[745] | 1 | /*
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| 2 | Unix SMB/CIFS implementation.
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| 3 | a async DNS handler
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| 4 | Copyright (C) Andrew Tridgell 1997-1998
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| 5 |
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| 6 | This program is free software; you can redistribute it and/or modify
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| 7 | it under the terms of the GNU General Public License as published by
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| 8 | the Free Software Foundation; either version 3 of the License, or
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| 9 | (at your option) any later version.
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| 10 |
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| 11 | This program is distributed in the hope that it will be useful,
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| 12 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 14 | GNU General Public License for more details.
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| 15 |
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| 16 | You should have received a copy of the GNU General Public License
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| 17 | along with this program. If not, see <http://www.gnu.org/licenses/>.
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| 18 | */
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[659] | 19 |
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[745] | 20 | #include "includes.h"
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| 21 | #include "nmbd/nmbd.h"
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[659] | 22 | #ifdef __OS2__
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[664] | 23 | #define pipe(A) os2_pipe(A)
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[659] | 24 | #endif
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[745] | 25 |
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| 26 | /***************************************************************************
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| 27 | Add a DNS result to the name cache.
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| 28 | ****************************************************************************/
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| 29 |
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| 30 | static struct name_record *add_dns_result(struct nmb_name *question, struct in_addr addr)
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| 31 | {
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| 32 | int name_type = question->name_type;
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| 33 | unstring qname;
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| 34 |
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| 35 | pull_ascii_nstring(qname, sizeof(qname), question->name);
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| 36 |
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| 37 | if (!addr.s_addr) {
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| 38 | /* add the fail to WINS cache of names. give it 1 hour in the cache */
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| 39 | DEBUG(3,("add_dns_result: Negative DNS answer for %s\n", qname));
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| 40 | add_name_to_subnet( wins_server_subnet, qname, name_type,
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| 41 | NB_ACTIVE, 60*60, DNSFAIL_NAME, 1, &addr );
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| 42 | return NULL;
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| 43 | }
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| 44 |
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| 45 | /* add it to our WINS cache of names. give it 2 hours in the cache */
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| 46 | DEBUG(3,("add_dns_result: DNS gave answer for %s of %s\n", qname, inet_ntoa(addr)));
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| 47 |
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| 48 | add_name_to_subnet( wins_server_subnet, qname, name_type,
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| 49 | NB_ACTIVE, 2*60*60, DNS_NAME, 1, &addr);
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| 50 |
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| 51 | return find_name_on_subnet(wins_server_subnet, question, FIND_ANY_NAME);
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| 52 | }
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| 53 |
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| 54 | #ifndef SYNC_DNS
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| 55 |
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| 56 | static int fd_in = -1, fd_out = -1;
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| 57 | static pid_t child_pid = -1;
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| 58 | static int in_dns;
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| 59 |
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| 60 | /* this is the structure that is passed between the parent and child */
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| 61 | struct query_record {
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| 62 | struct nmb_name name;
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| 63 | struct in_addr result;
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| 64 | };
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| 65 |
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| 66 | /* a queue of pending requests waiting to be sent to the DNS child */
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| 67 | static struct packet_struct *dns_queue;
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| 68 |
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| 69 | /* the packet currently being processed by the dns child */
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| 70 | static struct packet_struct *dns_current;
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| 71 |
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| 72 |
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| 73 | /***************************************************************************
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| 74 | return the fd used to gather async dns replies. This is added to the select
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| 75 | loop
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| 76 | ****************************************************************************/
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| 77 |
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| 78 | int asyncdns_fd(void)
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| 79 | {
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| 80 | return fd_in;
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| 81 | }
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| 82 |
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| 83 | /***************************************************************************
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| 84 | handle DNS queries arriving from the parent
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| 85 | ****************************************************************************/
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| 86 | static void asyncdns_process(void)
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| 87 | {
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| 88 | struct query_record r;
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| 89 | unstring qname;
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| 90 |
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| 91 | DEBUGLEVEL = -1;
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| 92 |
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| 93 | while (1) {
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| 94 | NTSTATUS status;
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| 95 |
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| 96 | status = read_data(fd_in, (char *)&r, sizeof(r));
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| 97 |
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| 98 | if (!NT_STATUS_IS_OK(status)) {
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| 99 | break;
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| 100 | }
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| 101 |
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| 102 | pull_ascii_nstring( qname, sizeof(qname), r.name.name);
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| 103 | r.result.s_addr = interpret_addr(qname);
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| 104 |
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| 105 | if (write_data(fd_out, (char *)&r, sizeof(r)) != sizeof(r))
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| 106 | break;
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| 107 | }
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| 108 |
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| 109 | _exit(0);
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| 110 | }
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| 111 |
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| 112 | /**************************************************************************** **
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| 113 | catch a sigterm (in the child process - the parent has a different handler
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| 114 | see nmbd.c for details).
