--- /dev/null
+/*
+ * Network proxy abstraction in PuTTY
+ *
+ * A proxy layer, if necessary, wedges itself between the
+ * network code and the higher level backend.
+ *
+ * Supported proxies: HTTP CONNECT, generic telnet
+ * In progress: SOCKS
+ */
+
+#ifndef PUTTY_PROXY_H
+#define PUTTY_PROXY_H
+
+#define PROXY_ERROR_GENERAL 8000
+#define PROXY_ERROR_UNEXPECTED 8001
+
+typedef struct Socket_proxy_tag * Proxy_Socket;
+
+struct Socket_proxy_tag {
+ struct socket_function_table *fn;
+ /* the above variable absolutely *must* be the first in this structure */
+
+ char * error;
+
+ Socket sub_socket;
+ Plug plug;
+ SockAddr remote_addr;
+ int remote_port;
+
+ bufchain pending_output_data;
+ bufchain pending_oob_output_data;
+ int pending_flush;
+ bufchain pending_input_data;
+
+#define PROXY_STATE_NEW -1
+#define PROXY_STATE_ACTIVE 0
+
+ int state; /* proxy states greater than 0 are implementation
+ * dependent, but represent various stages/states
+ * of the initialization/setup/negotiation with the
+ * proxy server.
+ */
+ int freeze; /* should we freeze the underlying socket when
+ * we are done with the proxy negotiation? this
+ * simply caches the value of sk_set_frozen calls.
+ */
+
+#define PROXY_CHANGE_NEW -1
+#define PROXY_CHANGE_CLOSING 0
+#define PROXY_CHANGE_SENT 1
+#define PROXY_CHANGE_RECEIVE 2
+#define PROXY_CHANGE_ACCEPTING 3
+
+ /* something has changed (a call from the sub socket
+ * layer into our Proxy Plug layer, or we were just
+ * created, etc), so the proxy layer needs to handle
+ * this change (the type of which is the second argument)
+ * and further the proxy negotiation process.
+ */
+
+ int (*negotiate) (Proxy_Socket /* this */, int /* change type */);
+
+ /* current arguments of plug handlers
+ * (for use by proxy's negotiate function)
+ */
+
+ /* closing */
+ char *closing_error_msg;
+ int closing_error_code;
+ int closing_calling_back;
+
+ /* receive */
+ int receive_urgent;
+ char *receive_data;
+ int receive_len;
+
+ /* sent */
+ int sent_bufsize;
+
+ /* accepting */
+ void *accepting_sock;
+
+ /* spin locks, for the critical switch from negotiating
+ * to active state. we have to dump all of our pending
+ * buffers without new events (read, writes, etc) corrupting
+ * things. we should not have built up a large amount of
+ * pending data during negotiation, so hopefully this will
+ * not have a large effect on performance.
+ */
+
+ char lock_close;
+ char lock_write;
+ char lock_write_oob;
+ char lock_receive;
+ char lock_flush;
+ char lock_closing;
+ char lock_sent;
+ char lock_accepting;
+ char lock_freeze;
+
+};
+
+typedef struct Plug_proxy_tag * Proxy_Plug;
+
+struct Plug_proxy_tag {
+ struct plug_function_table *fn;
+ /* the above variable absolutely *must* be the first in this structure */
+
+ Proxy_Socket proxy_socket;
+
+};
+
+extern void proxy_activate (Proxy_Socket);
+
+extern int proxy_http_negotiate (Proxy_Socket, int);
+extern int proxy_telnet_negotiate (Proxy_Socket, int);
+extern int proxy_socks_negotiate (Proxy_Socket, int);
+
+#endif