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Refactored DNS TXT resolver code

pull/271/head
SChernykh 2023-05-12 10:35:13 +02:00
parent 9aa748e628
commit 4fa344a0f7
3 changed files with 92 additions and 62 deletions
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77
src/p2p_server.cpp
View File

@ -31,15 +31,6 @@
#include <fstream>
#include <numeric>
#ifdef _WIN32
#include <WinDNS.h>
#elif defined(HAVE_RES_QUERY)
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#endif
static constexpr char log_category_prefix[] = "P2PServer ";
static constexpr char saved_peer_list_file_name[] = "p2pool_peers.txt";
static const char* seed_nodes[] = { "seeds.p2pool.io", ""};
@ -140,10 +131,6 @@ P2PServer::P2PServer(p2pool* pool)
PANIC_STOP();
}
#if !defined(_WIN32) && defined(HAVE_RES_QUERY)
res_init();
#endif
load_peer_list();
start_listening(params.m_p2pAddresses, params.m_upnp);
}
@ -499,55 +486,21 @@ void P2PServer::load_peer_list()
// Load peers from seed nodes if we're on the default or mini sidechain
auto load_from_seed_nodes = [&saved_list](const char** nodes, int p2p_port) {
for (size_t i = 0; nodes[i][0]; ++i) {
LOGINFO(4, "loading peers from " << nodes[i]);
const char* cur_node = nodes[i];
LOGINFO(4, "loading peers from " << cur_node);
// Prefer DNS TXT records
#ifdef _WIN32
PDNS_RECORD pQueryResults;
if (DnsQuery(nodes[i], DNS_TYPE_TEXT, DNS_QUERY_STANDARD, NULL, &pQueryResults, NULL) == 0) {
for (PDNS_RECORD p = pQueryResults; p; p = p->pNext) {
for (size_t j = 0; j < p->Data.TXT.dwStringCount; ++j) {
if (!saved_list.empty()) {
saved_list += ',';
}
LOGINFO(4, "added " << p->Data.TXT.pStringArray[j] << " from " << nodes[i]);
saved_list += p->Data.TXT.pStringArray[j];
}
const bool has_txt = get_dns_txt_records(cur_node, [&saved_list, cur_node](const char* s, size_t n) {
if (!saved_list.empty()) {
saved_list += ',';
}
DnsRecordListFree(pQueryResults, DnsFreeRecordList);
LOGINFO(4, "added " << log::const_buf(s, n) << " from " << cur_node);
saved_list.append(s, n);
});
if (has_txt) {
continue;
}
#elif defined(HAVE_RES_QUERY)
uint8_t answer[4096];
const int anslen = res_query(nodes[i], ns_c_in, ns_t_txt, answer, sizeof(answer));
if ((0 < anslen) && (anslen < static_cast<int>(sizeof(answer)))) {
ns_msg handle;
if (ns_initparse(answer, anslen, &handle) == 0) {
for (int rrnum = 0, n = ns_msg_count(handle, ns_s_an); rrnum < n; ++rrnum) {
ns_rr rr;
if ((ns_parserr(&handle, ns_s_an, rrnum, &rr) == 0) && (ns_rr_type(rr) == ns_t_txt)) {
const uint8_t* data = ns_rr_rdata(rr);
const int len = std::min<int>(ns_rr_rdlen(rr) - 1, *data);
if (len <= 0) {
continue;
}
++data;
if (!saved_list.empty()) {
saved_list += ',';
}
const char* c = reinterpret_cast<const char*>(data);
LOGINFO(4, "added " << log::const_buf(c, len) << " from " << nodes[i]);
saved_list.append(c, len);
}
}
continue;
}
}
#endif
addrinfo hints{};
hints.ai_family = AF_UNSPEC;
@ -555,11 +508,11 @@ void P2PServer::load_peer_list()
hints.ai_flags = AI_ADDRCONFIG;
addrinfo* result;
int err = getaddrinfo(nodes[i], nullptr, &hints, &result);
int err = getaddrinfo(cur_node, nullptr, &hints, &result);
if (err) {
LOGWARN(4, "getaddrinfo failed for " << nodes[i] << ": " << gai_strerror(err) << ", retrying with IPv4 only");
LOGWARN(4, "getaddrinfo failed for " << cur_node << ": " << gai_strerror(err) << ", retrying with IPv4 only");
hints.ai_family = AF_INET;
err = getaddrinfo(nodes[i], nullptr, &hints, &result);
err = getaddrinfo(cur_node, nullptr, &hints, &result);
}
if (err == 0) {
for (addrinfo* r = result; r != NULL; r = r->ai_next) {
@ -585,7 +538,7 @@ void P2PServer::load_peer_list()
}
if (s.m_pos) {
LOGINFO(4, "added " << static_cast<const char*>(buf) << " from " << nodes[i]);
LOGINFO(4, "added " << static_cast<const char*>(buf) << " from " << cur_node);
if (!saved_list.empty()) {
saved_list += ',';
}
@ -595,7 +548,7 @@ void P2PServer::load_peer_list()
freeaddrinfo(result);
}
else {
LOGWARN(3, "getaddrinfo failed for " << nodes[i] << ": " << gai_strerror(err));
LOGWARN(3, "getaddrinfo failed for " << cur_node << ": " << gai_strerror(err));
}
}
};