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| 115 | We need a separate term handler here so we don't release any
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| 116 | names that our parent is going to release, or overwrite a
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| 117 | WINS db that our parent is going to write.
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| 118 | **************************************************************************** */
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| 119 |
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| 120 | static void sig_term(int sig)
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| 121 | {
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| 122 | _exit(0);
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| 123 | }
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| 124 |
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| 125 | /***************************************************************************
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| 126 | Called by the parent process when it receives a SIGTERM - also kills the
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| 127 | child so we don't get child async dns processes lying around, causing trouble.
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| 128 | ****************************************************************************/
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| 129 |
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| 130 | void kill_async_dns_child(void)
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| 131 | {
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| 132 | if (child_pid > 0) {
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| 133 | kill(child_pid, SIGTERM);
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| 134 | child_pid = -1;
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| 135 | }
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| 136 | }
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| 137 |
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| 138 | /***************************************************************************
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| 139 | create a child process to handle DNS lookups
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| 140 | ****************************************************************************/
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| 141 | void start_async_dns(void)
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| 142 | {
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| 143 | int fd1[2], fd2[2];
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| 144 | NTSTATUS status;
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| 145 |
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| 146 | CatchChild();
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| 147 |
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| 148 | if (pipe(fd1) || pipe(fd2)) {
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| 149 | DEBUG(0,("can't create asyncdns pipes\n"));
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| 150 | return;
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| 151 | }
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| 152 |
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| 153 | child_pid = sys_fork();
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| 154 |
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| 155 | if (child_pid) {
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| 156 | fd_in = fd1[0];
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| 157 | fd_out = fd2[1];
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| 158 | close(fd1[1]);
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| 159 | close(fd2[0]);
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| 160 | DEBUG(0,("started asyncdns process %d\n", (int)child_pid));
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| 161 | return;
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| 162 | }
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| 163 |
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| 164 | fd_in = fd2[0];
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| 165 | fd_out = fd1[1];
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| 166 |
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| 167 | CatchSignal(SIGUSR2, SIG_IGN);
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| 168 | CatchSignal(SIGUSR1, SIG_IGN);
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| 169 | CatchSignal(SIGHUP, SIG_IGN);
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| 170 | CatchSignal(SIGTERM, sig_term);
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| 171 |
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| 172 | status = reinit_after_fork(nmbd_messaging_context(),
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| 173 | nmbd_event_context(),
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| 174 | procid_self(), true);
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| 175 |
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| 176 | if (!NT_STATUS_IS_OK(status)) {
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| 177 | DEBUG(0,("reinit_after_fork() failed\n"));
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| 178 | smb_panic("reinit_after_fork() failed");
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| 179 | }
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| 180 |
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| 181 | asyncdns_process();
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| 182 | }
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| 183 |
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| 184 |
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| 185 | /***************************************************************************
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| 186 | check if a particular name is already being queried
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| 187 | ****************************************************************************/
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| 188 | static bool query_current(struct query_record *r)
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| 189 | {
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| 190 | return dns_current &&
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| 191 | nmb_name_equal(&r->name,
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| 192 | &dns_current->packet.nmb.question.question_name);
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| 193 | }
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| 194 |
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| 195 |
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| 196 | /***************************************************************************
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| 197 | write a query to the child process
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| 198 | ****************************************************************************/
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| 199 | static bool write_child(struct packet_struct *p)
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| 200 | {
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| 201 | struct query_record r;
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| 202 |
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| 203 | r.name = p->packet.nmb.question.question_name;
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| 204 |
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| 205 | return write_data(fd_out, (char *)&r, sizeof(r)) == sizeof(r);
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| 206 | }
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| 207 |
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| 208 | /***************************************************************************
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| 209 | check the DNS queue
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| 210 | ****************************************************************************/
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| 211 | void run_dns_queue(void)
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| 212 | {
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| 213 | struct query_record r;
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| 214 | struct packet_struct *p, *p2;
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| 215 | struct name_record *namerec;
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| 216 | NTSTATUS status;
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| 217 |
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| 218 | if (fd_in == -1)
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| 219 | return;
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| 220 |
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| 221 | if (!process_exists_by_pid(child_pid)) {
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| 222 | close(fd_in);
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| 223 | close(fd_out);
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| 224 | start_async_dns();
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| 225 | }
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| 226 |
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| 227 | status = read_data(fd_in, (char *)&r, sizeof(r));
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| 228 |
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| 229 | if (!NT_STATUS_IS_OK(status)) {
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| 230 | DEBUG(0, ("read from child failed: %s\n", nt_errstr(status)));
