1 files changed, 413 insertions, 196 deletions

diff --git a/plugins/MirOTR/libotr/src/context.c b/plugins/MirOTR/libotr/src/context.c
index d0d912f76a..44d8b860f7 100644
--- a/plugins/MirOTR/libotr/src/context.c
+++ b/plugins/MirOTR/libotr/src/context.c
@@ -1,6 +1,8 @@
 /*
  *  Off-the-Record Messaging library
- *  Copyright (C) 2004-2008  Ian Goldberg, Chris Alexander, Nikita Borisov
+ *  Copyright (C) 2004-2014  Ian Goldberg, David Goulet, Rob Smits,
+ *                           Chris Alexander, Willy Lew, Lisa Du,
+ *                           Nikita Borisov
  *                           <otr@cypherpunks.ca>
  *
  *  This library is free software; you can redistribute it and/or
@@ -14,7 +16,7 @@
  *
  *  You should have received a copy of the GNU Lesser General Public
  *  License along with this library; if not, write to the Free Software
- *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
 /* system headers */
@@ -26,117 +28,339 @@
 
 /* libotr headers */
 #include "context.h"
+#include "instag.h"
+
+#if OTRL_DEBUGGING
+#include <stdio.h>
+
+void otrl_auth_dump(FILE *f, const OtrlAuthInfo *auth);
+void otrl_sm_dump(FILE *f, const OtrlSMState *sm);
+
+/* Dump the contents of a context to the FILE *f. */
+void otrl_context_dump(FILE *f, const ConnContext *context)
+{
+    const Fingerprint *fing;
+
+    fprintf(f, "Context %p:\n\n", context);
+
+    fprintf(f, "  Username: %s\n", context->username);
+    fprintf(f, "  Accountname: %s\n", context->accountname);
+    fprintf(f, "  Protocol: %s\n\n", context->protocol);
+    fprintf(f, "  Master context: %p%s\n", context->m_context,
+	    context->m_context == context ? " IS MASTER" : "");
+    fprintf(f, "  Recent recv child: %p\n", context->recent_rcvd_child);
+    fprintf(f, "  Recent sent child: %p\n", context->recent_sent_child);
+    fprintf(f, "  Recent child: %p\n\n", context->recent_child);
+    fprintf(f, "  Our instance:   %08x\n", context->our_instance);
+    fprintf(f, "  Their instance: %08x\n\n", context->their_instance);
+    fprintf(f, "  Msgstate: %d (%s)\n\n", context->msgstate,
+	context->msgstate == OTRL_MSGSTATE_PLAINTEXT ? "PLAINTEXT" :
+	context->msgstate == OTRL_MSGSTATE_ENCRYPTED ? "ENCRYPTED" :
+	context->msgstate == OTRL_MSGSTATE_FINISHED ? "FINISHED" :
+	"INVALID");
+    otrl_auth_dump(f, &context->auth);
+    fprintf(f, "\n  Fingerprints:\n");
+    for (fing = context->fingerprint_root.next; fing; fing = fing->next) {
+	fprintf(f, "    %p ", fing);
+	if (fing->fingerprint == NULL) {
+	    fprintf(f, "(null)");
+	} else {
+	    int i;
+	    for (i=0;i<20;++i) {
+		fprintf(f, "%02x", fing->fingerprint[i]);
+	    }
+	}
+	fprintf(f, " %p", fing->context);
+	if (fing->trust && fing->trust[0]) {
+	    fprintf(f, " %s", fing->trust);
+	}
+	fprintf(f, "\n");
+    }
+    fprintf(f, "\n  Active fingerprint: %p\n\n", context->active_fingerprint);
+    fprintf(f, "  Protocol version: %d\n", context->protocol_version);
+    fprintf(f, "  OTR offer: %d (%s)\n\n", context->otr_offer,
+	context->otr_offer == OFFER_NOT ? "NOT" :
+	context->otr_offer == OFFER_SENT ? "SENT" :
+	context->otr_offer == OFFER_REJECTED ? "REJECTED" :
+	context->otr_offer == OFFER_ACCEPTED ? "ACCEPTED" :
+	"INVALID");
+
+    fprintf(f, "  Application data: %p\n", context->app_data);
+    if (context->smstate == NULL) {
+	fprintf(f, "  SM state: NULL\n");
+    } else {
+	otrl_sm_dump(f, context->smstate);
+    }
+    fprintf(f, "\n");
+}
+
+/* Dump the master context of this context, and all of its children. */
+void otrl_context_siblings_dump(FILE *f, const ConnContext *context)
+{
+    const ConnContext *citer;
+    for (citer = context->m_context;
+	    citer && citer->m_context == context->m_context;
+	    citer = citer->next) {
+	if (citer == context) {
+	    fprintf(f, "*** ");
+	}
+	otrl_context_dump(f, citer);
+    }
+}
+
+/* Dump all contexts. */
+void otrl_context_all_dump(FILE *f, OtrlUserState us)
+{
+    const ConnContext *citer;
+    unsigned int ctxnum = 1;
+    for (citer = us->context_root; citer; citer = citer->next, ++ctxnum) {
+	fprintf(f, "%u. ", ctxnum);
+	otrl_context_dump(f, citer);
+    }
+}
+#endif
 
