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strongswan/src/pluto/dnskey.c

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/* Find public key in DNS
* Copyright (C) 2000-2002 D. Hugh Redelmeier.
*
* 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. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* 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.
*/
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <netdb.h> /* ??? for h_errno */
#include <sys/queue.h>
#include <freeswan.h>
#include <utils/identification.h>
#include <credentials/keys/public_key.h>
#include "constants.h"
#include "adns.h" /* needs <resolv.h> */
#include "defs.h"
#include "log.h"
#include "myid.h"
#include "connections.h"
#include "keys.h" /* needs connections.h */
#include "dnskey.h"
#include "packet.h"
#include "timer.h"
/* somebody has to decide */
#define MAX_TXT_RDATA ((MAX_KEY_BYTES * 8 / 6) + 40) /* somewhat arbitrary overkill */
/* ADNS stuff */
int adns_qfd = NULL_FD, /* file descriptor for sending queries to adns (O_NONBLOCK) */
adns_afd = NULL_FD; /* file descriptor for receiving answers from adns */
static pid_t adns_pid = 0;
const char *pluto_adns_option = NULL; /* path from --pluto_adns */
int adns_restart_count;
#define ADNS_RESTART_MAX 20
void
init_adns(void)
{
const char *adns_path = pluto_adns_option;
#ifndef USE_LWRES
static const char adns_name[] = "_pluto_adns";
const char *helper_bin_dir = getenv("IPSEC_LIBDIR");
#else /* USE_LWRES */
static const char adns_name[] = "lwdnsq";
const char *helper_bin_dir = getenv("IPSEC_EXECDIR");
#endif /* USE_LWRES */
char adns_path_space[4096]; /* plenty long? */
int qfds[2];
int afds[2];
/* find a pathname to the ADNS program */
if (adns_path == NULL)
{
/* pathname was not specified as an option: build it.
* First, figure out the directory to be used.
*/
ssize_t n;
if (helper_bin_dir != NULL)
{
n = strlen(helper_bin_dir);
if ((size_t)n <= sizeof(adns_path_space) - sizeof(adns_name))
{
strcpy(adns_path_space, helper_bin_dir);
if (n > 0 && adns_path_space[n -1] != '/')
{
adns_path_space[n++] = '/';
}
}
}
else
{
/* The program will be in the same directory as Pluto,
* so we use the sympolic link /proc/self/exe to
* tell us of the path prefix.
*/
n = readlink("/proc/self/exe", adns_path_space, sizeof(adns_path_space));
if (n < 0)
{
exit_log_errno((e
, "readlink(\"/proc/self/exe\") failed in init_adns()"));
}
}
if ((size_t)n > sizeof(adns_path_space) - sizeof(adns_name))
{
exit_log("path to %s is too long", adns_name);
}
while (n > 0 && adns_path_space[n - 1] != '/')
{
n--;
}
strcpy(adns_path_space + n, adns_name);
adns_path = adns_path_space;
}
if (access(adns_path, X_OK) < 0)
{
exit_log_errno((e, "%s missing or not executable", adns_path));
}
if (pipe(qfds) != 0 || pipe(afds) != 0)
{
exit_log_errno((e, "pipe(2) failed in init_adns()"));
}
adns_pid = fork();
switch (adns_pid)
{
case -1:
exit_log_errno((e, "fork() failed in init_adns()"));
case 0:
/* child */
{
/* Make stdin and stdout our pipes.
* Take care to handle case where pipes already use these fds.
*/
if (afds[1] == 0)
{
afds[1] = dup(afds[1]); /* avoid being overwritten */
}
if (qfds[0] != 0)
{
dup2(qfds[0], 0);
close(qfds[0]);
}
if (afds[1] != 1)
{
dup2(afds[1], 1);
close(qfds[1]);
}
if (afds[0] > 1)
{
close(afds[0]);
}
if (afds[1] > 1)
{
close(afds[1]);
}
DBG(DBG_DNS, execlp(adns_path, adns_name, "-d", NULL));
execlp(adns_path, adns_name, NULL);
exit_log_errno((e, "execlp of %s failed", adns_path));
}
default:
/* parent */
close(qfds[0]);
adns_qfd = qfds[1];
adns_afd = afds[0];
close(afds[1]);
fcntl(adns_qfd, F_SETFD, FD_CLOEXEC);
fcntl(adns_afd, F_SETFD, FD_CLOEXEC);
fcntl(adns_qfd, F_SETFL, O_NONBLOCK);
break;
}
}
void
stop_adns(void)
{
close_any(adns_qfd);
adns_qfd = NULL_FD;
close_any(adns_afd);
adns_afd = NULL_FD;
if (adns_pid != 0)
{
int status;
pid_t p = waitpid(adns_pid, &status, 0);
if (p == -1)
{
log_errno((e, "waitpid for ADNS process failed"));
}
else if (WIFEXITED(status))
{
if (WEXITSTATUS(status) != 0)
{
plog("ADNS process exited with status %d"
, (int) WEXITSTATUS(status));
}
}
else if (WIFSIGNALED(status))
{
plog("ADNS process terminated by signal %d", (int)WTERMSIG(status));
}
else
{
plog("wait for end of ADNS process returned odd status 0x%x\n"
, status);
}
}
}
/* tricky macro to pass any hot potato */
#define TRY(x) { err_t ugh = x; if (ugh != NULL) return ugh; }
/* Process TXT X-IPsec-Server record, accumulating relevant ones
* in cr->gateways_from_dns, a list sorted by "preference".
*
* Format of TXT record body: X-IPsec-Server ( nnn ) = iii kkk
* nnn is a 16-bit unsigned integer preference
* iii is @FQDN or dotted-decimal IPv4 address or colon-hex IPv6 address
* kkk is an optional RSA public signing key in base 64.
*
* NOTE: we've got to be very wary of anything we find -- bad guys
* might have prepared it.
