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https://github.com/nmap/nmap.git
synced 2026-10-22 03:41:32 +00:00
Let late replies count for DNS, but don't clobber results
Enforce invariants and use asserts to be sure requests aren't left unfinished or double-freed.
This commit is contained in:
dmiller
parent
ed8abf52f4
commit
cd74c02e2f
1 changed files with 88 additions and 56 deletions
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@ -119,6 +119,7 @@
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#include <fstream>
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#include <algorithm>
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#include <map>
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#include <set>
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#include "massdns.h"
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#include "netutil.h"
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#include <limits.h>
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@ -228,9 +229,9 @@ struct dns_server {
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struct request {
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enum status_t {
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READY,
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WRITE_PENDING,
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DONE
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READY, // May be sent again
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NORESULT, // Do not re-send. Okay to process matching answers.
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DONE // Do not re-send.
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};
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DNS::ResolverImpl *impl;
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DNS::Request *targ;
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@ -402,6 +403,9 @@ public:
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ResolverImpl::etchosts_init();
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init_host_cache();
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}
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~ResolverImpl(void) {
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reset();
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}
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/* Forward lookup table from /etc/hosts */
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typedef std::pair<std::string, RECORD_TYPE> NameRecord;
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static std::map<NameRecord, sockaddr_storage> etchosts;
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@ -413,8 +417,17 @@ public:
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stat.reset();
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stat.servers = servs.size();
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init_host_cache();
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new_reqs.clear();
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deferred_reqs.clear();
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while (!new_reqs.empty()) {
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request *req = new_reqs.front();
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new_reqs.pop_front();
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mark_as_done(req, false);
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}
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while (!deferred_reqs.empty()) {
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request *req = new_reqs.front();
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new_reqs.pop_front();
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mark_as_done(req, false);
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}
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clear_done();
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total_reqs = 0;
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}
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void add_dns_server(const std::string &hostname);
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@ -450,6 +463,7 @@ private:
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std::list<dns_server> servs;
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std::list<request *> new_reqs;
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std::list<request *> deferred_reqs;
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std::set<request *> done;
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int total_reqs;
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nsock_pool dnspool;
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nsock_proxychain proxy_chain;
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@ -474,6 +488,8 @@ private:
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void process_request(int action, request *tpreq, dns_server *server);
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bool process_result(const std::string &name, const Record *rr, request *tpreq);
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bool system_resolve(DNS::Request &reqt);
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void mark_as_done(request *req, bool has_answer);
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void clear_done(void);
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void output_summary(const Stats &stat);
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void handle_read(nsock_pool nsp, nsock_event evt, dns_server *srv);
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@ -758,24 +774,26 @@ bool DNS::ResolverImpl::resolve_nsock()
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std::list<request *>::iterator reqI;
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for(reqI = deferred_reqs.begin(); reqI != deferred_reqs.end(); reqI++) {
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status_cb(&stat);
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output_summary(stat);
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request *tpreq = *reqI;
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if (system_resolve(*tpreq->targ)) {
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stat.ok++;
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}
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else {
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stat.nx++;
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if (tpreq->status != request::DONE) {
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status_cb(&stat);
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output_summary(stat);
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if (system_resolve(*tpreq->targ)) {
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stat.ok++;
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}
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else {
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stat.nx++;
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}
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}
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delete tpreq;
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mark_as_done(tpreq, true);
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}
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output_summary(stat);
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}
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deferred_reqs.clear();
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clear_done();
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return true;
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}
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@ -786,12 +804,11 @@ bool DNS::ResolverImpl::resolve_system()
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while (total_reqs > 0) {
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request *tpreq = new_reqs.front();
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new_reqs.pop_front();
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total_reqs--;
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// System resolver can handle DNS::ANY as AF_UNSPEC, so no need for
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// alt_req's AAAA request.