 /* Create a new connection context. */
 static ConnContext * new_context(const char * user, const char * accountname,
 	const char * protocol)
 {
-	ConnContext * context;
-	OtrlSMState *smstate;
-	context = malloc(sizeof(*context));
-	assert(context != NULL);
-	context->username = _strdup(user);
-	context->accountname = _strdup(accountname);
-	context->protocol = _strdup(protocol);
-	context->fragment = NULL;
-	context->fragment_len = 0;
-	context->fragment_n = 0;
-	context->fragment_k = 0;
-	context->msgstate = OTRL_MSGSTATE_PLAINTEXT;
-	otrl_auth_new(&(context->auth));
-
-	smstate = malloc(sizeof(OtrlSMState));
-	assert(smstate != NULL);
-	otrl_sm_state_new(smstate);
-	context->smstate = smstate;
-
-	context->fingerprint_root.fingerprint = NULL;
-	context->fingerprint_root.context = context;
-	context->fingerprint_root.next = NULL;
-	context->fingerprint_root.tous = NULL;
-	context->active_fingerprint = NULL;
-	context->their_keyid = 0;
-	context->their_y = NULL;
-	context->their_old_y = NULL;
-	context->our_keyid = 0;
-	context->our_dh_key.groupid = 0;
-	context->our_dh_key.priv = NULL;
-	context->our_dh_key.pub = NULL;
-	context->our_old_dh_key.groupid = 0;
-	context->our_old_dh_key.priv = NULL;
-	context->our_old_dh_key.pub = NULL;
-	otrl_dh_session_blank(&(context->sesskeys[0][0]));
-	otrl_dh_session_blank(&(context->sesskeys[0][1]));
-	otrl_dh_session_blank(&(context->sesskeys[1][0]));
-	otrl_dh_session_blank(&(context->sesskeys[1][1]));
-	memset(context->sessionid, 0, 20);
-	context->sessionid_len = 0;
-	context->protocol_version = 0;
-	context->numsavedkeys = 0;
-	context->preshared_secret = NULL;
-	context->preshared_secret_len = 0;
-	context->saved_mac_keys = NULL;
-	context->generation = 0;
-	context->lastsent = 0;
-	context->lastmessage = NULL;
-	context->may_retransmit = 0;
-	context->otr_offer = OFFER_NOT;
-	context->app_data = NULL;
-	context->app_data_free = NULL;
-	context->next = NULL;
-	return context;
+    ConnContext * context;
+    OtrlSMState *smstate;
+
+    context = malloc(sizeof(ConnContext));
+    assert(context != NULL);
+
+    context->username = strdup(user);
+    context->accountname = strdup(accountname);
+    context->protocol = strdup(protocol);
+
+    context->msgstate = OTRL_MSGSTATE_PLAINTEXT;
+    otrl_auth_new(context);
+
+    smstate = malloc(sizeof(OtrlSMState));
+    assert(smstate != NULL);
+    otrl_sm_state_new(smstate);
+    context->smstate = smstate;
+
+    context->our_instance = 0;
+    context->their_instance = OTRL_INSTAG_MASTER;
+    context->fingerprint_root.fingerprint = NULL;
+    context->fingerprint_root.context = context;
+    context->fingerprint_root.next = NULL;
+    context->fingerprint_root.tous = NULL;
+    context->active_fingerprint = NULL;
+    memset(context->sessionid, 0, 20);
+    context->sessionid_len = 0;
+    context->protocol_version = 0;
+    context->otr_offer = OFFER_NOT;
+    context->app_data = NULL;
+    context->app_data_free = NULL;
+    context->context_priv = otrl_context_priv_new();
+    assert(context->context_priv != NULL);
+    context->next = NULL;
+    context->m_context = context;
+    context->recent_rcvd_child = NULL;
+    context->recent_sent_child = NULL;
+    context->recent_child = NULL;
+
+    return context;
 }
 
