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Diffstat (limited to 'source/nmbd/asyncdns.c')
| -rw-r--r-- | source/nmbd/asyncdns.c | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/source/nmbd/asyncdns.c b/source/nmbd/asyncdns.c new file mode 100644 index 00000000000..548781edeab --- /dev/null +++ b/source/nmbd/asyncdns.c @@ -0,0 +1,257 @@ +/* + Unix SMB/Netbios implementation. + Version 1.9. + a async DNS handler + Copyright (C) Andrew Tridgell 1994-1997 + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 2 of the License, or + (at your option) any later version. + + This program is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program; if not, write to the Free Software + Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + + Revision History: + + 14 jan 96: lkcl@pires.co.uk + added multiple workgroup domain master support + +*/ + +#include "includes.h" + +extern int DEBUGLEVEL; + + +/*************************************************************************** + add a DNS result to the name cache + ****************************************************************************/ +static struct name_record *add_dns_result(struct nmb_name *question, struct in_addr addr) +{ + int name_type = question->name_type; + char *qname = question->name; + + if (!addr.s_addr) { + /* add the fail to WINS cache of names. give it 1 hour in the cache */ + DEBUG(3,("Negative DNS answer for %s\n", qname)); + add_netbios_entry(wins_subnet,qname,name_type,NB_ACTIVE,60*60,DNSFAIL,addr, + True, True); + return NULL; + } + + /* add it to our WINS cache of names. give it 2 hours in the cache */ + DEBUG(3,("DNS gave answer for %s of %s\n", qname, inet_ntoa(addr))); + + return add_netbios_entry(wins_subnet,qname,name_type,NB_ACTIVE,2*60*60,DNS,addr, + True,True); +} + + + +#ifndef SYNC_DNS + +static int fd_in = -1, fd_out = -1; +static int child_pid = -1; +static int in_dns; + +/* this is the structure that is passed between the parent and child */ +struct query_record { + struct nmb_name name; + struct in_addr result; +}; + +/* a queue of pending requests waiting for DNS responses */ +static struct packet_struct *dns_queue; + + + +/*************************************************************************** + return the fd used to gather async dns replies. This is added to the select + loop + ****************************************************************************/ +int asyncdns_fd(void) +{ + return fd_in; +} + +/*************************************************************************** + handle DNS queries arriving from the parent + ****************************************************************************/ +static void asyncdns_process(void) +{ + struct query_record r; + fstring qname; + + DEBUGLEVEL = 0; + + while (1) { + if (read_data(fd_in, (char *)&r, sizeof(r)) != sizeof(r)) + break; + + fstrcpy(qname, r.name.name); + + r.result.s_addr = interpret_addr(qname); + + if (write_data(fd_out, (char *)&r, sizeof(r)) != sizeof(r)) + break; + } + + exit(0); +} + + +/*************************************************************************** + create a child process to handle DNS lookups + ****************************************************************************/ +void start_async_dns(void) +{ + int fd1[2], fd2[2]; + + signal(SIGCLD, SIG_IGN); + + if (pipe(fd1) || pipe(fd2)) { + return; + } + + child_pid = fork(); + + if (child_pid) { + fd_in = fd1[0]; + fd_out = fd2[1]; + close(fd1[1]); + close(fd2[0]); + DEBUG(3,("async DNS initialised\n")); + return; + } + + fd_in = fd2[0]; + fd_out = fd1[1]; + + asyncdns_process(); +} + + +/*************************************************************************** +check if a particular name is already being queried + ****************************************************************************/ +static BOOL query_in_queue(struct query_record *r) +{ + struct packet_struct *p; + for (p = dns_queue; p; p = p->next) { + struct nmb_packet *nmb = &p->packet.nmb; + struct nmb_name *question = &nmb->question.question_name; + + if (name_equal(question, &r->name)) + return True; + } + return False; +} + + +/*************************************************************************** + check the DNS queue + ****************************************************************************/ +void run_dns_queue(void) +{ + struct query_record r; + struct packet_struct *p, *p2; + + if (fd_in == -1) + return; + + if (read_data(fd_in, (char *)&r, sizeof(r)) != sizeof(r)) { + DEBUG(0,("Incomplete DNS answer from child!\n")); + fd_in = -1; + return; + } + + add_dns_result(&r.name, r.result); + + /* loop over the whole dns queue looking for entries that + match the result we just got */ + for (p = dns_queue; p;) { + struct nmb_packet *nmb = &p->packet.nmb; + struct nmb_name *question = &nmb->question.question_name; + + if (name_equal(question, &r.name)) { + DEBUG(3,("DNS calling reply_name_query\n")); + in_dns = 1; + reply_name_query(p); + in_dns = 0; + p->locked = False; + + if (p->prev) + p->prev->next = p->next; + else + dns_queue = p->next; + if (p->next) + p->next->prev = p->prev; + p2 = p->next; + free_packet(p); + p = p2; + } else { + p = p->next; + } + } + +} + +/*************************************************************************** +queue a DNS query + ****************************************************************************/ +BOOL queue_dns_query(struct packet_struct *p,struct nmb_name *question, + struct name_record **n) +{ + struct query_record r; + + if (in_dns || fd_in == -1) + return False; + + r.name = *question; + + if (!query_in_queue(&r) && + !write_data(fd_out, (char *)&r, sizeof(r))) { + DEBUG(3,("failed to send DNS query to child!\n")); + return False; + } + + p->locked = True; + p->next = dns_queue; + p->prev = NULL; + if (p->next) + p->next->prev = p; + dns_queue = p; + + + DEBUG(3,("added DNS query for %s\n", namestr(question))); + return True; +} + +#else + + +/*************************************************************************** + we use this then we can't do async DNS lookups + ****************************************************************************/ +BOOL queue_dns_query(struct packet_struct *p,struct nmb_name *question, + struct name_record **n) +{ + int name_type = question->name_type; + char *qname = question->name; + struct in_addr dns_ip; + + DEBUG(3,("DNS search for %s - ", namestr(question))); + + dns_ip.s_addr = interpret_addr(qname); + + *n = add_dns_result(question, dns_ip); + return False; +} +#endif |