*/
#define our_TXT_attr_string "X-IPsec-Server"
static const char our_TXT_attr[] = our_TXT_attr_string;
identification_t* decode_iii(u_char **pp)
{
identification_t *gw_id;
u_char *p = *pp + strspn(*pp, " \t");
u_char *e = p + strcspn(p, " \t");
u_char under = *e;
if (p == e)
{
return NULL;
}
*e = '\0';
gw_id = identification_create_from_string(p);
*e = under;
*pp = e + strspn(e, " \t");
return gw_id;
}
static err_t process_txt_rr_body(u_char *str, bool doit,
enum dns_auth_level dns_auth_level,
struct adns_continuation *const cr)
{
identification_t *client_id = cr->id; /* subject of query */
u_char *p = str;
unsigned long pref = 0;
struct gw_info gi;
p += strspn(p, " \t"); /* ignore leading whitespace */
/* is this for us? */
if (strncasecmp(p, our_TXT_attr, sizeof(our_TXT_attr)-1) != 0)
{
return NULL; /* neither interesting nor bad */
}
p += sizeof(our_TXT_attr) - 1; /* ignore our attribute name */
p += strspn(p, " \t"); /* ignore leading whitespace */
/* decode '(' nnn ')' */
if (*p != '(')
{
return "X-IPsec-Server missing '('";
}
{
char *e;
p++;
pref = strtoul(p, &e, 0);
if ((u_char *)e == p)
{
return "malformed X-IPsec-Server priority";
}
p = e + strspn(e, " \t");
if (*p != ')')
{
return "X-IPsec-Server priority missing ')'";
}
p++;
p += strspn(p, " \t");
if (pref > 0xFFFF)
{
return "X-IPsec-Server priority larger than 0xFFFF";
}
}
/* time for '=' */
if (*p != '=')
{
return "X-IPsec-Server priority missing '='";
}
p++;
p += strspn(p, " \t");
/* Decode iii (Security Gateway ID). */
zero(&gi); /* before first use */
gi.gw_id = decode_iii(&p);
if (gi.gw_id == NULL)
{
return "TXT " our_TXT_attr_string " badly formed (no gateway specified)";
}
if (!cr->sgw_specified)
{
/* we don't know the peer's ID (because we are initiating
* and we don't know who to initiate with.
* So we're looking for gateway specs with an IP address
*/
if (gi.gw_id->get_type(gi.gw_id) != ID_IPV4_ADDR &&
gi.gw_id->get_type(gi.gw_id) != ID_IPV6_ADDR)
{
DBG(DBG_DNS,
DBG_log("TXT %s record for '%Y': security gateway '%Y';"
" ignored because gateway's IP is unspecified",
our_TXT_attr, client_id, gi.gw_id);
)
return NULL; /* we cannot use this record, but it isn't wrong */
}
}
else
{
/* We do know the peer's ID (because we are responding)
* So we're looking for gateway specs specifying this known ID.
*/
identification_t *peer_id = cr->sgw_id;
if (!peer_id->equals(peer_id, gi.gw_id))
{
DBG(DBG_DNS,
DBG_log("TXT %s record for '%Y': security gateway '%Y';"
" ignored -- looking to confirm '%Y' as gateway",
our_TXT_attr, client_id, gi.gw_id, peer_id);
)
return NULL; /* we cannot use this record, but it isn't wrong */
}
}
if (doit)
{
/* really accept gateway */
struct gw_info **gwip; /* gateway insertion point */
gi.client_id = client_id; /* will need to unshare_id_content */
/* decode optional kkk: base 64 encoding of key */
gi.gw_key_present = *p != '\0';
if (gi.gw_key_present)
{
/* Decode base 64 encoding of key.
* Similar code is in process_lwdnsq_key.
*/
u_char buf[RSA_MAX_ENCODING_BYTES]; /* plenty of space for binary form of public key */
size_t sz;
err_t ugh;
chunk_t rfc3110_chunk;
public_key_t *key;
ugh = ttodatav(p, 0, 64, buf, sizeof(buf), &sz,
diag_space, sizeof(diag_space), TTODATAV_SPACECOUNTS);
if (ugh)
{
return builddiag("malformed key data: %s", ugh);
}
if (sz > sizeof(buf))
{
return builddiag("key data larger than %lu bytes",
(unsigned long) sizeof(buf));
}
rfc3110_chunk = chunk_create(buf, sz);
key = lib->creds->create(lib->creds, CRED_PRIVATE_KEY, KEY_RSA,
BUILD_BLOB_DNSKEY, rfc3110_chunk,
BUILD_END);
if (key == NULL)
{
return builddiag("invalid key data");
}
/* now find a key entry to put it in */
gi.key = public_key_from_rsa(key);
unreference_key(&cr->last_info);
cr->last_info = reference_key(gi.key);
}
/* we're home free! Allocate everything and add to gateways list. */
gi.refcnt = 1;
gi.pref = pref;
gi.key->dns_auth_level = dns_auth_level;
gi.key->last_tried_time = gi.key->last_worked_time = NO_TIME;
/* find insertion point */
for (gwip = &cr->gateways_from_dns; *gwip != NULL && (*gwip)->pref < pref; gwip = &(*gwip)->next)
;
DBG(DBG_DNS,
{
chunk_t keyid;
public_key_t *key = gi.key->public_key;
if (gi.gw_key_present &&
key->get_fingerprint(key, KEYID_PUBKEY_SHA1, &keyid))
{
DBG_log("gateway for %s is %s with key %#B",
client_id, gi.gw_id, &keyid);
}
else
{
DBG_log("gateway for '%Y' is '%Y'; no key specified",
client_id, gi.gw_id);
}
});
gi.next = *gwip;
*gwip = clone_thing(gi);
(*gwip)->gw_id = (*gwip)->gw_id->clone((*gwip)->gw_id);
(*gwip)->client_id = (*gwip)->client_id->clone((*gwip)->client_id);
}
return NULL;
}
static const char *
rr_typename(int type)
{
switch (type)
{
case T_TXT:
return "TXT";
case T_KEY:
return "KEY";
default:
return "???";
}
}
#ifdef USE_LWRES
# ifdef USE_KEYRR
static err_t
process_lwdnsq_key(u_char *str
, enum dns_auth_level dns_auth_level
, struct adns_continuation *const cr)
{
/* fields of KEY record. See RFC 2535 3.1 KEY RDATA format. */
unsigned long flags /* 16 bits */
, protocol /* 8 bits */
, algorithm; /* 8 bits */
char *rest = str
, *p
, *endofnumber;
/* flags */
p = strsep(&rest, " \t");
if (p == NULL)
return "lwdnsq KEY: missing flags";
flags = strtoul(p, &endofnumber, 10);
if (*endofnumber != '\0')
return "lwdnsq KEY: malformed flags";
/* protocol */
p = strsep(&rest, " \t");
if (p == NULL)
return "lwdnsq KEY: missing protocol";
protocol = strtoul(p, &endofnumber, 10);
if (*endofnumber != '\0')
return "lwdnsq KEY: malformed protocol";
/* algorithm */
p = strsep(&rest, " \t");
if (p == NULL)
return "lwdnsq KEY: missing algorithm";
algorithm = strtoul(p, &endofnumber, 10);
if (*endofnumber != '\0')
return "lwdnsq KEY: malformed algorithm";
/* is this key interesting? */
if (protocol == 4 /* IPSEC (RFC 2535 3.1.3) */
&& algorithm == 1 /* RSA/MD5 (RFC 2535 3.2) */
&& (flags & 0x8000ul) == 0 /* use for authentication (3.1.2) */
&& (flags & 0x2CF0ul) == 0) /* must be zero */
{
/* Decode base 64 encoding of key.
