Refactor confirm_weak to use SeatDialogText.

This centralises the messages for weak crypto algorithms (general, and
host keys in particular, the latter including a list of all the other
available host key types) into ssh/common.c, in much the same way as
we previously did for ordinary host key warnings.

The reason is the same too: I'm about to want to vary the text in one
of those dialog boxes, so it's convenient to start by putting it
somewhere that I can modify just once.

ssh/common.c

@@ -1085,6 +1085,79 @@ SeatPromptResult verify_ssh_host_key(
     return toret;
 }
 
+SeatPromptResult confirm_weak_crypto_primitive(
+    InteractionReadySeat iseat, const char *algtype, const char *algname,
+    void (*callback)(void *ctx, SeatPromptResult result), void *ctx)
+{
+    SeatDialogText *text = seat_dialog_text_new();
+    const SeatDialogPromptDescriptions *pds =
+        seat_prompt_descriptions(iseat.seat);
+
+    seat_dialog_text_append(text, SDT_TITLE, "%s Security Alert", appname);
+
+    seat_dialog_text_append(
+        text, SDT_PARA,
+        "The first %s supported by the server is %s, "
+        "which is below the configured warning threshold.",
+        algtype, algname);
+
+    /* In batch mode, we print the above information and then this
+     * abort message, and stop. */
+    seat_dialog_text_append(text, SDT_BATCH_ABORT, "Connection abandoned.");
+
+    seat_dialog_text_append(
+        text, SDT_PARA, "To accept the risk and continue, %s. "
+        "To abandon the connection, %s.",
+        pds->weak_accept_action, pds->weak_cancel_action);
+
+    seat_dialog_text_append(text, SDT_PROMPT, "Continue with connection?");
+
+    SeatPromptResult toret = seat_confirm_weak_crypto_primitive(
+        iseat, text, callback, ctx);
+    seat_dialog_text_free(text);
+    return toret;
+}
+
+SeatPromptResult confirm_weak_cached_hostkey(
+    InteractionReadySeat iseat, const char *algname, const char **betteralgs,
+    void (*callback)(void *ctx, SeatPromptResult result), void *ctx)
+{
+    SeatDialogText *text = seat_dialog_text_new();
+    const SeatDialogPromptDescriptions *pds =
+        seat_prompt_descriptions(iseat.seat);
+
+    seat_dialog_text_append(text, SDT_TITLE, "%s Security Alert", appname);
+
+    seat_dialog_text_append(
+        text, SDT_PARA,
+        "The first host key type we have stored for this server "
+        "is %s, which is below the configured warning threshold.", algname);
+
+    seat_dialog_text_append(
+        text, SDT_PARA,
+        "The server also provides the following types of host key "
+        "above the threshold, which we do not have stored:");
+
+    for (const char **p = betteralgs; *p; p++)
+        seat_dialog_text_append(text, SDT_DISPLAY, "%s", *p);
+
+    /* In batch mode, we print the above information and then this
+     * abort message, and stop. */
+    seat_dialog_text_append(text, SDT_BATCH_ABORT, "Connection abandoned.");
+
+    seat_dialog_text_append(
+        text, SDT_PARA, "To accept the risk and continue, %s. "
+        "To abandon the connection, %s.",
+        pds->weak_accept_action, pds->weak_cancel_action);
+
+    seat_dialog_text_append(text, SDT_PROMPT, "Continue with connection?");
+
+    SeatPromptResult toret = seat_confirm_weak_cached_hostkey(
+        iseat, text, callback, ctx);
+    seat_dialog_text_free(text);
+    return toret;
+}
+
 /* ----------------------------------------------------------------------
  * Common functions shared between SSH-1 layers.
  */

ssh/login1.c

@@ -323,7 +323,7 @@ static void ssh1_login_process_queue(PacketProtocolLayer *ppl)
 