-ConnContext * otrl_context_new(const char * user, const char * accountname,
-	const char * protocol)
+ConnContext * otrl_context_find_recent_instance(ConnContext * context,
+	otrl_instag_t recent_instag) {
+    ConnContext * m_context;
+
+    if (!context) return NULL;
+
+    m_context = context->m_context;
+
+    if (!m_context) return NULL;
+
+    switch(recent_instag) {
+	case OTRL_INSTAG_RECENT:
+	    return m_context->recent_child;
+	case OTRL_INSTAG_RECENT_RECEIVED:
+	    return m_context->recent_rcvd_child;
+	case OTRL_INSTAG_RECENT_SENT:
+	    return m_context->recent_sent_child;
+	default:
+	    return NULL;
+    }
+}
+
+/* Find the instance of this context that has the best security level,
+   and for which we have most recently received a message from. Note that most
+   recent in this case is limited to a one-second resolution. */
+ConnContext * otrl_context_find_recent_secure_instance(ConnContext * context)
 {
-	return new_context(user, accountname, protocol);
+    ConnContext *curp; /* for iteration */
+    ConnContext *m_context; /* master */
+    ConnContext *cresult = context;  /* best so far */
+
+    if (!context) {
+	return cresult;
+    }
+
+    m_context = context->m_context;
+
+    for (curp = m_context; curp && curp->m_context == m_context;
+	    curp = curp->next) {
+	int msgstate_improved = 0; /* 0 == same, 1 == improved   */
+	int trust_improved = 0;    /* (will immediately 'continue' if worse
+				    * than) */
+
+	if (cresult->msgstate == curp->msgstate) {
+	    msgstate_improved = 0;
+	} else if (curp->msgstate == OTRL_MSGSTATE_ENCRYPTED ||
+		(cresult->msgstate == OTRL_MSGSTATE_PLAINTEXT &&
+		curp->msgstate == OTRL_MSGSTATE_FINISHED)) {
+	    msgstate_improved = 1;
+	} else {
+	    continue;
+	}
+
+
+	if (otrl_context_is_fingerprint_trusted(cresult->active_fingerprint) ==
+		otrl_context_is_fingerprint_trusted(curp->active_fingerprint)) {
+
+	    trust_improved = 0;
+	} else if
+		(otrl_context_is_fingerprint_trusted(curp->active_fingerprint)){
+
+	    trust_improved = 1;
+	} else {
+	    continue;
+	}
+
+	if (msgstate_improved || trust_improved ||
+		(!msgstate_improved && !trust_improved &&
+		curp->context_priv->lastrecv >=
+		cresult->context_priv->lastrecv)) {
+	    cresult = curp;
+	}
+    }
+
+    return cresult;
 }
 