* Similar code is in process_txt_rr_body.
*/
u_char kb[RSA_MAX_ENCODING_BYTES]; /* plenty of space for binary form of public key */
chunk_t kbc;
err_t ugh = ttodatav(rest, 0, 64, kb, sizeof(kb), &kbc.len
, diag_space, sizeof(diag_space), TTODATAV_IGNORESPACE);
if (ugh != NULL)
return builddiag("malformed key data: %s", ugh);
if (kbc.len > sizeof(kb))
return builddiag("key data larger than %lu bytes"
, (unsigned long) sizeof(kb));
kbc.ptr = kb;
TRY(add_public_key(&cr->id, dns_auth_level, PUBKEY_ALG_RSA, &kbc
, &cr->keys_from_dns));
/* keep a reference to last one */
unreference_key(&cr->last_info);
cr->last_info = reference_key(cr->keys_from_dns->key);
}
return NULL;
}
# endif /* USE_KEYRR */
#else /* ! USE_LWRES */
/* structure of Query Reply (RFC 1035 4.1.1):
*
* +---------------------+
* | Header |
* +---------------------+
* | Question | the question for the name server
* +---------------------+
* | Answer | RRs answering the question
* +---------------------+
* | Authority | RRs pointing toward an authority
* +---------------------+
* | Additional | RRs holding additional information
* +---------------------+
*/
/* Header section format (as modified by RFC 2535 6.1):
* 1 1 1 1 1 1
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | ID |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* |QR| Opcode |AA|TC|RD|RA| Z|AD|CD| RCODE |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | QDCOUNT |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | ANCOUNT |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | NSCOUNT |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | ARCOUNT |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
*/
struct qr_header {
u_int16_t id; /* 16-bit identifier to match query */
u_int16_t stuff; /* packed crud: */
#define QRS_QR 0x8000 /* QR: on if this is a response */
#define QRS_OPCODE_SHIFT 11 /* OPCODE field */
#define QRS_OPCODE_MASK 0xF
#define QRSO_QUERY 0 /* standard query */
#define QRSO_IQUERY 1 /* inverse query */
#define QRSO_STATUS 2 /* server status request query */
#define QRS_AA 0x0400 /* AA: on if Authoritative Answer */
#define QRS_TC 0x0200 /* TC: on if truncation happened */
#define QRS_RD 0x0100 /* RD: on if recursion desired */
#define QRS_RA 0x0080 /* RA: on if recursion available */
#define QRS_Z 0x0040 /* Z: reserved; must be zero */
#define QRS_AD 0x0020 /* AD: on if authentic data (RFC 2535) */
#define QRS_CD 0x0010 /* AD: on if checking disabled (RFC 2535) */
#define QRS_RCODE_SHIFT 0 /* RCODE field: response code */
#define QRS_RCODE_MASK 0xF
#define QRSR_OK 0
u_int16_t qdcount; /* number of entries in question section */
u_int16_t ancount; /* number of resource records in answer section */
u_int16_t nscount; /* number of name server resource records in authority section */
u_int16_t arcount; /* number of resource records in additional records section */
};
static field_desc qr_header_fields[] = {
{ ft_nat, 16/BITS_PER_BYTE, "ID", NULL },
{ ft_nat, 16/BITS_PER_BYTE, "stuff", NULL },
{ ft_nat, 16/BITS_PER_BYTE, "QD Count", NULL },
{ ft_nat, 16/BITS_PER_BYTE, "Answer Count", NULL },
{ ft_nat, 16/BITS_PER_BYTE, "Authority Count", NULL },
{ ft_nat, 16/BITS_PER_BYTE, "Additional Count", NULL },
{ ft_end, 0, NULL, NULL }
};
static struct_desc qr_header_desc = {
"Query Response Header",
qr_header_fields,
sizeof(struct qr_header)
};
/* Messages for codes in RCODE (see RFC 1035 4.1.1) */
static const err_t rcode_text[QRS_RCODE_MASK + 1] = {
NULL, /* not an error */
"Format error - The name server was unable to interpret the query",
"Server failure - The name server was unable to process this query"
" due to a problem with the name server",
"Name Error - Meaningful only for responses from an authoritative name"
" server, this code signifies that the domain name referenced in"
" the query does not exist",
"Not Implemented - The name server does not support the requested"
" kind of query",
"Refused - The name server refuses to perform the specified operation"
" for policy reasons",
/* the rest are reserved for future use */
};
/* throw away a possibly compressed domain name */
static err_t
eat_name(pb_stream *pbs)
{
u_char name_buf[NS_MAXDNAME + 2];
u_char *ip = pbs->cur;
unsigned oi = 0;
unsigned jump_count = 0;
for (;;)
{
u_int8_t b;
if (ip >= pbs->roof)
return "ran out of message while skipping domain name";
b = *ip++;
if (jump_count == 0)
pbs->cur = ip;
if (b == 0)
break;
switch (b & 0xC0)
{
case 0x00:
/* we grab the next b characters */
if (oi + b > NS_MAXDNAME)
return "domain name too long";
if (pbs->roof - ip <= b)
return "domain name falls off end of message";
if (oi != 0)
name_buf[oi++] = '.';
memcpy(name_buf + oi, ip, b);
oi += b;
ip += b;
if (jump_count == 0)
pbs->cur = ip;
break;
case 0xC0:
{
unsigned ix;
if (ip >= pbs->roof)
return "ran out of message in middle of compressed domain name";
ix = ((b & ~0xC0u) << 8) | *ip++;
if (jump_count == 0)
pbs->cur = ip;
if (ix >= pbs_room(pbs))
return "impossible compressed domain name";
/* Avoid infinite loop.
* There can be no more jumps than there are bytes
* in the packet. Not a tight limit, but good enough.
