/* $NetBSD: ntp_intres.c,v 1.13 2024/08/18 20:47:13 christos Exp $ */
/*
* ntp_intres.c - Implements a generic blocking worker child or thread,
* initially to provide a nonblocking solution for DNS
* name to address lookups available with getaddrinfo().
*
* This is a new implementation as of 2009 sharing the filename and
* very little else with the prior implementation, which used a
* temporary file to receive a single set of requests from the parent,
* and a NTP mode 7 authenticated request to push back responses.
*
* A primary goal in rewriting this code was the need to support the
* pool configuration directive's requirement to retrieve multiple
* addresses resolving a single name, which has previously been
* satisfied with blocking resolver calls from the ntpd mainline code.
*
* A secondary goal is to provide a generic mechanism for other
* blocking operations to be delegated to a worker using a common
* model for both Unix and Windows ntpd. ntp_worker.c, work_fork.c,
* and work_thread.c implement the generic mechanism. This file
* implements the two current consumers, getaddrinfo_sometime() and the
* presently unused getnameinfo_sometime().
*
* Both routines deliver results to a callback and manage memory
* allocation, meaning there is no freeaddrinfo_sometime().
*
* The initial implementation for Unix uses a pair of unidirectional
* pipes, one each for requests and responses, connecting the forked
* blocking child worker with the ntpd mainline. The threaded code
* uses arrays of pointers to queue requests and responses.
*
* The parent drives the process, including scheduling sleeps between
* retries.
*
* Memory is managed differently for a child process, which mallocs
* request buffers to read from the pipe into, whereas the threaded
* code mallocs a copy of the request to hand off to the worker via
* the queueing array. The resulting request buffer is free()d by
* platform-independent code. A wrinkle is the request needs to be
* available to the requestor during response processing.
*
* Response memory allocation is also platform-dependent. With a
* separate process and pipes, the response is free()d after being
* written to the pipe. With threads, the same memory is handed
* over and the requestor frees it after processing is completed.
*
* The code should be generalized to support threads on Unix using
* much of the same code used for Windows initially.
*
*/
#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include "ntp_workimpl.h"
#ifdef WORKER
#include <stdio.h>
#include <ctype.h>
#include <signal.h>
/**/
#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif
#ifdef HAVE_NETINET_IN_H
#include <netinet/in.h>
#endif
#include <arpa/inet.h>
/**/
#ifdef HAVE_SYS_PARAM_H
# include <sys/param.h>
#endif
#if !defined(HAVE_RES_INIT) && defined(HAVE___RES_INIT)
# define HAVE_RES_INIT
#endif
#if defined(HAVE_RESOLV_H) && defined(HAVE_RES_INIT)
# ifdef HAVE_ARPA_NAMESER_H
# include <arpa/nameser.h> /* DNS HEADER struct */
# endif
# ifdef HAVE_NETDB_H
# include <netdb.h>
# endif
# include <resolv.h>
#endif
#include "ntp.h"
#include "ntp_debug.h"
#include "ntp_malloc.h"
#include "ntp_syslog.h"
#include "ntp_unixtime.h"
#include "ntp_intres.h"
#include "intreswork.h"
/*
* Following are implementations of getaddrinfo_sometime() and
* getnameinfo_sometime(). Each is implemented in three routines:
*
* getaddrinfo_sometime() getnameinfo_sometime()
* blocking_getaddrinfo() blocking_getnameinfo()
* getaddrinfo_sometime_complete() getnameinfo_sometime_complete()
*
* The first runs in the parent and marshalls (or serializes) request
* parameters into a request blob which is processed in the child by
* the second routine, blocking_*(), which serializes the results into
* a response blob unpacked by the third routine, *_complete(), which
* calls the callback routine provided with the request and frees
* _request_ memory allocated by the first routine. Response memory
* is managed by the code which calls the *_complete routines.
*/
/* === typedefs === */
typedef struct blocking_gai_req_tag { /* marshalled args */
size_t octets;
u_int dns_idx;
time_t scheduled;
time_t earliest;
int retry;
struct addrinfo hints;
u_int qflags;
gai_sometime_callback callback;
void * context;
size_t nodesize;
size_t servsize;
} blocking_gai_req;
typedef struct blocking_gai_resp_tag {
size_t octets;
int retcode;
int retry;
int gai_errno; /* for EAI_SYSTEM case */
int ai_count;
/*
* Followed by ai_count struct addrinfo and then ai_count
* sockaddr_u and finally the canonical name strings.
