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NeoStats-NeoIRCd/iauth/source/res.c
2002-08-13 14:45:13 +00:00

1711 lines
46 KiB
C

/*
* iauth/res.c (C)opyright 1992 Darren Reed. All rights reserved.
* This file may not be distributed without the author's permission in any
* shape or form. The author takes no responsibility for any damage or loss
* of property which results from the use of this software.
*
* $Id: res.c,v 1.2 2002/08/13 14:45:10 fishwaldo Exp $
*
* July 1999 - Rewrote a bunch of stuff here. Change hostent builder code,
* added callbacks and reference counting of returned hostents.
* --Bleep (Thomas Helvey <tomh@inxpress.net>)
*/
#include <assert.h>
#include <errno.h>
#include <string.h>
#include <stdlib.h>
#include <sys/time.h>
#include <sys/socket.h>
#include <fcntl.h>
#include <unistd.h>
#include <arpa/nameser.h>
#include <resolv.h>
#include <netdb.h>
#include <arpa/inet.h>
#include <limits.h>
#include "iauth.h"
#include "log.h"
#include "misc.h"
#include "res.h"
#include "sock.h"
#ifndef dn_skipname /* some systems don't define this */
#define dn_skipname __dn_skipname
#endif
#if (CHAR_BIT != 8)
#error this code needs to be able to address individual octets
#endif
#undef DEBUG /* because there is a lot of debug code in here :-) */
/*
* Some systems do not define INADDR_NONE (255.255.255.255)
* INADDR_NONE is actually a valid address, but it should never
* be returned from any nameserver.
* NOTE: The bit pattern for INADDR_NONE and INADDR_ANY (0.0.0.0) should be
* the same on all hosts so we shouldn't need to use htonl or ntohl to
* compare or set the values.
*/
#ifndef INADDR_NONE
#define INADDR_NONE ((unsigned int) 0xffffffff)
#endif
#define MAXPACKET 1024 /* rfc sez 512 but we expand names so ... */
#define RES_MAXALIASES 35 /* maximum aliases allowed */
#define RES_MAXADDRS 35 /* maximum addresses allowed */
/*
* macros used to calulate offsets into fixed query buffer
*/
#define ALIAS_BLEN (size_t) ((RES_MAXALIASES + 1) * sizeof(char*))
#define ADDRS_BLEN (size_t) ((RES_MAXADDRS + 1) * sizeof(struct in_addr*))
#define ADDRS_OFFSET (size_t) (ALIAS_BLEN + ADDRS_BLEN)
#define ADDRS_DLEN (size_t) (RES_MAXADDRS * sizeof(struct in_addr))
#define NAMES_OFFSET (size_t) (ADDRS_OFFSET + ADDRS_DLEN)
#define MAXGETHOSTLEN (size_t) (NAMES_OFFSET + MAXPACKET)
#define AR_TTL 600 /* TTL in seconds for dns cache entries */
/*
* the following values should be prime
*/
#define ARES_CACSIZE 307
#define MAXCACHED 281
/*
* RFC 1104/1105 wasn't very helpful about what these fields
* should be named, so for now, we'll just name them this way.
* we probably should look at what named calls them or something.
*/
#define TYPE_SIZE (size_t) 2
#define CLASS_SIZE (size_t) 2
#define TTL_SIZE (size_t) 4
#define RDLENGTH_SIZE (size_t) 2
#define ANSWER_FIXED_SIZE (TYPE_SIZE + CLASS_SIZE + TTL_SIZE + RDLENGTH_SIZE)
/*
* Building the Hostent
* The Hostent struct is arranged like this:
* +-------------------------------+
* Hostent: | struct hostent h |
* |-------------------------------|
* | char *buf |
* +-------------------------------+
*
* allocated:
*
* +-------------------------------+
* buf: | h_aliases pointer array | Max size: ALIAS_BLEN;
* | NULL | contains `char *'s
* |-------------------------------|
* | h_addr_list pointer array | Max size: ADDRS_BLEN;
* | NULL | contains `struct in_addr *'s
* |-------------------------------|
* | h_addr_list addresses | Max size: ADDRS_DLEN;
* | | contains `struct in_addr's
* |-------------------------------|
* | storage for hostname strings | Max size: ALIAS_DLEN;
* +-------------------------------+ contains `char's
*
* For requests the size of the h_aliases, and h_addr_list pointer
* array sizes are set to MAXALISES and MAXADDRS respectively, and
* buf is a fixed size with enough space to hold the largest expected
* reply from a nameserver, see RFC 1034 and RFC 1035.
* For cached entries the sizes are dependent on the actual number
* of aliases and addresses. If new aliases and addresses are found
* for cached entries, the buffer is grown and the new entries are added.
* The hostent struct is filled in with the addresses of the entries in
* the Hostent buf as follows:
* h_name - contains a pointer to the start of the hostname string area,
* or NULL if none is set. The h_name is followed by the
* aliases, in the storage for hostname strings area.
* h_aliases - contains a pointer to the start of h_aliases pointer array.
* This array contains pointers to the storage for hostname
* strings area and is terminated with a NULL. The first alias
* is stored directly after the h_name.
* h_addr_list - contains a pointer to the start of h_addr_list pointer array.
* This array contains pointers to in_addr structures in the
* h_addr_list addresses area and is terminated with a NULL.
*
* Filling the buffer this way allows for proper alignment of the h_addr_list
* addresses.
*
* This arrangement allows us to alias a Hostent struct pointer as a
* real struct hostent* without lying. It also allows us to change the
* values contained in the cached entries and requests without changing
* the actual hostent pointer, which is saved in a client struct and can't
* be changed without blowing things up or a lot more fiddling around.
* It also allows for defered allocation of the fixed size buffers until
* they are really needed.
