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ftpd: fix command fetching to not do it in 1-byte reads;

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fix command de-escaping. Tested to download files with embeeded \xff and LF.
libbb: tweaks for the above

function                                             old     new   delta
ftpd_main                                           2231    2321     +90
xmalloc_fgets_internal                               190     222     +32
xmalloc_fgets_str_len                                  -      27     +27
xmalloc_fgets_str                                      7      23     +16
xmalloc_fgetline_str                                  10      26     +16
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 4/0 up/down: 181/0)             Total: 181 bytes
This commit is contained in:
Denis Vlasenko 2009-03-18 17:32:44 +00:00
parent fce4a9454c
commit 9f57cf6604
4 changed files with 80 additions and 21 deletions
Download patch file Download diff file Expand all files Collapse all files

63
networking/ftpd.c
View file

@ -972,23 +972,60 @@ cmdio_get_cmd_and_arg(void)
free(G.ftp_cmd);
len = 8 * 1024; /* Paranoia. Peer may send 1 gigabyte long cmd... */
G.ftp_cmd = cmd = xmalloc_reads(STDIN_FILENO, NULL, &len);
G.ftp_cmd = cmd = xmalloc_fgets_str_len(stdin, "\r\n", &len);
if (!cmd)
exit(0);
/* TODO: de-escape telnet here: 0xff,0xff => 0xff */
/* RFC959 says that ABOR, STAT, QUIT may be sent even during
* data transfer, and may be preceded by telnet's "Interrupt Process"
* code (two-byte sequence 255,244) and then by telnet "Synch" code
* 255,242 (byte 242 is sent with TCP URG bit using send(MSG_OOB)
* and may generate SIGURG on our side. See RFC854).
* So far we don't support that (may install SIGURG handler if we'd want to),
* but we need to at least remove 255,xxx pairs. lftp sends those. */
/* De-escape telnet: 0xff,0xff => 0xff */
/* RFC959 says that ABOR, STAT, QUIT may be sent even during
* data transfer, and may be preceded by telnet's "Interrupt Process"
* code (two-byte sequence 255,244) and then by telnet "Synch" code
* 255,242 (byte 242 is sent with TCP URG bit using send(MSG_OOB)
* and may generate SIGURG on our side. See RFC854).
* So far we don't support that (may install SIGURG handler if we'd want to),
* but we need to at least remove 255,xxx pairs. lftp sends those. */
/* Then de-escape FTP: NUL => '\n' */
/* Testing for \xff:
* Create file named '\xff': echo Hello >`echo -ne "\xff"`
* Try to get it: ftpget -v 127.0.0.1 Eff `echo -ne "\xff\xff"`
* (need "\xff\xff" until ftpget applet is fixed to do escaping :)
* Testing for embedded LF:
* LF_HERE=`echo -ne "LF\nHERE"`
* echo Hello >"$LF_HERE"
* ftpget -v 127.0.0.1 LF_HERE "$LF_HERE"
*/
{
int dst, src;
/* Trailing '\n' is already stripped, strip '\r' */
len = strlen(cmd) - 1;
if ((ssize_t)len >= 0 && cmd[len] == '\r')
cmd[len--] = '\0';
/* Strip "\r\n" if it is there */
if (len != 0 && cmd[len - 1] == '\n') {
len--;
if (len != 0 && cmd[len - 1] == '\r')
len--;
cmd[len] = '\0';
}
src = strchrnul(cmd, 0xff) - cmd;
/* 99,99% there are neither NULs nor 255s and src == len */
if (src < len) {
dst = src;
do {
if ((unsigned char)(cmd[src]) == 255) {
src++;
/* 255,xxx - skip 255 */
if ((unsigned char)(cmd[src]) != 255) {
/* 255,!255 - skip both */
src++;
continue;
}
/* 255,255 - retain one 255 */
}
/* NUL => '\n' */
cmd[dst++] = cmd[src] ? cmd[src] : '\n';
src++;
} while (src < len);
cmd[dst] = '\0';
}
}
if (G.verbose > 1)
verbose_log(cmd);