+/*
+ * Copyright (c) 1983 Regents of the University of California.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * @(#)talkd.h 5.7 (Berkeley) 4/3/91
+ */
+
+#ifndef _TALKD_H_
+#define _TALKD_H_
+
+/*
+ * This describes the protocol used by the talk server and clients.
+ *
+ * The talk server acts a repository of invitations, responding to
+ * requests by clients wishing to rendezvous for the purpose of
+ * holding a conversation. In normal operation, a client, the caller,
+ * initiates a rendezvous by sending a CTL_MSG to the server of
+ * type LOOK_UP. This causes the server to search its invitation
+ * tables to check if an invitation currently exists for the caller
+ * (to speak to the callee specified in the message). If the lookup
+ * fails, the caller then sends an ANNOUNCE message causing the server
+ * to broadcast an announcement on the callee's login ports requesting
+ * contact. When the callee responds, the local server uses the
+ * recorded invitation to respond with the appropriate rendezvous
+ * address and the caller and callee client programs establish a
+ * stream connection through which the conversation takes place.
+ */
+
+/*
+ * Client->server request message format.
+ */
+typedef struct {
+ u_char vers; /* protocol version */
+ u_char type; /* request type, see below */
+ u_char answer; /* not used */
+ u_char pad;
+ u_long id_num; /* message id */
+ struct osockaddr addr; /* old (4.3) style */
+ struct osockaddr ctl_addr; /* old (4.3) style */
+ long pid; /* caller's process id */
+#define NAME_SIZE 12
+ char l_name[NAME_SIZE];/* caller's name */
+ char r_name[NAME_SIZE];/* callee's name */
+#define TTY_SIZE 16
+ char r_tty[TTY_SIZE];/* callee's tty name */
+} CTL_MSG;
+
+/*
+ * Server->client response message format.
+ */
+typedef struct {
+ u_char vers; /* protocol version */
+ u_char type; /* type of request message, see below */
+ u_char answer; /* respose to request message, see below */
+ u_char pad;
+ u_long id_num; /* message id */
+ struct osockaddr addr; /* address for establishing conversation */
+} CTL_RESPONSE;
+
+#define TALK_VERSION 1 /* protocol version */
+
+/* message type values */
+#define LEAVE_INVITE 0 /* leave invitation with server */
+#define LOOK_UP 1 /* check for invitation by callee */
+#define DELETE 2 /* delete invitation by caller */
+#define ANNOUNCE 3 /* announce invitation by caller */
+
+/* answer values */
+#define SUCCESS 0 /* operation completed properly */
+#define NOT_HERE 1 /* callee not logged in */
+#define FAILED 2 /* operation failed for unexplained reason */
+#define MACHINE_UNKNOWN 3 /* caller's machine name unknown */
+#define PERMISSION_DENIED 4 /* callee's tty doesn't permit announce */
+#define UNKNOWN_REQUEST 5 /* request has invalid type value */
+#define BADVERSION 6 /* request has invalid protocol version */
+#define BADADDR 7 /* request has invalid addr value */
+#define BADCTLADDR 8 /* request has invalid ctl_addr value */
+
+/*
+ * Operational parameters.
+ */
+#define MAX_LIFE 60 /* max time daemon saves invitations */
+/* RING_WAIT should be 10's of seconds less than MAX_LIFE */
+#define RING_WAIT 30 /* time to wait before resending invitation */
+
+#endif /* !_TALKD_H_ */
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