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gnupg/dirmngr/dns-stuff.c
Werner Koch de3a0988ef
dirmngr: This towel should better detect a changed resolv.conf. 
* dirmngr/dns-stuff.c (resolv_conf_changed_p): Fix initialization time
issue.
--

Fixes-commit: b5f356e9fba2d99909f8f54d7b7e6836bed87b68
Signed-off-by: Werner Koch <wk@gnupg.org>
2017-05-25 20:26:54 +02:00

2371 lines
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/* dns-stuff.c - DNS related code including CERT RR (rfc-4398)
* Copyright (C) 2003, 2005, 2006, 2009 Free Software Foundation, Inc.
* Copyright (C) 2005, 2006, 2009, 2015. 2016 Werner Koch
*
* This file is part of GnuPG.
*
* This file is free software; you can redistribute it and/or modify
* it under the terms of either
*
* - the GNU Lesser General Public License as published by the Free
* Software Foundation; either version 3 of the License, or (at
* your option) any later version.
*
* or
*
* - 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.
*
* or both in parallel, as here.
*
* This file 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, see <https://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <sys/types.h>
#ifdef HAVE_W32_SYSTEM
# define WIN32_LEAN_AND_MEAN
# ifdef HAVE_WINSOCK2_H
# include <winsock2.h>
# endif
# include <windows.h>
# include <iphlpapi.h>
#else
# if HAVE_SYSTEM_RESOLVER
# include <netinet/in.h>
# include <arpa/nameser.h>
# include <resolv.h>
# endif
# include <netdb.h>
#endif
#ifdef HAVE_STAT
# include <sys/stat.h>
#endif
#include <string.h>
#include <unistd.h>
/* William Ahern's DNS library, included as a source copy. */
#ifdef USE_LIBDNS
# include "dns.h"
#endif
/* dns.c has a dns_p_free but it is not exported. We use our own
* wrapper here so that we do not accidentally use xfree which would
* be wrong for dns.c allocated data. */
#define dns_free(a) free ((a))
#ifdef WITHOUT_NPTH /* Give the Makefile a chance to build without Pth. */
# undef USE_NPTH
#endif
#ifdef USE_NPTH
# include <npth.h>
#endif
#include "./dirmngr-err.h"
#include "../common/util.h"
#include "../common/host2net.h"
#include "dns-stuff.h"
#ifdef USE_NPTH
# define my_unprotect() npth_unprotect ()
# define my_protect() npth_protect ()
#else
# define my_unprotect() do { } while(0)
# define my_protect() do { } while(0)
#endif
/* We allow the use of 0 instead of AF_UNSPEC - check this assumption. */
#if AF_UNSPEC != 0
# error AF_UNSPEC does not have the value 0
#endif
/* Windows does not support the AI_ADDRCONFIG flag - use zero instead. */
#ifndef AI_ADDRCONFIG
# define AI_ADDRCONFIG 0
#endif
/* Not every installation has gotten around to supporting SRVs or
CERTs yet... */
#ifndef T_SRV
#define T_SRV 33
#endif
#undef T_CERT
#define T_CERT 37
/* The standard SOCKS and TOR ports. */
#define SOCKS_PORT 1080
#define TOR_PORT 9050
#define TOR_PORT2 9150 /* (Used by the Tor browser) */
/* The default nameserver used in Tor mode. */
#define DEFAULT_NAMESERVER "8.8.8.8"
/* The default timeout in seconds for libdns requests. */
#define DEFAULT_TIMEOUT 30
#define RESOLV_CONF_NAME "/etc/resolv.conf"
/* Two flags to enable verbose and debug mode. */
static int opt_verbose;
static int opt_debug;
/* The timeout in seconds for libdns requests. */
static int opt_timeout;
/* The flag to disable IPv4 access - right now this only skips
* returned A records. */
static int opt_disable_ipv4;
/* The flag to disable IPv6 access - right now this only skips
* returned AAAA records. */
static int opt_disable_ipv6;
/* If set force the use of the standard resolver. */
static int standard_resolver;
/* If set use recursive resolver when available. */
static int recursive_resolver;
/* If set Tor mode shall be used. */
static int tor_mode;
/* A string with the nameserver IP address used with Tor.
(40 should be sufficient for v6 but we add some extra for a scope.) */
static char tor_nameserver[40+20];
/* Two strings to hold the credentials presented to Tor. */
static char tor_socks_user[30];
static char tor_socks_password[20];
#ifdef USE_LIBDNS
/* Libdns gobal data. */
struct libdns_s
{
struct dns_resolv_conf *resolv_conf;
struct dns_hosts *hosts;
struct dns_hints *hints;
struct sockaddr_storage socks_host;
} libdns;
/* If this flag is set, libdns shall be reinited for the next use. */
static int libdns_reinit_pending;
/* The Tor port to be used. */
static int libdns_tor_port;
#endif /*USE_LIBDNS*/
/* Calling this function with YES set to True forces the use of the
* standard resolver even if dirmngr has been built with support for
* an alternative resolver. */
void
enable_standard_resolver (int yes)
{
standard_resolver = yes;
}
/* Return true if the standard resolver is used. */
int
standard_resolver_p (void)
{
return standard_resolver;
}
/* Calling this function with YES switches libdns into recursive mode.
* It has no effect on the standard resolver. */
void
enable_recursive_resolver (int yes)
{
recursive_resolver = yes;
#ifdef USE_LIBDNS
libdns_reinit_pending = 1;
#endif
}
/* Return true iff the recursive resolver is used. */
int
recursive_resolver_p (void)
{
#if USE_LIBDNS
return !standard_resolver && recursive_resolver;
#else
return 0;
#endif
}
/* Puts this module eternally into Tor mode. When called agained with
* NEW_CIRCUIT request a new TOR circuit for the next DNS query. */
void
enable_dns_tormode (int new_circuit)
{
if (!*tor_socks_user || new_circuit)
{
static unsigned int counter;
gpgrt_snprintf (tor_socks_user, sizeof tor_socks_user,
"dirmngr-%lu", (unsigned long)getpid ());
gpgrt_snprintf (tor_socks_password, sizeof tor_socks_password,
"p%u", counter);
counter++;
}
tor_mode = 1;
}
/* Disable tor mode. */
void
disable_dns_tormode (void)
{
tor_mode = 0;
}
/* Set verbosity and debug mode for this module. */
void
set_dns_verbose (int verbose, int debug)
{
opt_verbose = verbose;
opt_debug = debug;
}
/* Set the Disable-IPv4 flag so that the name resolver does not return
* A addresses. */
void
set_dns_disable_ipv4 (int yes)
{
opt_disable_ipv4 = !!yes;
}
/* Set the Disable-IPv6 flag so that the name resolver does not return
* AAAA addresses. */
void
set_dns_disable_ipv6 (int yes)
{
opt_disable_ipv6 = !!yes;
}
/* Set the timeout for libdns requests to SECONDS. A value of 0 sets
* the default timeout and values are capped at 10 minutes. */
void
set_dns_timeout (int seconds)
{
if (!seconds)
seconds = DEFAULT_TIMEOUT;
else if (seconds < 1)
seconds = 1;
else if (seconds > 600)
seconds = 600;
opt_timeout = seconds;
}
/* Change the default IP address of the nameserver to IPADDR. The
address needs to be a numerical IP address and will be used for the
next DNS query. Note that this is only used in Tor mode. */