* Nov. 17, 1997 --Bleep
*/
typedef struct Hostent {
struct hostent h; /* the hostent struct we are passing around */
char* buf; /* buffer for data pointed to from hostent */
} aHostent;
struct ResRequest {
struct ResRequest* next;
int id;
int sent; /* number of requests sent */
time_t ttl;
char type;
char retries; /* retry counter */
char sends; /* number of sends (>1 means resent) */
char resend; /* send flag. 0 == dont resend */
time_t sentat;
time_t timeout;
struct in_addr addr;
char* name;
struct DNSQuery query; /* query callback for this request */
aHostent he;
};
struct CacheEntry {
struct CacheEntry* hname_next;
struct CacheEntry* hnum_next;
struct CacheEntry* list_next;
time_t expireat;
time_t ttl;
struct Hostent he;
struct DNSReply reply;
};
struct CacheTable {
struct CacheEntry* num_list;
struct CacheEntry* name_list;
};
int ResolverFileDescriptor = -1; /* GLOBAL - used in s_bsd.c */
static time_t nextDNSCheck = 0;
static time_t nextCacheExpire = 1;
/*
* Keep a spare file descriptor open. res_init calls fopen to read the
* resolv.conf file. If ircd is hogging all the file descriptors below 256,
* on systems with crippled FILE structures this will cause wierd bugs.
* This is definitely needed for Solaris which uses an unsigned char to
* hold the file descriptor.
*/
static int spare_fd = -1;
static int cachedCount = 0;
static struct CacheTable hashtable[ARES_CACSIZE];
static struct CacheEntry* cacheTop;
static struct ResRequest* requestListHead; /* head of resolver request list */
static struct ResRequest* requestListTail; /* tail of resolver request list */
static void add_request(struct ResRequest* request);
static void rem_request(struct ResRequest* request);
static struct ResRequest* make_request(const struct DNSQuery* query);
static void rem_cache(struct CacheEntry*);
static void do_query_name(const struct DNSQuery* query,
const char* name,
struct ResRequest* request);
static void do_query_number(const struct DNSQuery* query,
const struct in_addr*,
struct ResRequest* request);
static void query_name(const char* name,
int query_class,
int query_type,
struct ResRequest* request);
static int send_res_msg(const char* buf, int len, int count);
static void resend_query(struct ResRequest* request);
static int proc_answer(struct ResRequest* request, HEADER* header,
char*, char *);
static struct CacheEntry* make_cache(struct ResRequest* request);
static struct CacheEntry* find_cache_name(const char* name);
static struct CacheEntry* find_cache_number(struct ResRequest* request,
const char* addr);
static struct ResRequest* find_id(int);
static int hash_number(const unsigned char *);
static void update_list(struct ResRequest *, struct CacheEntry *);
static int hash_name(const char* name);
static struct cacheinfo {
int ca_adds;
int ca_dels;
int ca_expires;
int ca_lookups;
int ca_na_hits;
int ca_nu_hits;
int ca_updates;
} cainfo;
static struct resinfo {
int re_errors;
int re_nu_look;
int re_na_look;
int re_replies;
int re_requests;
int re_resends;
int re_sent;
int re_timeouts;
int re_shortttl;
int re_unkrep;
} reinfo;
/*
* From bind 8.3, these aren't in earlier versions of bind
*
*/
extern u_short _getshort(const u_char *);
extern u_int _getlong(const u_char *);
/*
* int
* res_isourserver(ina)
* looks up "ina" in _res.ns_addr_list[]
* returns:
* 0 : not found
* >0 : found
* author:
* paul vixie, 29may94
*/
static int
res_ourserver(const struct __res_state* statp, const struct sockaddr_in *inp)
{
struct sockaddr_in ina;
int ns;
ina = *inp;
for (ns = 0; ns < statp->nscount; ns++) {
const struct sockaddr_in *srv = &statp->nsaddr_list[ns];
if (srv->sin_family == ina.sin_family &&
srv->sin_port == ina.sin_port &&
(srv->sin_addr.s_addr == INADDR_ANY ||
srv->sin_addr.s_addr == ina.sin_addr.s_addr))
return (1);
}
return (0);
}
/*
* start_resolver - do everything we need to read the resolv.conf file
* and initialize the resolver file descriptor if needed
*/
static void start_resolver(void)
{
/*
* close the spare file descriptor so res_init can read resolv.conf
* successfully. Needed on Solaris
*/
if (spare_fd > -1)
close(spare_fd);
res_init(); /* res_init always returns 0 */
/*
* make sure we have a valid file descriptor below 256 so we can
* do this again. Needed on Solaris
*/
spare_fd = open("/dev/null",O_RDONLY,0);
if ((spare_fd < 0) || (spare_fd > 255)) {
return;
}
if (!_res.nscount) {
_res.nscount = 1;
_res.nsaddr_list[0].sin_addr.s_addr = inet_addr("127.0.0.1");
}
_res.options |= RES_NOALIASES;
if (ResolverFileDescriptor < 0)
ResolverFileDescriptor = socket(AF_INET, SOCK_DGRAM, 0);
}
/*
* init_resolver - initialize resolver and resolver library
*/
int init_resolver(void)
{
#ifdef LRAND48
srand48(CurrentTime);
#endif
memset(&cainfo, 0, sizeof(cainfo));
memset(hashtable, 0, sizeof(hashtable));
memset(&reinfo, 0, sizeof(reinfo));
requestListHead = requestListTail = NULL;
start_resolver();
return ResolverFileDescriptor;
}
/*
* restart_resolver - flush the cache, reread resolv.conf, reopen socket
*/
void restart_resolver(void)
{
/* flush_cache(); flush the dns cache */
start_resolver();
}
/*
* add_local_domain - Add the domain to hostname, if it is missing
* (as suggested by eps@TOASTER.SFSU.EDU)
*/
void add_local_domain(char* hname, int size)
{
assert(0 != hname);
/*
* try to fix up unqualified names
*/
if ((_res.options & RES_DEFNAMES) && !strchr(hname, '.')) {
if (_res.defdname[0]) {
size_t len = strlen(hname);
if ((strlen(_res.defdname) + len + 2) < size) {
hname[len++] = '.';
strcpy(hname + len, _res.defdname);
}
}
}
}
/*
* add_request - place a new request in the request list
*/
static void add_request(struct ResRequest* request)
{
assert(0 != request);
if (!requestListHead)
requestListHead = requestListTail = request;
else {
requestListTail->next = request;
requestListTail = request;
}
request->next = NULL;
reinfo.re_requests++;
}
/*
* rem_request - remove a request from the list.