*/
jump_count++;
if (jump_count > pbs_room(pbs))
return "loop in compressed domain name";
ip = pbs->start + ix;
}
break;
default:
return "invalid code in label";
}
}
name_buf[oi++] = '\0';
DBG(DBG_DNS, DBG_log("skipping name %s", name_buf));
return NULL;
}
static err_t
eat_name_helpfully(pb_stream *pbs, const char *context)
{
err_t ugh = eat_name(pbs);
return ugh == NULL? ugh
: builddiag("malformed name within DNS record of %s: %s", context, ugh);
}
/* non-variable part of 4.1.2 Question Section entry:
* 1 1 1 1 1 1
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | |
* / QNAME /
* / /
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | QTYPE |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | QCLASS |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
*/
struct qs_fixed {
u_int16_t qtype;
u_int16_t qclass;
};
static field_desc qs_fixed_fields[] = {
{ ft_loose_enum, 16/BITS_PER_BYTE, "QTYPE", &rr_qtype_names },
{ ft_loose_enum, 16/BITS_PER_BYTE, "QCLASS", &rr_class_names },
{ ft_end, 0, NULL, NULL }
};
static struct_desc qs_fixed_desc = {
"Question Section entry fixed part",
qs_fixed_fields,
sizeof(struct qs_fixed)
};
/* 4.1.3. Resource record format:
* 1 1 1 1 1 1
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | |
* / /
* / NAME /
* | |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | TYPE |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | CLASS |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | TTL |
* | |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | RDLENGTH |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--|
* / RDATA /
* / /
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
*/
struct rr_fixed {
u_int16_t type;
u_int16_t class;
u_int32_t ttl; /* actually signed */
u_int16_t rdlength;
};
static field_desc rr_fixed_fields[] = {
{ ft_loose_enum, 16/BITS_PER_BYTE, "type", &rr_type_names },
{ ft_loose_enum, 16/BITS_PER_BYTE, "class", &rr_class_names },
{ ft_nat, 32/BITS_PER_BYTE, "TTL", NULL },
{ ft_nat, 16/BITS_PER_BYTE, "RD length", NULL },
{ ft_end, 0, NULL, NULL }
};
static struct_desc rr_fixed_desc = {
"Resource Record fixed part",
rr_fixed_fields,
/* note: following is tricky: avoids padding problems */
offsetof(struct rr_fixed, rdlength) + sizeof(u_int16_t)
};
/* RFC 1035 3.3.14: TXT RRs have text in the RDATA field.
* It is in the form of a sequence of <character-string>s as described in 3.3.
* unpack_txt_rdata() deals with this peculiar representation.
*/
/* RFC 2535 3.1 KEY RDATA format:
*
* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | flags | protocol | algorithm |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | /
* / public key /
* / /
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-|
*/
struct key_rdata {
u_int16_t flags;
u_int8_t protocol;
u_int8_t algorithm;
};
static field_desc key_rdata_fields[] = {
{ ft_nat, 16/BITS_PER_BYTE, "flags", NULL },
{ ft_nat, 8/BITS_PER_BYTE, "protocol", NULL },
{ ft_nat, 8/BITS_PER_BYTE, "algorithm", NULL },
{ ft_end, 0, NULL, NULL }
};
static struct_desc key_rdata_desc = {
"KEY RR RData fixed part",
key_rdata_fields,
sizeof(struct key_rdata)
};
/* RFC 2535 4.1 SIG RDATA format:
*
* 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | type covered | algorithm | labels |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | original TTL |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | signature expiration |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | signature inception |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | key tag | |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ signer's name +
* | /
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-/
* / /
* / signature /
* / /
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
*/
struct sig_rdata {
u_int16_t type_covered;
u_int8_t algorithm;
u_int8_t labels;
u_int32_t original_ttl;
u_int32_t sig_expiration;
u_int32_t sig_inception;
u_int16_t key_tag;
};
static field_desc sig_rdata_fields[] = {
{ ft_nat, 16/BITS_PER_BYTE, "type_covered", NULL},
{ ft_nat, 8/BITS_PER_BYTE, "algorithm", NULL},
{ ft_nat, 8/BITS_PER_BYTE, "labels", NULL},
{ ft_nat, 32/BITS_PER_BYTE, "original ttl", NULL},
{ ft_nat, 32/BITS_PER_BYTE, "sig expiration", NULL},
{ ft_nat, 32/BITS_PER_BYTE, "sig inception", NULL},
{ ft_nat, 16/BITS_PER_BYTE, "key tag", NULL},
{ ft_end, 0, NULL, NULL }
};
static struct_desc sig_rdata_desc = {
"SIG RR RData fixed part",
sig_rdata_fields,
sizeof(struct sig_rdata)
};
/* handle a KEY Resource Record. */
#ifdef USE_KEYRR
static err_t
process_key_rr(u_char *ptr, size_t len
, bool doit /* should we capture information? */
, enum dns_auth_level dns_auth_level
, struct adns_continuation *const cr)
{
pb_stream pbs;
struct key_rdata kr;
if (len < sizeof(struct key_rdata))
return "KEY Resource Record's RD Length is too small";
init_pbs(&pbs, ptr, len, "KEY RR");
if (!in_struct(&kr, &key_rdata_desc, &pbs, NULL))
return "failed to get fixed part of KEY Resource Record RDATA";
if (kr.protocol == 4 /* IPSEC (RFC 2535 3.1.3) */
&& kr.algorithm == 1 /* RSA/MD5 (RFC 2535 3.2) */
&& (kr.flags & 0x8000) == 0 /* use for authentication (3.1.2) */
&& (kr.flags & 0x2CF0) == 0) /* must be zero */
{
/* we have what seems to be a tasty key */
if (doit)
{
chunk_t k = { pbs.cur, pbs_left(&pbs) };
TRY(add_public_key(&cr->id, dns_auth_level, PUBKEY_ALG_RSA, &k
, &cr->keys_from_dns));
}
}
return NULL;
}
#endif /* USE_KEYRR */
/* unpack TXT rr RDATA into C string.
* A sequence of <character-string>s as described in RFC 1035 3.3.
* We concatenate them.
