From fce4a9454c5399c2ce8ca8e87048331c6e3d98fa Mon Sep 17 00:00:00 2001 From: Denis Vlasenko Date: Wed, 18 Mar 2009 16:02:54 +0000 Subject: [PATCH] ftpd: add some comments --- networking/ftpd.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/networking/ftpd.c b/networking/ftpd.c index eb3a3bd89..6630db710 100644 --- a/networking/ftpd.c +++ b/networking/ftpd.c @@ -702,7 +702,10 @@ handle_dir_common(int opts) line = xmalloc_fgetline(ls_fp); if (!line) break; - cmdio_write(0, line); /* hack: 0 results in no status at all */ + /* Hack: 0 results in no status at all */ + /* Note: it's ok that we don't prepend space, + * ftp.kernel.org doesn't do that too */ + cmdio_write(0, line); free(line); } WRITE_OK(FTP_STATFILE_OK); @@ -973,6 +976,15 @@ cmdio_get_cmd_and_arg(void) 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. */ + /* Trailing '\n' is already stripped, strip '\r' */ len = strlen(cmd) - 1; if ((ssize_t)len >= 0 && cmd[len] == '\r') @@ -1115,6 +1127,8 @@ int ftpd_main(int argc UNUSED_PARAM, char **argv) /* Set up options on the command socket (do we need these all? why?) */ setsockopt(STDIN_FILENO, IPPROTO_TCP, TCP_NODELAY, &const_int_1, sizeof(const_int_1)); setsockopt(STDIN_FILENO, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1)); + /* Telnet protocol over command link may send "urgent" data, + * we prefer it to be received in the "normal" data stream: */ setsockopt(STDIN_FILENO, SOL_SOCKET, SO_OOBINLINE, &const_int_1, sizeof(const_int_1)); WRITE_OK(FTP_GREET);