* This must also free any memory that has been allocated for
* temporary storage of DNS results.
*/
static void rem_request(struct ResRequest* request)
{
struct ResRequest** current;
struct ResRequest* prev = NULL;
assert(0 != request);
for (current = &requestListHead; *current; ) {
if (*current == request) {
*current = request->next;
if (requestListTail == request)
requestListTail = prev;
break;
}
prev = *current;
current = &(*current)->next;
}
#ifdef DEBUG
Debug((DEBUG_DNS, "rem_request:Remove %#x at %#x %#x",
old, *current, prev));
#endif
MyFree(request->he.buf);
MyFree(request->name);
MyFree(request);
}
/*
* make_request - Create a DNS request record for the server.
*/
static struct ResRequest* make_request(const struct DNSQuery* query)
{
struct ResRequest* request;
assert(0 != query);
request = (struct ResRequest*) MyMalloc(sizeof(struct ResRequest));
memset(request, 0, sizeof(struct ResRequest));
request->sentat = CurrentTime;
request->retries = 3;
request->resend = 1;
request->timeout = 4; /* start at 4 and exponential inc. */
request->addr.s_addr = INADDR_NONE;
request->he.h.h_addrtype = AF_INET;
request->he.h.h_length = sizeof(struct in_addr);
request->query.vptr = query->vptr;
request->query.callback = query->callback;
request->next = NULL;
request->he.buf = NULL;
request->he.h.h_name = NULL;
request->he.h.h_aliases = NULL;
request->he.h.h_addr_list = NULL;
add_request(request);
return request;
}
/*
* timeout_query_list - Remove queries from the list which have been
* there too long without being resolved.
*/
static time_t timeout_query_list(time_t now)
{
struct ResRequest* request;
struct ResRequest* next_request = 0;
time_t next_time = 0;
time_t timeout = 0;
#ifdef bingo
Debug((DEBUG_DNS, "timeout_query_list at %s", myctime(now)));
#endif
for (request = requestListHead; request; request = next_request) {
next_request = request->next;
timeout = request->sentat + request->timeout;
if (now >= timeout) {
if (--request->retries <= 0) {
reinfo.re_timeouts++;
(*request->query.callback)(request->query.vptr, 0);
rem_request(request);
continue;
}
else {
request->sentat = now;
request->timeout += request->timeout;
resend_query(request);
}
}
if (!next_time || timeout < next_time) {
next_time = timeout;
}
}
return (next_time > now) ? next_time : (now + AR_TTL);
}
/*
* expire_cache - removes entries from the cache which are older
* than their expiry times. returns the time at which the server
* should next poll the cache.
*/
static time_t expire_cache(time_t now)
{
struct CacheEntry* cp;
struct CacheEntry* cp_next;
time_t next = 0;
for (cp = cacheTop; cp; cp = cp_next) {
cp_next = cp->list_next;
if (cp->expireat < now) {
cainfo.ca_expires++;
rem_cache(cp);
}
else if (!next || next > cp->expireat)
next = cp->expireat;
}
return (next > now) ? next : (now + AR_TTL);
}
/*
* timeout_resolver - check request list and cache for expired entries
*/
time_t timeout_resolver(time_t now)
{
if (nextDNSCheck < now)
nextDNSCheck = timeout_query_list(now);
if (nextCacheExpire < now)
nextCacheExpire = expire_cache(now);
return IRCD_MIN(nextDNSCheck, nextCacheExpire);
}
/*
* delete_resolver_queries - cleanup outstanding queries
* for which there no longer exist clients or conf lines.
*/
void delete_resolver_queries(const void* vptr)
{
struct ResRequest* request;
struct ResRequest* next_request;
for (request = requestListHead; request; request = next_request) {
next_request = request->next;
if (vptr == request->query.vptr)
rem_request(request);
}
}
/*
* send_res_msg - sends msg to all nameservers found in the "_res" structure.
* This should reflect /etc/resolv.conf. We will get responses
* which arent needed but is easier than checking to see if nameserver
* isnt present. Returns number of messages successfully sent to
* nameservers or -1 if no successful sends.
*/
static int send_res_msg(const char* msg, int len, int rcount)
{
int i;
int sent = 0;
int max_queries = IRCD_MIN(_res.nscount, rcount);
assert(0 != msg);
/*
* RES_PRIMARY option is not implemented
* if (_res.options & RES_PRIMARY || 0 == max_queries)
*/
if (0 == max_queries)
max_queries = 1;
for (i = 0; i < max_queries; i++) {
#if 0
/*
* XXX - this should already have been done by res_init
*/
_res.nsaddr_list[i].sin_family = AF_INET;
#endif
if (sendto(ResolverFileDescriptor, msg, len, 0,
(struct sockaddr*) &(_res.nsaddr_list[i]),
sizeof(struct sockaddr_in)) == len) {
++reinfo.re_sent;
++sent;
}
else
log(L_ERROR, "Resolver: send failed %s", strerror(errno));
}
return sent;
}
/*
* find_id - find a dns request id (id is determined by dn_mkquery)
*/
static struct ResRequest* find_id(int id)
{
struct ResRequest* request;
for (request = requestListHead; request; request = request->next) {
if (request->id == id)
return request;
}
return NULL;
}
/*
* gethost_byname - get host address from name
*/
struct DNSReply* gethost_byname(const char* name,
const struct DNSQuery* query)
{
struct CacheEntry* cp;
assert(0 != name);
++reinfo.re_na_look;
if ((cp = find_cache_name(name)))
return &(cp->reply);
do_query_name(query, name, NULL);
nextDNSCheck = 1;
return NULL;
}
/*
* gethost_byaddr - get host name from address
*/
struct DNSReply* gethost_byaddr(const char* addr,
const struct DNSQuery* query)
{
struct CacheEntry *cp;
assert(0 != addr);
++reinfo.re_nu_look;
if ((cp = find_cache_number(NULL, addr)))
return &(cp->reply);
do_query_number(query, (const struct in_addr*) addr, NULL);
nextDNSCheck = 1;
return NULL;
}
/*
* do_query_name - nameserver lookup name
*/
static void do_query_name(const struct DNSQuery* query,
const char* name, struct ResRequest* request)
{
char hname[HOSTLEN + 1];
assert(0 != name);
strncpy_irc(hname, name, HOSTLEN);
hname[HOSTLEN] = '\0';
add_local_domain(hname, HOSTLEN);
if (!request) {
request = make_request(query);
request->type = T_A;
request->name = (char*) MyMalloc(strlen(hname) + 1);
strcpy(request->name, hname);
}
query_name(hname, C_IN, T_A, request);
}
/*
* do_query_number - Use this to do reverse IP# lookups.