*/
static err_t
unpack_txt_rdata(u_char *d, size_t dlen, const u_char *s, size_t slen)
{
size_t i = 0
, o = 0;
while (i < slen)
{
size_t cl = s[i++];
if (i + cl > slen)
return "TXT rr RDATA representation malformed";
if (o + cl >= dlen)
return "TXT rr RDATA too large";
memcpy(d + o, s + i, cl);
i += cl;
o += cl;
}
d[o] = '\0';
if (strlen(d) != o)
return "TXT rr RDATA contains a NUL";
return NULL;
}
static err_t
process_txt_rr(u_char *rdata, size_t rdlen
, bool doit /* should we capture information? */
, enum dns_auth_level dns_auth_level
, struct adns_continuation *const cr)
{
u_char str[RSA_MAX_ENCODING_BYTES * 8 / 6 + 20]; /* space for unpacked RDATA */
TRY(unpack_txt_rdata(str, sizeof(str), rdata, rdlen));
return process_txt_rr_body(str, doit, dns_auth_level, cr);
}
static err_t
process_answer_section(pb_stream *pbs
, bool doit /* should we capture information? */
, enum dns_auth_level *dns_auth_level
, u_int16_t ancount /* number of RRs in the answer section */
, struct adns_continuation *const cr)
{
const int type = cr->query.type; /* type of RR of interest */
unsigned c;
DBG(DBG_DNS, DBG_log("*Answer Section:"));
for (c = 0; c != ancount; c++)
{
struct rr_fixed rrf;
size_t tail;
/* ??? do we need to match the name? */
TRY(eat_name_helpfully(pbs, "Answer Section"));
if (!in_struct(&rrf, &rr_fixed_desc, pbs, NULL))
return "failed to get fixed part of Answer Section Resource Record";
if (rrf.rdlength > pbs_left(pbs))
return "RD Length extends beyond end of message";
/* ??? should we care about ttl? */
tail = rrf.rdlength;
if (rrf.type == type && rrf.class == C_IN)
{
err_t ugh = NULL;
switch (type)
{
#ifdef USE_KEYRR
case T_KEY:
ugh = process_key_rr(pbs->cur, tail, doit, *dns_auth_level, cr);
break;
#endif /* USE_KEYRR */
case T_TXT:
ugh = process_txt_rr(pbs->cur, tail, doit, *dns_auth_level, cr);
break;
case T_SIG:
/* Check if SIG RR authenticates what we are learning.
* The RRset covered by a SIG must have the same owner,
* class, and type.
* For us, the class is always C_IN, so that matches.
* We decode the SIG RR's fixed part to check
* that the type_covered field matches our query type
* (this may be redundant).
* We don't check the owner (apparently this is the
* name on the record) -- we assume that it matches
* or we would not have been given this SIG in the
* Answer Section.
*
* We only look on first pass, and only if we've something
* to learn. This cuts down on useless decoding.
*/
if (!doit && *dns_auth_level == DAL_UNSIGNED)
{
struct sig_rdata sr;
if (!in_struct(&sr, &sig_rdata_desc, pbs, NULL))
ugh = "failed to get fixed part of SIG Resource Record RDATA";
else if (sr.type_covered == type)
*dns_auth_level = DAL_SIGNED;
}
break;
default:
ugh = builddiag("unexpected RR type %d", type);
break;
}
if (ugh != NULL)
return ugh;
}
in_raw(NULL, tail, pbs, "RR RDATA");
}
return doit
&& cr->gateways_from_dns == NULL
#ifdef USE_KEYRR
&& cr->keys_from_dns == NULL
#endif /* USE_KEYRR */
? builddiag("no suitable %s record found in DNS", rr_typename(type))
: NULL;
}
/* process DNS answer -- TXT or KEY query */
static err_t
process_dns_answer(struct adns_continuation *const cr
, u_char ans[], int anslen)
{
const int type = cr->query.type; /* type of record being sought */
int r; /* all-purpose return value holder */
u_int16_t c; /* number of current RR in current answer section */
pb_stream pbs;
u_int8_t *ans_start; /* saved position of answer section */
struct qr_header qr_header;
enum dns_auth_level dns_auth_level;
init_pbs(&pbs, ans, anslen, "Query Response Message");
/* decode and check header */
if (!in_struct(&qr_header, &qr_header_desc, &pbs, NULL))
return "malformed header";
/* ID: nothing to do with us */
/* stuff -- lots of things */
if ((qr_header.stuff & QRS_QR) == 0)
return "not a response?!?";
if (((qr_header.stuff >> QRS_OPCODE_SHIFT) & QRS_OPCODE_MASK) != QRSO_QUERY)
return "unexpected opcode";
/* I don't think we care about AA */
if (qr_header.stuff & QRS_TC)
return "response truncated";
/* I don't think we care about RD, RA, or CD */
/* AD means "authentic data" */
dns_auth_level = qr_header.stuff & QRS_AD? DAL_UNSIGNED : DAL_NOTSEC;
if (qr_header.stuff & QRS_Z)
return "Z bit is not zero";
r = (qr_header.stuff >> QRS_RCODE_SHIFT) & QRS_RCODE_MASK;
if (r != 0)
return r < (int)countof(rcode_text)? rcode_text[r] : "unknown rcode";
if (qr_header.ancount == 0)
return builddiag("no %s RR found by DNS", rr_typename(type));
/* end of header checking */
/* Question Section processing */
/* 4.1.2. Question section format:
* 1 1 1 1 1 1
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | |
* / QNAME /
* / /
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | QTYPE |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
* | QCLASS |
* +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
*/
DBG(DBG_DNS, DBG_log("*Question Section:"));
for (c = 0; c != qr_header.qdcount; c++)
{
struct qs_fixed qsf;
TRY(eat_name_helpfully(&pbs, "Question Section"));
if (!in_struct(&qsf, &qs_fixed_desc, &pbs, NULL))
return "failed to get fixed part of Question Section";
if (qsf.qtype != type)
return "unexpected QTYPE in Question Section";
if (qsf.qclass != C_IN)
return "unexpected QCLASS in Question Section";
}
/* rest of sections are made up of Resource Records */
/* Answer Section processing -- error checking, noting T_SIG */
ans_start = pbs.cur; /* remember start of answer section */
TRY(process_answer_section(&pbs, FALSE, &dns_auth_level
, qr_header.ancount, cr));
/* Authority Section processing (just sanity checking) */
DBG(DBG_DNS, DBG_log("*Authority Section:"));
for (c = 0; c != qr_header.nscount; c++)
{
struct rr_fixed rrf;
size_t tail;
TRY(eat_name_helpfully(&pbs, "Authority Section"));
if (!in_struct(&rrf, &rr_fixed_desc, &pbs, NULL))
return "failed to get fixed part of Authority Section Resource Record";
if (rrf.rdlength > pbs_left(&pbs))
return "RD Length extends beyond end of message";
/* ??? should we care about ttl? */
tail = rrf.rdlength;
