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https://github.com/isc-projects/bind9.git
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Refactor fctx_getaddresses() into couple smaller functions
The fctx_getaddresses() was lengthy and little bit confusing with goto statements. Split the single function into smaller parts: one for forwarders, one for nameservers and one for alternates.
This commit is contained in:
Ondřej Surý
parent
1b90d2ffdb
commit
d51effdb48
1 changed files with 246 additions and 210 deletions
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@ -3411,73 +3411,34 @@ isstrictsubdomain(const dns_name_t *name1, const dns_name_t *name2) {
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return namereln == dns_namereln_subdomain;
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}
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static unsigned int
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fctx_getaddresses_allowed(fetchctx_t *fctx) {
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switch (fctx->depth) {
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case 0:
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return 3;
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case 1:
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return 2;
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case 2:
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return 1;
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default:
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return 0;
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}
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}
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static isc_result_t
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fctx_getaddresses(fetchctx_t *fctx) {
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isc_result_t result;
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dns_resolver_t *res;
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isc_stdtime_t now;
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unsigned int stdoptions = 0;
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dns_forwarder_t *fwd;
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dns_adbaddrinfo_t *ai;
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bool all_bad;
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dns_rdata_ns_t ns;
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bool need_alternate = false;
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bool all_spilled = false;
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bool have_address = false;
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unsigned int ns_processed = 0;
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size_t fetches_allowed = 0;
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FCTXTRACE5("getaddresses", "fctx->depth=", fctx->depth);
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/*
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* Don't pound on remote servers. (Failsafe!)
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*/
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fctx->restarts++;
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if (fctx->restarts > 100) {
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FCTXTRACE("too many restarts");
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return DNS_R_SERVFAIL;
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}
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res = fctx->res;
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if (fctx->depth > res->maxdepth) {
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isc_log_write(DNS_LOGCATEGORY_RESOLVER, DNS_LOGMODULE_RESOLVER,
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ISC_LOG_DEBUG(3),
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"too much NS indirection resolving '%s' "
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"(depth=%u, maxdepth=%u)",
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fctx->info, fctx->depth, res->maxdepth);
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return DNS_R_SERVFAIL;
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}
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/*
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* Forwarders.
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*/
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INSIST(ISC_LIST_EMPTY(fctx->forwaddrs));
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INSIST(ISC_LIST_EMPTY(fctx->altaddrs));
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/*
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* If we have DNS_FETCHOPT_NOFORWARD set and forwarding policy
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* allows us to not forward - skip forwarders and go straight
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* to NSes. This is currently used to make sure that priming
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* query gets root servers' IP addresses in ADDITIONAL section.
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*/
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if ((fctx->options & DNS_FETCHOPT_NOFORWARD) != 0 &&
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(fctx->fwdpolicy != dns_fwdpolicy_only))
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{
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goto normal_nses;
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}
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fctx_getaddresses_forwarders(fetchctx_t *fctx) {
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dns_resolver_t *res = fctx->res;
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/*
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* If this fctx has forwarders, use them; otherwise use any
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* selective forwarders specified in the view; otherwise use the
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* resolver's forwarders (if any).
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*/
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fwd = ISC_LIST_HEAD(fctx->forwarders);
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dns_forwarder_t *fwd = ISC_LIST_HEAD(fctx->forwarders);
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if (fwd == NULL) {
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dns_forwarders_t *forwarders = NULL;
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dns_name_t *name = fctx->name;
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dns_name_t suffix;
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isc_result_t result;
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/*
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* DS records are found in the parent server.
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@ -3515,8 +3476,11 @@ fctx_getaddresses(fetchctx_t *fctx) {
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}
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while (fwd != NULL) {
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isc_result_t result;
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dns_adbaddrinfo_t *ai;
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if ((isc_sockaddr_pf(&fwd->addr) == AF_INET &&
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res->dispatches4 == NULL) ||
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(isc_sockaddr_pf(&fwd->addr) == AF_INET6 &&
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res->dispatches6 == NULL))
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{
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@ -3552,18 +3516,180 @@ fctx_getaddresses(fetchctx_t *fctx) {
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fwd = ISC_LIST_NEXT(fwd, link);
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}
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return DNS_R_CONTINUE;
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}
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static isc_result_t
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fctx_getaddresses_nameservers(fetchctx_t *fctx, isc_stdtime_t now,
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unsigned int stdoptions,
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unsigned int fetches_allowed,
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bool *need_alternatep, bool *all_spilledp) {
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dns_rdata_ns_t ns;
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bool have_address = false;
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unsigned int ns_processed = 0;
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DNS_RDATASET_FOREACH(&fctx->nameservers) {
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isc_result_t result = ISC_R_SUCCESS;
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dns_rdata_t rdata = DNS_RDATA_INIT;
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bool overquota = false;
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unsigned int static_stub = 0;
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unsigned int no_fetch = 0;
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dns_rdataset_current(&fctx->nameservers, &rdata);
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/*
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* Extract the name from the NS record.