*/
static void do_query_number(const struct DNSQuery* query,
const struct in_addr* addr,
struct ResRequest* request)
{
char ipbuf[32];
const unsigned char* cp;
assert(0 != addr);
cp = (const unsigned char*) &addr->s_addr;
sprintf(ipbuf, "%u.%u.%u.%u.in-addr.arpa.",
(unsigned int)(cp[3]), (unsigned int)(cp[2]),
(unsigned int)(cp[1]), (unsigned int)(cp[0]));
if (!request) {
request = make_request(query);
request->type = T_PTR;
request->addr.s_addr = addr->s_addr;
}
query_name(ipbuf, C_IN, T_PTR, request);
}
/*
* query_name - generate a query based on class, type and name.
*/
static void query_name(const char* name, int query_class,
int type, struct ResRequest* request)
{
char buf[MAXPACKET];
int request_len = 0;
assert(0 != name);
assert(0 != request);
memset(buf, 0, sizeof(buf));
if ((request_len = res_mkquery(QUERY, name, query_class, type,
NULL, 0, NULL, buf, sizeof(buf))) > 0) {
HEADER* header = (HEADER*) buf;
#ifndef LRAND48
int k = 0;
struct timeval tv;
#endif
/*
* generate a unique id
* NOTE: we don't have to worry about converting this to and from
* network byte order, the nameserver does not interpret this value
* and returns it unchanged
*/
#ifdef LRAND48
do {
header->id = (header->id + lrand48()) & 0xffff;
} while (find_id(header->id));
#else
gettimeofday(&tv, NULL);
do {
header->id = (header->id + k + tv.tv_usec) & 0xffff;
k++;
} while (find_id(header->id));
#endif /* LRAND48 */
request->id = header->id;
++request->sends;
request->sent += send_res_msg(buf, request_len, request->sends);
}
}
static void resend_query(struct ResRequest* request)
{
assert(0 != request);
if (request->resend == 0)
return;
++reinfo.re_resends;
switch(request->type) {
case T_PTR:
do_query_number(NULL, &request->addr, request);
break;
case T_A:
do_query_name(NULL, request->name, request);
break;
default:
break;
}
}
/*
* proc_answer - process name server reply
* build a hostent struct in the passed request
*/
static int proc_answer(struct ResRequest* request, HEADER* header,
char* buf, char* eob)
{
char hostbuf[HOSTLEN + 1]; /* working buffer */
char* current; /* current position in buf */
char** alias; /* alias list */
char** addr; /* address list */
char* name; /* pointer to name string */
char* address; /* pointer to address */
char* endp; /* end of our buffer */
int query_class; /* answer class */
int type; /* answer type */
int rd_length; /* record data length */
int answer_count = 0; /* answer counter */
int n; /* temp count */
int addr_count = 0; /* number of addresses in hostent */
int alias_count = 0; /* number of aliases in hostent */
struct hostent* hp; /* hostent getting filled */
assert(0 != request);
assert(0 != header);
assert(0 != buf);
assert(0 != eob);
current = buf + sizeof(HEADER);
hp = &(request->he.h);
/*
* lazy allocation of request->he.buf, we don't allocate a buffer
* unless there is something to put in it.
*/
if (!request->he.buf) {
request->he.buf = (char*) MyMalloc(MAXGETHOSTLEN + 1);
request->he.buf[MAXGETHOSTLEN] = '\0';
/*
* array of alias list pointers starts at beginning of buf
*/
hp->h_aliases = (char**) request->he.buf;
hp->h_aliases[0] = NULL;
/*
* array of address list pointers starts after alias list pointers
* the actual addresses follow the the address list pointers
*/
hp->h_addr_list = (char**)(request->he.buf + ALIAS_BLEN);
/*
* don't copy the host address to the beginning of h_addr_list
*/
hp->h_addr_list[0] = NULL;
}
endp = request->he.buf + MAXGETHOSTLEN;
/*
* find the end of the address list
*/
addr = hp->h_addr_list;
while (*addr) {
++addr;
++addr_count;
}
/*
* make address point to first available address slot
*/
address = request->he.buf + ADDRS_OFFSET +
(sizeof(struct in_addr) * addr_count);
/*
* find the end of the alias list
*/
alias = hp->h_aliases;
while (*alias) {
++alias;
++alias_count;
}
/*
* make name point to first available space in request->buf
*/
if (alias_count > 0) {
name = hp->h_aliases[alias_count - 1];
name += (strlen(name) + 1);
}
else if (hp->h_name)
name = hp->h_name + strlen(hp->h_name) + 1;
else
name = request->he.buf + ADDRS_OFFSET + ADDRS_DLEN;
/*
* skip past queries
*/
for (; header->qdcount > 0; --header->qdcount) {
if ((n = dn_skipname(current, eob)) < 0)
break;
current += (size_t) n + QFIXEDSZ;
}
/*
* process each answer sent to us blech.
