLE_FEATURE_TFTP_PROGRESS_BAR
/* Save for progress bar. If 0 (tftp downloading),
@@ -690,7 +688,13 @@ static int tftp_protocol(
if (CMD_GET(option_mask32) && (opcode == TFTP_DATA)) {
if (recv_blk == block_nr) {
- int sz = full_write(local_fd, &rbuf[4], len - 4);
+ int sz;
+ if (local_fd == -1) {
+ local_fd = STDOUT_FILENO;
+ if (local_file)
+ local_fd = xopen(local_file, O_WRONLY | O_TRUNC | O_CREAT);
+ }
+ sz = full_write(local_fd, &rbuf[4], len - 4);
if (sz != len - 4) {
strcpy(G_error_pkt_str, bb_msg_write_error);
G_error_pkt_reason = ERR_WRITE;
@@ -739,7 +743,9 @@ static int tftp_protocol(
free(xbuf);
free(rbuf);
}
- return finished == 0; /* returns 1 on failure */
+ if (!finished)
+ goto err;
+ return EXIT_SUCCESS;
send_read_err_pkt:
strcpy(G_error_pkt_str, bb_msg_read_error);
@@ -750,6 +756,9 @@ static int tftp_protocol(
G.error_pkt[1] = TFTP_ERROR;
xsendto(socket_fd, G.error_pkt, 4 + 1 + strlen(G_error_pkt_str),
&peer_lsa->u.sa, peer_lsa->len);
+ err:
+ if (local_fd >= 0 && CMD_GET(option_mask32) && local_file)
+ unlink(local_file);
return EXIT_FAILURE;
#undef remote_file
}
@@ -767,7 +776,6 @@ int tftp_main(int argc UNUSED_PARAM, char **argv)
# endif
int result;
int port;
- IF_GETPUT(int opt;)
INIT_G();
@@ -808,7 +816,7 @@ int tftp_main(int argc UNUSED_PARAM, char **argv)
}
}
- IF_GETPUT(opt =) getopt32(argv, "^"
+ getopt32(argv, "^"
IF_FEATURE_TFTP_GET("g") IF_FEATURE_TFTP_PUT("p")
"l:r:" IF_FEATURE_TFTP_BLOCKSIZE("b:")
IF_FEATURE_TFTP_HPA_COMPAT("m:")
@@ -859,15 +867,12 @@ int tftp_main(int argc UNUSED_PARAM, char **argv)
# endif
result = tftp_protocol(
NULL /*our_lsa*/, peer_lsa,
- local_file, remote_file
+ (LONE_DASH(local_file) ? NULL : local_file), remote_file
IF_FEATURE_TFTP_BLOCKSIZE(, 1 /* want_transfer_size */)
IF_FEATURE_TFTP_BLOCKSIZE(, blksize)
);
tftp_progress_done();
- if (result != EXIT_SUCCESS && NOT_LONE_DASH(local_file) && CMD_GET(opt)) {
- unlink(local_file);
- }
return result;
}
#endif /* ENABLE_TFTP */
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