void
set_dns_nameserver (const char *ipaddr)
{
strncpy (tor_nameserver, ipaddr? ipaddr : DEFAULT_NAMESERVER,
sizeof tor_nameserver -1);
tor_nameserver[sizeof tor_nameserver -1] = 0;
#ifdef USE_LIBDNS
libdns_reinit_pending = 1;
libdns_tor_port = 0; /* Start again with the default port. */
#endif
}
/* Free an addressinfo linked list as returned by resolve_dns_name. */
void
free_dns_addrinfo (dns_addrinfo_t ai)
{
while (ai)
{
dns_addrinfo_t next = ai->next;
xfree (ai);
ai = next;
}
}
#ifndef HAVE_W32_SYSTEM
/* Return H_ERRNO mapped to a gpg-error code. Will never return 0. */
static gpg_error_t
get_h_errno_as_gpg_error (void)
{
gpg_err_code_t ec;
switch (h_errno)
{
case HOST_NOT_FOUND: ec = GPG_ERR_NO_NAME; break;
case TRY_AGAIN: ec = GPG_ERR_TRY_LATER; break;
case NO_RECOVERY: ec = GPG_ERR_SERVER_FAILED; break;
case NO_DATA: ec = GPG_ERR_NO_DATA; break;
default: ec = GPG_ERR_UNKNOWN_ERRNO; break;
}
return gpg_error (ec);
}
#endif /*!HAVE_W32_SYSTEM*/
static gpg_error_t
map_eai_to_gpg_error (int ec)
{
gpg_error_t err;
switch (ec)
{
case EAI_AGAIN: err = gpg_error (GPG_ERR_EAGAIN); break;
case EAI_BADFLAGS: err = gpg_error (GPG_ERR_INV_FLAG); break;
case EAI_FAIL: err = gpg_error (GPG_ERR_SERVER_FAILED); break;
case EAI_MEMORY: err = gpg_error (GPG_ERR_ENOMEM); break;
#ifdef EAI_NODATA
case EAI_NODATA: err = gpg_error (GPG_ERR_NO_DATA); break;
#endif
case EAI_NONAME: err = gpg_error (GPG_ERR_NO_NAME); break;
case EAI_SERVICE: err = gpg_error (GPG_ERR_NOT_SUPPORTED); break;
case EAI_FAMILY: err = gpg_error (GPG_ERR_EAFNOSUPPORT); break;
case EAI_SOCKTYPE: err = gpg_error (GPG_ERR_ESOCKTNOSUPPORT); break;
#ifndef HAVE_W32_SYSTEM
# ifdef EAI_ADDRFAMILY
case EAI_ADDRFAMILY:err = gpg_error (GPG_ERR_EADDRNOTAVAIL); break;
# endif
case EAI_SYSTEM: err = gpg_error_from_syserror (); break;
#endif
default: err = gpg_error (GPG_ERR_UNKNOWN_ERRNO); break;
}
return err;
}
#ifdef USE_LIBDNS
static gpg_error_t
libdns_error_to_gpg_error (int serr)
{
gpg_err_code_t ec;
switch (serr)
{
case 0: ec = 0; break;
case DNS_ENOBUFS: ec = GPG_ERR_BUFFER_TOO_SHORT; break;
case DNS_EILLEGAL: ec = GPG_ERR_INV_OBJ; break;
case DNS_EORDER: ec = GPG_ERR_INV_ORDER; break;
case DNS_ESECTION: ec = GPG_ERR_DNS_SECTION; break;
case DNS_EUNKNOWN: ec = GPG_ERR_DNS_UNKNOWN; break;
case DNS_EADDRESS: ec = GPG_ERR_DNS_ADDRESS; break;
case DNS_ENOQUERY: ec = GPG_ERR_DNS_NO_QUERY; break;
case DNS_ENOANSWER:ec = GPG_ERR_DNS_NO_ANSWER; break;
case DNS_EFETCHED: ec = GPG_ERR_ALREADY_FETCHED; break;
case DNS_ESERVICE: ec = GPG_ERR_NOT_SUPPORTED; break;
case DNS_ENONAME: ec = GPG_ERR_NO_NAME; break;
case DNS_EFAIL: ec = GPG_ERR_SERVER_FAILED; break;
case DNS_ECONNFIN: ec = GPG_ERR_DNS_CLOSED; break;
case DNS_EVERIFY: ec = GPG_ERR_DNS_VERIFY; break;
default:
if (serr >= 0)
ec = gpg_err_code_from_errno (serr);
else
ec = GPG_ERR_DNS_UNKNOWN;
break;
}
return gpg_error (ec);
}
#endif /*USE_LIBDNS*/
/* Return true if resolve.conf changed since it was last loaded. */
#ifdef USE_LIBDNS
static int
resolv_conf_changed_p (void)
{
#if defined(HAVE_W32_SYSTEM) || !defined(HAVE_STAT)
return 0;
#else
static time_t last_mtime;
const char *fname = RESOLV_CONF_NAME;
struct stat statbuf;
int changed = 0;
if (stat (fname, &statbuf))
{
log_error ("stat'ing '%s' failed: %s\n",
fname, gpg_strerror (gpg_error_from_syserror ()));
last_mtime = 1; /* Force a "changed" result the next time stat
* works. */
}
else if (!last_mtime)
last_mtime = statbuf.st_mtime;
else if (last_mtime != statbuf.st_mtime)
{
changed = 1;
last_mtime = statbuf.st_mtime;
}
return changed;
#endif
}
#endif /*USE_LIBDNS*/
#ifdef USE_LIBDNS
/* Initialize libdns. Returns 0 on success; prints a diagnostic and
* returns an error code on failure. */
static gpg_error_t
libdns_init (void)
{
gpg_error_t err;
struct libdns_s ld;
int derr;
char *cfgstr = NULL;
if (libdns.resolv_conf)
return 0; /* Already initialized. */
memset (&ld, 0, sizeof ld);
ld.resolv_conf = dns_resconf_open (&derr);
if (!ld.resolv_conf)
{
err = libdns_error_to_gpg_error (derr);
log_error ("failed to allocate DNS resconf object: %s\n",
gpg_strerror (err));
goto leave;
}
if (tor_mode)
{
if (!*tor_nameserver)
set_dns_nameserver (NULL);
if (!libdns_tor_port)
libdns_tor_port = TOR_PORT;
cfgstr = xtryasprintf ("[%s]:53", tor_nameserver);
if (!cfgstr)
err = gpg_error_from_syserror ();
else
err = libdns_error_to_gpg_error
(dns_resconf_pton (&ld.resolv_conf->nameserver[0], cfgstr));
if (err)
log_error ("failed to set nameserver '%s': %s\n",
cfgstr, gpg_strerror (err));
if (err)
goto leave;
ld.resolv_conf->options.tcp = DNS_RESCONF_TCP_SOCKS;
xfree (cfgstr);
cfgstr = xtryasprintf ("[%s]:%d", "127.0.0.1", libdns_tor_port);
if (!cfgstr)
err = gpg_error_from_syserror ();
else
err = libdns_error_to_gpg_error
(dns_resconf_pton (&ld.socks_host, cfgstr));
if (err)
{
log_error ("failed to set socks server '%s': %s\n",
cfgstr, gpg_strerror (err));
goto leave;
}
}
else
{
#ifdef HAVE_W32_SYSTEM
ULONG ninfo_len;
PFIXED_INFO ninfo;
PIP_ADDR_STRING pip;
int idx;
ninfo_len = 2048;
ninfo = xtrymalloc (ninfo_len);
if (!ninfo)
{
err = gpg_error_from_syserror ();
goto leave;
}
if (GetNetworkParams (ninfo, &ninfo_len))
{
log_error ("GetNetworkParms failed: %s\n", w32_strerror (-1));
err = gpg_error (GPG_ERR_GENERAL);
xfree (ninfo);
goto leave;
}
for (idx=0, pip = &(ninfo->DnsServerList);
pip && idx < DIM (ld.resolv_conf->nameserver);
pip = pip->Next)
{
if (opt_debug)
log_debug ("dns: dnsserver[%d] '%s'\n", idx, pip->IpAddress.String);
err = libdns_error_to_gpg_error
(dns_resconf_pton (&ld.resolv_conf->nameserver[idx],
pip->IpAddress.String));
if (err)
log_error ("failed to set nameserver[%d] '%s': %s\n",
idx, pip->IpAddress.String, gpg_strerror (err));
else
idx++;
}
xfree (ninfo);
#else /* Unix */
const char *fname;
fname = RESOLV_CONF_NAME;
resolv_conf_changed_p (); /* Reset timestamp. */
err = libdns_error_to_gpg_error
(dns_resconf_loadpath (ld.resolv_conf, fname));
if (err)
{
log_error ("failed to load '%s': %s\n", fname, gpg_strerror (err));
goto leave;
}
fname = "/etc/nsswitch.conf";
err = libdns_error_to_gpg_error
(dns_nssconf_loadpath (ld.resolv_conf, fname));
if (err)
{
/* This is not a fatal error: nsswitch.conf is not used on
* all systems; assume classic behavior instead. */
if (gpg_err_code (err) != GPG_ERR_ENOENT)
log_error ("failed to load '%s': %s\n", fname, gpg_strerror (err));
if (opt_debug)
log_debug ("dns: fallback resolution order, files then DNS\n");
ld.resolv_conf->lookup[0] = 'f';
ld.resolv_conf->lookup[1] = 'b';
ld.resolv_conf->lookup[2] = '\0';
err = GPG_ERR_NO_ERROR;
}
else if (!strchr (ld.resolv_conf->lookup, 'b'))
{
/* No DNS resolution type found in the list. This might be