*/
while (header->ancount-- > 0 && current < eob && name < endp) {
n = dn_expand(buf, eob, current, hostbuf, sizeof(hostbuf));
if (n < 0) {
/*
* broken message
*/
return 0;
}
else if (n == 0) {
/*
* no more answers left
*/
return answer_count;
}
hostbuf[HOSTLEN] = '\0';
/*
* With Address arithmetic you have to be very anal
* this code was not working on alpha due to that
* (spotted by rodder/jailbird/dianora)
*/
current += (size_t) n;
if (!((current + ANSWER_FIXED_SIZE) < eob))
break;
type = _getshort(current);
current += TYPE_SIZE;
query_class = _getshort(current);
current += CLASS_SIZE;
request->ttl = _getlong(current);
current += TTL_SIZE;
rd_length = _getshort(current);
current += RDLENGTH_SIZE;
/*
* Wait to set request->type until we verify this structure
*/
/* add_local_domain(hostbuf, HOSTLEN); */
switch(type) {
case T_A:
/*
* check for invalid rd_length or too many addresses
*/
if (rd_length != sizeof(struct in_addr))
return answer_count;
if (++addr_count < RES_MAXADDRS) {
if (answer_count == 1)
hp->h_addrtype = (query_class == C_IN) ? AF_INET : AF_UNSPEC;
memcpy(address, current, sizeof(struct in_addr));
*addr++ = address;
*addr = 0;
address += sizeof(struct in_addr);
if (!hp->h_name) {
strcpy(name, hostbuf);
hp->h_name = name;
name += strlen(name) + 1;
}
#ifdef bingo
Debug((DEBUG_INFO,"got ip # %s for %s",
inetntoa((char*) hp->h_addr_list[addr_count - 1]), hostbuf));
#endif
}
current += rd_length;
++answer_count;
break;
case T_PTR:
n = dn_expand(buf, eob, current, hostbuf, sizeof(hostbuf));
if (n < 0) {
/*
* broken message
*/
return 0;
}
else if (n == 0) {
/*
* no more answers left
*/
return answer_count;
}
/*
* This comment is based on analysis by Shadowfax, Wohali and johan,
* not me. (Dianora) I am only commenting it.
*
* dn_expand is guaranteed to not return more than sizeof(hostbuf)
* but do all implementations of dn_expand also guarantee
* buffer is terminated with null byte? Lets not take chances.
* -Dianora
*/
hostbuf[HOSTLEN] = '\0';
current += (size_t) n;
#ifdef bingo
Debug((DEBUG_INFO,"got host %s",hostbuf));
#endif
/*
* copy the returned hostname into the host name
* ignore duplicate ptr records
*/
if (!hp->h_name) {
strcpy(name, hostbuf);
hp->h_name = name;
name += strlen(name) + 1;
}
++answer_count;
break;
case T_CNAME:
#ifdef bingo
Debug((DEBUG_INFO,"got cname %s", hostbuf));
#endif
if (++alias_count < RES_MAXALIASES) {
strncpy_irc(name, hostbuf, endp - name);
*alias++ = name;
*alias = 0;
name += strlen(name) + 1;
}
current += rd_length;
++answer_count;
break;
default :
#ifdef DEBUG
Debug((DEBUG_INFO,"proc_answer: type:%d for:%s", type, hostbuf));
#endif
break;
}
}
return answer_count;
}
/*
* get_res - read a dns reply from the nameserver and process it.
*/
void get_res(void)
{
char buf[sizeof(HEADER) + MAXPACKET];
HEADER* header = 0;
struct ResRequest* request = 0;
struct CacheEntry* cp = 0;
int rc = 0;
int answer_count = 0;
int len = sizeof(struct sockaddr_in);
struct sockaddr_in sin;
rc = recvfrom(ResolverFileDescriptor, buf, sizeof(buf), 0,
(struct sockaddr*) &sin, &len);
if (rc <= sizeof(HEADER))
return;
/*
* convert DNS reply reader from Network byte order to CPU byte order.
*/
header = (HEADER*) buf;
/* header->id = ntohs(header->id); */
header->ancount = ntohs(header->ancount);
header->qdcount = ntohs(header->qdcount);
header->nscount = ntohs(header->nscount);
header->arcount = ntohs(header->arcount);
#ifdef DEBUG
Debug((DEBUG_NOTICE, "get_res:id = %d rcode = %d ancount = %d",
header->id, header->rcode, header->ancount));
#endif
++reinfo.re_replies;
/*
* response for an id which we have already received an answer for
* just ignore this response.
*/
if (0 == (request = find_id(header->id)))
return;
/*
* check against possibly fake replies
*/
if (!res_ourserver(&_res, &sin)) {
++reinfo.re_unkrep;
return;
}
if ((header->rcode != NOERROR) || (header->ancount == 0)) {
++reinfo.re_errors;
if (SERVFAIL == header->rcode)
resend_query(request);
else {
/*
* If a bad error was returned, we stop here and dont send
* send any more (no retries granted).
*/
#ifdef bingo
Debug((DEBUG_DNS, "Fatal DNS error: %d", header->rcode));
#endif
(*request->query.callback)(request->query.vptr, 0);
rem_request(request);
}
return;
}
/*
* If this fails there was an error decoding the received packet,
* try it again and hope it works the next time.
*/
answer_count = proc_answer(request, header, buf, buf + rc);
#ifdef DEBUG
Debug((DEBUG_INFO,"get_res:Proc answer = %d",a));
#endif
if (answer_count) {
if (T_PTR == request->type) {
struct DNSReply* reply = NULL;
if (0 == request->he.h.h_name) {
/*
* got a PTR response with no name, something bogus is happening
* don't bother trying again, the client address doesn't resolve
*/
(*request->query.callback)(request->query.vptr, reply);
rem_request(request);
return;
}
#ifdef bingo
Debug((DEBUG_DNS, "relookup %s <-> %s",
request->he.h.h_name, inetntoa((char*) &request->he.h.h_addr)));
#endif
/*
* Lookup the 'authoritive' name that we were given for the
* ip#. By using this call rather than regenerating the
* type we automatically gain the use of the cache with no
* extra kludges.