*/
} blocking_gai_resp;
typedef struct blocking_gni_req_tag {
size_t octets;
u_int dns_idx;
time_t scheduled;
time_t earliest;
int retry;
size_t hostoctets;
size_t servoctets;
int flags;
gni_sometime_callback callback;
void * context;
sockaddr_u socku;
} blocking_gni_req;
typedef struct blocking_gni_resp_tag {
size_t octets;
int retcode;
int gni_errno; /* for EAI_SYSTEM case */
int retry;
size_t hostoctets;
size_t servoctets;
/*
* Followed by hostoctets bytes of null-terminated host,
* then servoctets bytes of null-terminated service.
*/
} blocking_gni_resp;
/* per-DNS-worker state in parent */
typedef struct dnschild_ctx_tag {
u_int index;
time_t next_dns_timeslot;
} dnschild_ctx;
/* per-DNS-worker state in worker */
typedef struct dnsworker_ctx_tag {
blocking_child * c;
time_t ignore_scheduled_before;
#ifdef HAVE_RES_INIT
time_t next_res_init;
#endif
} dnsworker_ctx;
/* === variables === */
dnschild_ctx ** dnschild_contexts; /* parent */
u_int dnschild_contexts_alloc;
dnsworker_ctx ** dnsworker_contexts; /* child */
u_int dnsworker_contexts_alloc;
#ifdef HAVE_RES_INIT
static time_t next_res_init;
#endif
/* === forward declarations === */
static u_int reserve_dnschild_ctx(void);
static u_int get_dnschild_ctx(void);
static dnsworker_ctx * get_worker_context(blocking_child *, u_int);
static void scheduled_sleep(time_t, time_t,
dnsworker_ctx *);
static void manage_dns_retry_interval(time_t *, time_t *,
int *, time_t *,
int/*BOOL*/);
static int should_retry_dns(int, int);
#ifdef HAVE_RES_INIT
static void reload_resolv_conf(dnsworker_ctx *);
#else
# define reload_resolv_conf(wc) \
do { \
(void)(wc); \
} while (FALSE)
#endif
static void getaddrinfo_sometime_complete(blocking_work_req,
void *, size_t,
void *);
static void getnameinfo_sometime_complete(blocking_work_req,
void *, size_t,
void *);
/* === functions === */
/*
* getaddrinfo_sometime - uses blocking child to call getaddrinfo then
* invokes provided callback completion function.
*/
int
getaddrinfo_sometime_ex(
const char * node,
const char * service,
const struct addrinfo * hints,
int retry,
gai_sometime_callback callback,
void * context,
u_int qflags
)
{
blocking_gai_req * gai_req;
u_int idx;
dnschild_ctx * child_ctx;
size_t req_size;
size_t nodesize;
size_t servsize;
time_t now;
REQUIRE(NULL != node);
if (NULL != hints) {
REQUIRE(0 == hints->ai_addrlen);
REQUIRE(NULL == hints->ai_addr);
REQUIRE(NULL == hints->ai_canonname);
REQUIRE(NULL == hints->ai_next);
}
idx = get_dnschild_ctx();
child_ctx = dnschild_contexts[idx];
nodesize = strlen(node) + 1;
servsize = strlen(service) + 1;
req_size = sizeof(*gai_req) + nodesize + servsize;
gai_req = emalloc_zero(req_size);
gai_req->octets = req_size;
gai_req->dns_idx = idx;
now = time(NULL);
gai_req->scheduled = now;
gai_req->earliest = max(now, child_ctx->next_dns_timeslot);
