1 files changed, 372 insertions, 0 deletions

diff --git a/src/util/auto_clnt.c b/src/util/auto_clnt.c
new file mode 100644
index 0000000..cdbbe22
--- /dev/null
+++ b/src/util/auto_clnt.c
@@ -0,0 +1,372 @@
+/*++
+/* NAME
+/*	auto_clnt 3
+/* SUMMARY
+/*	client endpoint maintenance
+/* SYNOPSIS
+/*	#include <auto_clnt.h>
+/*
+/*	typedef void (*AUTO_CLNT_HANDSHAKE_FN)(VSTREAM *);
+/*
+/*	AUTO_CLNT *auto_clnt_create(service, timeout, max_idle, max_ttl)
+/*	const char *service;
+/*	int	timeout;
+/*	int	max_idle;
+/*	int	max_ttl;
+/*
+/*	VSTREAM	*auto_clnt_access(auto_clnt)
+/*	AUTO_CLNT *auto_clnt;
+/*
+/*	void	auto_clnt_recover(auto_clnt)
+/*	AUTO_CLNT *auto_clnt;
+/*
+/*	const char *auto_clnt_name(auto_clnt)
+/*	AUTO_CLNT *auto_clnt;
+/*
+/*	void	auto_clnt_free(auto_clnt)
+/*	AUTO_CLNT *auto_clnt;
+/*
+/*	void	auto_clnt_control(auto_clnt, name, value, ... AUTO_CLNT_CTL_END)
+/*	AUTO_CLNT *auto_clnt;
+/*	int	name;
+/* DESCRIPTION
+/*	This module maintains IPC client endpoints that automatically
+/*	disconnect after a being idle for a configurable amount of time,
+/*	that disconnect after a configurable time to live,
+/*	and that transparently handle most server-initiated disconnects.
+/*
+/*	This module tries each operation only a limited number of
+/*	times and then reports an error.  This is unlike the
+/*	clnt_stream(3) module which will retry forever, so that
+/*	the application never experiences an error.
+/*
+/*	auto_clnt_create() instantiates a client endpoint.
+/*
+/*	auto_clnt_access() returns an open stream to the service specified
+/*	to auto_clnt_create(). The stream instance may change between calls.
+/*	The result is a null pointer in case of failure.
+/*
+/*	auto_clnt_recover() recovers from a server-initiated disconnect
+/*	that happened in the middle of an I/O operation.
+/*
+/*	auto_clnt_name() returns the name of the specified client endpoint.
+/*
+/*	auto_clnt_free() destroys of the specified client endpoint.
+/*
+/*	auto_clnt_control() allows the user to fine tune the behavior of
+/*      the specified client. The arguments are a list of (name, value)
+/*      terminated with AUTO_CLNT_CTL_END.
+/*      The following lists the names and the types of the corresponding
+/*      value arguments.
+/* .IP "AUTO_CLNT_CTL_HANDSHAKE(VSTREAM *)"
+/*      A pointer to function that will be called at the start of a
+/*      new connection, and that returns 0 in case of success.
+/* .PP
+/*	Arguments:
+/* .IP service
+/*	The service argument specifies "transport:servername" where
+/*	transport is currently limited to one of the following:
+/* .RS
+/* .IP inet
+/*	servername has the form "inet:host:port".
+/* .IP local
+/*	servername has the form "local:private/servicename" or
+/*	"local:public/servicename". This is the preferred way to
+/*	specify Postfix daemons that are configured as "unix" in
+/*	master.cf.
+/* .IP unix
+/*	servername has the form "unix:private/servicename" or
+/*	"unix:public/servicename". This does not work on Solaris,
+/*	where Postfix uses STREAMS instead of UNIX-domain sockets.
+/* .RE
+/* .IP timeout
+/*	The time limit for sending, receiving, or for connecting
+/*	to a server. Specify a value <=0 to disable the time limit.
+/* .IP max_idle
+/*	Idle time after which the client disconnects. Specify 0 to
+/*	disable the limit.
+/* .IP max_ttl
+/*	Upper bound on the time that a connection is allowed to persist.
+/*	Specify 0 to disable the limit.
+/* .IP open_action
+/*	Application call-back routine that opens a stream or returns a
+/*	null pointer upon failure. In case of success, the call-back routine
+/*	is expected to set the stream pathname to the server endpoint name.
+/* .IP context
+/*	Application context that is passed to the open_action routine.
+/* .IP handshake
+/*	A null pointer, or a pointer to function that will be called
+/*	at the start of a new connection and that returns 0 in case
+/*	of success.
+/* DIAGNOSTICS
+/*	Warnings: communication failure. Fatal error: out of memory.
+/* LICENSE
+/* .ad
+/* .fi
+/*	The Secure Mailer license must be distributed with this software.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Wietse Venema
+/*	Google, Inc.