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| 231 | fd_in = -1;
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| 232 | return;
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| 233 | }
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| 234 |
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| 235 | namerec = add_dns_result(&r.name, r.result);
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| 236 |
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| 237 | if (dns_current) {
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| 238 | if (query_current(&r)) {
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| 239 | DEBUG(3,("DNS calling send_wins_name_query_response\n"));
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| 240 | in_dns = 1;
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| 241 | if(namerec == NULL)
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| 242 | send_wins_name_query_response(NAM_ERR, dns_current, NULL);
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| 243 | else
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| 244 | send_wins_name_query_response(0,dns_current,namerec);
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| 245 | in_dns = 0;
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| 246 | }
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| 247 |
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| 248 | dns_current->locked = False;
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| 249 | free_packet(dns_current);
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| 250 | dns_current = NULL;
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| 251 | }
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| 252 |
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| 253 | /* loop over the whole dns queue looking for entries that
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| 254 | match the result we just got */
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| 255 | for (p = dns_queue; p;) {
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| 256 | struct nmb_packet *nmb = &p->packet.nmb;
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| 257 | struct nmb_name *question = &nmb->question.question_name;
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| 258 |
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| 259 | if (nmb_name_equal(question, &r.name)) {
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| 260 | DEBUG(3,("DNS calling send_wins_name_query_response\n"));
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| 261 | in_dns = 1;
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| 262 | if(namerec == NULL)
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| 263 | send_wins_name_query_response(NAM_ERR, p, NULL);
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| 264 | else
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| 265 | send_wins_name_query_response(0,p,namerec);
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| 266 | in_dns = 0;
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| 267 | p->locked = False;
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| 268 |
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| 269 | p2 = p->next;
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| 270 | DLIST_REMOVE(dns_queue, p);
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| 271 | free_packet(p);
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| 272 | p = p2;
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| 273 | } else {
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| 274 | p = p->next;
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| 275 | }
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| 276 | }
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| 277 |
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| 278 | if (dns_queue) {
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| 279 | dns_current = dns_queue;
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| 280 | DLIST_REMOVE(dns_queue, dns_queue);
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| 281 |
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| 282 | if (!write_child(dns_current)) {
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| 283 | DEBUG(3,("failed to send DNS query to child!\n"));
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| 284 | return;
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| 285 | }
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| 286 | }
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| 287 | }
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| 288 |
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| 289 | /***************************************************************************
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| 290 | queue a DNS query
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| 291 | ****************************************************************************/
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| 292 |
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| 293 | bool queue_dns_query(struct packet_struct *p,struct nmb_name *question)
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| 294 | {
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| 295 | if (in_dns || fd_in == -1)
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| 296 | return False;
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| 297 |
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| 298 | if (!dns_current) {
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| 299 | if (!write_child(p)) {
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| 300 | DEBUG(3,("failed to send DNS query to child!\n"));
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| 301 | return False;
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| 302 | }
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| 303 | dns_current = p;
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| 304 | p->locked = True;
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| 305 | } else {
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| 306 | p->locked = True;
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| 307 | DLIST_ADD(dns_queue, p);
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| 308 | }
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| 309 |
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| 310 | DEBUG(3,("added DNS query for %s\n", nmb_namestr(question)));
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| 311 | return True;
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| 312 | }
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| 313 |
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| 314 | #else
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| 315 |
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| 316 |
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| 317 | /***************************************************************************
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| 318 | we use this when we can't do async DNS lookups
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| 319 | ****************************************************************************/
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| 320 |
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| 321 | bool queue_dns_query(struct packet_struct *p,struct nmb_name *question)
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| 322 | {
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| 323 | struct name_record *namerec = NULL;
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| 324 | struct in_addr dns_ip;
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| 325 | unstring qname;
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| 326 |
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| 327 | pull_ascii_nstring(qname, sizeof(qname), question->name);
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| 328 |
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| 329 | DEBUG(3,("DNS search for %s - ", nmb_namestr(question)));
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| 330 |
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| 331 | dns_ip.s_addr = interpret_addr(qname);
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| 332 |
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| 333 | namerec = add_dns_result(question, dns_ip);
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| 334 | if(namerec == NULL) {
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| 335 | send_wins_name_query_response(NAM_ERR, p, NULL);
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| 336 | } else {
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| 337 | send_wins_name_query_response(0, p, namerec);
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| 338 | }
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| 339 | return False;
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| 340 | }
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| 341 |
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| 342 | /***************************************************************************
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| 343 | With sync dns there is no child to kill on SIGTERM.
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| 344 | ****************************************************************************/
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| 345 |
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| 346 | void kill_async_dns_child(void)
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| 347 | {
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| 348 | return;
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| 349 | }
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| 350 | #endif
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