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*/
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result = dns_rdata_tostruct(&rdata, &ns, NULL);
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if (result != ISC_R_SUCCESS) {
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continue;
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}
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if (STATICSTUB(&fctx->nameservers) &&
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dns_name_equal(&ns.name, fctx->domain))
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{
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static_stub = DNS_ADBFIND_STATICSTUB;
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}
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/*
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* Make sure we only launch a limited number of
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* outgoing fetches.
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*/
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if (fctx->pending_running >= fetches_allowed) {
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no_fetch = DNS_ADBFIND_NOFETCH;
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}
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findname(fctx, &ns.name, 0, stdoptions | static_stub | no_fetch,
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0, now, &overquota, need_alternatep, &have_address);
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if (!overquota) {
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*all_spilledp = false;
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}
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dns_rdata_reset(&rdata);
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dns_rdata_freestruct(&ns);
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if (++ns_processed >= NS_PROCESSING_LIMIT) {
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break;
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}
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}
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if (fctx->pending_running == 0 && !have_address) {
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/*
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* We don't have any address and there are no
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* pending fetches running, indicate that we
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* need to continue looking.
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*/
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return DNS_R_CONTINUE;
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}
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return ISC_R_SUCCESS;
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}
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static void
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fctx_getaddresses_alternate(fetchctx_t *fctx, isc_stdtime_t now,
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unsigned int stdoptions) {
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dns_resolver_t *res = fctx->res;
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int family = (res->dispatches6 != NULL) ? AF_INET6 : AF_INET;
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ISC_LIST_FOREACH(res->alternates, a, link) {
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dns_adbaddrinfo_t *ai;
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isc_result_t result;
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if (!a->isaddress) {
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findname(fctx, &a->_u._n.name, a->_u._n.port,
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stdoptions, FCTX_ADDRINFO_DUALSTACK, now, NULL,
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NULL, NULL);
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continue;
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}
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if (isc_sockaddr_pf(&a->_u.addr) != family) {
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continue;
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}
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ai = NULL;
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result = dns_adb_findaddrinfo(fctx->adb, &a->_u.addr, &ai, 0);
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if (result != ISC_R_SUCCESS) {
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continue;
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}
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dns_adbaddrinfo_t *cur;
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ai->flags |= FCTX_ADDRINFO_FORWARDER;
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ai->flags |= FCTX_ADDRINFO_DUALSTACK;
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cur = ISC_LIST_HEAD(fctx->altaddrs);
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while (cur != NULL && cur->srtt < ai->srtt) {
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cur = ISC_LIST_NEXT(cur, publink);
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}
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if (cur != NULL) {
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ISC_LIST_INSERTBEFORE(fctx->altaddrs, cur, ai, publink);
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} else {
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ISC_LIST_APPEND(fctx->altaddrs, ai, publink);
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}
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}
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}
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static isc_result_t
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fctx_getaddresses(fetchctx_t *fctx) {
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isc_result_t result;
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dns_resolver_t *res;
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isc_stdtime_t now;
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unsigned int stdoptions = 0;
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bool all_bad;
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bool need_alternate = false;
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bool all_spilled = false;
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unsigned int fetches_allowed = 0;
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FCTXTRACE5("getaddresses", "fctx->depth=", fctx->depth);
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/*
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* If the forwarding policy is "only", we don't need the
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* addresses of the nameservers.
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* Don't pound on remote servers. (Failsafe!)
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*/
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if (fctx->fwdpolicy == dns_fwdpolicy_only) {
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goto out;
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fctx->restarts++;
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if (fctx->restarts > 100) {
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FCTXTRACE("too many restarts");
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return DNS_R_SERVFAIL;
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}
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res = fctx->res;
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if (fctx->depth > res->maxdepth) {
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isc_log_write(DNS_LOGCATEGORY_RESOLVER, DNS_LOGMODULE_RESOLVER,
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ISC_LOG_DEBUG(3),
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"too much NS indirection resolving '%s' "
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"(depth=%u, maxdepth=%u)",
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fctx->info, fctx->depth, res->maxdepth);
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return DNS_R_SERVFAIL;
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}
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/*
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* Forwarders.