child_ctx->next_dns_timeslot = gai_req->earliest;
if (hints != NULL)
gai_req->hints = *hints;
gai_req->retry = retry;
gai_req->callback = callback;
gai_req->context = context;
gai_req->nodesize = nodesize;
gai_req->servsize = servsize;
gai_req->qflags = qflags;
memcpy((char *)gai_req + sizeof(*gai_req), node, nodesize);
memcpy((char *)gai_req + sizeof(*gai_req) + nodesize, service,
servsize);
if (queue_blocking_request(
BLOCKING_GETADDRINFO,
gai_req,
req_size,
&getaddrinfo_sometime_complete,
gai_req)) {
msyslog(LOG_ERR, "unable to queue getaddrinfo request");
errno = EFAULT;
return -1;
}
return 0;
}
int
blocking_getaddrinfo(
blocking_child * c,
blocking_pipe_header * req
)
{
blocking_gai_req * gai_req;
dnsworker_ctx * worker_ctx;
blocking_pipe_header * resp;
blocking_gai_resp * gai_resp;
char * node;
char * service;
struct addrinfo * ai_res;
struct addrinfo * ai;
struct addrinfo * serialized_ai;
size_t canons_octets;
size_t this_octets;
size_t resp_octets;
char * cp;
time_t time_now;
gai_req = (void *)((char *)req + sizeof(*req));
node = (char *)gai_req + sizeof(*gai_req);
service = node + gai_req->nodesize;
worker_ctx = get_worker_context(c, gai_req->dns_idx);
scheduled_sleep(gai_req->scheduled, gai_req->earliest,
worker_ctx);
reload_resolv_conf(worker_ctx);
/*
* Take a shot at the final size, better to overestimate
* at first and then realloc to a smaller size.
*/
resp_octets = sizeof(*resp) + sizeof(*gai_resp) +
16 * (sizeof(struct addrinfo) +
sizeof(sockaddr_u)) +
256;
resp = emalloc_zero(resp_octets);
gai_resp = (void *)(resp + 1);
TRACE(2, ("blocking_getaddrinfo given node %s serv %s fam %d flags %x\n",
node, service, gai_req->hints.ai_family,
gai_req->hints.ai_flags));
#ifdef DEBUG
if (debug >= 2)
fflush(stdout);
#endif
ai_res = NULL;
gai_resp->retcode = getaddrinfo(node, service, &gai_req->hints,
&ai_res);
gai_resp->retry = gai_req->retry;
#ifdef EAI_SYSTEM
if (EAI_SYSTEM == gai_resp->retcode)
gai_resp->gai_errno = errno;
#endif
canons_octets = 0;
if (0 == gai_resp->retcode) {
ai = ai_res;
while (NULL != ai) {
gai_resp->ai_count++;
if (ai->ai_canonname)
canons_octets += strlen(ai->ai_canonname) + 1;
ai = ai->ai_next;
}
/*
* If this query succeeded only after retrying, DNS may have
* just become responsive. Ignore previously-scheduled
* retry sleeps once for each pending request, similar to
* the way scheduled_sleep() does when its worker_sleep()
* is interrupted.
*/
if (gai_resp->retry > INITIAL_DNS_RETRY) {
time_now = time(NULL);
worker_ctx->ignore_scheduled_before = time_now;
TRACE(1, ("DNS success after retry, ignoring sleeps scheduled before now (%s)\n",
humantime(time_now)));
}
}
/*
* Our response consists of a header, followed by ai_count
* addrinfo structs followed by ai_count sockaddr_storage
* structs followed by the canonical names.