*/
reply = gethost_byname(request->he.h.h_name, &request->query);
if (0 == reply) {
/*
* If name wasn't found, a request has been queued and it will
* be the last one queued. This is rather nasty way to keep
* a host alias with the query. -avalon
*/
MyFree(requestListTail->he.buf);
requestListTail->he.buf = request->he.buf;
request->he.buf = 0;
memcpy(&requestListTail->he.h, &request->he.h, sizeof(struct hostent));
}
else
(*request->query.callback)(request->query.vptr, reply);
rem_request(request);
}
else {
/*
* got a name and address response, client resolved
*/
cp = make_cache(request);
(*request->query.callback)(request->query.vptr, &cp->reply);
rem_request(request);
}
}
else if (!request->sent) {
/*
* XXX - we got a response for a query we didn't send with a valid id?
* this should never happen, bail here and leave the client unresolved
*/
(*request->query.callback)(request->query.vptr, 0);
rem_request(request);
}
}
static size_t calc_hostent_buffer_size(const struct hostent* hp)
{
char** p;
size_t count = 0;
assert(0 != hp);
/*
* space for name
*/
count += (strlen(hp->h_name) + 1);
/*
* space for aliases
*/
for (p = hp->h_aliases; *p; ++p)
count += (strlen(*p) + 1 + sizeof(char*));
/*
* space for addresses
*/
for (p = hp->h_addr_list; *p; ++p)
count += (hp->h_length + sizeof(char*));
/*
* space for 2 nulls to terminate h_aliases and h_addr_list
*/
count += (2 * sizeof(char*));
return count;
}
/*
* dup_hostent - Duplicate a hostent struct, allocate only enough memory for
* the data we're putting in it.
*/
static void dup_hostent(aHostent* new_hp, struct hostent* hp)
{
char* p;
char** ap;
char** pp;
int alias_count = 0;
int addr_count = 0;
size_t bytes_needed = 0;
assert(0 != new_hp);
assert(0 != hp);
/* how much buffer do we need? */
bytes_needed += (strlen(hp->h_name) + 1);
pp = hp->h_aliases;
while (*pp) {
bytes_needed += (strlen(*pp++) + 1 + sizeof(char*));
++alias_count;
}
pp = hp->h_addr_list;
while (*pp++) {
bytes_needed += (hp->h_length + sizeof(char*));
++addr_count;
}
/* Reserve space for 2 nulls to terminate h_aliases and h_addr_list */
bytes_needed += (2 * sizeof(char*));
/* Allocate memory */
new_hp->buf = (char*) MyMalloc(bytes_needed);
new_hp->h.h_addrtype = hp->h_addrtype;
new_hp->h.h_length = hp->h_length;
/* first write the address list */
pp = hp->h_addr_list;
ap = new_hp->h.h_addr_list =
(char**)(new_hp->buf + ((alias_count + 1) * sizeof(char*)));
p = (char*)ap + ((addr_count + 1) * sizeof(char*));
while (*pp)
{
*ap++ = p;
memcpy(p, *pp++, hp->h_length);
p += hp->h_length;
}
*ap = 0;
/* next write the name */
new_hp->h.h_name = p;
strcpy(p, hp->h_name);
p += (strlen(p) + 1);
/* last write the alias list */
pp = hp->h_aliases;
ap = new_hp->h.h_aliases = (char**) new_hp->buf;
while (*pp) {
*ap++ = p;
strcpy(p, *pp++);
p += (strlen(p) + 1);
}
*ap = 0;
}
/*
* update_hostent - Add records to a Hostent struct in place.
*/
static void update_hostent(aHostent* hp, char** addr, char** alias)
{
char* p;
char** ap;
char** pp;
int alias_count = 0;
int addr_count = 0;
char* buf = NULL;
size_t bytes_needed = 0;
if (!hp || !hp->buf)
return;
/* how much buffer do we need? */
bytes_needed = strlen(hp->h.h_name) + 1;
pp = hp->h.h_aliases;
while (*pp) {
bytes_needed += (strlen(*pp++) + 1 + sizeof(char*));
++alias_count;
}
if (alias) {
pp = alias;
while (*pp) {
bytes_needed += (strlen(*pp++) + 1 + sizeof(char*));
++alias_count;
}
}
pp = hp->h.h_addr_list;
while (*pp++) {
bytes_needed += (hp->h.h_length + sizeof(char*));
++addr_count;
}
if (addr) {
pp = addr;
while (*pp++) {
bytes_needed += (hp->h.h_length + sizeof(char*));
++addr_count;
}
}
/* Reserve space for 2 nulls to terminate h_aliases and h_addr_list */
bytes_needed += 2 * sizeof(char*);
/* Allocate memory */
buf = (char*) MyMalloc(bytes_needed);
assert(0 != buf);
/* first write the address list */
pp = hp->h.h_addr_list;
ap = hp->h.h_addr_list =
(char**)(buf + ((alias_count + 1) * sizeof(char*)));
p = (char*)ap + ((addr_count + 1) * sizeof(char*));
while (*pp) {
memcpy(p, *pp++, hp->h.h_length);
*ap++ = p;
p += hp->h.h_length;
}
if (addr) {
while (*addr) {
memcpy(p, *addr++, hp->h.h_length);
*ap++ = p;
p += hp->h.h_length;
}
}
*ap = 0;
/* next write the name */
strcpy(p, hp->h.h_name);
hp->h.h_name = p;
p += (strlen(p) + 1);
/* last write the alias list */
pp = hp->h.h_aliases;
ap = hp->h.h_aliases = (char**) buf;
while (*pp) {
strcpy(p, *pp++);
*ap++ = p;
p += (strlen(p) + 1);
}
if (alias) {
while (*alias) {
strcpy(p, *alias++);
*ap++ = p;
p += (strlen(p) + 1);
}
}
*ap = 0;
/* release the old buffer */
p = hp->buf;
hp->buf = buf;
MyFree(p);
}
/*
* hash_number - IP address hash function
*/
static int hash_number(const unsigned char* ip)
{
/* could use loop but slower */
unsigned int hashv;
assert(0 != ip);
hashv = *ip++;
hashv += hashv + *ip++;
hashv += hashv + *ip++;
hashv += hashv + *ip;
hashv %= ARES_CACSIZE;
return hashv;
}
/*
* hash_name - hostname hash function
*/
static int hash_name(const char* name)
{
unsigned int hashv = 0;
assert(0 != name);
for (; *name && *name != '.'; name++)
hashv += *name;
hashv %= ARES_CACSIZE;
return hashv;
}
/*
* add_to_cache - Add a new cache item to the queue and hash table.