in_raw(NULL, tail, &pbs, "RR RDATA");
}
/* Additional Section processing (just sanity checking) */
DBG(DBG_DNS, DBG_log("*Additional Section:"));
for (c = 0; c != qr_header.arcount; c++)
{
struct rr_fixed rrf;
size_t tail;
TRY(eat_name_helpfully(&pbs, "Additional Section"));
if (!in_struct(&rrf, &rr_fixed_desc, &pbs, NULL))
return "failed to get fixed part of Additional Section Resource Record";
if (rrf.rdlength > pbs_left(&pbs))
return "RD Length extends beyond end of message";
/* ??? should we care about ttl? */
tail = rrf.rdlength;
in_raw(NULL, tail, &pbs, "RR RDATA");
}
/* done all sections */
/* ??? is padding legal, or can we complain if more left in record? */
/* process Answer Section again -- accept contents */
pbs.cur = ans_start; /* go back to start of answer section */
return process_answer_section(&pbs, TRUE, &dns_auth_level
, qr_header.ancount, cr);
}
#endif /* ! USE_LWRES */
/****************************************************************/
static err_t build_dns_name(u_char name_buf[NS_MAXDNAME + 2],
unsigned long serial USED_BY_DEBUG,
identification_t *id,
const char *typename USED_BY_DEBUG,
identification_t *gw USED_BY_DEBUG)
{
/* note: all end in "." to suppress relative searches */
id = resolve_myid(id);
switch (id->get_type(id))
{
case ID_IPV4_ADDR:
{
chunk_t b = id->get_encoding(id);
snprintf(name_buf, NS_MAXDNAME + 2, "%d.%d.%d.%d.in-addr.arpa.",
b.ptr[3], b.ptr[2], b.ptr[1], b.ptr[0]);
break;
}
case ID_IPV6_ADDR:
{
chunk_t b = id->get_encoding(id);
size_t bl;
u_char *op = name_buf;
static const char suffix[] = "IP6.INT.";
for (bl = b.len; bl-- != 0; )
{
if (op + 4 + sizeof(suffix) >= name_buf + NS_MAXDNAME + 1)
{
return "IPv6 reverse name too long";
}
op += sprintf(op, "%x.%x.", b.ptr[bl] & 0xF, b.ptr[bl] >> 4);
}
strcpy(op, suffix);
break;
}
case ID_FQDN:
{
if (snprintf(name_buf, NS_MAXDNAME + 2, "%Y.", id) > NS_MAXDNAME + 1)
{
return "FQDN too long for domain name";
}
break;
}
default:
return "can only query DNS for key for ID that is a FQDN, IPV4_ADDR, or IPV6_ADDR";
}
DBG(DBG_CONTROL | DBG_DNS,
DBG_log("DNS query %lu for %s for %s (gw: %Y)", serial, typename, name_buf, gw)
)
return NULL;
}
void gw_addref(struct gw_info *gw)
{
if (gw != NULL)
{
DBG(DBG_DNS, DBG_log("gw_addref: %p refcnt: %d++", gw, gw->refcnt))
gw->refcnt++;
}
}
void gw_delref(struct gw_info **gwp)
{
struct gw_info *gw = *gwp;
if (gw != NULL)
{
DBG(DBG_DNS, DBG_log("gw_delref: %p refcnt: %d--", gw, gw->refcnt));
passert(gw->refcnt != 0);
gw->refcnt--;
if (gw->refcnt == 0)
{
DESTROY_IF(gw->client_id);
DESTROY_IF(gw->gw_id);
if (gw->gw_key_present)
{
unreference_key(&gw->key);
}
gw_delref(&gw->next);
free(gw); /* trickery could make this a tail-call */
}
*gwp = NULL;
}
}
static int adns_in_flight = 0; /* queries outstanding */
/* Start an asynchronous DNS query.
*
* For KEY record, the result will be a list in cr->keys_from_dns.
* For TXT records, the result will be a list in cr->gateways_from_dns.
*
* If sgw_id is null, only consider TXT records that specify an
* IP address for the gatway: we need this in the initiation case.
*
* If sgw_id is non-null, only consider TXT records that specify
* this id as the security gatway; this is useful to the Responder
* for confirming claims of gateways.
*
* Continuation cr gives information for continuing when the result shows up.
*
* Two kinds of errors must be handled: synchronous (immediate)
* and asynchronous. Synchronous errors are indicated by the returned
* value of start_adns_query; in this case, the continuation will
* have been freed and the continuation routine will not be called.
* Asynchronous errors are indicated by the ugh parameter passed to the
* continuation routine.
*
* After the continuation routine has completed, handle_adns_answer
* will free the continuation. The continuation routine should have
* freed any axiliary resources.
*
* Note: in the synchronous error case, start_adns_query will have
* freed the continuation; this means that the caller will have to
* be very careful to release any auxiliary resources that were in
* the continuation record without using the continuation record.
*
* Either there will be an error result passed to the continuation routine,
* or the results will be in cr->keys_from_dns or cr->gateways_from_dns.
* The result variables must by left NULL by the continutation routine.
* The continuation routine is responsible for establishing and
* disestablishing any logging context (whack_log_fd, cur_*).
*/
static struct adns_continuation *continuations = NULL; /* newest of queue */
static struct adns_continuation *next_query = NULL; /* oldest not sent */
static struct adns_continuation *continuation_for_qtid(unsigned long qtid)
{
struct adns_continuation *cr = NULL;
if (qtid != 0)
{
for (cr = continuations; cr != NULL && cr->qtid != qtid; cr = cr->previous)
;
}
return cr;
}
static void release_adns_continuation(struct adns_continuation *cr)
{
passert(cr != next_query);
gw_delref(&cr->gateways_from_dns);
#ifdef USE_KEYRR
free_public_keys(&cr->keys_from_dns);
#endif /* USE_KEYRR */
cr->id = cr->id->clone(cr->id);
cr->sgw_id = cr->sgw_id->clone(cr->sgw_id);
/* unlink from doubly-linked list */
if (cr->next == NULL)
{
continuations = cr->previous;
}
else
{
cr->next->previous = cr->previous;
}
if (cr->previous != NULL)
{
cr->previous->next = cr->next;
}
free(cr);
}
err_t start_adns_query(identification_t *id, /* domain to query */
identification_t *sgw_id, /* if non-null, any accepted gw_info must match */
int type, /* T_TXT or T_KEY, selecting rr type of interest */
cont_fn_t cont_fn,
struct adns_continuation *cr)
{
static unsigned long qtid = 1; /* query transaction id; NOTE: static */
const char *typename = rr_typename(type);
if(adns_pid == 0 && adns_restart_count < ADNS_RESTART_MAX)
{
plog("ADNS helper was not running. Restarting attempt %d",adns_restart_count);
init_adns();
}
/* Splice this in at head of doubly-linked list of continuations.
* Note: this must be done before any release_adns_continuation().