*/
gai_resp->octets = sizeof(*gai_resp)
+ gai_resp->ai_count
* (sizeof(gai_req->hints)
+ sizeof(sockaddr_u))
+ canons_octets;
resp_octets = sizeof(*resp) + gai_resp->octets;
resp = erealloc(resp, resp_octets);
gai_resp = (void *)(resp + 1);
/* cp serves as our current pointer while serializing */
cp = (void *)(gai_resp + 1);
canons_octets = 0;
if (0 == gai_resp->retcode) {
ai = ai_res;
while (NULL != ai) {
memcpy(cp, ai, sizeof(*ai));
serialized_ai = (void *)cp;
cp += sizeof(*ai);
/* transform ai_canonname into offset */
if (NULL != ai->ai_canonname) {
serialized_ai->ai_canonname = (char *)canons_octets;
canons_octets += strlen(ai->ai_canonname) + 1;
}
/* leave fixup of ai_addr pointer for receiver */
ai = ai->ai_next;
}
ai = ai_res;
while (NULL != ai) {
INSIST(ai->ai_addrlen <= sizeof(sockaddr_u));
memcpy(cp, ai->ai_addr, ai->ai_addrlen);
cp += sizeof(sockaddr_u);
ai = ai->ai_next;
}
ai = ai_res;
while (NULL != ai) {
if (NULL != ai->ai_canonname) {
this_octets = strlen(ai->ai_canonname) + 1;
memcpy(cp, ai->ai_canonname, this_octets);
cp += this_octets;
}
ai = ai->ai_next;
}
freeaddrinfo(ai_res);
}
/*
* make sure our walk and earlier calc match
*/
DEBUG_INSIST((size_t)(cp - (char *)resp) == resp_octets);
if (queue_blocking_response(c, resp, resp_octets, req)) {
msyslog(LOG_ERR, "blocking_getaddrinfo can not queue response");
return -1;
}
return 0;
}
int
getaddrinfo_sometime(
const char * node,
const char * service,
const struct addrinfo * hints,
int retry,
gai_sometime_callback callback,
void * context
)
{
return getaddrinfo_sometime_ex(node, service, hints, retry,
callback, context, 0);
}
static void
getaddrinfo_sometime_complete(
blocking_work_req rtype,
void * context,
size_t respsize,
void * resp
)
{
blocking_gai_req * gai_req;
blocking_gai_resp * gai_resp;
dnschild_ctx * child_ctx;
struct addrinfo * ai;
struct addrinfo * next_ai;
sockaddr_u * psau;
char * node;
char * service;
char * canon_start;
time_t time_now;
int again, noerr;
int af;
const char * fam_spec;
int i;
gai_req = context;
gai_resp = resp;
DEBUG_REQUIRE(BLOCKING_GETADDRINFO == rtype);
DEBUG_REQUIRE(respsize == gai_resp->octets);
node = (char *)gai_req + sizeof(*gai_req);
service = node + gai_req->nodesize;
child_ctx = dnschild_contexts[gai_req->dns_idx];
if (0 == gai_resp->retcode) {
/*
* If this query succeeded only after retrying, DNS may have
* just become responsive.
*/
if (gai_resp->retry > INITIAL_DNS_RETRY) {
time_now = time(NULL);
child_ctx->next_dns_timeslot = time_now;
TRACE(1, ("DNS success after retry, %u next_dns_timeslot reset (%s)\n",
gai_req->dns_idx, humantime(time_now)));
}
} else {
noerr = !!(gai_req->qflags & GAIR_F_IGNDNSERR);
again = noerr || should_retry_dns(
gai_resp->retcode, gai_resp->gai_errno);
/*
* exponential backoff of DNS retries to 64s
*/
if (gai_req->retry > 0 && again) {
/* log the first retry only */
if (INITIAL_DNS_RETRY == gai_req->retry)
NLOG(NLOG_SYSINFO) {
af = gai_req->hints.ai_family;
fam_spec = (AF_INET6 == af)
? " (AAAA)"
: (AF_INET == af)
? " (A)"
: "";
#ifdef EAI_SYSTEM
if (EAI_SYSTEM == gai_resp->retcode) {
errno = gai_resp->gai_errno;
msyslog(LOG_INFO,
"retrying DNS %s%s: EAI_SYSTEM %d: %m",
node, fam_spec,
gai_resp->gai_errno);
} else
#endif
msyslog(LOG_INFO,
"retrying DNS %s%s: %s (%d)",
node, fam_spec,
gai_strerror(gai_resp->retcode),
gai_resp->retcode);
}
manage_dns_retry_interval(
&gai_req->scheduled, &gai_req->earliest,
&gai_req->retry, &child_ctx->next_dns_timeslot,
noerr);
if (!queue_blocking_request(