* due to systemd based systems which allow for custom
* keywords which are not known to us and thus we do not
* know whether DNS is wanted or not. Because DNS is
* important for our infrastructure, we forcefully append
* DNS to the end of the list. */
if (strlen (ld.resolv_conf->lookup)+2 < sizeof ld.resolv_conf->lookup)
{
if (opt_debug)
log_debug ("dns: appending DNS to resolution order\n");
strcat (ld.resolv_conf->lookup, "b");
}
else
log_error ("failed to append DNS to resolution order\n");
}
#endif /* Unix */
}
ld.hosts = dns_hosts_open (&derr);
if (!ld.hosts)
{
err = libdns_error_to_gpg_error (derr);
log_error ("failed to initialize hosts file: %s\n", gpg_strerror (err));
goto leave;
}
{
#if HAVE_W32_SYSTEM
char *hosts_path = xtryasprintf ("%s\\System32\\drivers\\etc\\hosts",
getenv ("SystemRoot"));
if (! hosts_path)
{
err = gpg_error_from_syserror ();
goto leave;
}
derr = dns_hosts_loadpath (ld.hosts, hosts_path);
xfree (hosts_path);
#else
derr = dns_hosts_loadpath (ld.hosts, "/etc/hosts");
#endif
if (derr)
{
err = libdns_error_to_gpg_error (derr);
log_error ("failed to load hosts file: %s\n", gpg_strerror (err));
err = 0; /* Do not bail out - having no /etc/hosts is legal. */
}
}
/* dns_hints_local for stub mode, dns_hints_root for recursive. */
ld.hints = (recursive_resolver
? dns_hints_root (ld.resolv_conf, &derr)
: dns_hints_local (ld.resolv_conf, &derr));
if (!ld.hints)
{
err = libdns_error_to_gpg_error (derr);
log_error ("failed to load DNS hints: %s\n", gpg_strerror (err));
goto leave;
}
/* All fine. Make the data global. */
libdns = ld;
if (opt_debug)
log_debug ("dns: libdns initialized%s\n", tor_mode?" (tor mode)":"");
leave:
xfree (cfgstr);
return err;
}
#endif /*USE_LIBDNS*/
#ifdef USE_LIBDNS
/* Deinitialize libdns. */
static void
libdns_deinit (void)
{
struct libdns_s ld;
if (!libdns.resolv_conf)
return; /* Not initialized. */
ld = libdns;
memset (&libdns, 0, sizeof libdns);
dns_hints_close (ld.hints);
dns_hosts_close (ld.hosts);
dns_resconf_close (ld.resolv_conf);
}
#endif /*USE_LIBDNS*/
/* SIGHUP action handler for this module. With FORCE set objects are
* all immediately released. */
void
reload_dns_stuff (int force)
{
#ifdef USE_LIBDNS
if (force)
{
libdns_deinit ();
libdns_reinit_pending = 0;
}
else
{
libdns_reinit_pending = 1;
libdns_tor_port = 0; /* Start again with the default port. */
}
#else
(void)force;
#endif
}
#ifdef USE_LIBDNS
/*
* Initialize libdns if needed and open a dns_resolver context.
* Returns 0 on success and stores the new context at R_RES. On
* failure an error code is returned and NULL stored at R_RES.
*/
static gpg_error_t
libdns_res_open (struct dns_resolver **r_res)
{
gpg_error_t err;
struct dns_resolver *res;
int derr;
*r_res = NULL;
/* Force a reload if resolv.conf has changed. */
if (resolv_conf_changed_p ())
{
if (opt_debug)
log_debug ("dns: resolv.conf changed - forcing reload\n");
libdns_reinit_pending = 1;
}
if (libdns_reinit_pending)
{
libdns_reinit_pending = 0;
libdns_deinit ();
}
err = libdns_init ();
if (err)
return err;
if (!opt_timeout)
set_dns_timeout (0);
res = dns_res_open (libdns.resolv_conf, libdns.hosts, libdns.hints, NULL,
dns_opts (.socks_host = &libdns.socks_host,
.socks_user = tor_socks_user,
.socks_password = tor_socks_password ),
&derr);
if (!res)
return libdns_error_to_gpg_error (derr);
*r_res = res;
return 0;
}
#endif /*USE_LIBDNS*/
#ifdef USE_LIBDNS
/* Helper to test whether we need to try again after having switched
* the Tor port. */
static int
libdns_switch_port_p (gpg_error_t err)
{
if (tor_mode && gpg_err_code (err) == GPG_ERR_ECONNREFUSED
&& libdns_tor_port == TOR_PORT)
{
/* Switch port and try again. */
if (opt_debug)
log_debug ("dns: switching from SOCKS port %d to %d\n",
TOR_PORT, TOR_PORT2);
libdns_tor_port = TOR_PORT2;
libdns_reinit_pending = 1;
return 1;
}
return 0;
}
#endif /*USE_LIBDNS*/
#ifdef USE_LIBDNS
/* Wrapper around dns_res_submit. */
static gpg_error_t
libdns_res_submit (struct dns_resolver *res, const char *qname,
enum dns_type qtype, enum dns_class qclass)
{
return libdns_error_to_gpg_error (dns_res_submit (res, qname, qtype, qclass));
}
#endif /*USE_LIBDNS*/
#ifdef USE_LIBDNS
/* Standard event handling loop. */
gpg_error_t
libdns_res_wait (struct dns_resolver *res)
{
gpg_error_t err;
while ((err = libdns_error_to_gpg_error (dns_res_check (res)))
&& gpg_err_code (err) == GPG_ERR_EAGAIN)
{
if (dns_res_elapsed (res) > opt_timeout)
{
err = gpg_error (GPG_ERR_DNS_TIMEOUT);
break;
}
my_unprotect ();
dns_res_poll (res, 1);
my_protect ();
}
return err;
}
#endif /*USE_LIBDNS*/
#ifdef USE_LIBDNS
static gpg_error_t
resolve_name_libdns (const char *name, unsigned short port,
int want_family, int want_socktype,
dns_addrinfo_t *r_dai, char **r_canonname)
{
gpg_error_t err;
dns_addrinfo_t daihead = NULL;
dns_addrinfo_t dai;
struct dns_resolver *res = NULL;
struct dns_addrinfo *ai = NULL;
struct addrinfo hints;
struct addrinfo *ent;
char portstr_[21];
char *portstr = NULL;
char *namebuf = NULL;
int derr;
*r_dai = NULL;
if (r_canonname)
*r_canonname = NULL;
memset (&hints, 0, sizeof hints);
hints.ai_family = want_family;
hints.ai_socktype = want_socktype;
hints.ai_flags = AI_ADDRCONFIG;
if (r_canonname)
hints.ai_flags |= AI_CANONNAME;
if (port)
{
snprintf (portstr_, sizeof portstr_, "%hu", port);
portstr = portstr_;
}
err = libdns_res_open (&res);
if (err)
goto leave;
if (is_ip_address (name))
{
hints.ai_flags |= AI_NUMERICHOST;
/* libdns does not grok brackets - remove them. */
if (*name == '[' && name[strlen(name)-1] == ']')
{
namebuf = xtrymalloc (strlen (name));
if (!namebuf)
{
err = gpg_error_from_syserror ();
goto leave;
}
strcpy (namebuf, name+1);
namebuf[strlen (namebuf)-1] = 0;
name = namebuf;
}
}
ai = dns_ai_open (name, portstr, 0, &hints, res, &derr);
if (!ai)
{
err = libdns_error_to_gpg_error (derr);
goto leave;
}
/* Loop over all records. */
for (;;)
{
err = libdns_error_to_gpg_error (dns_ai_nextent (&ent, ai));
if (gpg_err_code (err) == GPG_ERR_ENOENT)
{
if (daihead)
err = 0; /* We got some results, we're good. */
break; /* Ready. */
}
if (gpg_err_code (err) == GPG_ERR_EAGAIN)
{
if (dns_ai_elapsed (ai) > opt_timeout)
{
err = gpg_error (GPG_ERR_DNS_TIMEOUT);
goto leave;
}
my_unprotect ();
dns_ai_poll (ai, 1);
my_protect ();
continue;
}
if (err)
goto leave;
if (r_canonname && ! *r_canonname && ent && ent->ai_canonname)
{
*r_canonname = xtrystrdup (ent->ai_canonname);
if (!*r_canonname)
{
err = gpg_error_from_syserror ();
goto leave;
}
/* Libdns appends the root zone part which is problematic
* for most other functions - strip it. */
if (**r_canonname && (*r_canonname)[strlen (*r_canonname)-1] == '.')