+/*	111 8th Avenue
+/*	New York, NY 10011, USA
+/*--*/
+
+/* System library. */
+
+#include <sys_defs.h>
+#include <string.h>
+
+/* Utility library. */
+
+#include <msg.h>
+#include <mymalloc.h>
+#include <vstream.h>
+#include <events.h>
+#include <iostuff.h>
+#include <connect.h>
+#include <split_at.h>
+#include <auto_clnt.h>
+
+/* Application-specific. */
+
+ /*
+  * AUTO_CLNT is an opaque structure. None of the access methods can easily
+  * be implemented as a macro, and access is not performance critical anyway.
+  */
+struct AUTO_CLNT {
+    VSTREAM *vstream;			/* buffered I/O */
+    char   *endpoint;			/* host:port or pathname */
+    int     timeout;			/* I/O time limit */
+    int     max_idle;			/* time before client disconnect */
+    int     max_ttl;			/* time before client disconnect */
+    AUTO_CLNT_HANDSHAKE_FN handshake;	/* new connection only */
+    int     (*connect) (const char *, int, int);	/* unix, local, inet */
+};
+
+static void auto_clnt_close(AUTO_CLNT *);
+
+/* auto_clnt_event - server-initiated disconnect or client-side max_idle */
+
+static void auto_clnt_event(int unused_event, void *context)
+{
+    AUTO_CLNT *auto_clnt = (AUTO_CLNT *) context;
+
+    /*
+     * Sanity check. This routine causes the stream to be closed, so it
+     * cannot be called when the stream is already closed.
+     */
+    if (auto_clnt->vstream == 0)
+	msg_panic("auto_clnt_event: stream is closed");
+
+    auto_clnt_close(auto_clnt);
+}
+
+/* auto_clnt_ttl_event - client-side expiration */
+
+static void auto_clnt_ttl_event(int event, void *context)
+{
+
+    /*
+     * XXX This function is needed only because event_request_timer() cannot
+     * distinguish between requests that specify the same call-back routine
+     * and call-back context. The fix is obvious: specify a request ID along
+     * with the call-back routine, but there is too much code that would have
+     * to be changed.
+     * 
+     * XXX Should we be concerned that an overly aggressive optimizer will
+     * eliminate this function and replace calls to auto_clnt_ttl_event() by
+     * direct calls to auto_clnt_event()? It should not, because there exists
+     * code that takes the address of both functions.
+     */
+    auto_clnt_event(event, context);
+}
+
+/* auto_clnt_open - connect to service */
+
+static void auto_clnt_open(AUTO_CLNT *auto_clnt)
+{
+    const char *myname = "auto_clnt_open";
+    int     fd;
+
+    /*
+     * Sanity check.
+     */
+    if (auto_clnt->vstream)
+	msg_panic("auto_clnt_open: stream is open");
+
+    /*
+     * Schedule a read event so that we can clean up when the remote side
+     * disconnects, and schedule a timer event so that we can cleanup an idle
+     * connection. Note that both events are handled by the same routine.
+     * 
+     * Finally, schedule an event to force disconnection even when the
+     * connection is not idle. This is to prevent one client from clinging on
+     * to a server forever.
+     */
+    fd = auto_clnt->connect(auto_clnt->endpoint, BLOCKING, auto_clnt->timeout);
+    if (fd < 0) {
+	msg_warn("connect to %s: %m", auto_clnt->endpoint);
+    } else {
+	if (msg_verbose)
+	    msg_info("%s: connected to %s", myname, auto_clnt->endpoint);
+	auto_clnt->vstream = vstream_fdopen(fd, O_RDWR);
+	vstream_control(auto_clnt->vstream,
+			CA_VSTREAM_CTL_PATH(auto_clnt->endpoint),
+			CA_VSTREAM_CTL_TIMEOUT(auto_clnt->timeout),
+			CA_VSTREAM_CTL_END);
+    }
+
+    if (auto_clnt->vstream != 0) {
+	close_on_exec(vstream_fileno(auto_clnt->vstream), CLOSE_ON_EXEC);
+	event_enable_read(vstream_fileno(auto_clnt->vstream), auto_clnt_event,
+			  (void *) auto_clnt);
+	if (auto_clnt->max_idle > 0)
+	    event_request_timer(auto_clnt_event, (void *) auto_clnt,
+				auto_clnt->max_idle);
+	if (auto_clnt->max_ttl > 0)
+	    event_request_timer(auto_clnt_ttl_event, (void *) auto_clnt,
+				auto_clnt->max_ttl);
+    }
+}
+
+/* auto_clnt_close - disconnect from service */
+
+static void auto_clnt_close(AUTO_CLNT *auto_clnt)
+{
+    const char *myname = "auto_clnt_close";
+
+    /*
+     * Sanity check.