BLOCKING_GETADDRINFO,
gai_req,
gai_req->octets,
&getaddrinfo_sometime_complete,
gai_req))
return;
else
msyslog(LOG_ERR,
"unable to retry hostname %s",
node);
}
}
/*
* fixup pointers in returned addrinfo array
*/
ai = (void *)((char *)gai_resp + sizeof(*gai_resp));
next_ai = NULL;
for (i = gai_resp->ai_count - 1; i >= 0; i--) {
ai[i].ai_next = next_ai;
next_ai = &ai[i];
}
psau = (void *)((char *)ai + gai_resp->ai_count * sizeof(*ai));
canon_start = (char *)psau + gai_resp->ai_count * sizeof(*psau);
for (i = 0; i < gai_resp->ai_count; i++) {
if (NULL != ai[i].ai_addr)
ai[i].ai_addr = &psau->sa;
psau++;
if (NULL != ai[i].ai_canonname)
ai[i].ai_canonname += (size_t)canon_start;
}
ENSURE((char *)psau == canon_start);
if (!gai_resp->ai_count)
ai = NULL;
(*gai_req->callback)(gai_resp->retcode, gai_resp->gai_errno,
gai_req->context, node, service,
&gai_req->hints, ai);
free(gai_req);
/* gai_resp is part of block freed by process_blocking_resp() */
}
#ifdef TEST_BLOCKING_WORKER
void gai_test_callback(int rescode, int gai_errno, void *context, const char *name, const char *service, const struct addrinfo *hints, const struct addrinfo *ai_res)
{
sockaddr_u addr;
if (rescode) {
TRACE(1, ("gai_test_callback context %p error rescode %d %s serv %s\n",
context, rescode, name, service));
return;
}
while (!rescode && NULL != ai_res) {
ZERO_SOCK(&addr);
memcpy(&addr, ai_res->ai_addr, ai_res->ai_addrlen);
TRACE(1, ("ctx %p fam %d addr %s canon '%s' type %s at %p ai_addr %p ai_next %p\n",
context,
AF(&addr),
stoa(&addr),
(ai_res->ai_canonname)
? ai_res->ai_canonname
: "",
(SOCK_DGRAM == ai_res->ai_socktype)
? "DGRAM"
: (SOCK_STREAM == ai_res->ai_socktype)
? "STREAM"
: "(other)",
ai_res,
ai_res->ai_addr,
ai_res->ai_next));
getnameinfo_sometime((sockaddr_u *)ai_res->ai_addr, 128, 32, 0, gni_test_callback, context);
ai_res = ai_res->ai_next;
}
}
#endif /* TEST_BLOCKING_WORKER */
int
getnameinfo_sometime(
sockaddr_u * psau,
size_t hostoctets,
size_t servoctets,
int flags,
gni_sometime_callback callback,
void * context
)
{
blocking_gni_req * gni_req;
u_int idx;
dnschild_ctx * child_ctx;
time_t time_now;
REQUIRE(hostoctets);
REQUIRE(hostoctets + servoctets < 1024);
idx = get_dnschild_ctx();
child_ctx = dnschild_contexts[idx];
gni_req = emalloc_zero(sizeof(*gni_req));
gni_req->octets = sizeof(*gni_req);
gni_req->dns_idx = idx;
time_now = time(NULL);
gni_req->scheduled = time_now;
gni_req->earliest = max(time_now, child_ctx->next_dns_timeslot);
child_ctx->next_dns_timeslot = gni_req->earliest;
memcpy(&gni_req->socku, psau, SOCKLEN(psau));
gni_req->hostoctets = hostoctets;
gni_req->servoctets = servoctets;
gni_req->flags = flags;
gni_req->retry = INITIAL_DNS_RETRY;
gni_req->callback = callback;
gni_req->context = context;
if (queue_blocking_request(
BLOCKING_GETNAMEINFO,
gni_req,
sizeof(*gni_req),
&getnameinfo_sometime_complete,
gni_req)) {
msyslog(LOG_ERR, "unable to queue getnameinfo request");
errno = EFAULT;
return -1;
}
return 0;
}
int
blocking_getnameinfo(
blocking_child * c,
blocking_pipe_header * req
)
{
blocking_gni_req * gni_req;
dnsworker_ctx * worker_ctx;
blocking_pipe_header * resp;
blocking_gni_resp * gni_resp;
size_t octets;
size_t resp_octets;
char * service;
char * cp;
int rc;
time_t time_now;
char host[1024];
gni_req = (void *)((char *)req + sizeof(*req));
octets = gni_req->hostoctets + gni_req->servoctets;
/*
* Some alloca() implementations are fragile regarding
* large allocations. We only need room for the host
* and service names.