*/
static struct CacheEntry* add_to_cache(struct CacheEntry* ocp)
{
int hashv;
assert(0 != ocp);
ocp->list_next = cacheTop;
cacheTop = ocp;
hashv = hash_name(ocp->he.h.h_name);
ocp->hname_next = hashtable[hashv].name_list;
hashtable[hashv].name_list = ocp;
hashv = hash_number(ocp->he.h.h_addr);
ocp->hnum_next = hashtable[hashv].num_list;
hashtable[hashv].num_list = ocp;
/*
* LRU deletion of excessive cache entries.
*/
if (++cachedCount > MAXCACHED) {
struct CacheEntry* cp;
for (cp = cacheTop; cp->list_next; cp = cp->list_next)
;
rem_cache(cp);
}
++cainfo.ca_adds;
return ocp;
}
/*
* update_list - does not alter the cache structure passed. It is assumed that
* it already contains the correct expire time, if it is a new entry. Old
* entries have the expirey time updated.
*/
static void update_list(struct ResRequest* request, struct CacheEntry* cachep)
{
struct CacheEntry** cpp;
struct CacheEntry* cp = cachep;
char* s;
char* t;
int i;
int j;
char** ap;
char* addrs[RES_MAXADDRS + 1];
char* aliases[RES_MAXALIASES + 1];
/*
* search for the new cache item in the cache list by hostname.
* If found, move the entry to the top of the list and return.
*/
++cainfo.ca_updates;
for (cpp = &cacheTop; *cpp; cpp = &((*cpp)->list_next)) {
if (cp == *cpp)
break;
}
if (!*cpp)
return;
*cpp = cp->list_next;
cp->list_next = cacheTop;
cacheTop = cp;
if (!request)
return;
/*
* Compare the cache entry against the new record. Add any
* previously missing names for this entry.
*/
*aliases = 0;
ap = aliases;
for (i = 0, s = request->he.h.h_name; s; s = request->he.h.h_aliases[i++]) {
for (j = 0, t = cp->he.h.h_name; t; t = cp->he.h.h_aliases[j++]) {
if (0 == strcasecmp(t, s))
break;
}
if (!t) {
*ap++ = s;
*ap = 0;
}
}
/*
* Do the same again for IP#'s.
*/
*addrs = 0;
ap = addrs;
for (i = 0; (s = request->he.h.h_addr_list[i]); i++) {
for (j = 0; (t = cp->he.h.h_addr_list[j]); j++) {
if (!memcmp(t, s, sizeof(struct in_addr)))
break;
}
if (!t) {
*ap++ = s;
*ap = 0;
}
}
if (*addrs || *aliases)
update_hostent(&cp->he, addrs, aliases);
}
/*
* find_cache_name - find name in nameserver cache
*/
static struct CacheEntry* find_cache_name(const char* name)
{
struct CacheEntry* cp;
char* s;
int hashv;
int i;
assert(0 != name);
hashv = hash_name(name);
cp = hashtable[hashv].name_list;
#ifdef DEBUG
Debug((DEBUG_DNS,"find_cache_name:find %s : hashv = %d",name,hashv));
#endif
for (; cp; cp = cp->hname_next) {
for (i = 0, s = cp->he.h.h_name; s; s = cp->he.h.h_aliases[i++]) {
if (strcasecmp(s, name) == 0) {
++cainfo.ca_na_hits;
update_list(NULL, cp);
return cp;
}
}
}
for (cp = cacheTop; cp; cp = cp->list_next) {
/*
* if no aliases or the hash value matches, we've already
* done this entry and all possiblilities concerning it.
*/
if (!*cp->he.h.h_aliases)
continue;
if (!cp->he.h.h_name) /* don't trust anything -Dianora */
continue;
if (hashv == hash_name(cp->he.h.h_name))
continue;
for (i = 0, s = cp->he.h.h_aliases[i]; s && i < RES_MAXALIASES; i++) {
if (!strcasecmp(name, s)) {
cainfo.ca_na_hits++;
update_list(NULL, cp);
return cp;
}
}
}
return NULL;
}
/*
* find_cache_number - find a cache entry by ip# and update its expire time
*/
static struct CacheEntry* find_cache_number(struct ResRequest* request, const char* addr)
{
struct CacheEntry* cp;
int hashv;
int i;
assert(0 != addr);
hashv = hash_number((unsigned char*) addr);
cp = hashtable[hashv].num_list;
for (; cp; cp = cp->hnum_next) {
for (i = 0; cp->he.h.h_addr_list[i]; i++) {
if (!memcmp(cp->he.h.h_addr_list[i], addr, sizeof(struct in_addr))) {
cainfo.ca_nu_hits++;
update_list(NULL, cp);
return cp;
}
}
}
for (cp = cacheTop; cp; cp = cp->list_next) {
/*
* single address entry...would have been done by hashed
* search above...
*/
if (!cp->he.h.h_addr_list[1])
continue;
/*
* if the first IP# has the same hashnumber as the IP# we
* are looking for, its been done already.
*/
if (hashv == hash_number(cp->he.h.h_addr_list[0]))
continue;
for (i = 1; cp->he.h.h_addr_list[i]; i++) {
if (!memcmp(cp->he.h.h_addr_list[i], addr, sizeof(struct in_addr))) {
cainfo.ca_nu_hits++;
update_list(NULL, cp);
return cp;
}
}
}
return NULL;
}
static struct CacheEntry* make_cache(struct ResRequest* request)
{
struct CacheEntry* cp;
int i;
struct hostent* hp;
assert(0 != request);
hp = &request->he.h;
/*
* shouldn't happen but it just might...