-/* Look up a connection context by name/account/protocol from the given
+/* Look up a connection context by name/account/protocol/instag from the given
  * OtrlUserState.  If add_if_missing is true, allocate and return a new
  * context if one does not currently exist.  In that event, call
  * add_app_data(data, context) so that app_data and app_data_free can be
- * filled in by the application, and set *addedp to 1. */
+ * filled in by the application, and set *addedp to 1.
+ * In the 'their_instance' field note that you can also specify a 'meta-
+ * instance' value such as OTRL_INSTAG_MASTER, OTRL_INSTAG_RECENT,
+ * OTRL_INSTAG_RECENT_RECEIVED and OTRL_INSTAG_RECENT_SENT. */
 ConnContext * otrl_context_find(OtrlUserState us, const char *user,
-	const char *accountname, const char *protocol, int add_if_missing,
-	int *addedp,
+	const char *accountname, const char *protocol,
+	otrl_instag_t their_instance, int add_if_missing, int *addedp,
 	void (*add_app_data)(void *data, ConnContext *context), void *data)
 {
-	ConnContext ** curp;
-	int usercmp = 1, acctcmp = 1, protocmp = 1;
-	if (addedp) *addedp = 0;
-	if (!user || !accountname || !protocol) return NULL;
-	for (curp = &(us->context_root); *curp; curp = &((*curp)->next)) {
-		if ((usercmp = strcmp((*curp)->username, user)) > 0 ||
+    ConnContext ** curp;
+    int usercmp = 1, acctcmp = 1, protocmp = 1;
+    if (addedp) *addedp = 0;
+    if (!user || !accountname || !protocol) return NULL;
+
+    for (curp = &(us->context_root); *curp; curp = &((*curp)->next)) {
+	if ((usercmp = strcmp((*curp)->username, user)) > 0 ||
 		(usercmp == 0 &&
-		  (acctcmp = strcmp((*curp)->accountname, accountname)) > 0) ||
+		(acctcmp = strcmp((*curp)->accountname, accountname)) > 0) ||
 		(usercmp == 0 && acctcmp == 0 &&
-		  (protocmp = strcmp((*curp)->protocol, protocol)) >= 0))
-		/* We're at the right place in the list.  We've either found
-		 * it, or gone too far. */
-		break;
+		(protocmp = strcmp((*curp)->protocol, protocol)) > 0) ||
+		(usercmp == 0 && acctcmp == 0 && protocmp == 0
+		&& (their_instance < OTRL_MIN_VALID_INSTAG ||
+		    ((*curp)->their_instance >= their_instance))))
+	    /* We're at the right place in the list.  We've either found
+	     * it, or gone too far. */
+	    break;
+    }
+
+    if (usercmp == 0 && acctcmp == 0 && protocmp == 0 && *curp &&
+	    (their_instance < OTRL_MIN_VALID_INSTAG ||
+	    (their_instance == (*curp)->their_instance))) {
+	/* Found one! */
+	if (their_instance >= OTRL_MIN_VALID_INSTAG ||
+		their_instance == OTRL_INSTAG_MASTER) {
+	    return *curp;
 	}
-	if (usercmp == 0 && acctcmp == 0 && protocmp == 0) {
-	/* Found it! */
-	return *curp;
+
+	/* We need to go back and check more values in the context */
+	switch(their_instance) {
+	    case OTRL_INSTAG_BEST:
+		return otrl_context_find_recent_secure_instance(*curp);
+	    case OTRL_INSTAG_RECENT:
+	    case OTRL_INSTAG_RECENT_RECEIVED:
+	    case OTRL_INSTAG_RECENT_SENT:
+		return otrl_context_find_recent_instance(*curp, their_instance);
+	    default:
+		return NULL;
 	}
-	if (add_if_missing) {
+    }
+
+    if (add_if_missing) {
 	ConnContext *newctx;
+	OtrlInsTag *our_instag = (OtrlInsTag *)otrl_instag_find(us, accountname,
+		protocol);
+
 	if (addedp) *addedp = 1;
 	newctx = new_context(user, accountname, protocol);
 	newctx->next = *curp;
 	if (*curp) {
-		(*curp)->tous = &(newctx->next);
+	    (*curp)->tous = &(newctx->next);
 	}
 	*curp = newctx;
 	newctx->tous = curp;
 	if (add_app_data) {
-		add_app_data(data, *curp);
+	    add_app_data(data, *curp);
 	}
-	return *curp;
+
+	/* Initialize specified instance tags */
+	if (our_instag) {
+	    newctx->our_instance = our_instag->instag;
 	}
-	return NULL;
+
+	if (their_instance >= OTRL_MIN_VALID_INSTAG ||
+		their_instance == OTRL_INSTAG_MASTER) {
+	    newctx->their_instance = their_instance;
+	}
+
+	if (their_instance >= OTRL_MIN_VALID_INSTAG) {
+	    newctx->m_context = otrl_context_find(us, user, accountname,
+		protocol, OTRL_INSTAG_MASTER, 1, NULL, add_app_data, data);
+	}
+
+	if (their_instance == OTRL_INSTAG_MASTER) {
+	    /* if we're adding a master, there are no children, so the most
+	     * recent context is the one we add. */
+	    newctx->recent_child = newctx;
+	    newctx->recent_rcvd_child = newctx;
+	    newctx->recent_sent_child = newctx;
+	}
+
+	return *curp;
+    }
+    return NULL;
+}
+
+/* Return true iff the given fingerprint is marked as trusted. */
+int otrl_context_is_fingerprint_trusted(Fingerprint *fprint) {
+    return fprint && fprint->trust && fprint->trust[0] != '\0';
+}
+
+/* This method gets called after sending or receiving a message, to
+ * update the master context's "recent context" pointers. */
+void otrl_context_update_recent_child(ConnContext *context,
+	unsigned int sent_msg) {
+    ConnContext *m_context = context->m_context;
+
+    if (sent_msg) {
+	m_context->recent_sent_child = context;
+    } else {
+	m_context->recent_rcvd_child = context;
+    }
+
+    m_context->recent_child = context;
+
 }
 