*/
REQUIRE(octets < sizeof(host));
service = host + gni_req->hostoctets;
worker_ctx = get_worker_context(c, gni_req->dns_idx);
scheduled_sleep(gni_req->scheduled, gni_req->earliest,
worker_ctx);
reload_resolv_conf(worker_ctx);
/*
* Take a shot at the final size, better to overestimate
* then realloc to a smaller size.
*/
resp_octets = sizeof(*resp) + sizeof(*gni_resp) + octets;
resp = emalloc_zero(resp_octets);
gni_resp = (void *)((char *)resp + sizeof(*resp));
TRACE(2, ("blocking_getnameinfo given addr %s flags 0x%x hostlen %lu servlen %lu\n",
stoa(&gni_req->socku), gni_req->flags,
(u_long)gni_req->hostoctets, (u_long)gni_req->servoctets));
gni_resp->retcode = getnameinfo(&gni_req->socku.sa,
SOCKLEN(&gni_req->socku),
host,
gni_req->hostoctets,
service,
gni_req->servoctets,
gni_req->flags);
gni_resp->retry = gni_req->retry;
#ifdef EAI_SYSTEM
if (EAI_SYSTEM == gni_resp->retcode)
gni_resp->gni_errno = errno;
#endif
if (0 != gni_resp->retcode) {
gni_resp->hostoctets = 0;
gni_resp->servoctets = 0;
} else {
gni_resp->hostoctets = strlen(host) + 1;
gni_resp->servoctets = strlen(service) + 1;
/*
* If this query succeeded only after retrying, DNS may have
* just become responsive. Ignore previously-scheduled
* retry sleeps once for each pending request, similar to
* the way scheduled_sleep() does when its worker_sleep()
* is interrupted.
*/
if (gni_req->retry > INITIAL_DNS_RETRY) {
time_now = time(NULL);
worker_ctx->ignore_scheduled_before = time_now;
TRACE(1, ("DNS success after retrying, ignoring sleeps scheduled before now (%s)\n",
humantime(time_now)));
}
}
octets = gni_resp->hostoctets + gni_resp->servoctets;
/*
* Our response consists of a header, followed by the host and
* service strings, each null-terminated.
*/
resp_octets = sizeof(*resp) + sizeof(*gni_resp) + octets;
resp = erealloc(resp, resp_octets);
gni_resp = (void *)(resp + 1);
gni_resp->octets = sizeof(*gni_resp) + octets;
/* cp serves as our current pointer while serializing */
cp = (void *)(gni_resp + 1);
if (0 == gni_resp->retcode) {
memcpy(cp, host, gni_resp->hostoctets);
cp += gni_resp->hostoctets;
memcpy(cp, service, gni_resp->servoctets);
cp += gni_resp->servoctets;
}
INSIST((size_t)(cp - (char *)resp) == resp_octets);
INSIST(resp_octets - sizeof(*resp) == gni_resp->octets);
rc = queue_blocking_response(c, resp, resp_octets, req);
if (rc)
msyslog(LOG_ERR, "blocking_getnameinfo unable to queue response");
return rc;
}
static void
getnameinfo_sometime_complete(
blocking_work_req rtype,
void * context,
size_t respsize,
void * resp
)
{
blocking_gni_req * gni_req;
blocking_gni_resp * gni_resp;
dnschild_ctx * child_ctx;
char * host;
char * service;
time_t time_now;
int again;
gni_req = context;
gni_resp = resp;
DEBUG_REQUIRE(BLOCKING_GETNAMEINFO == rtype);
DEBUG_REQUIRE(respsize == gni_resp->octets);
child_ctx = dnschild_contexts[gni_req->dns_idx];
if (0 == gni_resp->retcode) {
/*
* If this query succeeded only after retrying, DNS may have
* just become responsive.
