Record the time the last COMMIT was sent from a master context

This will be used to clear the committed key from the master context
once we don't expect any more instances of our buddy to respond with a
DHKEY message.

src/auth.c

@@ -59,6 +59,8 @@ void otrl_auth_dump(FILE *f, const OtrlAuthInfo *auth)
     fprintf(f, "\n    Proto version = %d\n", auth->protocol_version);
     fprintf(f, "\n    Lastauthmsg = %s\n",
 	auth->lastauthmsg ? auth->lastauthmsg : "(nil)");
+    fprintf(f, "\n    Commit sent time = %ld\n",
+	(long) auth->commit_sent_time);
 }
 
 #endif
@@ -90,6 +92,7 @@ void otrl_auth_new(struct context *context)
     memset(auth->secure_session_id, 0, 20);
     auth->secure_session_id_len = 0;
     auth->lastauthmsg = NULL;
+    auth->commit_sent_time = 0;
     auth->context = context;
 }
 
@@ -128,6 +131,7 @@ void otrl_auth_clear(OtrlAuthInfo *auth)
     auth->secure_session_id_len = 0;
     free(auth->lastauthmsg);
     auth->lastauthmsg = NULL;
+    auth->commit_sent_time = 0;
 }
 
 /*

src/auth.h

@@ -22,6 +22,7 @@
 #define __AUTH_H__
 
 #include <gcrypt.h>
+#include <time.h>
 #include "dh.h"
 
 
@@ -75,6 +76,12 @@ typedef struct {
 					     (base-64 encoded) we sent,
 					     in case we need to
 					     retransmit it. */
+
+    time_t commit_sent_time;              /* The time we last sent the
+                                             lastauthmsg, if it was a
+					     COMMIT message, and this is
+					     a master context.  0
+					     otherwise. */
 } OtrlAuthInfo;
 
 #include "privkey-t.h"

src/message.c

@@ -451,14 +451,23 @@ static gcry_error_t send_or_error_auth(const OtrlMessageAppOps *ops,
 	if (msg && *msg) {
 	    fragment_and_send(ops, opdata, context, msg,
 		    OTRL_FRAGMENT_SEND_ALL, NULL);
+	    time_t now = time(NULL);
 	    /* Update the "last sent" fields, unless this is a version 3
 	     * message typing to update the master context (as happens
 	     * when sending a v3 COMMIT message, for example). */
 	    if (context != context->m_context ||
 		    context->auth.protocol_version != 3) {
-		context->context_priv->lastsent = time(NULL);
+		context->context_priv->lastsent = now;
 		otrl_context_update_recent_child(context, 1);
 	    }
+
+	    /* If this is a master context, and we're sending a COMMIT
+	     * message, update the commit_sent_time timestamp, so we can
+	     * expire it. */
+	    if (context == context->m_context &&
+		context->auth.authstate == OTRL_AUTHSTATE_AWAITING_DHKEY) {
+		context->auth.commit_sent_time = now;
+	    }
 	}
     } else {
 	if (ops->handle_msg_event) {