 /* Find a fingerprint in a given context, perhaps adding it if not
@@ -144,107 +368,70 @@ ConnContext * otrl_context_find(OtrlUserState us, const char *user,
 Fingerprint *otrl_context_find_fingerprint(ConnContext *context,
 	unsigned char fingerprint[20], int add_if_missing, int *addedp)
 {
-	Fingerprint *f = context->fingerprint_root.next;
-	if (addedp) *addedp = 0;
-	while(f) {
+    Fingerprint *f;
+    if (addedp) *addedp = 0;
+
+    if (!context || !context->m_context) return NULL;
+
+    context = context->m_context;
+
+    f = context->fingerprint_root.next;
+    while(f) {
 	if (!memcmp(f->fingerprint, fingerprint, 20)) return f;
 	f = f->next;
-	}
-	/* Didn't find it. */
-	if (add_if_missing) {
+    }
+
+    /* Didn't find it. */
+    if (add_if_missing) {
 	if (addedp) *addedp = 1;
 	f = malloc(sizeof(*f));
 	assert(f != NULL);
 	f->fingerprint = malloc(20);
 	assert(f->fingerprint != NULL);
-	memcpy(f->fingerprint, fingerprint, 20);
+	memmove(f->fingerprint, fingerprint, 20);
 	f->context = context;
 	f->trust = NULL;
 	f->next = context->fingerprint_root.next;
 	if (f->next) {
-		f->next->tous = &(f->next);
+	    f->next->tous = &(f->next);
 	}
 	context->fingerprint_root.next = f;
 	f->tous = &(context->fingerprint_root.next);
 	return f;
-	}
-	return NULL;
+    }
+    return NULL;
 }
 
 /* Set the trust level for a given fingerprint */
 void otrl_context_set_trust(Fingerprint *fprint, const char *trust)
 {
-	if (fprint == NULL) return;
-
-	free(fprint->trust);
-	fprint->trust = trust ? _strdup(trust) : NULL;
-}
+    if (fprint == NULL) return;
 
-/* Set the preshared secret for a given fingerprint.  Note that this
- * currently only stores the secret in the ConnContext structure, but
- * doesn't yet do anything with it. */
-void otrl_context_set_preshared_secret(ConnContext *context,
-	const unsigned char *secret, size_t secret_len)
-{
-	free(context->preshared_secret);
-	context->preshared_secret = NULL;
-	context->preshared_secret_len = 0;
-
-	if (secret_len) {
-	context->preshared_secret = malloc(secret_len);
-	if (context->preshared_secret) {
-		memcpy(context->preshared_secret, secret, secret_len);
-		context->preshared_secret_len = secret_len;
-	}
-	}
+    free(fprint->trust);
+    fprint->trust = trust ? strdup(trust) : NULL;
 }
 
