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* http.c (connect_server): Use DNS SRV to get a server list. Fail over to

Browse Source 
A records if necessary.

* Makefile.am, srv.h, srv.c: New DNS SRV handling code.
This commit is contained in:
David Shaw 2003-03-11 22:04:53 +00:00
parent 48b55931dc
commit 81844d2b65
5 changed files with 391 additions and 59 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
util/ChangeLog
View File

@ -1,3 +1,10 @@
2003-03-11 David Shaw <dshaw@jabberwocky.com>
* http.c (connect_server): Use DNS SRV to get a server list. Fail
over to A records if necessary.
* Makefile.am, srv.h, srv.c: New DNS SRV handling code.
2003-02-22 David Shaw <dshaw@jabberwocky.com>
* ttyio.c (tty_print_utf8_string, tty_print_utf8_string2): Use 0

11
util/Makefile.am
View File

@ -27,14 +27,15 @@ EXTRA_libutil_a_SOURCES = regcomp.c regex.c regexec.c regex_internal.c regex_int
#libutil_a_LDFLAGS =
libutil_a_SOURCES = g10u.c logger.c fileutil.c miscutil.c strgutil.c \
ttyio.c argparse.c memory.c secmem.c errors.c iobuf.c \
dotlock.c http.c simple-gettext.c w32reg.c
dotlock.c http.c srv.h srv.c simple-gettext.c w32reg.c
libutil_a_DEPENDENCIES = @REGEX_O@
libutil_a_LIBADD = @REGEX_O@
http-test: http.c
gcc -DHAVE_CONFIG_H -I. -I. -I.. $(INCLUDES) -g -Wall -DTEST \
-o http-test http.c libutil.a ../mpi/libmpi.a @INTLLIBS@
gcc -DHAVE_CONFIG_H -I. -I. -I.. $(INCLUDES) $(LDFLAGS) -g -Wall \
-DTEST -o http-test http.c libutil.a @INTLLIBS@ @SRVLIBS@ @CAPLIBS@
srv-test: srv.c
gcc -DHAVE_CONFIG_H -I. -I. -I.. $(INCLUDES) $(LDFLAGS) -g -Wall \
-DTEST -o srv-test srv.c libutil.a @INTLLIBS@ @SRVLIBS@ @CAPLIBS@