*/
cr->next = NULL;
cr->previous = continuations;
if (continuations != NULL)
{
continuations->next = cr;
}
continuations = cr;
cr->qtid = qtid++;
cr->type = type;
cr->cont_fn = cont_fn;
cr->id = id->clone(id);
cr->sgw_specified = (sgw_id != NULL);
cr->sgw_id = cr->sgw_specified ?
sgw_id->clone(sgw_id) :
identification_create_from_string("%any");
cr->gateways_from_dns = NULL;
#ifdef USE_KEYRR
cr->keys_from_dns = NULL;
#endif /* USE_KEYRR */
#ifdef DEBUG
cr->debugging = cur_debugging;
#else
cr->debugging = LEMPTY;
#endif
zero(&cr->query);
{
err_t ugh = build_dns_name(cr->query.name_buf, cr->qtid, id,
typename, cr->sgw_id);
if (ugh)
{
release_adns_continuation(cr);
return ugh;
}
}
if (next_query == NULL)
next_query = cr;
unsent_ADNS_queries = TRUE;
return NULL;
}
/* send remaining ADNS queries (until pipe full or none left)
*
* This is a co-routine, so it uses static variables to
* preserve state across calls.
*/
bool unsent_ADNS_queries = FALSE;
void
send_unsent_ADNS_queries(void)
{
static const unsigned char *buf_end = NULL; /* NOTE STATIC */
static const unsigned char *buf_cur = NULL; /* NOTE STATIC */
if (adns_qfd == NULL_FD)
return; /* nothing useful to do */
for (;;)
{
if (buf_cur != buf_end)
{
static int try = 0; /* NOTE STATIC */
size_t n = buf_end - buf_cur;
ssize_t r = write(adns_qfd, buf_cur, n);
if (r == -1)
{
switch (errno)
{
case EINTR:
continue; /* try again now */
case EAGAIN:
DBG(DBG_DNS, DBG_log("EAGAIN writing to ADNS"));
break; /* try again later */
default:
try++;
log_errno((e, "error %d writing DNS query", try));
break; /* try again later */
}
unsent_ADNS_queries = TRUE;
break; /* done! */
}
else
{
passert(r >= 0);
try = 0;
buf_cur += r;
}
}
else
{
if (next_query == NULL)
{
unsent_ADNS_queries = FALSE;
break; /* done! */
}
#ifdef USE_LWRES
next_query->used = FALSE;
{
/* NOTE STATIC: */
static unsigned char qbuf[LWDNSQ_CMDBUF_LEN + 1]; /* room for NUL */
snprintf(qbuf, sizeof(qbuf), "%s %lu %s\n"
, rr_typename(next_query->type)
, next_query->qtid
, next_query->query.name_buf);
DBG(DBG_DNS, DBG_log("lwdnsq query: %.*s", (int)(strlen(qbuf) - 1), qbuf));
buf_cur = qbuf;
buf_end = qbuf + strlen(qbuf);
}
#else /* !USE_LWRES */
next_query->query.debugging = next_query->debugging;
next_query->query.serial = next_query->qtid;
next_query->query.len = sizeof(next_query->query);
next_query->query.qmagic = ADNS_Q_MAGIC;
next_query->query.type = next_query->type;
buf_cur = (const void *)&next_query->query;
buf_end = buf_cur + sizeof(next_query->query);
#endif /* !USE_LWRES */
next_query = next_query->next;
adns_in_flight++;
}
}
}
#ifdef USE_LWRES
/* Process a line of lwdnsq answer.
* Returns with error message iff lwdnsq result is malformed.
* Most errors will be in DNS data and will be handled by cr->cont_fn.
*/
static err_t process_lwdnsq_answer(char *ts)
{
err_t ugh = NULL;
char *rest;
char *p;
char *endofnumber;
struct adns_continuation *cr = NULL;
unsigned long qtid;
time_t anstime; /* time of answer */
char *atype; /* type of answer */
long ttl; /* ttl of answer; int, but long for conversion */
bool AuthenticatedData = FALSE;
static char scratch_null_str[] = ""; /* cannot be const, but isn't written */
/* query transaction id */
rest = ts;
p = strsep(&rest, " \t");
if (p == NULL)
return "lwdnsq: answer missing query transaction ID";
qtid = strtoul(p, &endofnumber, 10);
if (*endofnumber != '\0')
return "lwdnsq: malformed query transaction ID";
cr = continuation_for_qtid(qtid);
if (qtid != 0 && cr == NULL)
return "lwdnsq: unrecognized qtid"; /* can't happen! */
/* time */
p = strsep(&rest, " \t");
if (p == NULL)
return "lwdnsq: missing time";
anstime = strtoul(p, &endofnumber, 10);
if (*endofnumber != '\0')
return "lwdnsq: malformed time";
/* TTL */
p = strsep(&rest, " \t");
if (p == NULL)
return "lwdnsq: missing TTL";
ttl = strtol(p, &endofnumber, 10);
if (*endofnumber != '\0')
return "lwdnsq: malformed TTL";
/* type */
atype = strsep(&rest, " \t");
if (atype == NULL)
return "lwdnsq: missing type";
/* if rest is NULL, make it "", otherwise eat whitespace after type */
rest = rest == NULL? scratch_null_str : rest + strspn(rest, " \t");
if (strncasecmp(atype, "AD-", 3) == 0)
{
AuthenticatedData = TRUE;
atype += 3;
}
/* deal with each type */
if (cr == NULL)
{
/* we don't actually know which this applies to */
return builddiag("lwdnsq: 0 qtid invalid with %s", atype);
}
else if (strcaseeq(atype, "START"))
{
/* ignore */
}
else if (strcaseeq(atype, "DONE"))
{
if (!cr->used)
{
/* "no results returned by lwdnsq" should not happen */
cr->cont_fn(cr
, cr->gateways_from_dns == NULL
#ifdef USE_KEYRR
&& cr->keys_from_dns == NULL
#endif /* USE_KEYRR */
? "no results returned by lwdnsq" : NULL);
cr->used = TRUE;
}
reset_globals();
release_adns_continuation(cr);
adns_in_flight--;
}
else if (strcaseeq(atype, "RETRY"))
{
if (!cr->used)
{
cr->cont_fn(cr, rest);
cr->used = TRUE;
}
}
else if (strcaseeq(atype, "FATAL"))
{
if (!cr->used)
{
cr->cont_fn(cr, rest);
cr->used = TRUE;
}
}
else if (strcaseeq(atype, "DNSSEC"))
{
/* ignore */
}
else if (strcaseeq(atype, "NAME"))
{
/* ignore */
}
else if (strcaseeq(atype, "TXT"))
{
char *end = rest + strlen(rest);
err_t txt_ugh;
if (*rest == '"' && end[-1] == '"')
{
/* strip those pesky quotes */
rest++;
*--end = '\0';
}
txt_ugh = process_txt_rr_body(rest
, TRUE
, AuthenticatedData? DAL_SIGNED : DAL_NOTSEC
, cr);
if (txt_ugh != NULL)
{
DBG(DBG_DNS,
DBG_log("error processing TXT resource record (%s) while processing: %s"
, txt_ugh, rest));
cr->cont_fn(cr, txt_ugh);
cr->used = TRUE;
}
}
else if (strcaseeq(atype, "SIG"))
{
/* record the SIG records for posterity */
if (cr->last_info != NULL)
{
free(cr->last_info->dns_sig);
cr->last_info->dns_sig = clone_str(rest);
}
}
else if (strcaseeq(atype, "A"))
{
/* ignore */
}
else if (strcaseeq(atype, "AAAA"))
{
/* ignore */
}
else if (strcaseeq(atype, "CNAME"))
{
/* ignore */
}
else if (strcaseeq(atype, "CNAMEFROM"))
{
/* ignore */
}
else if (strcaseeq(atype, "PTR"))
{
/* ignore */
}
#ifdef USE_KEYRR
else if (strcaseeq(atype, "KEY"))
{
err_t key_ugh = process_lwdnsq_key(rest
, AuthenticatedData? DAL_SIGNED : DAL_NOTSEC
, cr);
if (key_ugh != NULL)
{
DBG(DBG_DNS,
DBG_log("error processing KEY resource record (%s) while processing: %s"
, key_ugh, rest));
cr->cont_fn(cr, key_ugh);
cr->used = TRUE;
}
}
#endif /* USE_KEYRR */
else
{
ugh = "lwdnsq: unrecognized type";
}
return ugh;
}
#endif /* USE_LWRES */
static void recover_adns_die(void)
{
struct adns_continuation *cr = NULL;
adns_pid = 0;
if(adns_restart_count < ADNS_RESTART_MAX) {
adns_restart_count++;
/* next DNS query will restart it */
/* we have to walk the list of the outstanding requests,
* and redo them!
