New SSH bug flag, for 'can't handle SSH2_MSG_IGNORE'. Another user

today reported an SSH2_MSG_UNIMPLEMENTED from a Cisco router which
looks as if it was triggered by SSH2_MSG_IGNORE, so I'm
experimentally putting this flag in. Currently must be manually
enabled, though if it turns out to solve the user's problem then
I'll probably add at least one version string...

[Edited commit message: actually, I also committed in error a piece
of experimental code as part of this checkin. Serve me right for not
running 'svn diff' first.]

git-svn-id: svn://svn.tartarus.org/sgt/putty@8926 cda61777-01e9-0310-a592-d414129be87e

diff --git a/config.c b/config.c
index 464a241..bc48e27 100644 (file)
--- a/config.c
+++ b/config.c
@@ -2284,6 +2284,9 @@ void setup_config_box(struct controlbox *b, int midsession,
            ctrl_droplist(s, "Chokes on SSH-1 RSA authentication", 'r', 20,
                          HELPCTX(ssh_bugs_rsa1),
                          sshbug_handler, I(offsetof(Config,sshbug_rsa1)));
+           ctrl_droplist(s, "Chokes on SSH-2 ignore messages", '2', 20,
+                         HELPCTX(ssh_bugs_ignore2),
+                         sshbug_handler, I(offsetof(Config,sshbug_ignore2)));
            ctrl_droplist(s, "Miscomputes SSH-2 HMAC keys", 'm', 20,
                          HELPCTX(ssh_bugs_hmac2),
                          sshbug_handler, I(offsetof(Config,sshbug_hmac2)));

diff --git a/doc/config.but b/doc/config.but
index 27704ee..c36e818 100644 (file)
--- a/doc/config.but
+++ b/doc/config.but
@@ -2948,9 +2948,6 @@ enabled when talking to a correct server, the session will succeed,
 but keepalives will not work and the session might be more
 vulnerable to eavesdroppers than it could be.
 
-This is an SSH-1-specific bug. No known SSH-2 server fails to deal
-with SSH-2 ignore messages.
-
 \S{config-ssh-bug-plainpw1} \q{Refuses all SSH-1 \i{password camouflage}}
 
 \cfg{winhelp-topic}{ssh.bugs.plainpw1}
@@ -2992,6 +2989,23 @@ will be impossible.
 
 This is an SSH-1-specific bug.
 
+\S{config-ssh-bug-ignore2} \q{Chokes on SSH-2 \i{ignore message}s}
+
+\cfg{winhelp-topic}{ssh.bugs.ignore2}
+
+An ignore message (SSH_MSG_IGNORE) is a message in the SSH protocol
+which can be sent from the client to the server, or from the server
+to the client, at any time. Either side is required to ignore the
+message whenever it receives it. PuTTY uses ignore messages in SSH-2
+to confuse the encrypted data stream and make it harder to
+cryptanalyse. It also uses ignore messages for connection
+\i{keepalives} (see \k{config-keepalive}).
+
+If it believes the server to have this bug, PuTTY will stop using
+ignore messages. If this bug is enabled when talking to a correct
+server, the session will succeed, but keepalives will not work and
+the session might be less cryptographically secure than it could be.
+
 \S{config-ssh-bug-hmac2} \q{Miscomputes SSH-2 HMAC keys}
 
 \cfg{winhelp-topic}{ssh.bugs.hmac2}

diff --git a/putty.h b/putty.h
index 6303968..ca232bc 100644 (file)
--- a/putty.h
+++ b/putty.h
@@ -592,7 +592,8 @@ struct config_tag {
     /* SSH bug compatibility modes */
     int sshbug_ignore1, sshbug_plainpw1, sshbug_rsa1,
        sshbug_hmac2, sshbug_derivekey2, sshbug_rsapad2,
-       sshbug_pksessid2, sshbug_rekey2, sshbug_maxpkt2;
+       sshbug_pksessid2, sshbug_rekey2, sshbug_maxpkt2,
+       sshbug_ignore2;
     /*
      * ssh_simple means that we promise never to open any channel other
      * than the main one, which means it can safely use a very large
@@ -825,6 +826,7 @@ void term_free(Terminal *);
 void term_size(Terminal *, int, int, int);
 void term_paint(Terminal *, Context, int, int, int, int, int);
 void term_scroll(Terminal *, int, int);
+void term_scroll_to_selection(Terminal *, int);
 void term_pwron(Terminal *, int);
 void term_clrsb(Terminal *);
 void term_mouse(Terminal *, Mouse_Button, Mouse_Button, Mouse_Action,

