diff options
Diffstat (limited to 'networking/telnetd.c')
| -rw-r--r-- | networking/telnetd.c | 34 |
1 files changed, 30 insertions, 4 deletions
diff --git a/networking/telnetd.c b/networking/telnetd.c index fa618a9..0da2941 100644 --- a/networking/telnetd.c +++ b/networking/telnetd.c @@ -60,6 +60,7 @@ struct tsession { int sockfd_read; int sockfd_write; int ptyfd; + smallint buffered_IAC_for_pty; /* two circular buffers */ /*char *buf1, *buf2;*/ @@ -91,7 +92,7 @@ struct globals { } while (0) -/* Write some buf1 data to pty, processing IAC's. +/* Write some buf1 data to pty, processing IACs. * Update wridx1 and size1. Return < 0 on error. * Buggy if IAC is present but incomplete: skips them. */ @@ -105,6 +106,21 @@ safe_write_to_pty_decode_iac(struct tsession *ts) buf = TS_BUF1(ts) + ts->wridx1; wr = MIN(BUFSIZE - ts->wridx1, ts->size1); + /* wr is at least 1 here */ + + if (ts->buffered_IAC_for_pty) { + /* Last time we stopped on a "dangling" IAC byte. + * We removed it from the buffer back then. + * Now pretend it's still there, and jump to IAC processing. + */ + ts->buffered_IAC_for_pty = 0; + wr++; + ts->size1++; + buf--; /* Yes, this can point before the buffer. It's ok */ + ts->wridx1--; + goto handle_iac; + } + found = memchr(buf, IAC, wr); if (found != buf) { /* There is a "prefix" of non-IAC chars. @@ -140,11 +156,17 @@ safe_write_to_pty_decode_iac(struct tsession *ts) * IAC WONT ECHO, IAC WILL NAWS, IAC SB NAWS <cols> <rows> IAC SE, IAC DO SGA */ if (wr <= 1) { -/* BUG: only the single IAC byte is in the buffer, we just eat IAC */ + /* Only the single IAC byte is in the buffer, eat it + * and set a flag "process the rest of the sequence + * next time we are here". + */ + //bb_error_msg("dangling IAC!"); + ts->buffered_IAC_for_pty = 1; rc = 1; goto update_and_return; } + handle_iac: /* 2-byte commands (240..250 and 255): * IAC IAC (255) Literal 255. Supported. * IAC NOP (241) NOP. Supported. @@ -162,7 +184,8 @@ safe_write_to_pty_decode_iac(struct tsession *ts) * IAC GA (249) Go ahead. For half-duplex lines: "now you talk". */ if (buf[1] == IAC) { /* Literal 255 (emacs M-DEL) */ - rc = safe_write(ts->ptyfd, buf, 1); + //bb_error_msg("255!"); + rc = safe_write(ts->ptyfd, &buf[1], 1); if (rc <= 0) return rc; rc = 2; @@ -174,7 +197,10 @@ safe_write_to_pty_decode_iac(struct tsession *ts) } if (wr <= 2) { -/* BUG: only 2 bytes of the IAC is in the buffer, we just eat them */ +/* BUG: only 2 bytes of the IAC is in the buffer, we just eat them. + * This is not a practical problem since >2 byte IACs are seen only + * in initial negotiation, when buffer is empty + */ rc = 2; goto update_and_return; } |