*/
cr = continuations;
/* find the head of the list */
if(continuations != NULL) {
for (; cr->previous != NULL; cr = cr->previous);
}
next_query = cr;
if(next_query != NULL) {
unsent_ADNS_queries = TRUE;
}
}
}
void reset_adns_restart_count(void)
{
adns_restart_count=0;
}
void handle_adns_answer(void)
{
/* These are retained across calls to handle_adns_answer. */
static size_t buflen = 0; /* bytes in answer buffer */
#ifndef USE_LWRES
static struct adns_answer buf;
#else /* USE_LWRES */
static char buf[LWDNSQ_RESULT_LEN_MAX];
static char buf_copy[LWDNSQ_RESULT_LEN_MAX];
#endif /* USE_LWRES */
ssize_t n;
passert(buflen < sizeof(buf));
n = read(adns_afd, (unsigned char *)&buf + buflen, sizeof(buf) - buflen);
if (n < 0)
{
if (errno != EINTR)
{
log_errno((e, "error reading answer from adns"));
/* ??? how can we recover? */
}
n = 0; /* now n reflects amount read */
}
else if (n == 0)
{
/* EOF */
if (adns_in_flight != 0)
{
plog("EOF from ADNS with %d queries outstanding (restarts %d)"
, adns_in_flight, adns_restart_count);
recover_adns_die();
}
if (buflen != 0)
{
plog("EOF from ADNS with %lu bytes of a partial answer outstanding"
"(restarts %d)"
, (unsigned long)buflen
, adns_restart_count);
recover_adns_die();
}
stop_adns();
return;
}
else
{
passert(adns_in_flight > 0);
}
buflen += n;
#ifndef USE_LWRES
while (buflen >= offsetof(struct adns_answer, ans) && buflen >= buf.len)
{
/* we've got a tasty answer -- process it */
err_t ugh;
struct adns_continuation *cr = continuation_for_qtid(buf.serial); /* assume it works */
const char *typename = rr_typename(cr->query.type);
const char *name_buf = cr->query.name_buf;
#ifdef USE_KEYRR
passert(cr->keys_from_dns == NULL);
#endif /* USE_KEYRR */
passert(cr->gateways_from_dns == NULL);
adns_in_flight--;
if (buf.result == -1)
{
/* newer resolvers support statp->res_h_errno as well as h_errno.
* That might be better, but older resolvers don't.
* See resolver(3), if you have it.
* The undocumented(!) h_errno values are defined in
* /usr/include/netdb.h.
*/
switch (buf.h_errno_val)
{
case NO_DATA:
ugh = builddiag("no %s record for %s", typename, name_buf);
break;
case HOST_NOT_FOUND:
ugh = builddiag("no host %s for %s record", name_buf, typename);
break;
default:
ugh = builddiag("failure querying DNS for %s of %s: %s"
, typename, name_buf, hstrerror(buf.h_errno_val));
break;
}
}
else if (buf.result > (int) sizeof(buf.ans))
{
ugh = builddiag("(INTERNAL ERROR) answer too long (%ld) for buffer"
, (long)buf.result);
}
else
{
ugh = process_dns_answer(cr, buf.ans, buf.result);
if (ugh != NULL)
ugh = builddiag("failure processing %s record of DNS answer for %s: %s"
, typename, name_buf, ugh);
}
DBG(DBG_RAW | DBG_CRYPT | DBG_PARSING | DBG_CONTROL | DBG_DNS,
DBG_log(BLANK_FORMAT);
if (ugh == NULL)
DBG_log("asynch DNS answer %lu for %s of %s"
, cr->query.serial, typename, name_buf);
else
DBG_log("asynch DNS answer %lu %s", cr->query.serial, ugh);
);
passert(GLOBALS_ARE_RESET());
cr->cont_fn(cr, ugh);
reset_globals();
release_adns_continuation(cr);
/* shift out answer that we've consumed */
buflen -= buf.len;
memmove((unsigned char *)&buf, (unsigned char *)&buf + buf.len, buflen);
}
#else /* USE_LWRES */
for (;;)
{
err_t ugh;
char *nlp = memchr(buf, '\n', buflen);
if (nlp == NULL)
break;
/* we've got a line */
*nlp++ = '\0';
DBG(DBG_RAW | DBG_CRYPT | DBG_PARSING | DBG_CONTROL | DBG_DNS
, DBG_log("lwdns: %s", buf));
/* process lwdnsq_answer may modify buf, so make a copy. */
buf_copy[0]='\0';
strncat(buf_copy, buf, sizeof(buf_copy));
ugh = process_lwdnsq_answer(buf_copy);
if (ugh != NULL)
plog("failure processing lwdnsq output: %s; record: %s"
, ugh, buf);
passert(GLOBALS_ARE_RESET());
reset_globals();
/* shift out answer that we've consumed */
buflen -= nlp - buf;
memmove(buf, nlp, buflen);
}
#endif /* USE_LWRES */
}
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