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if (tpreq->alt_req) {
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delete tpreq;
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mark_as_done(tpreq, true);
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stat.actual--;
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continue;
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}
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@ -805,9 +822,10 @@ bool DNS::ResolverImpl::resolve_system()
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else {
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stat.nx++;
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}
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delete tpreq;
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mark_as_done(tpreq, true);
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}
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assert(new_reqs.empty());
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clear_done();
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return true;
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}
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@ -840,8 +858,18 @@ void DNS::ResolverImpl::close_dns_servers() {
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if (serverI->status != dns_server::DISCONNECTED) {
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nsock_iod_delete(serverI->nsd, NSOCK_PENDING_SILENT);
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serverI->status = dns_server::DISCONNECTED;
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serverI->to_process.clear();
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serverI->in_process.clear();
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while (!serverI->to_process.empty()) {
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request *req = serverI->to_process.front();
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serverI->to_process.pop_front();
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assert(req->status != request::READY);
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mark_as_done(req, false);
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}
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while (!serverI->in_process.empty()) {
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request *req = serverI->in_process.front();
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serverI->in_process.pop_front();
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assert(req->status != request::READY);
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mark_as_done(req, false);
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}
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serverI->records.clear();
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}
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}
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@ -855,18 +883,20 @@ bool DNS::ResolverImpl::server_send(dns_server &serv) {
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}
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request *tpreq = NULL;
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if (!new_reqs.empty()) {
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tpreq = new_reqs.front();
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assert(tpreq != NULL);
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assert(tpreq->targ != NULL);
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tpreq->first_server = &serv;
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new_reqs.pop_front();
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} else if (!serv.to_process.empty()) {
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tpreq = serv.to_process.front();
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serv.to_process.pop_front();
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} else {
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return false;
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}
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do {
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if (!new_reqs.empty()) {
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tpreq = new_reqs.front();
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assert(tpreq != NULL);
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assert(tpreq->targ != NULL);
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tpreq->first_server = &serv;
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new_reqs.pop_front();
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} else if (!serv.to_process.empty()) {
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tpreq = serv.to_process.front();
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serv.to_process.pop_front();
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} else {
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return false;
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}
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} while (tpreq->status != request::READY);
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assert(tpreq != NULL);
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assert(tpreq->targ != NULL);
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@ -922,14 +952,6 @@ void DNS::ResolverImpl::handle_write(nsock_pool nsp, nsock_event evt, request *r
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server->in_process.remove(req);
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server->to_process.push_front(req);
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}
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if (req->status == request::DONE) {
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delete req;
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}
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else {
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assert(req->status == request::WRITE_PENDING);
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req->status = request::READY;
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}
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}
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static DNS::RECORD_TYPE wire_type(DNS::RECORD_TYPE t) {
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@ -969,7 +991,6 @@ void DNS::ResolverImpl::put_dns_packet_on_wire(request *req, dns_server *srv) {
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srv->in_process.push_front(req);
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srv->records[req->id] = req;
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req->status = request::WRITE_PENDING;
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nsock_write(dnspool, srv->nsd, &DNS::ResolverImpl::write_evt_handler, WRITE_TIMEOUT, req,
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reinterpret_cast<const char *>(packet), plen);
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}
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@ -1050,14 +1071,7 @@ int DNS::ResolverImpl::deal_with_timedout_reads(bool adjust_timing) {
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output_summary(stat);
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stat.dropped++;
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total_reqs--;
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servI->records.erase(tpreq->id);
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if (tpreq->status != request::WRITE_PENDING) {
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delete tpreq;
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}
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else {
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tpreq->status = request::DONE;
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}
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mark_as_done(tpreq, false);
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tpreq = NULL;
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// **** OR We start at the back of this server's queue
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@ -1104,8 +1118,8 @@ void DNS::ResolverImpl::process_request(int action, request *tpreq, dns_server *
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server->records.erase(tpreq->id);
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server->in_process.remove(tpreq);
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server->to_process.remove(tpreq);
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mark_as_done(tpreq, action == ACTION_FINISHED);
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server->reqs_on_wire--;
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total_reqs--;
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if (action == ACTION_SYSTEM_RESOLVE) {
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// System resolver can handle DNS::ANY as AF_UNSPEC, so no need for
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// alt_req's AAAA request.
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@ -1116,12 +1130,6 @@ void DNS::ResolverImpl::process_request(int action, request *tpreq, dns_server *
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}
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stat.actual--;
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}
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if (tpreq->status != request::WRITE_PENDING) {
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delete tpreq;
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}
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else {
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tpreq->status = request::DONE;
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}
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tpreq = NULL;
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break;
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@ -1232,6 +1240,10 @@ void DNS::ResolverImpl::handle_read(nsock_pool nsp, nsock_event evt, dns_server
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}
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request *tpreq = infoI->second;
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assert(p.id == tpreq->id);
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// If a different response completed the request, don't continue
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if (tpreq->status == request::DONE) {
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return;
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}
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DNS::Request *reqt = tpreq->targ;
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assert(reqt != NULL);
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// Response must contain a matching query. p.queries.empty() was already checked.
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@ -1659,6 +1671,26 @@ bool DNS::ResolverImpl::system_resolve(DNS::Request &reqt)
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return true;
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}
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void DNS::ResolverImpl::mark_as_done(request *req, bool has_answer)
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{
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if (req->status == request::READY) {
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total_reqs--;
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}
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req->status = (has_answer ? request::DONE : request::NORESULT);
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done.insert(req);
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}
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void DNS::ResolverImpl::clear_done(void)
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{
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for (std::set<request *>::iterator it = done.begin();
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it != done.end(); ++it) {
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request *req = *it;
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assert(req->status != request::READY);
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delete req;
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}
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done.clear();
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}
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static const char hex[] = "0123456789abcdef";
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bool DNS::Factory::ipToPtr(const sockaddr_storage &ip, std::string &ptr)
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{
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