72
src/util.cpp
View File

@ -31,6 +31,15 @@
#include "upnpcommands.h"
#endif
#ifdef _WIN32
#include <WinDNS.h>
#elif defined(HAVE_RES_QUERY)
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <resolv.h>
#endif
static constexpr char log_category_prefix[] = "Util ";
namespace p2pool {
@ -462,6 +471,69 @@ bool resolve_host(std::string& host, bool& is_v6)
return true;
}
bool get_dns_txt_records_base(const std::string& host, Callback<void, const char*, size_t>::Base&& callback)
{
if (disable_resolve_host) {
LOGERR(1, "get_dns_txt_records was called with DNS disabled for host " << host);
return false;
}
#ifdef _WIN32
PDNS_RECORD pQueryResults;
if (DnsQuery(host.c_str(), DNS_TYPE_TEXT, DNS_QUERY_STANDARD, NULL, &pQueryResults, NULL) != 0) {
return false;
}
for (PDNS_RECORD p = pQueryResults; p; p = p->pNext) {
for (size_t j = 0; j < p->Data.TXT.dwStringCount; ++j) {
const char* s = p->Data.TXT.pStringArray[j];
const size_t n = strlen(s);
if (n > 0) {
callback(s, n);
}
}
}
DnsRecordListFree(pQueryResults, DnsFreeRecordList);
return true;
#elif defined(HAVE_RES_QUERY)
static const int res_init_result = res_init();
if (res_init_result != 0) {
return false;
}
uint8_t answer[4096];
const int anslen = res_query(host.c_str(), ns_c_in, ns_t_txt, answer, sizeof(answer));
if ((anslen <= 0) || (anslen > static_cast<int>(sizeof(answer)))) {
return false;
}
ns_msg handle;
if (ns_initparse(answer, anslen, &handle) != 0) {
return false;
}
for (int rrnum = 0, n = ns_msg_count(handle, ns_s_an); rrnum < n; ++rrnum) {
ns_rr rr;
if ((ns_parserr(&handle, ns_s_an, rrnum, &rr) == 0) && (ns_rr_type(rr) == ns_t_txt)) {
const uint8_t* s = ns_rr_rdata(rr);
const int n = std::min<int>(ns_rr_rdlen(rr) - 1, *s);
if (n > 0) {
callback(reinterpret_cast<const char*>(s + 1), static_cast<size_t>(n));
}
}
}
return true;
#else
(void)host;
(void)callback;
return false;
#endif
}
RandomDeviceSeed RandomDeviceSeed::instance;
struct BSR8

5
src/util.h
View File

@ -296,6 +296,11 @@ struct Callback
};
};
bool get_dns_txt_records_base(const std::string& host, Callback<void, const char*, size_t>::Base&& callback);
template<typename T>
FORCEINLINE bool get_dns_txt_records(const std::string& host, T&& callback) { return get_dns_txt_records_base(host, Callback<void, const char*, size_t>::Derived<T>(std::move(callback))); }
} // namespace p2pool
void memory_tracking_start();