 /* Force a context into the OTRL_MSGSTATE_FINISHED state. */
 void otrl_context_force_finished(ConnContext *context)
 {
-	context->msgstate = OTRL_MSGSTATE_FINISHED;
-	otrl_auth_clear(&(context->auth));
-	free(context->fragment);
-	context->fragment = NULL;
-	context->fragment_len = 0;
-	context->fragment_n = 0;
-	context->fragment_k = 0;
-	context->active_fingerprint = NULL;
-	context->their_keyid = 0;
-	gcry_mpi_release(context->their_y);
-	context->their_y = NULL;
-	gcry_mpi_release(context->their_old_y);
-	context->their_old_y = NULL;
-	context->our_keyid = 0;
-	otrl_dh_keypair_free(&(context->our_dh_key));
-	otrl_dh_keypair_free(&(context->our_old_dh_key));
-	otrl_dh_session_free(&(context->sesskeys[0][0]));
-	otrl_dh_session_free(&(context->sesskeys[0][1]));
-	otrl_dh_session_free(&(context->sesskeys[1][0]));
-	otrl_dh_session_free(&(context->sesskeys[1][1]));
-	memset(context->sessionid, 0, 20);
-	context->sessionid_len = 0;
-	free(context->preshared_secret);
-	context->preshared_secret = NULL;
-	context->preshared_secret_len = 0;
-	context->protocol_version = 0;
-	context->numsavedkeys = 0;
-	free(context->saved_mac_keys);
-	context->saved_mac_keys = NULL;
-	gcry_free(context->lastmessage);
-	context->lastmessage = NULL;
-	context->may_retransmit = 0;
-	otrl_sm_state_free(context->smstate);
+    context->msgstate = OTRL_MSGSTATE_FINISHED;
+    otrl_auth_clear(&(context->auth));
+    context->active_fingerprint = NULL;
+    memset(context->sessionid, 0, 20);
+    context->sessionid_len = 0;
+    context->protocol_version = 0;
+    otrl_sm_state_free(context->smstate);
+    otrl_context_priv_force_finished(context->context_priv);
 }
 
 /* Force a context into the OTRL_MSGSTATE_PLAINTEXT state. */
 void otrl_context_force_plaintext(ConnContext *context)
 {
-	/* First clean up everything we'd need to do for the FINISHED state */
-	otrl_context_force_finished(context);
+    /* First clean up everything we'd need to do for the FINISHED state */
+    otrl_context_force_finished(context);
 
-	/* And just set the state properly */
-	context->msgstate = OTRL_MSGSTATE_PLAINTEXT;
+    /* And just set the state properly */
+    context->msgstate = OTRL_MSGSTATE_PLAINTEXT;
 }
 
 /* Forget a fingerprint (so long as it's not the active one.  If it's a
@@ -255,76 +442,106 @@ void otrl_context_force_plaintext(ConnContext *context)
 void otrl_context_forget_fingerprint(Fingerprint *fprint,
 	int and_maybe_context)
 {
-	ConnContext *context = fprint->context;
-	if (fprint == &(context->fingerprint_root)) {
+    ConnContext *context = fprint->context;
+    if (fprint == &(context->fingerprint_root)) {
 	if (context->msgstate == OTRL_MSGSTATE_PLAINTEXT &&
 		and_maybe_context) {
-		otrl_context_forget(context);
+	    otrl_context_forget(context);
 	}
-	} else {
+    } else {
 	if (context->msgstate != OTRL_MSGSTATE_PLAINTEXT ||
 		context->active_fingerprint != fprint) {
-		free(fprint->fingerprint);
-		free(fprint->trust);
-		*(fprint->tous) = fprint->next;
-		if (fprint->next) {
+
+	    free(fprint->fingerprint);
+	    free(fprint->trust);
+	    *(fprint->tous) = fprint->next;
+	    if (fprint->next) {
 		fprint->next->tous = fprint->tous;
-		}
-		free(fprint);
-		if (context->msgstate == OTRL_MSGSTATE_PLAINTEXT &&
-			context->fingerprint_root.next == NULL &&
-			and_maybe_context) {
+	    }
+	    free(fprint);
+	    if (context->msgstate == OTRL_MSGSTATE_PLAINTEXT &&
+		    context->fingerprint_root.next == NULL &&
+		    and_maybe_context) {
 		/* We just deleted the only fingerprint.  Forget the
 		 * whole thing. */
 		otrl_context_forget(context);
-		}
-	}
+	    }
 	}
+    }
 }
 