*/
assert(0 != hp->h_name);
assert(0 != hp->h_addr_list[0]);
if (!hp->h_name || !hp->h_addr_list[0])
return NULL;
/*
* Make cache entry. First check to see if the cache already exists
* and if so, return a pointer to it.
*/
for (i = 0; hp->h_addr_list[i]; ++i) {
if ((cp = find_cache_number(request, hp->h_addr_list[i])))
return cp;
}
/*
* a matching entry wasnt found in the cache so go and make one up.
*/
cp = (struct CacheEntry*) MyMalloc(sizeof(struct CacheEntry));
assert(0 != cp);
memset(cp, 0, sizeof(struct CacheEntry));
dup_hostent(&cp->he, hp);
cp->reply.hp = &cp->he.h;
/*
* hmmm... we could time out the cache after 10 minutes regardless
* would that be reasonable since we don't save the reply?
*/
if (request->ttl < AR_TTL) {
++reinfo.re_shortttl;
cp->ttl = AR_TTL;
}
else
cp->ttl = request->ttl;
cp->expireat = CurrentTime + cp->ttl;
return add_to_cache(cp);
}
/*
* rem_cache - delete a cache entry from the cache structures
* and lists and return all memory used for the cache back to the memory pool.
*/
static void rem_cache(struct CacheEntry* ocp)
{
struct CacheEntry** cp;
int hashv;
struct hostent* hp;
assert(0 != ocp);
if (0 < ocp->reply.ref_count) {
ocp->expireat = CurrentTime + AR_TTL;
log(L_INFO, "Resolver: referenced cache entry not removed for: %s",
ocp->he.h.h_name);
return;
}
/*
* remove cache entry from linked list
*/
for (cp = &cacheTop; *cp; cp = &((*cp)->list_next)) {
if (*cp == ocp) {
*cp = ocp->list_next;
break;
}
}
hp = &ocp->he.h;
/*
* remove cache entry from hashed name list
*/
assert(0 != hp->h_name);
hashv = hash_name(hp->h_name);
for (cp = &hashtable[hashv].name_list; *cp; cp = &((*cp)->hname_next)) {
if (*cp == ocp) {
*cp = ocp->hname_next;
break;
}
}
/*
* remove cache entry from hashed number list
*/
hashv = hash_number(hp->h_addr);
assert(-1 < hashv);
for (cp = &hashtable[hashv].num_list; *cp; cp = &((*cp)->hnum_next)) {
if (*cp == ocp) {
*cp = ocp->hnum_next;
break;
}
}
/*
* free memory used to hold the various host names and the array
* of alias pointers.
*/
MyFree(ocp->he.buf);
MyFree(ocp);
--cachedCount;
++cainfo.ca_dels;
}
#ifdef bingo
/*
* m_dns - dns status query
*/
int m_dns(struct Client *cptr, struct Client *sptr, int parc, char *parv[])
{
struct CacheEntry* cp;
int i;
struct hostent* hp;
if (parv[1] && *parv[1] == 'l') {
for(cp = cacheTop; cp; cp = cp->list_next) {
hp = &cp->he.h;
sendto_one(sptr, "NOTICE %s :Ex %d ttl %d host %s(%s)",
parv[0], cp->expireat - CurrentTime, cp->ttl,
hp->h_name, inetntoa(hp->h_addr));
for (i = 0; hp->h_aliases[i]; i++)
sendto_one(sptr,"NOTICE %s : %s = %s (CN)",
parv[0], hp->h_name, hp->h_aliases[i]);
for (i = 1; hp->h_addr_list[i]; i++)
sendto_one(sptr,"NOTICE %s : %s = %s (IP)",
parv[0], hp->h_name, inetntoa(hp->h_addr_list[i]));
}
return 0;
}
if (parv[1] && *parv[1] == 'd') {
sendto_one(sptr, "NOTICE %s :ResolverFileDescriptor = %d",
parv[0], ResolverFileDescriptor);
return 0;
}
sendto_one(sptr,"NOTICE %s :Ca %d Cd %d Ce %d Cl %d Ch %d:%d Cu %d",
sptr->name,
cainfo.ca_adds, cainfo.ca_dels, cainfo.ca_expires,
cainfo.ca_lookups, cainfo.ca_na_hits, cainfo.ca_nu_hits,
cainfo.ca_updates);
sendto_one(sptr,"NOTICE %s :Re %d Rl %d/%d Rp %d Rq %d",
sptr->name, reinfo.re_errors, reinfo.re_nu_look,
reinfo.re_na_look, reinfo.re_replies, reinfo.re_requests);
sendto_one(sptr,"NOTICE %s :Ru %d Rsh %d Rs %d(%d) Rt %d", sptr->name,
reinfo.re_unkrep, reinfo.re_shortttl, reinfo.re_sent,
reinfo.re_resends, reinfo.re_timeouts);
return 0;
}
#endif /* bingo */
unsigned long cres_mem(struct Client* sptr)
{
struct CacheEntry* entry;
struct ResRequest* request;
size_t cache_mem = 0;
int cache_count = 0;
size_t request_mem = 0;
int request_count = 0;
for (entry = cacheTop; entry; entry = entry->list_next) {
cache_mem += sizeof(struct CacheEntry);
cache_mem += calc_hostent_buffer_size(&entry->he.h);
++cache_count;
}
for (request = requestListHead; request; request = request->next) {
request_mem += sizeof(struct ResRequest);
if (request->name)
request_mem += strlen(request->name) + 1;
if (request->he.buf)
request_mem += MAXGETHOSTLEN + 1;
++request_count;
}
if (cachedCount != cache_count) {
#ifdef bingo
sendto_one(sptr,
":%s %d %s :Resolver: cache count mismatch: %d != %d",
me.name, RPL_STATSDEBUG, sptr->name, cachedCount, cache_count);
#endif
assert(cachedCount == cache_count);
}
#ifdef bingo
sendto_one(sptr, ":%s %d %s :Resolver: cache %d(%d) requests %d(%d)",
me.name, RPL_STATSDEBUG, sptr->name, cache_count, cache_mem,
request_count, request_mem);
#endif
return cache_mem + request_mem;
}