*/
if (gni_resp->retry > INITIAL_DNS_RETRY) {
time_now = time(NULL);
child_ctx->next_dns_timeslot = time_now;
TRACE(1, ("DNS success after retry, %u next_dns_timeslot reset (%s)\n",
gni_req->dns_idx, humantime(time_now)));
}
} else {
again = should_retry_dns(gni_resp->retcode, gni_resp->gni_errno);
/*
* exponential backoff of DNS retries to 64s
*/
if (gni_req->retry > 0)
manage_dns_retry_interval(&gni_req->scheduled,
&gni_req->earliest, &gni_req->retry,
&child_ctx->next_dns_timeslot, FALSE);
if (gni_req->retry > 0 && again) {
if (!queue_blocking_request(
BLOCKING_GETNAMEINFO,
gni_req,
gni_req->octets,
&getnameinfo_sometime_complete,
gni_req))
return;
msyslog(LOG_ERR, "unable to retry reverse lookup of %s", stoa(&gni_req->socku));
}
}
if (!gni_resp->hostoctets) {
host = NULL;
service = NULL;
} else {
host = (char *)gni_resp + sizeof(*gni_resp);
service = (gni_resp->servoctets)
? host + gni_resp->hostoctets
: NULL;
}
(*gni_req->callback)(gni_resp->retcode, gni_resp->gni_errno,
&gni_req->socku, gni_req->flags, host,
service, gni_req->context);
free(gni_req);
/* gni_resp is part of block freed by process_blocking_resp() */
}
#ifdef TEST_BLOCKING_WORKER
void gni_test_callback(int rescode, int gni_errno, sockaddr_u *psau, int flags, const char *host, const char *service, void *context)
{
if (!rescode)
TRACE(1, ("gni_test_callback got host '%s' serv '%s' for addr %s context %p\n",
host, service, stoa(psau), context));
else
TRACE(1, ("gni_test_callback context %p rescode %d gni_errno %d flags 0x%x addr %s\n",
context, rescode, gni_errno, flags, stoa(psau)));
}
#endif /* TEST_BLOCKING_WORKER */
#ifdef HAVE_RES_INIT
static void
reload_resolv_conf(
dnsworker_ctx * worker_ctx
)
{
time_t time_now;
/*
* This is ad-hoc. Reload /etc/resolv.conf once per minute
* to pick up on changes from the DHCP client. [Bug 1226]
* When using threads for the workers, this needs to happen
* only once per minute process-wide.
*/
time_now = time(NULL);
# ifdef WORK_THREAD
worker_ctx->next_res_init = next_res_init;
# endif
if (worker_ctx->next_res_init <= time_now) {
if (worker_ctx->next_res_init != 0)
res_init();
worker_ctx->next_res_init = time_now + 60;
# ifdef WORK_THREAD
next_res_init = worker_ctx->next_res_init;
# endif
}
}
#endif /* HAVE_RES_INIT */
static u_int
reserve_dnschild_ctx(void)
{
const size_t ps = sizeof(dnschild_contexts[0]);
const size_t cs = sizeof(*dnschild_contexts[0]);
u_int c;
u_int new_alloc;
size_t octets;
size_t new_octets;
c = 0;
while (TRUE) {
for ( ; c < dnschild_contexts_alloc; c++) {
if (NULL == dnschild_contexts[c]) {
dnschild_contexts[c] = emalloc_zero(cs);
return c;
}
}
new_alloc = dnschild_contexts_alloc + 20;
new_octets = new_alloc * ps;
octets = dnschild_contexts_alloc * ps;
dnschild_contexts = erealloc_zero(dnschild_contexts,
new_octets, octets);
dnschild_contexts_alloc = new_alloc;
}
}
static u_int
get_dnschild_ctx(void)
{
static u_int shared_ctx = UINT_MAX;
if (worker_per_query)
return reserve_dnschild_ctx();
if (UINT_MAX == shared_ctx)
shared_ctx = reserve_dnschild_ctx();
return shared_ctx;
}
static dnsworker_ctx *
get_worker_context(
blocking_child * c,
u_int idx
)
{
u_int min_new_alloc;
u_int new_alloc;
size_t octets;
size_t new_octets;
dnsworker_ctx * retv;
worker_global_lock(TRUE);
if (dnsworker_contexts_alloc <= idx) {
min_new_alloc = 1 + idx;
/* round new_alloc up to nearest multiple of 4 */
new_alloc = (min_new_alloc + 4) & ~(4 - 1);
new_octets = new_alloc * sizeof(dnsworker_ctx*);
octets = dnsworker_contexts_alloc * sizeof(dnsworker_ctx*);