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*/
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INSIST(ISC_LIST_EMPTY(fctx->forwaddrs));
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INSIST(ISC_LIST_EMPTY(fctx->altaddrs));
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/*
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* Skip forwarders only if DNS_FETCHOPT_NOFORWARD is not set or if the
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* forwarding policy doesn't allow us to not forward.
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*
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* This is currently used to make sure that priming query gets root
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* servers' IP addresses in ADDITIONAL section.
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*/
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if ((fctx->options & DNS_FETCHOPT_NOFORWARD) == 0 ||
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(fctx->fwdpolicy == dns_fwdpolicy_only))
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{
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result = fctx_getaddresses_forwarders(fctx);
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if (result != DNS_R_CONTINUE) {
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return result;
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}
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/*
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* If the forwarding policy is "only", we don't need the
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* addresses of the nameservers.
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*/
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if (fctx->fwdpolicy == dns_fwdpolicy_only) {
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goto out;
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}
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}
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/*
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* Normal nameservers.
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*/
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normal_nses:
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stdoptions = DNS_ADBFIND_WANTEVENT | DNS_ADBFIND_EMPTYEVENT;
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if (fctx->restarts == 1) {
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/*
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@ -3597,124 +3723,35 @@ normal_nses:
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INSIST(ISC_LIST_EMPTY(fctx->finds));
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INSIST(ISC_LIST_EMPTY(fctx->altfinds));
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switch (fctx->depth) {
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case 0:
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fetches_allowed = 3;
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break;
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case 1:
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fetches_allowed = 2;
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break;
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case 2:
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fetches_allowed = 1;
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break;
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default:
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fetches_allowed = 0;
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break;
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}
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for (;;) {
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DNS_RDATASET_FOREACH(&fctx->nameservers) {
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dns_rdata_t rdata = DNS_RDATA_INIT;
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bool overquota = false;
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unsigned int static_stub = 0;
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unsigned int no_fetch = 0;
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dns_rdataset_current(&fctx->nameservers, &rdata);
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/*
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* Extract the name from the NS record.
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*/
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result = dns_rdata_tostruct(&rdata, &ns, NULL);
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if (result != ISC_R_SUCCESS) {
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continue;
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}
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if (STATICSTUB(&fctx->nameservers) &&
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dns_name_equal(&ns.name, fctx->domain))
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{
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static_stub = DNS_ADBFIND_STATICSTUB;
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}
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/*
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* Make sure we only launch a limited number of
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* outgoing fetches.
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*/
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if (fctx->pending_running >= fetches_allowed) {
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no_fetch = DNS_ADBFIND_NOFETCH;
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}
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findname(fctx, &ns.name, 0,
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stdoptions | static_stub | no_fetch,
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0, now, &overquota, &need_alternate,
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&have_address);
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if (!overquota) {
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all_spilled = false;
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}
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dns_rdata_reset(&rdata);
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dns_rdata_freestruct(&ns);
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if (++ns_processed >= NS_PROCESSING_LIMIT) {
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break;
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}
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}
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/*
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* Don't start alternate fetch if we just started one above.
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*/
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if (fctx->pending_running > 0) {
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stdoptions |= DNS_ADBFIND_NOFETCH;
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break;
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} else if (have_address || fetches_allowed != 0) {
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break;
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}
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fetches_allowed = fctx_getaddresses_allowed(fctx);
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result = fctx_getaddresses_nameservers(fctx, now, stdoptions,
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fetches_allowed, &need_alternate,
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&all_spilled);
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if (result == DNS_R_CONTINUE && fetches_allowed == 0) {
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/*
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* We have no addresses and we haven't allowed any
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* fetches to be started. Allow one extra fetch and try
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* again.
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*/
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fetches_allowed = 1;
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(void)fctx_getaddresses_nameservers(fctx, now, stdoptions, 1,
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&need_alternate,
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&all_spilled);
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}
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/*
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* Don't start alternate fetch if we just started one above.
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*/
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if (fctx->pending_running > 0) {
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stdoptions |= DNS_ADBFIND_NOFETCH;
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}
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/*
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* Do we need to use 6 to 4?
