From 4b7930dbbd8a11fb5db3e1cc81ca9ca5b0a69fc0 Mon Sep 17 00:00:00 2001
From: Ton Roosendaal <ton@blender.org>
Date: Mon, 17 Jan 2011 15:16:08 +0000
Subject: [PATCH] Bugfix #25681

Python API allowed to make links with input->output reversed.
Now node api checks for this case and flips order.
---
 source/blender/blenkernel/intern/node.c       | 58 +++++++++++++++++--
 source/blender/makesrna/intern/rna_nodetree.c | 13 +++--
 2 files changed, 59 insertions(+), 12 deletions(-)

diff --git a/source/blender/blenkernel/intern/node.c b/source/blender/blenkernel/intern/node.c
index c4d54cd6296..fd0edd83c7d 100644
--- a/source/blender/blenkernel/intern/node.c
+++ b/source/blender/blenkernel/intern/node.c
@@ -1082,15 +1082,61 @@ bNode *nodeCopyNode(struct bNodeTree *ntree, struct bNode *node, int internal)
 	return nnode;
 }
 
+/* fromsock and tosock can be NULL */
+/* also used via rna api, so we check for proper input output direction */
 bNodeLink *nodeAddLink(bNodeTree *ntree, bNode *fromnode, bNodeSocket *fromsock, bNode *tonode, bNodeSocket *tosock)
 {
-	bNodeLink *link= MEM_callocN(sizeof(bNodeLink), "link");
+	bNodeSocket *sock;
+	bNodeLink *link= NULL; 
+	int from= 0, to= 0;
 	
-	BLI_addtail(&ntree->links, link);
-	link->fromnode= fromnode;
-	link->fromsock= fromsock;
-	link->tonode= tonode;
-	link->tosock= tosock;
+	if(fromsock) {
+		/* test valid input */
+		for(sock= fromnode->outputs.first; sock; sock= sock->next)
+			if(sock==fromsock)
+				break;
+		if(sock)
+			from= 1; /* OK */
+		else {
+			for(sock= fromnode->inputs.first; sock; sock= sock->next)
+				if(sock==fromsock)
+					break;
+			if(sock)
+				from= -1; /* OK but flip */
+		}
+	}
+	if(tosock) {
+		for(sock= tonode->inputs.first; sock; sock= sock->next)
+			if(sock==tosock)
+				break;
+		if(sock)
+			to= 1; /* OK */
+		else {
+			for(sock= tonode->outputs.first; sock; sock= sock->next)
+				if(sock==tosock)
+					break;
+			if(sock)
+				to= -1; /* OK but flip */
+		}
+	}
+	
+	/* this allows NULL sockets to work */
+	if(from >= 0 && to >= 0) {
+		link= MEM_callocN(sizeof(bNodeLink), "link");
+		BLI_addtail(&ntree->links, link);
+		link->fromnode= fromnode;
+		link->fromsock= fromsock;
+		link->tonode= tonode;
+		link->tosock= tosock;
+	}
+	else if(from <= 0 && to <= 0) {
+		link= MEM_callocN(sizeof(bNodeLink), "link");
+		BLI_addtail(&ntree->links, link);
+		link->fromnode= tonode;
+		link->fromsock= tosock;
+		link->tonode= fromnode;
+		link->tosock= fromsock;
+	}
 	
 	return link;
 }
diff --git a/source/blender/makesrna/intern/rna_nodetree.c b/source/blender/makesrna/intern/rna_nodetree.c
index 9d4575b2f43..5c962145c55 100644
--- a/source/blender/makesrna/intern/rna_nodetree.c
+++ b/source/blender/makesrna/intern/rna_nodetree.c
@@ -524,15 +524,16 @@ static bNodeLink *rna_NodeTree_link_new(bNodeTree *ntree, ReportList *reports, b
 	nodeRemSocketLinks(ntree, out);
 
 	ret= nodeAddLink(ntree, fromnode, in, tonode, out);
+	
+	if(ret) {
+		NodeTagChanged(ntree, tonode);
 
-	NodeTagChanged(ntree, tonode);
+		nodeVerifyGroup(ntree); /* update group node socket links*/
 
-	nodeVerifyGroup(ntree); /* update group node socket links*/
-
-	ntreeSolveOrder(ntree);
-
-	WM_main_add_notifier(NC_NODE|NA_EDITED, ntree);
+		ntreeSolveOrder(ntree);
 
+		WM_main_add_notifier(NC_NODE|NA_EDITED, ntree);
+	}
 	return ret;
 }