--- src/security/Handshake.cc.orig	2020-06-07 15:42:16 UTC

+++ src/security/Handshake.cc

@@ -9,6 +9,7 @@

 /* DEBUG: section 83    SSL-Bump Server/Peer negotiation */

 #include "squid.h"

+#include "sbuf/Stream.h"

 #include "security/Handshake.h"

 #if USE_OPENSSL

 #include "ssl/support.h"

@@ -104,25 +105,52 @@ class Extension (public)

 typedef std::unordered_set<Extension::Type> Extensions;

 static Extensions SupportedExtensions();

-} // namespace Security

-

 /// parse TLS ProtocolVersion (uint16) and convert it to AnyP::ProtocolVersion

+/// \retval PROTO_NONE for unsupported values (in relaxed mode)

 static AnyP::ProtocolVersion

-ParseProtocolVersion(Parser::BinaryTokenizer &tk, const char *contextLabel = ".version")

+ParseProtocolVersionBase(Parser::BinaryTokenizer &tk, const char *contextLabel, const bool beStrict)

 {

     Parser::BinaryTokenizerContext context(tk, contextLabel);

     uint8_t vMajor = tk.uint8(".major");

     uint8_t vMinor = tk.uint8(".minor");

+

     if (vMajor == 0 && vMinor == 2)

         return AnyP::ProtocolVersion(AnyP::PROTO_SSL, 2, 0);

-    Must(vMajor == 3);

-    if (vMinor == 0)

-        return AnyP::ProtocolVersion(AnyP::PROTO_SSL, 3, 0);

+    if (vMajor == 3) {

+        if (vMinor == 0)

+            return AnyP::ProtocolVersion(AnyP::PROTO_SSL, 3, 0);

+        return AnyP::ProtocolVersion(AnyP::PROTO_TLS, 1, (vMinor - 1));

+    }

-    return AnyP::ProtocolVersion(AnyP::PROTO_TLS, 1, (vMinor - 1));

+    /* handle unsupported versions */

+

+    const uint16_t vRaw = (vMajor << 8) | vMinor;

+    debugs(83, 7, "unsupported: " << asHex(vRaw));

+    if (beStrict)

+        throw TextException(ToSBuf("unsupported TLS version: ", asHex(vRaw)), Here());

+    // else hide unsupported version details from the caller behind PROTO_NONE

+    return AnyP::ProtocolVersion();

 }

+/// parse a framing-related TLS ProtocolVersion

+/// \returns a supported SSL or TLS Anyp::ProtocolVersion, never PROTO_NONE

+static AnyP::ProtocolVersion

+ParseProtocolVersion(Parser::BinaryTokenizer &tk)

+{

+    return ParseProtocolVersionBase(tk, ".version", true);

+}

+

+/// parse a framing-unrelated TLS ProtocolVersion

+/// \retval PROTO_NONE for unsupported values

+static AnyP::ProtocolVersion

+ParseOptionalProtocolVersion(Parser::BinaryTokenizer &tk, const char *contextLabel)

+{

+    return ParseProtocolVersionBase(tk, contextLabel, false);

+}

+

+} // namespace Security

+

 Security::TLSPlaintext::TLSPlaintext(Parser::BinaryTokenizer &tk)

 {

     Parser::BinaryTokenizerContext context(tk, "TLSPlaintext");

@@ -431,6 +459,8 @@ Security::HandshakeParser::parseExtensions(const SBuf 

             break;

         case 16: { // Application-Layer Protocol Negotiation Extension, RFC 7301

             Parser::BinaryTokenizer tkAPN(extension.data);

+            // Store the entire protocol list, including unsupported-by-Squid

+            // values (if any). We have to use all when peeking at the server.

             details->tlsAppLayerProtoNeg = tkAPN.pstring16("APN");

             break;

         }

@@ -441,8 +471,9 @@ Security::HandshakeParser::parseExtensions(const SBuf 

         case 43: // supported_versions extension; RFC 8446

             parseSupportedVersionsExtension(extension.data);

             break;

-        case 13172: // Next Protocol Negotiation Extension (expired draft?)

         default:

+            // other extensions, including those that Squid does not support, do

+            // not require special handling here, but see unsupportedExtensions

             break;

         }

     }

@@ -455,7 +486,7 @@ Security::HandshakeParser::parseCiphers(const SBuf &ra

     Parser::BinaryTokenizer tk(raw);

     while (!tk.atEnd()) {

         const uint16_t cipher = tk.uint16("cipher");

-        details->ciphers.insert(cipher);

+        details->ciphers.insert(cipher); // including Squid-unsupported ones

     }

 }

@@ -473,7 +504,7 @@ Security::HandshakeParser::parseV23Ciphers(const SBuf 

         const uint8_t prefix = tk.uint8("prefix");

         const uint16_t cipher = tk.uint16("cipher");

         if (prefix == 0)

-            details->ciphers.insert(cipher);

+            details->ciphers.insert(cipher); // including Squid-unsupported ones

     }

 }

@@ -486,6 +517,7 @@ Security::HandshakeParser::parseServerHelloHandshakeMe

     details->tlsSupportedVersion = ParseProtocolVersion(tk);

     tk.skip(HelloRandomSize, ".random");

     details->sessionId = tk.pstring8(".session_id");

+    // cipherSuite may be unsupported by a peeking Squid

     details->ciphers.insert(tk.uint16(".cipher_suite"));

     details->compressionSupported = tk.uint8(".compression_method") != 0; // not null

     if (!tk.atEnd()) // extensions present

@@ -554,12 +586,15 @@ Security::HandshakeParser::parseSupportedVersionsExten

         Parser::BinaryTokenizer tkList(extensionData);

         Parser::BinaryTokenizer tkVersions(tkList.pstring8("SupportedVersions"));

         while (!tkVersions.atEnd()) {

-            const auto version = ParseProtocolVersion(tkVersions, "supported_version");

+            const auto version = ParseOptionalProtocolVersion(tkVersions, "supported_version");

+            // ignore values unsupported by Squid,represented by a falsy version

+            if (!version)

+                continue;

             if (!supportedVersionMax || TlsVersionEarlierThan(supportedVersionMax, version))

                 supportedVersionMax = version;

         }

-        // ignore empty supported_versions

+        // ignore empty and ignored-values-only supported_versions

         if (!supportedVersionMax)

             return;

@@ -569,7 +604,11 @@ Security::HandshakeParser::parseSupportedVersionsExten

     } else {

         assert(messageSource == fromServer);

         Parser::BinaryTokenizer tkVersion(extensionData);

-        const auto version = ParseProtocolVersion(tkVersion, "selected_version");

+        const auto version = ParseOptionalProtocolVersion(tkVersion, "selected_version");

+        // Ignore values unsupported by Squid. There should not be any until we

+        // start seeing TLS v2+, but they do not affect TLS framing anyway.

+        if (!version)

+            return;

         // RFC 8446 Section 4.2.1:

         // A server which negotiates a version of TLS prior to TLS 1.3 [...]

         // MUST NOT send the "supported_versions" extension.