(*r_canonname)[strlen (*r_canonname)-1] = 0;
}
dai = xtrymalloc (sizeof *dai);
if (dai == NULL)
{
err = gpg_error_from_syserror ();
goto leave;
}
dai->family = ent->ai_family;
dai->socktype = ent->ai_socktype;
dai->protocol = ent->ai_protocol;
dai->addrlen = ent->ai_addrlen;
memcpy (dai->addr, ent->ai_addr, ent->ai_addrlen);
dai->next = daihead;
daihead = dai;
xfree (ent);
}
leave:
dns_ai_close (ai);
dns_res_close (res);
if (err)
{
if (r_canonname)
{
xfree (*r_canonname);
*r_canonname = NULL;
}
free_dns_addrinfo (daihead);
}
else
*r_dai = daihead;
xfree (namebuf);
return err;
}
#endif /*USE_LIBDNS*/
/* Resolve a name using the standard system function. */
static gpg_error_t
resolve_name_standard (const char *name, unsigned short port,
int want_family, int want_socktype,
dns_addrinfo_t *r_dai, char **r_canonname)
{
gpg_error_t err = 0;
dns_addrinfo_t daihead = NULL;
dns_addrinfo_t dai;
struct addrinfo *aibuf = NULL;
struct addrinfo hints, *ai;
char portstr[21];
int ret;
*r_dai = NULL;
if (r_canonname)
*r_canonname = NULL;
memset (&hints, 0, sizeof hints);
hints.ai_family = want_family;
hints.ai_socktype = want_socktype;
hints.ai_flags = AI_ADDRCONFIG;
if (r_canonname)
hints.ai_flags |= AI_CANONNAME;
if (is_ip_address (name))
hints.ai_flags |= AI_NUMERICHOST;
if (port)
snprintf (portstr, sizeof portstr, "%hu", port);
else
*portstr = 0;
/* We can't use the AI_IDN flag because that does the conversion
using the current locale. However, GnuPG always used UTF-8. To
support IDN we would need to make use of the libidn API. */
ret = getaddrinfo (name, *portstr? portstr : NULL, &hints, &aibuf);
if (ret)
{
aibuf = NULL;
err = map_eai_to_gpg_error (ret);
if (gpg_err_code (err) == GPG_ERR_NO_NAME)
{
/* There seems to be a bug in the glibc getaddrinfo function
if the CNAME points to a long list of A and AAAA records
in which case the function return NO_NAME. Let's do the
CNAME redirection again. */
char *cname;
if (get_dns_cname (name, &cname))
goto leave; /* Still no success. */
ret = getaddrinfo (cname, *portstr? portstr : NULL, &hints, &aibuf);
xfree (cname);
if (ret)
{
aibuf = NULL;
err = map_eai_to_gpg_error (ret);
goto leave;
}
err = 0; /* Yep, now it worked. */
}
else
goto leave;
}
if (r_canonname && aibuf && aibuf->ai_canonname)
{
*r_canonname = xtrystrdup (aibuf->ai_canonname);
if (!*r_canonname)
{
err = gpg_error_from_syserror ();
goto leave;
}
}
for (ai = aibuf; ai; ai = ai->ai_next)
{
if (ai->ai_family != AF_INET6 && ai->ai_family != AF_INET)
continue;
if (opt_disable_ipv4 && ai->ai_family == AF_INET)
continue;
if (opt_disable_ipv6 && ai->ai_family == AF_INET6)
continue;
dai = xtrymalloc (sizeof *dai);
dai->family = ai->ai_family;
dai->socktype = ai->ai_socktype;
dai->protocol = ai->ai_protocol;
dai->addrlen = ai->ai_addrlen;
memcpy (dai->addr, ai->ai_addr, ai->ai_addrlen);
dai->next = daihead;
daihead = dai;
}
leave:
if (aibuf)
freeaddrinfo (aibuf);
if (err)
{
if (r_canonname)
{
xfree (*r_canonname);
*r_canonname = NULL;
}
free_dns_addrinfo (daihead);
}
else
*r_dai = daihead;
return err;
}
/* This a wrapper around getaddrinfo with slightly different semantics.
NAME is the name to resolve.
PORT is the requested port or 0.
WANT_FAMILY is either 0 (AF_UNSPEC), AF_INET6, or AF_INET4.
WANT_SOCKETTYPE is either SOCK_STREAM or SOCK_DGRAM.
