Hi, Thanks for this - could I ask you to create a bug at https://bugzilla.mindrot.org for this and attach your patch? This will make sure it doesn't get lost. Thanks, Damien On Mon, 12 Oct 2015, Alex Dowad wrote: > Even when the user has not pressed a key, ANSI-compatible terminal emulators > can send escape sequences to ssh's stdin at any time. For example, any time that > the server sends an "<ESC>[6n" (query cursor position) sequence, an > ANSI-compatible terminal will send back "<ESC>[<ROW>;<COLUMN>R". ssh sees these > escape sequences just as if they were characters typed in by the user. This > causes problems if the user is attempting to type an SSH escape sequence, > starting with "<ENTER>~". > > Therefore, when scanning user input for SSH escape sequences, skip over any > ANSI terminal control sequences which appear in the input. > --- > > Dear OpenSSH-Portable Devs, > > Please CC replies as I am not (yet) a subscriber! > > I should probably send this upstream, but I've been searching for the right > mailing list and haven't found anything. Your feedback will be appreciated. > I've read your style guidelines and attempted to follow them. > > This patch was prompted by the observation that SSH escapes (using ~) don't work > at all when the remote shell is BusyBox ash (used by Alpine Linux and some > other minimalist and/or embedded Linux distributions). > > This is because the BusyBox shell *always* sends a "query cursor position" > terminal control escape sequence each time you press the <ENTER> key. > Quick as a flash, as your pinky finger is descending towards the tilda key, > the terminal sends back a "report cursor position" sequence. The result is > that the SSH client *never* sees your tilda as immediately following the > newline. > > Those ANSI terminal control sequences always begin with "<ESC>[" and end > with an alphabetic character. Hence the call to isalpha() in my code. > Can someone confirm that isalpha() *always* treats a-z and A-Z as alphabetic, > no matter what the locale is? > > Thank you, > Alex Dowad > > clientloop.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/clientloop.c b/clientloop.c > index 87ceb3d..b15e470 100644 > --- a/clientloop.c > +++ b/clientloop.c > @@ -1096,7 +1096,17 @@ process_escapes(Channel *c, Buffer *bin, Buffer *bout, Buffer *berr, > /* Get one character at a time. */ > ch = buf[i]; > > - if (*escape_pendingp) { > + /* ANSI terminal escape sequences may appear anywhere in input stream. */ > + /* They do not affect our processing of our own escapes. */ > + if (ch == 0x1B && buf[i+1] == '[') { > + for (; i < (u_int)len; i++) { > + ch = buf[i]; > + buffer_put_char(bin, ch); > + if (isalpha(ch)) > + break; > + } > + continue; > + } else if (*escape_pendingp) { > /* We have previously seen an escape character. */ > /* Clear the flag now. */ > *escape_pendingp = 0; > -- > 2.0.0.GIT > > _______________________________________________ > openssh-unix-dev mailing list > openssh-unix-dev@xxxxxxxxxxx > https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev > _______________________________________________ openssh-unix-dev mailing list openssh-unix-dev@xxxxxxxxxxx https://lists.mindrot.org/mailman/listinfo/openssh-unix-dev