-/* Forget a whole context, so long as it's PLAINTEXT. */
-void otrl_context_forget(ConnContext *context)
+/* Forget a whole context, so long as it's PLAINTEXT. If a context has child
+ * instances, don't remove this instance unless children are also all in
+ * PLAINTEXT state. In this case, the children will also be removed.
+ * Returns 0 on success, 1 on failure. */
+int otrl_context_forget(ConnContext *context)
 {
-	if (context->msgstate != OTRL_MSGSTATE_PLAINTEXT) return;
+    if (context->msgstate != OTRL_MSGSTATE_PLAINTEXT) return 1;
 
-	/* Just to be safe, force to plaintext.  This also frees any
-	 * extraneous data lying around. */
-	otrl_context_force_plaintext(context);
+    if (context->their_instance == OTRL_INSTAG_MASTER) {
+	ConnContext *c_iter;
 
-	/* First free all the Fingerprints */
-	while(context->fingerprint_root.next) {
-	otrl_context_forget_fingerprint(context->fingerprint_root.next, 0);
+	for (c_iter = context; c_iter &&
+		c_iter->m_context == context->m_context;
+		c_iter = c_iter->next) {
+	    if (c_iter->msgstate != OTRL_MSGSTATE_PLAINTEXT) return 1;
 	}
-	/* Now free all the dynamic info here */
-	free(context->username);
-	free(context->accountname);
-	free(context->protocol);
-	free(context->smstate);
-	context->username = NULL;
-	context->accountname = NULL;
-	context->protocol = NULL;
-	context->smstate = NULL;
-
-	/* Free the application data, if it exists */
-	if (context->app_data && context->app_data_free) {
+
+	c_iter = context->next;
+	while (c_iter && c_iter->m_context == context->m_context) {
+	    if (!otrl_context_forget(c_iter)) {
+		c_iter = context->next;
+	    } else {
+		return 1;
+	    }
+	}
+
+    }
+
+    /* Just to be safe, force to plaintext.  This also frees any
+     * extraneous data lying around. */
+    otrl_context_force_plaintext(context);
+
+    /* First free all the Fingerprints */
+    while(context->fingerprint_root.next) {
+	otrl_context_forget_fingerprint(context->fingerprint_root.next, 0);
+    }
+    /* Now free all the dynamic info here */
+    free(context->username);
+    free(context->accountname);
+    free(context->protocol);
+    free(context->smstate);
+    context->username = NULL;
+    context->accountname = NULL;
+    context->protocol = NULL;
+    context->smstate = NULL;
+
+    /* Free the application data, if it exists */
+    if (context->app_data && context->app_data_free) {
 	(context->app_data_free)(context->app_data);
 	context->app_data = NULL;
-	}
+    }
 
-	/* Fix the list linkages */
-	*(context->tous) = context->next;
-	if (context->next) {
+    /* Fix the list linkages */
+    *(context->tous) = context->next;
+    if (context->next) {
 	context->next->tous = context->tous;
-	}
+    }
 
-	free(context);
+    free(context);
+    return 0;
 }
 
 /* Forget all the contexts in a given OtrlUserState. */
 void otrl_context_forget_all(OtrlUserState us)
 {
-	while (us->context_root) {
-	otrl_context_force_plaintext(us->context_root);
+    ConnContext *c_iter;
+
+    for (c_iter = us->context_root; c_iter; c_iter = c_iter->next) {
+	otrl_context_force_plaintext(c_iter);
+    }
+
+    while (us->context_root) {
 	otrl_context_forget(us->context_root);
-	}
+    }
 }