On success the result is stored in a linked list with the head
stored at the address R_AI; the caller must call gpg_addrinfo_free
on this. If R_CANONNAME is not NULL the official name of the host
is stored there as a malloced string; if that name is not available
NULL is stored. */
gpg_error_t
resolve_dns_name (const char *name, unsigned short port,
int want_family, int want_socktype,
dns_addrinfo_t *r_ai, char **r_canonname)
{
gpg_error_t err;
#ifdef USE_LIBDNS
if (!standard_resolver)
{
err = resolve_name_libdns (name, port, want_family, want_socktype,
r_ai, r_canonname);
if (err && libdns_switch_port_p (err))
err = resolve_name_libdns (name, port, want_family, want_socktype,
r_ai, r_canonname);
}
else
#endif /*USE_LIBDNS*/
err = resolve_name_standard (name, port, want_family, want_socktype,
r_ai, r_canonname);
if (opt_debug)
log_debug ("dns: resolve_dns_name(%s): %s\n", name, gpg_strerror (err));
return err;
}
#ifdef USE_LIBDNS
/* Resolve an address using libdns. */
static gpg_error_t
resolve_addr_libdns (const struct sockaddr_storage *addr, int addrlen,
unsigned int flags, char **r_name)
{
gpg_error_t err;
char host[DNS_D_MAXNAME + 1];
struct dns_resolver *res = NULL;
struct dns_packet *ans = NULL;
struct dns_ptr ptr;
int derr;
*r_name = NULL;
/* First we turn ADDR into a DNS name (with ".arpa" suffix). */
err = 0;
if (addr->ss_family == AF_INET6)
{
const struct sockaddr_in6 *a6 = (const struct sockaddr_in6 *)addr;
if (!dns_aaaa_arpa (host, sizeof host, (void*)&a6->sin6_addr))
err = gpg_error (GPG_ERR_INV_OBJ);
}
else if (addr->ss_family == AF_INET)
{
const struct sockaddr_in *a4 = (const struct sockaddr_in *)addr;
if (!dns_a_arpa (host, sizeof host, (void*)&a4->sin_addr))
err = gpg_error (GPG_ERR_INV_OBJ);
}
else
err = gpg_error (GPG_ERR_EAFNOSUPPORT);
if (err)
goto leave;
err = libdns_res_open (&res);
if (err)
goto leave;
err = libdns_res_submit (res, host, DNS_T_PTR, DNS_C_IN);
if (err)
goto leave;
err = libdns_res_wait (res);
if (err)
goto leave;
ans = dns_res_fetch (res, &derr);
if (!ans)
{
err = libdns_error_to_gpg_error (derr);
goto leave;
}
/* Check the rcode. */
switch (dns_p_rcode (ans))
{
case DNS_RC_NOERROR:
break;
case DNS_RC_NXDOMAIN:
err = gpg_error (GPG_ERR_NO_NAME);
break;
default:
err = GPG_ERR_SERVER_FAILED;
goto leave;
}
/* Parse the result. */
if (!err)
{
struct dns_rr rr;
struct dns_rr_i rri;
memset (&rri, 0, sizeof rri);
dns_rr_i_init (&rri, ans);
rri.section = DNS_S_ALL & ~DNS_S_QD;
rri.name = host;
rri.type = DNS_T_PTR;
if (!dns_rr_grep (&rr, 1, &rri, ans, &derr))
{
err = gpg_error (GPG_ERR_NOT_FOUND);
goto leave;
}
err = libdns_error_to_gpg_error (dns_ptr_parse (&ptr, &rr, ans));
if (err)
goto leave;
/* Copy result. */
*r_name = xtrystrdup (ptr.host);
if (!*r_name)
{
err = gpg_error_from_syserror ();
goto leave;
}
/* Libdns appends the root zone part which is problematic
* for most other functions - strip it. */
if (**r_name && (*r_name)[strlen (*r_name)-1] == '.')
(*r_name)[strlen (*r_name)-1] = 0;
}
else /* GPG_ERR_NO_NAME */
{
char *buffer, *p;
int buflen;
int ec;
buffer = ptr.host;
buflen = sizeof ptr.host;
p = buffer;
if (addr->ss_family == AF_INET6 && (flags & DNS_WITHBRACKET))
{
*p++ = '[';
buflen -= 2;
}
ec = getnameinfo ((const struct sockaddr *)addr,
addrlen, p, buflen, NULL, 0, NI_NUMERICHOST);
if (ec)
{
err = map_eai_to_gpg_error (ec);
goto leave;
}
if (addr->ss_family == AF_INET6 && (flags & DNS_WITHBRACKET))
strcat (buffer, "]");
}
leave:
dns_free (ans);
dns_res_close (res);
return err;
}
#endif /*USE_LIBDNS*/
/* Resolve an address using the standard system function. */
static gpg_error_t
resolve_addr_standard (const struct sockaddr_storage *addr, int addrlen,
unsigned int flags, char **r_name)
{
gpg_error_t err;
int ec;
char *buffer, *p;
int buflen;
*r_name = NULL;
buflen = NI_MAXHOST;
buffer = xtrymalloc (buflen + 2 + 1);
if (!buffer)
return gpg_error_from_syserror ();
if ((flags & DNS_NUMERICHOST) || tor_mode)
ec = EAI_NONAME;
else
ec = getnameinfo ((const struct sockaddr *)addr,
addrlen, buffer, buflen, NULL, 0, NI_NAMEREQD);
if (!ec && *buffer == '[')
ec = EAI_FAIL; /* A name may never start with a bracket. */
else if (ec == EAI_NONAME)
{
p = buffer;
if (addr->ss_family == AF_INET6 && (flags & DNS_WITHBRACKET))
{
*p++ = '[';
buflen -= 2;
}
ec = getnameinfo ((const struct sockaddr *)addr,
addrlen, p, buflen, NULL, 0, NI_NUMERICHOST);
if (!ec && addr->ss_family == AF_INET6 && (flags & DNS_WITHBRACKET))
strcat (buffer, "]");
}
if (ec)
err = map_eai_to_gpg_error (ec);
else
{
p = xtryrealloc (buffer, strlen (buffer)+1);
if (!p)
err = gpg_error_from_syserror ();
else
{
buffer = p;
err = 0;
}
}
if (err)
xfree (buffer);
else
*r_name = buffer;
return err;
}
/* A wrapper around getnameinfo. */
gpg_error_t
resolve_dns_addr (const struct sockaddr_storage *addr, int addrlen,
unsigned int flags, char **r_name)
{
gpg_error_t err;
#ifdef USE_LIBDNS
/* Note that we divert to the standard resolver for NUMERICHOST. */
if (!standard_resolver && !(flags & DNS_NUMERICHOST))
{
err = resolve_addr_libdns (addr, addrlen, flags, r_name);
if (err && libdns_switch_port_p (err))
err = resolve_addr_libdns (addr, addrlen, flags, r_name);
}
else
#endif /*USE_LIBDNS*/
err = resolve_addr_standard (addr, addrlen, flags, r_name);
if (opt_debug)
log_debug ("dns: resolve_dns_addr(): %s\n", gpg_strerror (err));
return err;
}
/* Check whether NAME is an IP address. Returns a true if it is
* either an IPv6 or a IPv4 numerical address. The actual return
* values can also be used to identify whether it is v4 or v6: The
* true value will surprisingly be 4 for IPv4 and 6 for IPv6. */
int
is_ip_address (const char *name)
{
const char *s;
int ndots, dblcol, n;
if (*name == '[')
return 6; /* yes: A legal DNS name may not contain this character;
this must be bracketed v6 address. */
if (*name == '.')
return 0; /* No. A leading dot is not a valid IP address. */
/* Check whether this is a v6 address. */
ndots = n = dblcol = 0;
for (s=name; *s; s++)
{
if (*s == ':')
{
ndots++;
if (s[1] == ':')
{
ndots++;
if (dblcol)
return 0; /* No: Only one "::" allowed. */
dblcol++;
if (s[1])
s++;
}
n = 0;
}
else if (*s == '.')
goto legacy;
else if (!strchr ("0123456789abcdefABCDEF", *s))
return 0; /* No: Not a hex digit. */
else if (++n > 4)
return 0; /* To many digits in a group. */
}
if (ndots > 7)
return 0; /* No: Too many colons. */
else if (ndots > 1)
return 6; /* Yes: At least 2 colons indicate an v6 address. */
legacy:
/* Check whether it is legacy IP address. */
ndots = n = 0;
for (s=name; *s; s++)
{
if (*s == '.')