dnsworker_contexts = erealloc_zero(dnsworker_contexts,
new_octets, octets);
dnsworker_contexts_alloc = new_alloc;
retv = emalloc_zero(sizeof(dnsworker_ctx));
dnsworker_contexts[idx] = retv;
} else if (NULL == (retv = dnsworker_contexts[idx])) {
retv = emalloc_zero(sizeof(dnsworker_ctx));
dnsworker_contexts[idx] = retv;
}
worker_global_lock(FALSE);
ZERO(*retv);
retv->c = c;
return retv;
}
static void
scheduled_sleep(
time_t scheduled,
time_t earliest,
dnsworker_ctx * worker_ctx
)
{
time_t now;
if (scheduled < worker_ctx->ignore_scheduled_before) {
TRACE(1, ("ignoring sleep until %s scheduled at %s (before %s)\n",
humantime(earliest), humantime(scheduled),
humantime(worker_ctx->ignore_scheduled_before)));
return;
}
now = time(NULL);
if (now < earliest) {
TRACE(1, ("sleep until %s scheduled at %s (>= %s)\n",
humantime(earliest), humantime(scheduled),
humantime(worker_ctx->ignore_scheduled_before)));
if (-1 == worker_sleep(worker_ctx->c, earliest - now)) {
/* our sleep was interrupted */
now = time(NULL);
worker_ctx->ignore_scheduled_before = now;
#ifdef HAVE_RES_INIT
worker_ctx->next_res_init = now + 60;
next_res_init = worker_ctx->next_res_init;
res_init();
#endif
TRACE(1, ("sleep interrupted by daemon, ignoring sleeps scheduled before now (%s)\n",
humantime(worker_ctx->ignore_scheduled_before)));
}
}
}
/*
* manage_dns_retry_interval is a helper used by
* getaddrinfo_sometime_complete and getnameinfo_sometime_complete
* to calculate the new retry interval and schedule the next query.
*/
static void
manage_dns_retry_interval(
time_t * pscheduled,
time_t * pwhen,
int * pretry,
time_t * pnext_timeslot,
int forever
)
{
time_t now;
time_t when;
int retry;
int retmax;
now = time(NULL);
retry = *pretry;
when = max(now + retry, *pnext_timeslot);
*pnext_timeslot = when;
/* this exponential backoff is slower than doubling up: The
* sequence goes 2-3-4-6-8-12-16-24-32... and the upper limit is
* 64 seconds for things that should not repeat forever, and
* 1024 when repeated forever.
*/
retmax = forever ? 1024 : 64;
retry <<= 1;
if (retry & (retry - 1))
retry &= (retry - 1);
else
retry -= (retry >> 2);
retry = min(retmax, retry);
*pscheduled = now;
*pwhen = when;
*pretry = retry;
}
/*
* should_retry_dns is a helper used by getaddrinfo_sometime_complete
* and getnameinfo_sometime_complete which implements ntpd's DNS retry
* policy.
*/
static int
should_retry_dns(
int rescode,
int res_errno
)
{
static int eai_again_seen;
int again;
#if defined (EAI_SYSTEM) && defined(DEBUG)
char msg[256];
#endif
/*
* If the resolver failed, see if the failure is
* temporary. If so, return success.
*/
again = 0;
switch (rescode) {
case EAI_FAIL:
again = 1;
break;
case EAI_AGAIN:
again = 1;
eai_again_seen = 1; /* [Bug 1178] */
break;
case EAI_NONAME:
#if defined(EAI_NODATA) && (EAI_NODATA != EAI_NONAME)
case EAI_NODATA:
#endif
again = !eai_again_seen; /* [Bug 1178] */
break;
#ifdef EAI_SYSTEM
case EAI_SYSTEM:
/*
* EAI_SYSTEM means the real error is in errno. We should be more
* discriminating about which errno values require retrying, but
* this matches existing behavior.
*/
again = 1;
# ifdef DEBUG
errno_to_str(res_errno, msg, sizeof(msg));
TRACE(1, ("intres: EAI_SYSTEM errno %d (%s) means try again, right?\n",
res_errno, msg));
# endif
break;
#endif
}
TRACE(2, ("intres: resolver returned: %s (%d), %sretrying\n",
gai_strerror(rescode), rescode, again ? "" : "not "));
return again;
}
#else /* !WORKER follows */
int ntp_intres_nonempty_compilation_unit;
#endif