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*/
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if (need_alternate) {
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int family;
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family = (res->dispatches6 != NULL) ? AF_INET6 : AF_INET;
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ISC_LIST_FOREACH(res->alternates, a, link) {
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if (!a->isaddress) {
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findname(fctx, &a->_u._n.name, a->_u._n.port,
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stdoptions, FCTX_ADDRINFO_DUALSTACK,
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now, NULL, NULL, NULL);
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continue;
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}
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if (isc_sockaddr_pf(&a->_u.addr) != family) {
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continue;
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}
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ai = NULL;
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result = dns_adb_findaddrinfo(fctx->adb, &a->_u.addr,
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&ai, 0);
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if (result == ISC_R_SUCCESS) {
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dns_adbaddrinfo_t *cur;
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ai->flags |= FCTX_ADDRINFO_FORWARDER;
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ai->flags |= FCTX_ADDRINFO_DUALSTACK;
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cur = ISC_LIST_HEAD(fctx->altaddrs);
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while (cur != NULL && cur->srtt < ai->srtt) {
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cur = ISC_LIST_NEXT(cur, publink);
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}
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if (cur != NULL) {
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ISC_LIST_INSERTBEFORE(fctx->altaddrs,
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cur, ai, publink);
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} else {
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ISC_LIST_APPEND(fctx->altaddrs, ai,
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publink);
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}
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}
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}
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fctx_getaddresses_alternate(fctx, now, stdoptions);
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}
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out:
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/*
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* Mark all known bad servers.
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@ -3724,55 +3761,54 @@ out:
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/*
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* How are we doing?
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*/
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if (all_bad) {
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/*
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* We've got no addresses.
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*/
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if (fctx->pending_running > 0) {
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/*
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* We're fetching the addresses, but don't have
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* any yet. Tell the caller to wait for an
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* answer.
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*/
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result = DNS_R_WAIT;
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} else {
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/*
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* We've lost completely. We don't know any
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* addresses, and the ADB has told us it can't
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* get them.
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*/
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FCTXTRACE("no addresses");
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result = ISC_R_FAILURE;
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/*
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* If all of the addresses found were over the
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* fetches-per-server quota, increase the ServerQuota
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* counter and return the configured response.
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*/
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if (all_spilled) {
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result = res->quotaresp[dns_quotatype_server];
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inc_stats(res, dns_resstatscounter_serverquota);
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}
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/*
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* If we are using a 'forward only' policy, and all
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* the forwarders are bad, increase the ForwardOnlyFail
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* counter.
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*/
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if (fctx->fwdpolicy == dns_fwdpolicy_only) {
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inc_stats(res,
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dns_resstatscounter_forwardonlyfail);
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}
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}
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} else {
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if (!all_bad) {
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/*
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* We've found some addresses. We might still be
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* looking for more addresses.
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*/
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sort_finds(&fctx->finds, res->view->v6bias);
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sort_finds(&fctx->altfinds, 0);
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||||
result = ISC_R_SUCCESS;
|
||||
return ISC_R_SUCCESS;
|
||||
}
|
||||
|
||||
/*
|
||||
* We've got no addresses.
|
||||
*/
|
||||
if (fctx->pending_running > 0) {
|
||||
/*
|
||||
* We're fetching the addresses, but don't have
|
||||
* any yet. Tell the caller to wait for an
|
||||
* answer.
|
||||
*/
|
||||
return DNS_R_WAIT;
|
||||
}
|
||||
|
||||
/*
|
||||
* We've lost completely. We don't know any
|
||||
* addresses, and the ADB has told us it can't
|
||||
* get them.
|
||||
*/
|
||||
FCTXTRACE("no addresses");
|
||||
|
||||
result = ISC_R_FAILURE;
|
||||
|
||||
/*
|
||||
* If all of the addresses found were over the
|
||||
* fetches-per-server quota, increase the ServerQuota
|
||||
* counter and return the configured response.
|
||||
*/
|
||||
if (all_spilled) {
|
||||
result = res->quotaresp[dns_quotatype_server];
|
||||
inc_stats(res, dns_resstatscounter_serverquota);
|
||||
}
|
||||
|
||||
/*
|
||||
* If we are using a 'forward only' policy, and all
|
||||
* the forwarders are bad, increase the ForwardOnlyFail
|
||||
* counter.
|
||||
*/
|
||||
if (fctx->fwdpolicy == dns_fwdpolicy_only) {
|
||||
inc_stats(res, dns_resstatscounter_forwardonlyfail);
|
||||
}
|
||||
|
||||
return result;
|
||||
|
|
|
|||
Loading…
Reference in a new issue