{
if (s[1] == '.')
return 0; /* No: Double dot. */
if (atoi (s+1) > 255)
return 0; /* No: Ipv4 byte value too large. */
ndots++;
n = 0;
}
else if (!strchr ("0123456789", *s))
return 0; /* No: Not a digit. */
else if (++n > 3)
return 0; /* No: More than 3 digits. */
}
return (ndots == 3)? 4 : 0;
}
/* Return true if NAME is an onion address. */
int
is_onion_address (const char *name)
{
size_t len;
len = name? strlen (name) : 0;
if (len < 8 || strcmp (name + len - 6, ".onion"))
return 0;
/* Note that we require at least 2 characters before the suffix. */
return 1; /* Yes. */
}
/* libdns version of get_dns_cert. */
#ifdef USE_LIBDNS
static gpg_error_t
get_dns_cert_libdns (const char *name, int want_certtype,
void **r_key, size_t *r_keylen,
unsigned char **r_fpr, size_t *r_fprlen, char **r_url)
{
gpg_error_t err;
struct dns_resolver *res = NULL;
struct dns_packet *ans = NULL;
struct dns_rr rr;
struct dns_rr_i rri;
char host[DNS_D_MAXNAME + 1];
int derr;
int qtype;
/* Get the query type from WANT_CERTTYPE (which in general indicates
* the subtype we want). */
qtype = (want_certtype < DNS_CERTTYPE_RRBASE
? T_CERT
: (want_certtype - DNS_CERTTYPE_RRBASE));
err = libdns_res_open (&res);
if (err)
goto leave;
if (dns_d_anchor (host, sizeof host, name, strlen (name)) >= sizeof host)
{
err = gpg_error (GPG_ERR_ENAMETOOLONG);
goto leave;
}
err = libdns_res_submit (res, name, qtype, DNS_C_IN);
if (err)
goto leave;
err = libdns_res_wait (res);
if (err)
goto leave;
ans = dns_res_fetch (res, &derr);
if (!ans)
{
err = libdns_error_to_gpg_error (derr);
goto leave;
}
/* Check the rcode. */
switch (dns_p_rcode (ans))
{
case DNS_RC_NOERROR: break;
case DNS_RC_NXDOMAIN: err = gpg_error (GPG_ERR_NO_NAME); break;
default: err = GPG_ERR_SERVER_FAILED; break;
}
if (err)
goto leave;
memset (&rri, 0, sizeof rri);
dns_rr_i_init (&rri, ans);
rri.section = DNS_S_ALL & ~DNS_S_QD;
rri.name = host;
rri.type = qtype;
err = gpg_error (GPG_ERR_NOT_FOUND);
while (dns_rr_grep (&rr, 1, &rri, ans, &derr))
{
unsigned char *rp = ans->data + rr.rd.p;
unsigned short len = rr.rd.len;
u16 subtype;
if (!len)
{
/* Definitely too short - skip. */
}
else if (want_certtype >= DNS_CERTTYPE_RRBASE
&& rr.type == (want_certtype - DNS_CERTTYPE_RRBASE)
&& r_key)
{
*r_key = xtrymalloc (len);
if (!*r_key)
err = gpg_error_from_syserror ();
else
{
memcpy (*r_key, rp, len);
*r_keylen = len;
err = 0;
}
goto leave;
}
else if (want_certtype >= DNS_CERTTYPE_RRBASE)
{
/* We did not found the requested RR - skip. */
}
else if (rr.type == T_CERT && len > 5)
{
/* We got a CERT type. */
subtype = buf16_to_u16 (rp);
rp += 2; len -= 2;
/* Skip the CERT key tag and algo which we don't need. */
rp += 3; len -= 3;
if (want_certtype && want_certtype != subtype)
; /* Not the requested subtype - skip. */
else if (subtype == DNS_CERTTYPE_PGP && len && r_key && r_keylen)
{
/* PGP subtype */
*r_key = xtrymalloc (len);
if (!*r_key)
err = gpg_error_from_syserror ();
else
{
memcpy (*r_key, rp, len);
*r_keylen = len;
err = 0;
}
goto leave;
}
else if (subtype == DNS_CERTTYPE_IPGP
&& len && len < 1023 && len >= rp[0] + 1)
{
/* IPGP type */
*r_fprlen = rp[0];
if (*r_fprlen)
{
*r_fpr = xtrymalloc (*r_fprlen);
if (!*r_fpr)
{
err = gpg_error_from_syserror ();
goto leave;
}
memcpy (*r_fpr, rp+1, *r_fprlen);
}
else
*r_fpr = NULL;
if (len > *r_fprlen + 1)
{
*r_url = xtrymalloc (len - (*r_fprlen + 1) + 1);
if (!*r_url)
{
err = gpg_error_from_syserror ();
xfree (*r_fpr);
*r_fpr = NULL;
goto leave;
}
memcpy (*r_url, rp + *r_fprlen + 1, len - (*r_fprlen + 1));
(*r_url)[len - (*r_fprlen + 1)] = 0;
}
else
*r_url = NULL;
err = 0;
goto leave;
}
else
{
/* Unknown subtype or record too short - skip. */
}
}
else
{
/* Not a requested type - skip. */
}
}
leave:
dns_free (ans);
dns_res_close (res);
return err;
}
#endif /*USE_LIBDNS*/
/* Standard resolver version of get_dns_cert. */
static gpg_error_t
get_dns_cert_standard (const char *name, int want_certtype,
void **r_key, size_t *r_keylen,
unsigned char **r_fpr, size_t *r_fprlen, char **r_url)
{
#ifdef HAVE_SYSTEM_RESOLVER
gpg_error_t err;
unsigned char *answer;
int r;
u16 count;
/* Allocate a 64k buffer which is the limit for an DNS response. */
answer = xtrymalloc (65536);
if (!answer)
return gpg_error_from_syserror ();
err = gpg_error (GPG_ERR_NOT_FOUND);
r = res_query (name, C_IN,
(want_certtype < DNS_CERTTYPE_RRBASE
? T_CERT
: (want_certtype - DNS_CERTTYPE_RRBASE)),
answer, 65536);
/* Not too big, not too small, no errors and at least 1 answer. */
if (r >= sizeof (HEADER) && r <= 65536
&& (((HEADER *)(void *) answer)->rcode) == NOERROR
&& (count = ntohs (((HEADER *)(void *) answer)->ancount)))
{
int rc;
unsigned char *pt, *emsg;
emsg = &answer[r];
pt = &answer[sizeof (HEADER)];
/* Skip over the query */
rc = dn_skipname (pt, emsg);
if (rc == -1)
{
err = gpg_error (GPG_ERR_INV_OBJ);
goto leave;
}
pt += rc + QFIXEDSZ;
/* There are several possible response types for a CERT request.
We're interested in the PGP (a key) and IPGP (a URI) types.
