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Added a hostname check if connecting via domain hostname (Not IPv4/IPv6 - IPv6 still not supported / tested).

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This commit is contained in:
DcruBro
2025-11-11 17:35:53 +01:00
parent eda3cf87d1
commit fbafeafc9f
3 changed files with 82 additions and 2 deletions
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1
include/columnlynx/client/net/tcp/tcp_client.hpp
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@@ -69,5 +69,6 @@ namespace ColumnLynx::Net::TCP {
std::chrono::steady_clock::time_point mLastHeartbeatReceived;
std::chrono::steady_clock::time_point mLastHeartbeatSent;
int mMissedHeartbeats = 0;
bool mIsHostDomain;
};
}

52
include/columnlynx/common/libsodium_wrapper.hpp
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@@ -14,6 +14,7 @@
#include <openssl/x509.h>
#include <openssl/x509_vfy.h>
#include <openssl/pem.h>
#include <openssl/x509v3.h>
namespace ColumnLynx {
using PublicKey = std::array<uint8_t, crypto_sign_PUBLICKEYBYTES>; // Ed25519
@@ -222,6 +223,57 @@ namespace ColumnLynx::Utils {
return result == 1;
}
static inline std::vector<std::string> getCertificateHostname(const std::vector<uint8_t>& cert_der) {
std::vector<std::string> names;
if (cert_der.empty())
return names;
// Parse DER certificate
const unsigned char* p = cert_der.data();
X509* cert = d2i_X509(nullptr, &p, cert_der.size());
if (!cert)
return names;
// --- Subject Alternative Names (SAN) ---
GENERAL_NAMES* san_names =
(GENERAL_NAMES*)X509_get_ext_d2i(cert, NID_subject_alt_name, nullptr, nullptr);
if (san_names) {
int san_count = sk_GENERAL_NAME_num(san_names);
for (int i = 0; i < san_count; i++) {
const GENERAL_NAME* current = sk_GENERAL_NAME_value(san_names, i);
if (current->type == GEN_DNS) {
const char* dns_name = (const char*)ASN1_STRING_get0_data(current->d.dNSName);
// Safety: ensure no embedded nulls
if (ASN1_STRING_length(current->d.dNSName) == (int)std::strlen(dns_name)) {
names.emplace_back(dns_name);
}
}
}
GENERAL_NAMES_free(san_names);
}
// --- Fallback: Common Name (CN) ---
if (names.empty()) {
X509_NAME* subject = X509_get_subject_name(cert);
if (subject) {
int idx = X509_NAME_get_index_by_NID(subject, NID_commonName, -1);
if (idx >= 0) {
X509_NAME_ENTRY* entry = X509_NAME_get_entry(subject, idx);
ASN1_STRING* cn_asn1 = X509_NAME_ENTRY_get_data(entry);
const char* cn_str = (const char*)ASN1_STRING_get0_data(cn_asn1);
if (ASN1_STRING_length(cn_asn1) == (int)std::strlen(cn_str)) {
names.emplace_back(cn_str);
}
}
}
}
X509_free(cert);
return names;
}
private:
std::array<uint8_t, crypto_sign_PUBLICKEYBYTES> mPublicKey;
std::array<uint8_t, crypto_sign_SECRETKEYBYTES> mPrivateKey;

31
src/client/net/tcp/tcp_client.cpp
View File

@@ -3,6 +3,7 @@
// Distributed under the terms of the GNU General Public License, either version 2 only or version 3. See LICENSES/ for details.
#include <columnlynx/client/net/tcp/tcp_client.hpp>
#include <arpa/inet.h>
namespace ColumnLynx::Net::TCP {
void TCPClient::start() {
@@ -24,6 +25,11 @@ namespace ColumnLynx::Net::TCP {
// Init connection handshake
Utils::log("Sending handshake init to server.");
// Check if hostname or IPv4/IPv6
sockaddr_in addr4{};
sockaddr_in6 addr6{};
self->mIsHostDomain = inet_pton(AF_INET, mHost.c_str(), (void*)(&addr4)) != 1 && inet_pton(AF_INET6, mHost.c_str(), (void*)(&addr6)) != 1;
std::vector<uint8_t> payload;
payload.reserve(1 + crypto_box_PUBLICKEYBYTES);
payload.push_back(Utils::protocolVersion());
@@ -136,7 +142,6 @@ namespace ColumnLynx::Net::TCP {
std::vector<uint8_t> serverPublicKeyVec(std::begin(mServerPublicKey), std::end(mServerPublicKey));
// Verify server public key
// TODO: Verify / Match hostname of public key to hostname of server
if (!Utils::LibSodiumWrapper::verifyCertificateWithSystemCAs(serverPublicKeyVec)) {
if (!(*mInsecureMode)) {
Utils::error("Server public key verification failed. Terminating connection.");
@@ -144,7 +149,29 @@ namespace ColumnLynx::Net::TCP {
return;
}
Utils::log("Warning: Server public key verification failed, but continuing due to insecure mode.");
Utils::warn("Warning: Server public key verification failed, but continuing due to insecure mode.");
}
// Extract and verify hostname from certificate if not IP
if (mIsHostDomain) {
std::vector<std::string> certHostnames = Utils::LibSodiumWrapper::getCertificateHostname(serverPublicKeyVec);
// Temp: print extracted hostnames if any
for (const auto& hostname : certHostnames) {
Utils::log("Extracted hostname from certificate: " + hostname);
}
if (certHostnames.empty() || std::find(certHostnames.begin(), certHostnames.end(), mHost) == certHostnames.end()) {
if (!(*mInsecureMode)) {
Utils::error("Server hostname verification failed. Terminating connection.");
disconnect();
return;
}
Utils::warn("Warning: Server hostname verification failed, but continuing due to insecure mode.");
}
} else {
Utils::warn("Connecting via IP address, I can't verify the server's identity! You might be getting MITM'd!");
}
// Generate and send challenge