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diff --git a/doc/spec/proposals/ideas/xxx-separate-streams-by-port.txt b/doc/spec/proposals/ideas/xxx-separate-streams-by-port.txt
new file mode 100644
index 0000000000..cebde65a9b
--- /dev/null
+++ b/doc/spec/proposals/ideas/xxx-separate-streams-by-port.txt
@@ -0,0 +1,61 @@
+Filename: xxx-separate-streams-by-port.txt
+Title: Separate streams across circuits by destination port
+Version: $Revision$
+Last-Modified: $Date$
+Author: Robert Hogan
+Created: 21-Oct-2008
+Status: Draft
+
+Here's a patch Robert Hogan wrote to use only one destination port per
+circuit. It's based on a wishlist item Roger wrote, to never send AIM
+usernames over the same circuit that we're hoping to browse anonymously
+through. The remaining open question is: how many extra circuits does this
+cause an ordinary user to create? My guess is not very many, but I'm wary
+of putting this in until we have some better estimate. On the other hand,
+not putting it in means that we have a known security flaw. Hm.
+
+Index: src/or/or.h
+===================================================================
+--- src/or/or.h (revision 17143)
++++ src/or/or.h (working copy)
+@@ -1874,6 +1874,7 @@
+
+   uint8_t state; /**< Current status of this circuit. */
+   uint8_t purpose; /**< Why are we creating this circuit? */
++  uint16_t service; /**< Port conn must have to use this circuit. */
+
+   /** How many relay data cells can we package (read from edge streams)
+    * on this circuit before we receive a circuit-level sendme cell asking
+Index: src/or/circuituse.c
+===================================================================
+--- src/or/circuituse.c (revision 17143)
++++ src/or/circuituse.c (working copy)
+@@ -62,10 +62,16 @@
+       return 0;
+   }
+
+-  if (purpose == CIRCUIT_PURPOSE_C_GENERAL)
++  if (purpose == CIRCUIT_PURPOSE_C_GENERAL) {
+     if (circ->timestamp_dirty &&
+        circ->timestamp_dirty+get_options()->MaxCircuitDirtiness <= now)
+       return 0;
++    /* If the circuit is dirty and used for services on another port,
++      then it is not suitable. */
++    if (circ->service && conn->socks_request->port &&
++       (circ->service != conn->socks_request->port))
++      return 0;
++  }
+
+   /* decide if this circ is suitable for this conn */
+
+@@ -1351,7 +1357,9 @@
+     if (connection_ap_handshake_send_resolve(conn) < 0)
+       return -1;
+   }
+-
++  if (conn->socks_request->port
++     && (TO_CIRCUIT(circ)->purpose == CIRCUIT_PURPOSE_C_GENERAL))
++    TO_CIRCUIT(circ)->service = conn->socks_request->port;
+   return 1;
+ }
+