Skip all others. TODO: A key is better than a URI since
we've gone through all this bother to fetch it, so favor that
if we have both PGP and IPGP? */
while (count-- > 0 && pt < emsg)
{
u16 type, class, dlen, ctype;
rc = dn_skipname (pt, emsg); /* the name we just queried for */
if (rc == -1)
{
err = gpg_error (GPG_ERR_INV_OBJ);
goto leave;
}
pt += rc;
/* Truncated message? 15 bytes takes us to the point where
we start looking at the ctype. */
if ((emsg - pt) < 15)
break;
type = buf16_to_u16 (pt);
pt += 2;
class = buf16_to_u16 (pt);
pt += 2;
if (class != C_IN)
break;
/* ttl */
pt += 4;
/* data length */
dlen = buf16_to_u16 (pt);
pt += 2;
/* Check the type and parse. */
if (want_certtype >= DNS_CERTTYPE_RRBASE
&& type == (want_certtype - DNS_CERTTYPE_RRBASE)
&& r_key)
{
*r_key = xtrymalloc (dlen);
if (!*r_key)
err = gpg_error_from_syserror ();
else
{
memcpy (*r_key, pt, dlen);
*r_keylen = dlen;
err = 0;
}
goto leave;
}
else if (want_certtype >= DNS_CERTTYPE_RRBASE)
{
/* We did not found the requested RR. */
pt += dlen;
}
else if (type == T_CERT)
{
/* We got a CERT type. */
ctype = buf16_to_u16 (pt);
pt += 2;
/* Skip the CERT key tag and algo which we don't need. */
pt += 3;
dlen -= 5;
/* 15 bytes takes us to here */
if (want_certtype && want_certtype != ctype)
; /* Not of the requested certtype. */
else if (ctype == DNS_CERTTYPE_PGP && dlen && r_key && r_keylen)
{
/* PGP type */
*r_key = xtrymalloc (dlen);
if (!*r_key)
err = gpg_error_from_syserror ();
else
{
memcpy (*r_key, pt, dlen);
*r_keylen = dlen;
err = 0;
}
goto leave;
}
else if (ctype == DNS_CERTTYPE_IPGP
&& dlen && dlen < 1023 && dlen >= pt[0] + 1)
{
/* IPGP type */
*r_fprlen = pt[0];
if (*r_fprlen)
{
*r_fpr = xtrymalloc (*r_fprlen);
if (!*r_fpr)
{
err = gpg_error_from_syserror ();
goto leave;
}
memcpy (*r_fpr, &pt[1], *r_fprlen);
}
else
*r_fpr = NULL;
if (dlen > *r_fprlen + 1)
{
*r_url = xtrymalloc (dlen - (*r_fprlen + 1) + 1);
if (!*r_url)
{
err = gpg_error_from_syserror ();
xfree (*r_fpr);
*r_fpr = NULL;
goto leave;
}
memcpy (*r_url, &pt[*r_fprlen + 1],
dlen - (*r_fprlen + 1));
(*r_url)[dlen - (*r_fprlen + 1)] = '\0';
}
else
*r_url = NULL;
err = 0;
goto leave;
}
/* No subtype matches, so continue with the next answer. */
pt += dlen;
}
else
{
/* Not a requested type - might be a CNAME. Try next item. */
pt += dlen;
}
}
}
leave:
xfree (answer);
return err;
#else /*!HAVE_SYSTEM_RESOLVER*/
(void)name;
(void)want_certtype;
(void)r_key;
(void)r_keylen;
(void)r_fpr;
(void)r_fprlen;
(void)r_url;
return gpg_error (GPG_ERR_NOT_SUPPORTED);
#endif /*!HAVE_SYSTEM_RESOLVER*/
}
/* Returns 0 on success or an error code. If a PGP CERT record was
found, the malloced data is returned at (R_KEY, R_KEYLEN) and
the other return parameters are set to NULL/0. If an IPGP CERT
record was found the fingerprint is stored as an allocated block at
R_FPR and its length at R_FPRLEN; an URL is allocated as a
string and returned at R_URL. If WANT_CERTTYPE is 0 this function
returns the first CERT found with a supported type; it is expected
that only one CERT record is used. If WANT_CERTTYPE is one of the
supported certtypes only records with this certtype are considered
and the first found is returned. (R_KEY,R_KEYLEN) are optional. */
gpg_error_t
get_dns_cert (const char *name, int want_certtype,
void **r_key, size_t *r_keylen,
unsigned char **r_fpr, size_t *r_fprlen, char **r_url)
{
gpg_error_t err;
if (r_key)
*r_key = NULL;
if (r_keylen)
*r_keylen = 0;
*r_fpr = NULL;
*r_fprlen = 0;
*r_url = NULL;
#ifdef USE_LIBDNS
if (!standard_resolver)
{
err = get_dns_cert_libdns (name, want_certtype, r_key, r_keylen,
r_fpr, r_fprlen, r_url);
if (err && libdns_switch_port_p (err))
err = get_dns_cert_libdns (name, want_certtype, r_key, r_keylen,
r_fpr, r_fprlen, r_url);
}
else
#endif /*USE_LIBDNS*/
err = get_dns_cert_standard (name, want_certtype, r_key, r_keylen,
r_fpr, r_fprlen, r_url);
if (opt_debug)
log_debug ("dns: get_dns_cert(%s): %s\n", name, gpg_strerror (err));
return err;
}
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;
}
/* Libdns based helper for getsrv. Note that it is expected that NULL
* is stored at the address of LIST and 0 is stored at the address of
* R_COUNT. */
#ifdef USE_LIBDNS
static gpg_error_t
getsrv_libdns (const char *name, struct srventry **list, unsigned int *r_count)
{
gpg_error_t err;
struct dns_resolver *res = NULL;
struct dns_packet *ans = NULL;
struct dns_rr rr;
struct dns_rr_i rri;
char host[DNS_D_MAXNAME + 1];
int derr;
unsigned int srvcount = 0;
err = libdns_res_open (&res);
if (err)
goto leave;
if (dns_d_anchor (host, sizeof host, name, strlen (name)) >= sizeof host)
{
err = gpg_error (GPG_ERR_ENAMETOOLONG);
goto leave;
}
err = libdns_res_submit (res, name, DNS_T_SRV, DNS_C_IN);
if (err)
goto leave;
err = libdns_res_wait (res);
if (err)
goto leave;
ans = dns_res_fetch (res, &derr);
if (!ans)
{
err = libdns_error_to_gpg_error (derr);
goto leave;
}
/* Check the rcode. */
switch (dns_p_rcode (ans))
{
case DNS_RC_NOERROR: break;
case DNS_RC_NXDOMAIN: err = gpg_error (GPG_ERR_NO_NAME); break;
default: err = GPG_ERR_SERVER_FAILED; break;
}
if (err)
goto leave;
memset (&rri, 0, sizeof rri);
dns_rr_i_init (&rri, ans);
rri.section = DNS_S_ALL & ~DNS_S_QD;
rri.name = host;
rri.type = DNS_T_SRV;
while (dns_rr_grep (&rr, 1, &rri, ans, &derr))
{
struct dns_srv dsrv;
struct srventry *srv;
struct srventry *newlist;
err = libdns_error_to_gpg_error (dns_srv_parse(&dsrv, &rr, ans));
if (err)
goto leave;
newlist = xtryrealloc (*list, (srvcount+1)*sizeof(struct srventry));
if (!newlist)
{
err = gpg_error_from_syserror ();
goto leave;
}
*list = newlist;
memset (&(*list)[srvcount], 0, sizeof(struct srventry));
srv = &(*list)[srvcount];
srvcount++;
srv->priority = dsrv.priority;
srv->weight = dsrv.weight;
srv->port = dsrv.port;
mem2str (srv->target, dsrv.target, sizeof srv->target);
/* Libdns appends the root zone part which is problematic for
* most other functions - strip it. */
if (*srv->target && (srv->target)[strlen (srv->target)-1] == '.')
