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b008274afd
We better do this once and for all instead of cluttering all future commits with diffs of trailing white spaces. In the majority of cases blank or single lines are affected and thus this change won't disturb a git blame too much. For future commits the pre-commit scripts checks that this won't happen again.
322 lines
8.0 KiB
C
322 lines
8.0 KiB
C
/* srv.c - DNS SRV code
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* Copyright (C) 2003, 2009 Free Software Foundation, Inc.
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*
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* This file is part of GNUPG.
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*
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* GNUPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* GNUPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#include <config.h>
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#include <sys/types.h>
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#ifdef _WIN32
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#include <windows.h>
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#else
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#include <netinet/in.h>
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#include <arpa/nameser.h>
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#include <resolv.h>
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#endif
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#ifdef USE_ADNS
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# include <adns.h>
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# ifndef HAVE_ADNS_FREE
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# define adns_free free
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# endif
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#endif
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#include "util.h"
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#include "srv.h"
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/* Not every installation has gotten around to supporting SRVs
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yet... */
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#ifndef T_SRV
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#define T_SRV 33
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#endif
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static int
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priosort(const void *a,const void *b)
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{
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const struct srventry *sa=a,*sb=b;
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if(sa->priority>sb->priority)
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return 1;
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else if(sa->priority<sb->priority)
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return -1;
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else
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return 0;
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}
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int
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getsrv (const char *name,struct srventry **list)
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{
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int srvcount=0;
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u16 count;
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int i, rc;
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*list = NULL;
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#ifdef USE_ADNS
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{
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adns_state state;
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adns_answer *answer = NULL;
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rc = adns_init (&state, adns_if_noerrprint, NULL);
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if (rc)
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{
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log_error ("error initializing adns: %s\n", strerror (errno));
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return -1;
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}
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rc = adns_synchronous (state, name, adns_r_srv, adns_qf_quoteok_query,
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&answer);
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if (rc)
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{
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log_error ("DNS query failed: %s\n", strerror (errno));
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adns_finish (state);
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return -1;
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}
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if (answer->status != adns_s_ok
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|| answer->type != adns_r_srv || !answer->nrrs)
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{
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log_error ("DNS query returned an error or no records: %s (%s)\n",
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adns_strerror (answer->status),
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adns_errabbrev (answer->status));
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adns_free (answer);
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adns_finish (state);
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return 0;
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}
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for (count = 0; count < answer->nrrs; count++)
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{
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struct srventry *srv = NULL;
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struct srventry *newlist;
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if (strlen (answer->rrs.srvha[count].ha.host) >= MAXDNAME)
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{
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log_info ("hostname in SRV record too long - skipped\n");
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continue;
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}
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newlist = xtryrealloc (*list, (srvcount+1)*sizeof(struct srventry));
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if (!newlist)
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goto fail;
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*list = newlist;
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memset (&(*list)[srvcount], 0, sizeof(struct srventry));
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srv = &(*list)[srvcount];
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srvcount++;
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srv->priority = answer->rrs.srvha[count].priority;
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srv->weight = answer->rrs.srvha[count].weight;
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srv->port = answer->rrs.srvha[count].port;
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strcpy (srv->target, answer->rrs.srvha[count].ha.host);
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}
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adns_free (answer);
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adns_finish (state);
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}
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#else /*!USE_ADNS*/
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{
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unsigned char answer[2048];
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HEADER *header = (HEADER *)answer;
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unsigned char *pt, *emsg;
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int r;
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u16 dlen;
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r = res_query (name, C_IN, T_SRV, answer, sizeof answer);
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if (r < sizeof (HEADER) || r > sizeof answer)
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return -1;
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if (header->rcode != NOERROR || !(count=ntohs (header->ancount)))
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return 0; /* Error or no record found. */
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emsg = &answer[r];
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pt = &answer[sizeof(HEADER)];
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/* Skip over the query */
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rc = dn_skipname (pt, emsg);
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if (rc == -1)
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goto fail;
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pt += rc + QFIXEDSZ;
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while (count-- > 0 && pt < emsg)
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{
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struct srventry *srv=NULL;
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u16 type,class;
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struct srventry *newlist;
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newlist = xtryrealloc (*list, (srvcount+1)*sizeof(struct srventry));
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if (!newlist)
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goto fail;
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*list = newlist;
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memset(&(*list)[srvcount],0,sizeof(struct srventry));
