Added basic HTTP request processing in router.

- request to connection mapping in engine;
- requests queue in connection;
- engine port creation;
- connected ports hash for each process;
- engine port data messages processing (app responses);

src/nxt_conn.h

@@ -141,6 +141,8 @@ struct nxt_conn_s {
 
     nxt_conn_io_t                 *io;
 
+    nxt_queue_t                   requests; /* of nxt_req_conn_link_t */
+
 #if (NXT_SSLTLS || NXT_THREADS)
     /* SunC does not support "zero-sized struct/union". */
 
@@ -180,6 +182,16 @@ struct nxt_conn_s {
 };
 
 
+typedef uint32_t nxt_req_id_t;
+
+typedef struct {
+    nxt_req_id_t      req_id;
+    nxt_conn_t        *conn;
+
+    nxt_queue_link_t  link;
+} nxt_req_conn_link_t;
+
+
 #define nxt_conn_timer_init(ev, c, wq)                                        \
     do {                                                                      \
         (ev)->work_queue = (wq);                                              \
@@ -347,4 +359,10 @@ NXT_EXPORT void nxt_conn_proxy(nxt_task_t *task, nxt_conn_proxy_t *p);
 #define nxt_event_conn_close     nxt_conn_close
 
 
+NXT_EXPORT nxt_req_conn_link_t *nxt_conn_request_add(nxt_conn_t *c,
+    nxt_req_id_t req_id);
+NXT_EXPORT void nxt_conn_request_remove(nxt_conn_t *c,
+    nxt_req_conn_link_t *rc);
+
+
 #endif /* _NXT_CONN_H_INCLUDED_ */