1 files changed, 119 insertions, 0 deletions
diff --git a/proxy/interactor.c b/proxy/interactor.c
new file mode 100644
index 00000000..d069d226
--- /dev/null
+++ b/proxy/interactor.c
@@ -0,0 +1,119 @@
+/*
+ * Centralised functions for the Interactor trait.
+ */
+
+#include "putty.h"
+
+Seat *interactor_borrow_seat(Interactor *itr)
+{
+    Seat *clientseat = interactor_get_seat(itr);
+    if (!clientseat)
+        return NULL;
+
+    /* If the client has already had its Seat borrowed, then look
+     * through the existing TempSeat to find the underlying one. */
+    if (is_tempseat(clientseat))
+        return tempseat_get_real(clientseat);
+
+    /* Otherwise, make a new TempSeat and give that to the client. */
+    Seat *tempseat = tempseat_new(clientseat);
+    interactor_set_seat(itr, tempseat);
+    return clientseat;
+}
+
+static Interactor *interactor_toplevel(Interactor *itr, unsigned *level_out)
+{
+    /*
+     * Find the Interactor at the top of the chain, so that all the
+     * Interactors in a stack can share that one's last-to-talk field.
+     * Also, count how far we had to go to get to it, to put in the
+     * message.
+     */
+    Interactor *itr_top = itr;
+    unsigned level = 0;
+    while (itr_top->parent) {
+        itr_top = itr_top->parent;
+        level++;
+    }
+
+    if (level_out)
+        *level_out = level;
+    return itr_top;
+}
+
+void interactor_return_seat(Interactor *itr)
+{
+    Seat *tempseat = interactor_get_seat(itr);
+    if (!is_tempseat(tempseat))
+        return;                        /* no-op */
+
+    /*
+     * We're about to hand this seat back to the parent Interactor to
+     * do its own thing with. It will typically expect to start in the
+     * same state as if the seat had never been borrowed, i.e. in the
+     * starting trust state.
+     *
+     * However, this may be overridden by the tempseat_flush call.
+     */
+    Seat *realseat = tempseat_get_real(tempseat);
+    seat_set_trust_status(realseat, true);
+
+    tempseat_flush(tempseat);
+    interactor_set_seat(itr, realseat);
+    tempseat_free(tempseat);
+
+    /*
+     * If we have a parent Interactor, and anyone has ever called
+     * interactor_announce, then all Interactors from now on will
+     * announce themselves even if they have nothing to say.
+     */
+    Interactor *itr_top = interactor_toplevel(itr, NULL);
+    if (itr_top->last_to_talk)
+        interactor_announce(itr);
+}
+
+InteractionReadySeat interactor_announce(Interactor *itr)
+{
+    Seat *seat = interactor_get_seat(itr);
+    assert(!is_tempseat(seat) &&
+           "Shouldn't call announce when someone else is using our seat");
+
+    InteractionReadySeat iseat;
+    iseat.seat = seat;
+
+    unsigned level;
+    Interactor *itr_top = interactor_toplevel(itr, &level);
+
+    /*
+     * Generally, we should announce ourself if the previous
+     * Interactor that said anything was not us. That includes if
+     * there was no previous Interactor to talk (i.e. if we're the
+     * first to say anything) - *except* that the primary Interactor
+     * doesn't need to announce itself, if no proxy has intervened
+     * before it.
+     */
+    bool need_announcement = (itr_top->last_to_talk != itr);
+    if (!itr->parent && !itr_top->last_to_talk)
+        need_announcement = false;
+
+    if (need_announcement) {
+        const char *prefix = "";
+        if (itr_top->last_to_talk != NULL)
+            seat_antispoof_msg(iseat, ""); /* leave a separating blank line */
+
+        char *desc = interactor_description(itr);
+        char *adjective = (level == 0 ? dupstr("primary") :
+                           level == 1 ? dupstr("proxy") :
+                           dupprintf("proxy^%u", level));
+        char *msg = dupprintf("%sMaking %s %s", prefix, adjective, desc);
+        sfree(adjective);
+        sfree(desc);
+
+        seat_antispoof_msg(iseat, msg);
+        sfree(msg);
+
+        itr_top->last_to_talk = itr;
+    }
+
+    return iseat;
+}