143
util/http.c
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@ -42,8 +42,8 @@
#include "util.h"
#include "iobuf.h"
#include "i18n.h"
#include "http.h"
#include "srv.h"
#ifdef __riscos__
#define HTTP_PROXY_ENV "GnuPG$HttpProxy"
@ -80,7 +80,7 @@ static int send_request( HTTP_HD hd );
static byte *build_rel_path( PARSED_URI uri );
static int parse_response( HTTP_HD hd );
static int connect_server( const char *server, ushort port );
static int connect_server(const char *server, ushort port, unsigned int flags);
static int write_server( int sock, const char *data, size_t length );
#ifdef __MINGW32__
@ -494,11 +494,11 @@ send_request( HTTP_HD hd )
return G10ERR_NETWORK;
}
hd->sock = connect_server( *uri->host? uri->host : "localhost",
uri->port? uri->port : 80 );
uri->port? uri->port : 80, 0 );
release_parsed_uri( uri );
}
else
hd->sock = connect_server( server, port );
hd->sock = connect_server( server, port, hd->flags );
if( hd->sock == -1 )
return G10ERR_NETWORK;
@ -707,19 +707,17 @@ start_server()
#endif
static int
connect_server( const char *server, ushort port )
connect_server( const char *server, ushort port, unsigned int flags )
{
int sock,i=0;
int sock,srv,srvcount=0;
struct sockaddr_in addr;
struct hostent *host=NULL;
unsigned long l;
struct srventry *srvlist=NULL;
memset(&addr,0,sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = htons(port);
#ifdef __MINGW32__
init_sockets ();
@ -740,63 +738,100 @@ connect_server( const char *server, ushort port )
#ifdef __MINGW32__
/* Win32 gethostbyname doesn't handle IP addresses internally, so we
try inet_addr first on that platform only. */
if((l=inet_addr(server))==SOCKET_ERROR)
#endif
if((host=gethostbyname(server))==NULL)
{
#ifdef __MINGW32__
log_error("%s: host not found: ec=%d\n",server,(int)WSAGetLastError());
#else
log_error("%s: host not found\n",server);
#endif
sock_close(sock);
return -1;
}
if(host)
if((addr.sin_addr.s_addr=inet_addr(server))!=SOCKET_ERROR)
{
if(host->h_addrtype != AF_INET)
{
log_error ("%s: unknown address family\n", server);
sock_close(sock);
return -1;
}
addr.sin_port = htons(port);
if(host->h_length != 4 )
{
log_error ("%s: illegal address length\n", server);
sock_close(sock);
return -1;
}
/* Try all A records until one responds. */
while(host->h_addr_list[i])
{
memcpy(&addr.sin_addr,host->h_addr_list[i],host->h_length);
if(connect(sock,(struct sockaddr *)&addr,sizeof(addr))==0)
break;
i++;
}
if(host->h_addr_list[i]==0)
if(connect(sock,(struct sockaddr *)&addr,sizeof(addr))==0)
return sock;
else
{
sock_close(sock);
return -1;
}
}
else
{
memcpy(&addr.sin_addr,&l,sizeof(l));
#endif
if(connect(sock,(struct sockaddr *)&addr,sizeof(addr))!=0)
#ifdef USE_DNS_SRV
/* Do the SRV thing */
if(flags&HTTP_FLAG_TRY_SRV)
{
/* We're using SRV, so append the tags */
char srvname[MAXDNAME];
strcpy(srvname,"_hkp._tcp.");
strncat(srvname,server,MAXDNAME-11);
srvname[MAXDNAME-1]='\0';
srvcount=getsrv(srvname,&srvlist);
}
#endif
if(srvlist==NULL)
{
/* Either we're not using SRV, or the SRV lookup failed. Make
up a fake SRV record. */
srvlist=m_alloc_clear(sizeof(struct srventry));
srvlist->port=port;
strncpy(srvlist->target,server,MAXDNAME);
srvcount=1;
}
for(srv=0;srv<srvcount;srv++)
{
int i=0;
addr.sin_port = htons(srvlist[srv].port);
if((host=gethostbyname(srvlist[srv].target))==NULL)
continue;
if(host)
{
sock_close(sock);
return -1;
if(host->h_addrtype != AF_INET)
{
log_error ("%s: unknown address family\n", srvlist[srv].target);
sock_close(sock);
m_free(srvlist);
return -1;
}
if(host->h_length != 4 )
{
log_error ("%s: illegal address length\n", srvlist[srv].target);
sock_close(sock);
m_free(srvlist);
return -1;
}
/* Try all A records until one responds. */
while(host->h_addr_list[i])
{
memcpy(&addr.sin_addr,host->h_addr_list[i],host->h_length);
if(connect(sock,(struct sockaddr *)&addr,sizeof(addr))==0)
break;
i++;
}
if(host->h_addr_list[i])
break;
}
}
m_free(srvlist);
if(!host)
{
#ifdef __MINGW32__
log_error("%s: host not found: ec=%d\n",server,(int)WSAGetLastError());
#else
log_error("%s: host not found\n",server);
#endif
sock_close(sock);
return -1;
}
return sock;
}