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srv=&(*list)[srvcount];
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srvcount++;
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rc = dn_skipname(pt,emsg); /* the name we just queried for */
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if (rc == -1)
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goto fail;
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pt+=rc;
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/* Truncated message? */
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if((emsg-pt)<16)
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goto fail;
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type=*pt++ << 8;
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type|=*pt++;
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/* We asked for SRV and got something else !? */
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if(type!=T_SRV)
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goto fail;
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class=*pt++ << 8;
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class|=*pt++;
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/* We asked for IN and got something else !? */
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if(class!=C_IN)
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goto fail;
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pt+=4; /* ttl */
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dlen=*pt++ << 8;
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dlen|=*pt++;
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srv->priority=*pt++ << 8;
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srv->priority|=*pt++;
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srv->weight=*pt++ << 8;
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srv->weight|=*pt++;
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srv->port=*pt++ << 8;
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srv->port|=*pt++;
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/* Get the name. 2782 doesn't allow name compression, but
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dn_expand still works to pull the name out of the
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packet. */
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rc = dn_expand(answer,emsg,pt,srv->target,MAXDNAME);
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if (rc == 1 && srv->target[0] == 0) /* "." */
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{
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xfree(*list);
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*list = NULL;
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return 0;
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}
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if (rc == -1)
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goto fail;
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pt += rc;
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/* Corrupt packet? */
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if (dlen != rc+6)
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goto fail;
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}
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}
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#endif /*!USE_ADNS*/
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/* Now we have an array of all the srv records. */
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/* Order by priority */
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qsort(*list,srvcount,sizeof(struct srventry),priosort);
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/* For each priority, move the zero-weighted items first. */
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for (i=0; i < srvcount; i++)
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{
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int j;
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for (j=i;j < srvcount && (*list)[i].priority == (*list)[j].priority; j++)
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{
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if((*list)[j].weight==0)
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{
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/* Swap j with i */
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if(j!=i)
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{
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struct srventry temp;
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memcpy (&temp,&(*list)[j],sizeof(struct srventry));
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memcpy (&(*list)[j],&(*list)[i],sizeof(struct srventry));
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memcpy (&(*list)[i],&temp,sizeof(struct srventry));
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}
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break;
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}
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}
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}
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/* Run the RFC-2782 weighting algorithm. We don't need very high
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quality randomness for this, so regular libc srand/rand is
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sufficient. Fixme: It is a bit questionaly to reinitalize srand
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- better use a gnupg fucntion for this. */
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srand(time(NULL)*getpid());
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for (i=0; i < srvcount; i++)
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{
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int j;
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float prio_count=0,chose;
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for (j=i; j < srvcount && (*list)[i].priority == (*list)[j].priority; j++)
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{
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prio_count+=(*list)[j].weight;
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(*list)[j].run_count=prio_count;
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}
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chose=prio_count*rand()/RAND_MAX;
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for (j=i;j<srvcount && (*list)[i].priority==(*list)[j].priority;j++)
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{
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if (chose<=(*list)[j].run_count)
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{
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/* Swap j with i */
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if(j!=i)
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{
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struct srventry temp;
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memcpy(&temp,&(*list)[j],sizeof(struct srventry));
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memcpy(&(*list)[j],&(*list)[i],sizeof(struct srventry));
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memcpy(&(*list)[i],&temp,sizeof(struct srventry));
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}
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break;
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}
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}
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}
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return srvcount;
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fail:
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xfree(*list);
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*list=NULL;
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return -1;
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}
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#ifdef TEST
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int
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main(int argc,char *argv[])
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{
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struct srventry *srv;
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int rc,i;
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rc=getsrv("_hkp._tcp.wwwkeys.pgp.net",&srv);
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printf("Count=%d\n\n",rc);
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for(i=0;i<rc;i++)
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{
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printf("priority=%hu\n",srv[i].priority);
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printf("weight=%hu\n",srv[i].weight);
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printf("port=%hu\n",srv[i].port);
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printf("target=%s\n",srv[i].target);
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printf("\n");
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}
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xfree(srv);
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return 0;
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}
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#endif /* TEST */
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/*
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Local Variables:
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compile-command: "cc -DTEST -I.. -I../include -Wall -g -o srv srv.c -lresolv ../tools/no-libgcrypt.o ../jnlib/libjnlib.a"
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End:
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*/
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