+     */
+    if (auto_clnt->vstream == 0)
+	msg_panic("%s: stream is closed", myname);
+
+    /*
+     * Be sure to disable read and timer events.
+     */
+    if (msg_verbose)
+	msg_info("%s: disconnect %s stream",
+		 myname, VSTREAM_PATH(auto_clnt->vstream));
+    event_disable_readwrite(vstream_fileno(auto_clnt->vstream));
+    event_cancel_timer(auto_clnt_event, (void *) auto_clnt);
+    event_cancel_timer(auto_clnt_ttl_event, (void *) auto_clnt);
+    (void) vstream_fclose(auto_clnt->vstream);
+    auto_clnt->vstream = 0;
+}
+
+/* auto_clnt_recover - recover from server-initiated disconnect */
+
+void    auto_clnt_recover(AUTO_CLNT *auto_clnt)
+{
+
+    /*
+     * Clean up. Don't re-connect until the caller needs it.
+     */
+    if (auto_clnt->vstream)
+	auto_clnt_close(auto_clnt);
+}
+
+/* auto_clnt_access - access a client stream */
+
+VSTREAM *auto_clnt_access(AUTO_CLNT *auto_clnt)
+{
+    AUTO_CLNT_HANDSHAKE_FN handshake;
+
+    /*
+     * Open a stream or restart the idle timer.
+     * 
+     * Important! Do not restart the TTL timer!
+     */
+    if (auto_clnt->vstream == 0) {
+	auto_clnt_open(auto_clnt);
+	handshake = (auto_clnt->vstream ? auto_clnt->handshake : 0);
+    } else {
+	if (auto_clnt->max_idle > 0)
+	    event_request_timer(auto_clnt_event, (void *) auto_clnt,
+				auto_clnt->max_idle);
+	handshake = 0;
+    }
+    if (handshake != 0 && handshake(auto_clnt->vstream) != 0)
+	return (0);
+    return (auto_clnt->vstream);
+}
+
+/* auto_clnt_create - create client stream object */
+
+AUTO_CLNT *auto_clnt_create(const char *service, int timeout,
+			            int max_idle, int max_ttl)
+{
+    const char *myname = "auto_clnt_create";
+    char   *transport = mystrdup(service);
+    char   *endpoint;
+    AUTO_CLNT *auto_clnt;
+
+    /*
+     * Don't open the stream until the caller needs it.
+     */
+    if ((endpoint = split_at(transport, ':')) == 0
+	|| *endpoint == 0 || *transport == 0)
+	msg_fatal("need service transport:endpoint instead of \"%s\"", service);
+    if (msg_verbose)
+	msg_info("%s: transport=%s endpoint=%s", myname, transport, endpoint);
+    auto_clnt = (AUTO_CLNT *) mymalloc(sizeof(*auto_clnt));
+    auto_clnt->vstream = 0;
+    auto_clnt->endpoint = mystrdup(endpoint);
+    auto_clnt->timeout = timeout;
+    auto_clnt->max_idle = max_idle;
+    auto_clnt->max_ttl = max_ttl;
+    auto_clnt->handshake = 0;
+    if (strcmp(transport, "inet") == 0) {
+	auto_clnt->connect = inet_connect;
+    } else if (strcmp(transport, "local") == 0) {
+	auto_clnt->connect = LOCAL_CONNECT;
+    } else if (strcmp(transport, "unix") == 0) {
+	auto_clnt->connect = unix_connect;
+    } else {
+	msg_fatal("invalid transport name: %s in service: %s",
+		  transport, service);
+    }
+    myfree(transport);
+    return (auto_clnt);
+}
+
+/* auto_clnt_name - return client stream name */
+
+const char *auto_clnt_name(AUTO_CLNT *auto_clnt)
+{
+    return (auto_clnt->endpoint);
+}
+
+/* auto_clnt_free - destroy client stream instance */
+
+void    auto_clnt_free(AUTO_CLNT *auto_clnt)
+{
+    if (auto_clnt->vstream)
+	auto_clnt_close(auto_clnt);
+    myfree(auto_clnt->endpoint);
+    myfree((void *) auto_clnt);
+}
+
+/* auto_clnt_control - fine control */
+
+void    auto_clnt_control(AUTO_CLNT *client, int name,...)
+{
+    const char *myname = "auto_clnt_control";
+    va_list ap;
+
+    for (va_start(ap, name); name != AUTO_CLNT_CTL_END; name = va_arg(ap, int)) {
+	switch (name) {
+	case AUTO_CLNT_CTL_HANDSHAKE:
+	    client->handshake = va_arg(ap, AUTO_CLNT_HANDSHAKE_FN);
+	    break;
+	default:
+	    msg_panic("%s: bad name %d", myname, name);
+	}
+    }
+    va_end(ap);
+}