         /* Warn about chosen cipher if necessary. */
         if (warn) {
-            s->spr = seat_confirm_weak_crypto_primitive(
+            s->spr = confirm_weak_crypto_primitive(
                 ppl_get_iseat(&s->ppl), "cipher", cipher_string,
                 ssh1_login_dialog_callback, s);
             crMaybeWaitUntilV(s->spr.kind != SPRK_INCOMPLETE);

ssh/server.c

@@ -98,11 +98,11 @@ void mainchan_terminal_size(mainchan *mc, int width, int height) {}
 /* Seat functions to ensure we don't get choosy about crypto - as the
  * server, it's not up to us to give user warnings */
 static SeatPromptResult server_confirm_weak_crypto_primitive(
-    Seat *seat, const char *algtype, const char *algname,
+    Seat *seat, SeatDialogText *text,
     void (*callback)(void *ctx, SeatPromptResult result), void *ctx)
 { return SPR_OK; }
 static SeatPromptResult server_confirm_weak_cached_hostkey(
-    Seat *seat, const char *algname, const char *betteralgs,
+    Seat *seat, SeatDialogText *text,
     void (*callback)(void *ctx, SeatPromptResult result), void *ctx)
 { return SPR_OK; }
 

ssh/transport2.c

@@ -1514,7 +1514,8 @@ static void ssh2_transport_process_queue(PacketProtocolLayer *ppl)
 
     if (s->warn_hk) {
         int j, k;
-        char *betteralgs;
+        const char **betteralgs = NULL;
+        size_t nbetter = 0, bettersize = 0;
 
         /*
          * Change warning box wording depending on why we chose a
@@ -1523,7 +1524,6 @@ static void ssh2_transport_process_queue(PacketProtocolLayer *ppl)
          * could usefully cross-certify. Otherwise, use the same
          * standard wording as any other weak crypto primitive.
          */
-        betteralgs = NULL;
         for (j = 0; j < s->n_uncert_hostkeys; j++) {
             const struct ssh_signkey_with_user_pref_id *hktype =
                 &ssh2_hostkey_algs[s->uncert_hostkeys[j]];
@@ -1538,19 +1538,16 @@ static void ssh2_transport_process_queue(PacketProtocolLayer *ppl)
                 }
             }
             if (better) {
-                if (betteralgs) {
-                    char *old_ba = betteralgs;
-                    betteralgs = dupcat(betteralgs, ",", hktype->alg->ssh_id);
-                    sfree(old_ba);
-                } else {
-                    betteralgs = dupstr(hktype->alg->ssh_id);
-                }
+                sgrowarray(betteralgs, bettersize, nbetter);
+                betteralgs[nbetter++] = hktype->alg->ssh_id;
             }
         }
         if (betteralgs) {
             /* Use the special warning prompt that lets us provide
              * a list of better algorithms */
-            s->spr = seat_confirm_weak_cached_hostkey(
+            sgrowarray(betteralgs, bettersize, nbetter);
+            betteralgs[nbetter] = NULL;
+            s->spr = confirm_weak_cached_hostkey(
                 ppl_get_iseat(&s->ppl), s->hostkey_alg->ssh_id, betteralgs,
                 ssh2_transport_dialog_callback, s);
             sfree(betteralgs);
@@ -2389,7 +2386,7 @@ static int ca_blob_compare(void *av, void *bv)
 }
 
 /*
- * Wrapper on seat_confirm_weak_crypto_primitive(), which uses the
+ * Wrapper on confirm_weak_crypto_primitive(), which uses the
  * tree234 s->weak_algorithms_consented_to to ensure we ask at most
  * once about any given crypto primitive.
  */
@@ -2401,7 +2398,7 @@ static SeatPromptResult ssh2_transport_confirm_weak_crypto_primitive(
         return SPR_OK;
     add234(s->weak_algorithms_consented_to, (void *)alg);
 
-    return seat_confirm_weak_crypto_primitive(
+    return confirm_weak_crypto_primitive(
         ppl_get_iseat(&s->ppl), type, name, ssh2_transport_dialog_callback, s);
 }