diff --git a/settings.c b/settings.c
index 9985e2d..38c4188 100644 (file)
--- a/settings.c
+++ b/settings.c
@@ -477,6 +477,7 @@ void save_open_settings(void *sesskey, Config *cfg)
     write_setting_i(sesskey, "BugIgnore1", 2-cfg->sshbug_ignore1);
     write_setting_i(sesskey, "BugPlainPW1", 2-cfg->sshbug_plainpw1);
     write_setting_i(sesskey, "BugRSA1", 2-cfg->sshbug_rsa1);
+    write_setting_i(sesskey, "BugIgnore2", 2-cfg->sshbug_ignore2);
     write_setting_i(sesskey, "BugHMAC2", 2-cfg->sshbug_hmac2);
     write_setting_i(sesskey, "BugDeriveKey2", 2-cfg->sshbug_derivekey2);
     write_setting_i(sesskey, "BugRSAPad2", 2-cfg->sshbug_rsapad2);
@@ -817,6 +818,7 @@ void load_open_settings(void *sesskey, Config *cfg)
     gppi(sesskey, "BugIgnore1", 0, &i); cfg->sshbug_ignore1 = 2-i;
     gppi(sesskey, "BugPlainPW1", 0, &i); cfg->sshbug_plainpw1 = 2-i;
     gppi(sesskey, "BugRSA1", 0, &i); cfg->sshbug_rsa1 = 2-i;
+    gppi(sesskey, "BugIgnore2", 0, &i); cfg->sshbug_ignore2 = 2-i;
     {
        int i;
        gppi(sesskey, "BugHMAC2", 0, &i); cfg->sshbug_hmac2 = 2-i;

diff --git a/ssh.c b/ssh.c
index 8887d9b..029c78a 100644 (file)
--- a/ssh.c
+++ b/ssh.c
@@ -194,6 +194,7 @@ static const char *const ssh2_disconnect_reasons[] = {
 #define BUG_SSH2_REKEY                           64
 #define BUG_SSH2_PK_SESSIONID                   128
 #define BUG_SSH2_MAXPKT                                256
+#define BUG_CHOKES_ON_SSH2_IGNORE               512
 
 /*
  * Codes for terminal modes.
@@ -2011,7 +2012,8 @@ static void ssh2_pkt_defer_noqueue(Ssh ssh, struct Packet *pkt, int noignore)
 {
     int len;
     if (ssh->cscipher != NULL && (ssh->cscipher->flags & SSH_CIPHER_IS_CBC) &&
-       ssh->deferred_len == 0 && !noignore) {
+       ssh->deferred_len == 0 && !noignore &&
+       !(ssh->remote_bugs & BUG_CHOKES_ON_SSH2_IGNORE)) {
        /*
         * Interpose an SSH_MSG_IGNORE to ensure that user data don't
         * get encrypted with a known IV.
@@ -2141,7 +2143,8 @@ static void ssh2_pkt_send_with_padding(Ssh ssh, struct Packet *pkt,
         * unavailable, we don't do this trick at all, because we
         * gain nothing by it.)
         */
-       if (ssh->cscipher) {
+       if (ssh->cscipher &&
+           !(ssh->remote_bugs & BUG_CHOKES_ON_SSH2_IGNORE)) {
            int stringlen, i;
 
            stringlen = (256 - ssh->deferred_len);
@@ -2508,6 +2511,15 @@ static void ssh_detect_bugs(Ssh ssh, char *vstring)
        ssh->remote_bugs |= BUG_SSH2_MAXPKT;
        logevent("We believe remote version ignores SSH-2 maximum packet size");
     }
+
+    if (ssh->cfg.sshbug_ignore2 == FORCE_ON) {
+       /*
+        * Servers that don't support SSH2_MSG_IGNORE. Currently,
+        * none detected automatically.
+        */
+       ssh->remote_bugs |= BUG_CHOKES_ON_SSH2_IGNORE;
+       logevent("We believe remote version has SSH-2 ignore bug");
+    }
 }
 
