diff --git a/socket.h b/socket.h
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--- /dev/null
+++ b/socket.h
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+/*
+ * Copyright (C) 2015 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef __ADB_SOCKET_H
+#define __ADB_SOCKET_H
+
+#include <stddef.h>
+
+#include "fdevent.h"
+
+struct apacket;
+class atransport;
+
+/* An asocket represents one half of a connection between a local and
+** remote entity.  A local asocket is bound to a file descriptor.  A
+** remote asocket is bound to the protocol engine.
+*/
+struct asocket {
+        /* chain pointers for the local/remote list of
+        ** asockets that this asocket lives in
+        */
+    asocket *next;
+    asocket *prev;
+
+        /* the unique identifier for this asocket
+        */
+    unsigned id;
+
+        /* flag: set when the socket's peer has closed
+        ** but packets are still queued for delivery
+        */
+    int    closing;
+
+    // flag: set when the socket failed to write, so the socket will not wait to
+    // write packets and close directly.
+    bool has_write_error;
+
+        /* flag: quit adbd when both ends close the
+        ** local service socket
+        */
+    int    exit_on_close;
+
+        /* the asocket we are connected to
+        */
+
+    asocket *peer;
+
+        /* For local asockets, the fde is used to bind
+        ** us to our fd event system.  For remote asockets
+        ** these fields are not used.
+        */
+    fdevent fde;
+    int fd;
+
+        /* queue of apackets waiting to be written
+        */
+    apacket *pkt_first;
+    apacket *pkt_last;
+
+        /* enqueue is called by our peer when it has data
+        ** for us.  It should return 0 if we can accept more
+        ** data or 1 if not.  If we return 1, we must call
+        ** peer->ready() when we once again are ready to
+        ** receive data.
+        */
+    int (*enqueue)(asocket *s, apacket *pkt);
+
+        /* ready is called by the peer when it is ready for
+        ** us to send data via enqueue again
+        */
+    void (*ready)(asocket *s);
+
+        /* shutdown is called by the peer before it goes away.
+        ** the socket should not do any further calls on its peer.
+        ** Always followed by a call to close. Optional, i.e. can be NULL.
+        */
+    void (*shutdown)(asocket *s);
+
+        /* close is called by the peer when it has gone away.
+        ** we are not allowed to make any further calls on the
+        ** peer once our close method is called.
+        */
+    void (*close)(asocket *s);
+
+        /* A socket is bound to atransport */
+    atransport *transport;
+
+    size_t get_max_payload() const;
+};
+
+asocket *find_local_socket(unsigned local_id, unsigned remote_id);
+void install_local_socket(asocket *s);
+void remove_socket(asocket *s);
+void close_all_sockets(atransport *t);
+
+asocket *create_local_socket(int fd);
+asocket *create_local_service_socket(const char* destination,
+                                     const atransport* transport);
+
+asocket *create_remote_socket(unsigned id, atransport *t);
+void connect_to_remote(asocket *s, const char *destination);
+void connect_to_smartsocket(asocket *s);
+
+#endif  // __ADB_SOCKET_H