(srv->target)[strlen (srv->target)-1] = 0;
}
*r_count = srvcount;
leave:
if (err)
{
xfree (*list);
*list = NULL;
}
dns_free (ans);
dns_res_close (res);
return err;
}
#endif /*USE_LIBDNS*/
/* Standard resolver based helper for getsrv. Note that it is
* expected that NULL is stored at the address of LIST and 0 is stored
* at the address of R_COUNT. */
static gpg_error_t
getsrv_standard (const char *name,
struct srventry **list, unsigned int *r_count)
{
#ifdef HAVE_SYSTEM_RESOLVER
union {
unsigned char ans[2048];
HEADER header[1];
} res;
unsigned char *answer = res.ans;
HEADER *header = res.header;
unsigned char *pt, *emsg;
int r, rc;
u16 dlen;
unsigned int srvcount = 0;
u16 count;
/* Do not allow a query using the standard resolver in Tor mode. */
if (tor_mode)
return gpg_error (GPG_ERR_NOT_ENABLED);
my_unprotect ();
r = res_query (name, C_IN, T_SRV, answer, sizeof res.ans);
my_protect ();
if (r < 0)
return get_h_errno_as_gpg_error ();
if (r < sizeof (HEADER))
return gpg_error (GPG_ERR_SERVER_FAILED);
if (r > sizeof res.ans)
return gpg_error (GPG_ERR_SYSTEM_BUG);
if (header->rcode != NOERROR || !(count=ntohs (header->ancount)))
return gpg_error (GPG_ERR_NO_NAME); /* Error or no record found. */
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;
u16 type, class;
struct srventry *newlist;
newlist = xtryrealloc (*list, (srvcount+1)*sizeof(struct srventry));
if (!newlist)
goto fail;
*list = newlist;
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 = buf16_to_u16 (pt);
pt += 2;
/* We asked for SRV and got something else !? */
if (type != T_SRV)
goto fail;
class = buf16_to_u16 (pt);
pt += 2;
/* We asked for IN and got something else !? */
if (class != C_IN)
goto fail;
pt += 4; /* ttl */
dlen = buf16_to_u16 (pt);
pt += 2;
srv->priority = buf16_to_ushort (pt);
pt += 2;
srv->weight = buf16_to_ushort (pt);
pt += 2;
srv->port = buf16_to_ushort (pt);
pt += 2;
/* 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, sizeof srv->target);
if (rc == 1 && srv->target[0] == 0) /* "." */
{
xfree(*list);
*list = NULL;
return 0;
}
if (rc == -1)
goto fail;
pt += rc;
/* Corrupt packet? */
if (dlen != rc+6)
goto fail;
}
*r_count = srvcount;
return 0;
fail:
xfree (*list);
*list = NULL;
return gpg_error (GPG_ERR_GENERAL);
#else /*!HAVE_SYSTEM_RESOLVER*/
(void)name;
(void)list;
(void)r_count;
return gpg_error (GPG_ERR_NOT_SUPPORTED);
#endif /*!HAVE_SYSTEM_RESOLVER*/
}
/* Query a SRV record for SERVICE and PROTO for NAME. If SERVICE is
* NULL, NAME is expected to contain the full query name. Note that
* we do not return NONAME but simply store 0 at R_COUNT. On error an
* error code is returned and 0 stored at R_COUNT. */
gpg_error_t
get_dns_srv (const char *name, const char *service, const char *proto,
struct srventry **list, unsigned int *r_count)
{
gpg_error_t err;
char *namebuffer = NULL;
unsigned int srvcount;
int i;
*list = NULL;
*r_count = 0;
srvcount = 0;
/* If SERVICE is given construct the query from it and PROTO. */
if (service)
{
namebuffer = xtryasprintf ("_%s._%s.%s",
service, proto? proto:"tcp", name);
if (!namebuffer)
{
err = gpg_error_from_syserror ();
goto leave;
}
name = namebuffer;
}
#ifdef USE_LIBDNS
if (!standard_resolver)
{
err = getsrv_libdns (name, list, &srvcount);
if (err && libdns_switch_port_p (err))
err = getsrv_libdns (name, list, &srvcount);
}
else
#endif /*USE_LIBDNS*/
err = getsrv_standard (name, list, &srvcount);
if (err)
{
if (gpg_err_code (err) == GPG_ERR_NO_NAME)
err = 0;
goto leave;
}
/* 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. */
{
static int done;
if (!done)
{
done = 1;
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;
}
}
}
leave:
if (opt_debug)
{
if (err)
log_debug ("dns: getsrv(%s): %s\n", name, gpg_strerror (err));
else
log_debug ("dns: getsrv(%s) -> %u records\n", name, srvcount);
}
if (!err)
*r_count = srvcount;
xfree (namebuffer);
return err;
}
#ifdef USE_LIBDNS
/* libdns version of get_dns_cname. */
gpg_error_t
get_dns_cname_libdns (const char *name, char **r_cname)
{
gpg_error_t err;
struct dns_resolver *res;
struct dns_packet *ans = NULL;
struct dns_cname cname;
int derr;
err = libdns_res_open (&res);
if (err)
goto leave;
err = libdns_res_submit (res, name, DNS_T_CNAME, DNS_C_IN);
if (err)
goto leave;
err = libdns_res_wait (res);
if (err)
goto leave;
ans = dns_res_fetch (res, &derr);
if (!ans)
{
err = libdns_error_to_gpg_error (derr);
goto leave;
}
/* Check the rcode. */
switch (dns_p_rcode (ans))
{
case DNS_RC_NOERROR: break;
case DNS_RC_NXDOMAIN: err = gpg_error (GPG_ERR_NO_NAME); break;
default: err = GPG_ERR_SERVER_FAILED; break;
}
if (err)
goto leave;
/* Parse the result into CNAME. */
err = libdns_error_to_gpg_error (dns_p_study (ans));
if (err)
goto leave;
if (!dns_d_cname (&cname, sizeof cname, name, strlen (name), ans, &derr))
{
err = libdns_error_to_gpg_error (derr);
goto leave;
}
/* Copy result. */
*r_cname = xtrystrdup (cname.host);
if (!*r_cname)
err = gpg_error_from_syserror ();
else
{
/* Libdns appends the root zone part which is problematic
* for most other functions - strip it. */
if (**r_cname && (*r_cname)[strlen (*r_cname)-1] == '.')
(*r_cname)[strlen (*r_cname)-1] = 0;
}
leave:
dns_free (ans);
dns_res_close (res);
return err;
}
#endif /*USE_LIBDNS*/
/* Standard resolver version of get_dns_cname. */
gpg_error_t
get_dns_cname_standard (const char *name, char **r_cname)
{
#ifdef HAVE_SYSTEM_RESOLVER
gpg_error_t err;
int rc;
union {
unsigned char ans[2048];
HEADER header[1];
} res;
unsigned char *answer = res.ans;
HEADER *header = res.header;
unsigned char *pt, *emsg;
int r;
char *cname;
int cnamesize = 1025;
u16 count;
/* Do not allow a query using the standard resolver in Tor mode. */
if (tor_mode)
return -1;
my_unprotect ();
r = res_query (name, C_IN, T_CERT, answer, sizeof res.ans);
my_protect ();
if (r < 0)
return get_h_errno_as_gpg_error ();
if (r < sizeof (HEADER))
return gpg_error (GPG_ERR_SERVER_FAILED);
if (r > sizeof res.ans)
return gpg_error (GPG_ERR_SYSTEM_BUG);
if (header->rcode != NOERROR || !(count=ntohs (header->ancount)))
return gpg_error (GPG_ERR_NO_NAME); /* Error or no record found. */
if (count != 1)
return gpg_error (GPG_ERR_SERVER_FAILED);
emsg = &answer[r];
pt = &answer[sizeof(HEADER)];
rc = dn_skipname (pt, emsg);
if (rc == -1)
return gpg_error (GPG_ERR_SERVER_FAILED);
pt += rc + QFIXEDSZ;
if (pt >= emsg)
return gpg_error (GPG_ERR_SERVER_FAILED);
rc = dn_skipname (pt, emsg);
if (rc == -1)
return gpg_error (GPG_ERR_SERVER_FAILED);
pt += rc + 2 + 2 + 4;
if (pt+2 >= emsg)
return gpg_error (GPG_ERR_SERVER_FAILED);
pt += 2; /* Skip rdlen */
cname = xtrymalloc (cnamesize);
if (!cname)
return gpg_error_from_syserror ();
rc = dn_expand (answer, emsg, pt, cname, cnamesize -1);
if (rc == -1)
{
xfree (cname);
return gpg_error (GPG_ERR_SERVER_FAILED);
}
*r_cname = xtryrealloc (cname, strlen (cname)+1);
if (!*r_cname)
{
err = gpg_error_from_syserror ();
xfree (cname);
return err;
}
return 0;
#else /*!HAVE_SYSTEM_RESOLVER*/
(void)name;
(void)r_cname;
return gpg_error (GPG_ERR_NOT_IMPLEMENTED);
#endif /*!HAVE_SYSTEM_RESOLVER*/
}
gpg_error_t
get_dns_cname (const char *name, char **r_cname)
{
gpg_error_t err;
*r_cname = NULL;
#ifdef USE_LIBDNS
if (!standard_resolver)
{
err = get_dns_cname_libdns (name, r_cname);
if (err && libdns_switch_port_p (err))
err = get_dns_cname_libdns (name, r_cname);
return err;
}
#endif /*USE_LIBDNS*/
err = get_dns_cname_standard (name, r_cname);
if (opt_debug)
log_debug ("get_dns_cname(%s)%s%s\n", name,
err ? ": " : " -> ",
err ? gpg_strerror (err) : *r_cname);
return err;
}
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