180807d214
- yp_dblookup.c: Create non-DB specific database access functions. Using these allows access to the underlying database functions without needing explicit knowledge of Berkeley DB. (These are used only when DB_CACHE is #defined. Other programs that use the non-caching functions (yp_mkdb, ypxfr, yppush, rpc.yppasswdd) shouldn't notice the difference.) - yp_dnslookup: Implement async DNS lookups. We send our own DNS requests using UDP and put the request in a queue. When the response arrives, we use the ID in the header to find the corresponsing queue entry and then send the response to the client. We can go about our business and handle other YP requests in the meantime. This way, we can deal with time consuming DNS requests without blocking and without forking. - yp_server.c: Convert to using new non-DB-specific database access functions. This simplifies the code a bit and removes the need for this module to know anything about Berkeley DB. Also convert the ypproc_match_2_svc() function to use the async DNS lookup routines. - yp_main.c: tweak yp_svc_run() to add the resolver socket to the set of descriptors monitored in the select() loop. Also add a timeout to select(); we may get stale DNS requests stuck in the queue which we want to invalidate after a while. If the timeout hits, we decrement the ttl on all pending DNS requests and nuke those requests that aren't handled before ttl hits zero. - yp_extern.h: Add prototypes for new stuff. - yp_svc_udp.c (new file): The async resolver code needs to be able to rummage around inside the RPC UDP transport handle in order to work correcty. There's basically one transport handle, and each time a request comes in, the transaction ID in the handle is changed. This means that if we queue a DNS request, then we handle some other unrelated requests, we will be unable to send the DNS response because the transaction ID and remote address of the client that made the DNS request will have been lost. What we need to do is save the client address and transaction ID in the queue entry for the DNS request, then put the transaction ID and address back in the transport handle when we're ready to reply. (And then we have to undo the change so as not to confuse any other part of the server.) The trouble is that the transaction ID is hidden in an opaque part of the transport handle, and only the code in the svc_udp module in the RPC library knows how to handle it. This file contains a couple of functions that let us read and set the transaction ID in spite of this. This is really a dirty trick and I should be taken out and shot for even thinking about it, but there's no other way to get this stuff to work. - Makefile: add yp_svc_udp.c to SRCS.
114 lines
4.1 KiB
C
114 lines
4.1 KiB
C
/*
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* Copyright (c) 1995
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* Bill Paul <wpaul@ctr.columbia.edu>. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Bill Paul.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL Bill Paul OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id: yp_extern.h,v 1.3 1996/12/22 15:53:55 wpaul Exp $
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*/
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/cdefs.h>
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#include <sys/types.h>
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#include <limits.h>
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#include <db.h>
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#include <rpc/rpc.h>
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#include <rpcsvc/yp.h>
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#ifndef _PATH_YP
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#define _PATH_YP "/var/yp/"
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#endif
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#ifndef _PATH_LIBEXEC
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#define _PATH_LIBEXEC "/usr/libexec/"
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#endif
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#ifndef MAX_CHILDREN
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#define MAX_CHILDREN 20
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#endif
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#define YP_SECURE 0x1
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#define YP_INTERDOMAIN 0x2
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/*
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* External functions and variables.
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*/
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extern int debug;
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extern int ypdb_debug;
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extern int do_dns;
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extern int children;
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extern int resfd;
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extern char *progname;
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extern char *yp_dir;
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extern enum ypstat yp_errno;
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extern void yp_error __P((const char *, ...));
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#ifdef DB_CACHE
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extern int yp_get_record __P(( DB *, const DBT *, DBT *, int));
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#else
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extern int yp_get_record __P(( const char *, const char *, const DBT *, DBT *, int));
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#endif
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extern int yp_first_record __P((const DB *, DBT *, DBT *, int));
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extern int yp_next_record __P((const DB *, DBT *, DBT *, int, int));
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extern char *yp_dnsname __P(( char * ));
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extern char *yp_dnsaddr __P(( const char * ));
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#ifdef DB_CACHE
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extern int yp_access __P((const char *, const char *, const struct svc_req * ));
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#else
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extern int yp_access __P((const char *, const struct svc_req * ));
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#endif
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extern int yp_validdomain __P((const char * ));
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extern DB *yp_open_db __P(( const char *, const char *));
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extern DB *yp_open_db_cache __P(( const char *, const char *, const char *, int ));
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extern void yp_flush_all __P(( void ));
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extern void yp_init_dbs __P(( void ));
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extern int yp_testflag __P(( char *, char *, int ));
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extern void load_securenets __P(( void ));
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#ifdef DB_CACHE
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extern ypstat yp_select_map __P(( char *, char *, keydat *, int ));
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extern ypstat yp_getbykey __P(( keydat *, valdat * ));
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extern ypstat yp_firstbykey __P(( keydat *, valdat * ));
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extern ypstat yp_nextbykey __P(( keydat *, valdat * ));
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#endif
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extern unsigned long svcudp_set_xid __P(( SVCXPRT *, unsigned long ));
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extern unsigned long svcudp_get_xid __P(( SVCXPRT * ));
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#ifndef RESOLVER_TIMEOUT
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#define RESOLVER_TIMEOUT 3600
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#endif
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extern int yp_init_resolver __P(( void ));
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extern int yp_dnsq_pending __P(( void ));
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extern void yp_run_dnsq __P(( void ));
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extern void yp_prune_dnsq __P(( void ));
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extern ypstat yp_async_lookup_name __P(( SVCXPRT *, char * ));
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extern ypstat yp_async_lookup_addr __P(( SVCXPRT *, char * ));
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