From 9d3ffa096ad1c618461953241cdf1c99624fa6a1 Mon Sep 17 00:00:00 2001
From: AnotherTest <ali.mpfard@gmail.com>
Date: Sun, 2 Aug 2020 05:26:21 +0430
Subject: [PATCH] LibTLS: Add (basic) support for sending client certificates

---
 Libraries/LibTLS/ClientHandshake.cpp |  8 +++--
 Libraries/LibTLS/Exchange.cpp        | 53 ++++++++++++++++++++++++++--
 2 files changed, 57 insertions(+), 4 deletions(-)

diff --git a/Libraries/LibTLS/ClientHandshake.cpp b/Libraries/LibTLS/ClientHandshake.cpp
index 28d27215dc..52389f0e0f 100644
--- a/Libraries/LibTLS/ClientHandshake.cpp
+++ b/Libraries/LibTLS/ClientHandshake.cpp
@@ -439,7 +439,9 @@ ssize_t TLSv12::handle_payload(const ByteBuffer& vbuffer)
             } else {
                 // we do not support "certificate request"
                 dbg() << "certificate request";
-                ASSERT_NOT_REACHED();
+                if (on_tls_certificate_request)
+                    on_tls_certificate_request(*this);
+                m_context.client_verified = VerificationNeeded;
             }
             break;
         case ServerHelloDone:
@@ -590,8 +592,10 @@ ssize_t TLSv12::handle_payload(const ByteBuffer& vbuffer)
             // nothing to write
             break;
         case WritePacketStage::ClientHandshake:
-            // Note: currently not used
             if (m_context.client_verified == VerificationNeeded) {
+#ifdef TLS_DEBUG
+                dbg() << "> Client Certificate";
+#endif
                 auto packet = build_certificate();
                 write_packet(packet);
                 m_context.client_verified = Verified;
diff --git a/Libraries/LibTLS/Exchange.cpp b/Libraries/LibTLS/Exchange.cpp
index aeaa9c1cc4..9350977131 100644
--- a/Libraries/LibTLS/Exchange.cpp
+++ b/Libraries/LibTLS/Exchange.cpp
@@ -166,8 +166,57 @@ bool TLSv12::compute_master_secret(size_t length)
 
 ByteBuffer TLSv12::build_certificate()
 {
-    dbg() << "FIXME: build_certificate";
-    return {};
+    PacketBuilder builder { MessageType::Handshake, m_context.version };
+
+    Vector<const Certificate*> certificates;
+    Vector<Certificate>* local_certificates = nullptr;
+
+    if (m_context.is_server) {
+        dbg() << "Unsupported: Server mode";
+        ASSERT_NOT_REACHED();
+    } else {
+        local_certificates = &m_context.client_certificates;
+    }
+
+    constexpr size_t der_length_delta = 3;
+    constexpr size_t certificate_vector_header_size = 3;
+
+    size_t total_certificate_size = 0;
+
+    for (size_t i = 0; i < local_certificates->size(); ++i) {
+        auto& certificate = local_certificates->at(i);
+        if (!certificate.der.is_empty()) {
+            total_certificate_size += certificate.der.size() + der_length_delta;
+
+            // FIXME: Check for and respond with only the requested certificate types.
+            if (true) {
+                certificates.append(&certificate);
+            }
+        }
+    }
+
+    builder.append((u8)HandshakeType::CertificateMessage);
+
+    if (!total_certificate_size) {
+#ifdef TLS_DEBUG
+        dbg() << "No certificates, sending empty certificate message";
+#endif
+        builder.append_u24(certificate_vector_header_size);
+        builder.append_u24(total_certificate_size);
+    } else {
+        builder.append_u24(total_certificate_size + certificate_vector_header_size); // 3 bytes for header
+        builder.append_u24(total_certificate_size);
+
+        for (auto& certificate : certificates) {
+            if (!certificate->der.is_empty()) {
+                builder.append_u24(certificate->der.size());
+                builder.append(certificate->der);
+            }
+        }
+    }
+    auto packet = builder.build();
+    update_packet(packet);
+    return packet;
 }
 
 ByteBuffer TLSv12::build_change_cipher_spec()