246
util/srv.c Normal file
View File

@ -0,0 +1,246 @@
/* srv.c - DNS SRV code
* Copyright (C) 2003 Free Software Foundation, Inc.
*
* This file is part of GNUPG.
*
* GNUPG 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.
*
* GNUPG 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include <config.h>
#ifdef USE_DNS_SRV
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include "memory.h"
#include "types.h"
#include "srv.h"
#ifndef T_SRV
#define T_SRV 33
#endif
static int priosort(const void *a,const void *b)
{
const struct srventry *sa=a,*sb=b;
if(sa->priority>sb->priority)
return 1;
else if(sa->priority<sb->priority)
return -1;
else
return 0;
}
int
getsrv(const char *name,struct srventry **list)
{
char answer[PACKETSZ];
int r,srvcount=0;
char *pt,*emsg;
u16 count,dlen;
*list=NULL;
r=res_query(name,C_IN,T_SRV,answer,PACKETSZ);
if(r<sizeof(HEADER))
return -1;
if((((HEADER *)answer)->rcode)==NOERROR &&
(count=ntohs(((HEADER *)answer)->ancount)))
{
int i,rc;
emsg=&answer[r];
pt=&answer[sizeof(HEADER)];
/* Skip over the query */
rc=dn_skipname(pt,emsg);
if(rc==-1)
goto fail;
pt+=rc+QFIXEDSZ;
while(count-->0 && pt<emsg)
{
struct srventry *srv=NULL;
u16 type,class;
*list=m_realloc(*list,(srvcount+1)*sizeof(struct srventry));
memset(&(*list)[srvcount],0,sizeof(struct srventry));
srv=&(*list)[srvcount];
srvcount++;
rc=dn_skipname(pt,emsg); /* the name we just queried for */
if(rc==-1)
goto fail;
pt+=rc;
/* Truncated message? */
if((emsg-pt)<16)
goto fail;
type=*pt++ << 8;
type|=*pt++;
/* We asked for SRV and got something else !? */
if(type!=T_SRV)
goto fail;
class=*pt++ << 8;
class|=*pt++;
/* We asked for IN and got something else !? */
if(class!=C_IN)
goto fail;
pt+=4; /* ttl */
dlen=*pt++ << 8;
dlen|=*pt++;
srv->priority=*pt++ << 8;
srv->priority|=*pt++;
srv->weight=*pt++ << 8;
srv->weight|=*pt++;
srv->port=*pt++ << 8;
srv->port|=*pt++;
/* Get the name. 2782 doesn't allow name compression, but
dn_expand still works to pull the name out of the
packet. */
rc=dn_expand(answer,emsg,pt,srv->target,MAXDNAME);
if(rc==1 && srv->target[0]==0) /* "." */
goto noanswer;
if(rc==-1)
goto fail;
pt+=rc;
/* Corrupt packet? */
if(dlen!=rc+6)
goto fail;
#if 0
printf("count=%d\n",srvcount);
printf("priority=%d\n",srv->priority);
printf("weight=%d\n",srv->weight);
printf("port=%d\n",srv->port);
printf("target=%s\n",srv->target);
#endif
}
/* Now we have an array of all the srv records. */
/* Order by priority */
qsort(*list,srvcount,sizeof(struct srventry),priosort);
/* For each priority, move the zero-weighted items first. */
for(i=0;i<srvcount;i++)
{
int j;
for(j=i;j<srvcount && (*list)[i].priority==(*list)[j].priority;j++)
{
if((*list)[j].weight==0)
{
/* Swap j with i */
if(j!=i)
{
struct srventry temp;
memcpy(&temp,&(*list)[j],sizeof(struct srventry));
memcpy(&(*list)[j],&(*list)[i],sizeof(struct srventry));
memcpy(&(*list)[i],&temp,sizeof(struct srventry));
}
break;
}
}
}
/* Run the RFC-2782 weighting algorithm. We don't need very
high quality randomness for this, so regular libc srand/rand
is sufficient. */
srand(time(NULL)*getpid());
for(i=0;i<srvcount;i++)
{
int j;
float prio_count=0,chose;
for(j=i;j<srvcount && (*list)[i].priority==(*list)[j].priority;j++)
{
prio_count+=(*list)[j].weight;
(*list)[j].run_count=prio_count;
}
chose=prio_count*rand()/RAND_MAX;
for(j=i;j<srvcount && (*list)[i].priority==(*list)[j].priority;j++)
{
if(chose<=(*list)[j].run_count)
{
/* Swap j with i */
if(j!=i)
{
struct srventry temp;
memcpy(&temp,&(*list)[j],sizeof(struct srventry));
memcpy(&(*list)[j],&(*list)[i],sizeof(struct srventry));
memcpy(&(*list)[i],&temp,sizeof(struct srventry));
}
break;
}
}
}
}
return srvcount;
noanswer:
m_free(*list);
*list=NULL;
return 0;
fail:
m_free(*list);
*list=NULL;
return -1;
}
#endif /* USE_DNS_SRV */
#ifdef TEST
int
main(int argc,char *argv[])
{
struct srventry *srv;
int rc,i;
rc=getsrv("_hkp._tcp.pgp.net",&srv);
printf("Count=%d\n\n",rc);
for(i=0;i<rc;i++)
{
printf("priority=%d\n",srv[i].priority);
printf("weight=%d\n",srv[i].weight);
printf("port=%d\n",srv[i].port);
printf("target=%s\n",srv[i].target);
printf("\n");
}
m_free(srv);
return 0;
}
#endif /* TEST */

43
util/srv.h Normal file
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@ -0,0 +1,43 @@
/* srv.h
* Copyright (C) 2003 Free Software Foundation, Inc.
*
* This file is part of GNUPG.
*
* GNUPG 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.
*
* GNUPG 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#ifndef _SRV_H_
#define _SRV_H_
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#ifndef MAXDNAME
#define MAXDNAME 1025
#endif
struct srventry
{
uint16_t priority;
uint16_t weight;
uint16_t port;
int run_count;
char target[MAXDNAME];
};
int getsrv(const char *name,struct srventry **list);
#endif /* !_SRV_H_ */