 /*
@@ -9426,8 +9438,10 @@ static const struct telnet_special *ssh_get_specials(void *handle)
     static const struct telnet_special ssh1_ignore_special[] = {
        {"IGNORE message", TS_NOP}
     };
-    static const struct telnet_special ssh2_transport_specials[] = {
+    static const struct telnet_special ssh2_ignore_special[] = {
        {"IGNORE message", TS_NOP},
+    };
+    static const struct telnet_special ssh2_rekey_special[] = {
        {"Repeat key exchange", TS_REKEY},
     };
     static const struct telnet_special ssh2_session_specials[] = {
@@ -9452,7 +9466,8 @@ static const struct telnet_special *ssh_get_specials(void *handle)
        {NULL, TS_EXITMENU}
     };
     /* XXX review this length for any changes: */
-    static struct telnet_special ssh_specials[lenof(ssh2_transport_specials) +
+    static struct telnet_special ssh_specials[lenof(ssh2_ignore_special) +
+                                             lenof(ssh2_rekey_special) +
                                              lenof(ssh2_session_specials) +
                                              lenof(specials_end)];
     Ssh ssh = (Ssh) handle;
@@ -9471,7 +9486,10 @@ static const struct telnet_special *ssh_get_specials(void *handle)
        if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE))
            ADD_SPECIALS(ssh1_ignore_special);
     } else if (ssh->version == 2) {
-       ADD_SPECIALS(ssh2_transport_specials);
+       if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH2_IGNORE))
+           ADD_SPECIALS(ssh2_ignore_special);
+       if (!(ssh->remote_bugs & BUG_SSH2_REKEY))
+           ADD_SPECIALS(ssh2_rekey_special);
        if (ssh->mainchan)
            ADD_SPECIALS(ssh2_session_specials);
     } /* else we're not ready yet */
@@ -9521,9 +9539,11 @@ static void ssh_special(void *handle, Telnet_Special code)
            if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH1_IGNORE))
                send_packet(ssh, SSH1_MSG_IGNORE, PKT_STR, "", PKT_END);
        } else {
-           pktout = ssh2_pkt_init(SSH2_MSG_IGNORE);
-           ssh2_pkt_addstring_start(pktout);
-           ssh2_pkt_send_noqueue(ssh, pktout);
+           if (!(ssh->remote_bugs & BUG_CHOKES_ON_SSH2_IGNORE)) {
+               pktout = ssh2_pkt_init(SSH2_MSG_IGNORE);
+               ssh2_pkt_addstring_start(pktout);
+               ssh2_pkt_send_noqueue(ssh, pktout);
+           }
        }
     } else if (code == TS_REKEY) {
        if (!ssh->kex_in_progress && ssh->version == 2) {

diff --git a/terminal.c b/terminal.c
index aaf8705..c0c809c 100644 (file)
--- a/terminal.c
+++ b/terminal.c
@@ -5137,6 +5137,31 @@ void term_scroll(Terminal *term, int rel, int where)
 }
 
 /*
+ * Scroll the scrollback to centre it on the beginning or end of the
+ * current selection, if any.
+ */
+void term_scroll_to_selection(Terminal *term, int which_end)
+{
+    pos target;
+    int y;
+    int sbtop = -sblines(term);
+
+    if (term->selstate != SELECTED)
+       return;
+    if (which_end)
+       target = term->selend;
+    else
+       target = term->selstart;
+
+    y = target.y - term->rows/2;
+    if (y < sbtop)
+       y = sbtop;
+    else if (y > 0)
+       y = 0;
+    term_scroll(term, -1, y);
+}
+
+/*
  * Helper routine for clipme(): growing buffer.
  */
 typedef struct {

diff --git a/windows/window.c b/windows/window.c
index 3f092ae..96f6499 100644 (file)
--- a/windows/window.c
+++ b/windows/window.c
@@ -3811,6 +3811,10 @@ static int TranslateKey(UINT message, WPARAM wParam, LPARAM lParam,
            SendMessage(hwnd, WM_VSCROLL, SB_LINEDOWN, 0);
            return 0;
        }
+       if ((wParam == VK_PRIOR || wParam == VK_NEXT) && shift_state == 3) {
+           term_scroll_to_selection(term, (wParam == VK_PRIOR ? 0 : 1));
+           return 0;
+       }
        if (wParam == VK_INSERT && shift_state == 1) {
            request_paste(NULL);
            return 0;