Backending infrastructure

2 files changed, 198 insertions, 0 deletions

diff --git a/poppler/CryptoSignBackend.cc b/poppler/CryptoSignBackend.cc
new file mode 100644
index 00000000..86703470
--- /dev/null
+++ b/poppler/CryptoSignBackend.cc
@@ -0,0 +1,97 @@
+//========================================================================
+//
+// CryptoSignBackend.cc
+//
+// This file is licensed under the GPLv2 or later
+//
+// Copyright 2023 g10 Code GmbH, Author: Sune Stolborg Vuorela <sune@vuorela.dk>
+//========================================================================
+#include "CryptoSignBackend.h"
+#include "config.h"
+#ifdef ENABLE_NSS3
+#    include "SignatureHandler.h"
+#endif
+
+namespace CryptoSign {
+
+void Factory::setPreferredBackend(CryptoSign::Backend::Type backend)
+{
+    preferredBackend = backend;
+}
+static std::string_view toStringView(const char *str)
+{
+    if (str) {
+        return std::string_view(str);
+    }
+    return {};
+}
+
+std::optional<CryptoSign::Backend::Type> Factory::typeFromString(std::string_view string)
+{
+    if (string.empty()) {
+        return std::nullopt;
+    }
+    if ("NSS" == string) {
+        return Backend::Type::NSS3;
+    }
+    return std::nullopt;
+}
+
+CryptoSign::Backend::Type Factory::getActive()
+{
+    if (preferredBackend) {
+        return *preferredBackend;
+    }
+    static auto backendFromEnvironment = typeFromString(toStringView(getenv("POPPLER_SIGNATURE_BACKEND")));
+    if (backendFromEnvironment) {
+        return *backendFromEnvironment;
+    }
+    static auto backendFromCompiledDefault = typeFromString(toStringView(DEFAULT_SIGNATURE_BACKEND));
+    if (backendFromCompiledDefault) {
+        return *backendFromCompiledDefault;
+    }
+
+    return Backend::Type::None;
+}
+static std::vector<Backend::Type> createAvailableBackends()
+{
+    std::vector<Backend::Type> backends;
+#ifdef ENABLE_NSS3
+    backends.push_back(Backend::Type::NSS3);
+#endif
+    return backends;
+}
+std::vector<Backend::Type> Factory::getAvailable()
+{
+    static std::vector<Backend::Type> availableBackends = createAvailableBackends();
+    return availableBackends;
+}
+std::unique_ptr<Backend> Factory::createActive()
+{
+    return create(getActive());
+}
+std::unique_ptr<CryptoSign::Backend> CryptoSign::Factory::create(Backend::Type backend)
+{
+    switch (backend) {
+    case Backend::Type::NSS3:
+#ifdef ENABLE_NSS3
+        return std::make_unique<NSSCryptoSignBackend>();
+#else
+        return nullptr;
+#endif
+    case Backend::Type::None: {
+        return nullptr;
+    }
+    }
+    return nullptr;
+}
+/// backend specific settings
+
+// Android build wants some methods out of line in the interfaces
+Backend::~Backend() = default;
+SigningInterface::~SigningInterface() = default;
+VerificationInterface::~VerificationInterface() = default;
+
+std::optional<Backend::Type> Factory::preferredBackend = std::nullopt;
+
+} // namespace Signature;
diff --git a/poppler/CryptoSignBackend.h b/poppler/CryptoSignBackend.h
new file mode 100644
index 00000000..b106ec47
--- /dev/null
+++ b/poppler/CryptoSignBackend.h
@@ -0,0 +1,101 @@
+//========================================================================
+//
+// CryptoSignBackend.h
+//
+// This file is licensed under the GPLv2 or later
+//
+// Copyright 2023 g10 Code GmbH, Author: Sune Stolborg Vuorela <sune@vuorela.dk>
+//========================================================================
+
+#ifndef SIGNATUREBACKEND_H
+#define SIGNATUREBACKEND_H
+
+#include <vector>
+#include <memory>
+#include <chrono>
+#include <optional>
+#include "HashAlgorithm.h"
+#include "CertificateInfo.h"
+#include "SignatureInfo.h"
+#include "goo/GooString.h"
+#include "poppler_private_export.h"
+
+namespace CryptoSign {
+
+// experiments seems to say that this is a bit above
+// what we have seen in the wild, and much larger than
+// what we have managed to get nss and gpgme to create.
+static const int maxSupportedSignatureSize = 10000;
+
+// Classes to help manage signature backends
+
+class VerificationInterface
+{
+public:
+    virtual void addData(unsigned char *data_block, int data_len) = 0;
+    virtual SignatureValidationStatus validateSignature() = 0;
+    virtual std::chrono::system_clock::time_point getSigningTime() const = 0;
+    virtual std::string getSignerName() const = 0;
+    virtual std::string getSignerSubjectDN() const = 0;
+    virtual HashAlgorithm getHashAlgorithm() const = 0;
+    virtual CertificateValidationStatus validateCertificate(std::chrono::system_clock::time_point validation_time, bool ocspRevocationCheck, bool useAIACertFetch) = 0;
+    virtual std::unique_ptr<X509CertificateInfo> getCertificateInfo() const = 0;
+    virtual ~VerificationInterface();
+    VerificationInterface() = default;
+    VerificationInterface(const VerificationInterface &other) = delete;
+    VerificationInterface &operator=(const VerificationInterface &other) = delete;
+};
+
+class SigningInterface
+{
+public:
+    virtual void addData(unsigned char *data_block, int data_len) = 0;
+    virtual std::unique_ptr<X509CertificateInfo> getCertificateInfo() const = 0;
+    virtual std::optional<GooString> signDetached(const std::string &password) = 0;
+    virtual ~SigningInterface();
+    SigningInterface() = default;
+    SigningInterface(const SigningInterface &other) = delete;
+    SigningInterface &operator=(const SigningInterface &other) = delete;
+};
+
+class Backend
+{
+public:
+    enum class Type
+    {
+        None,
+        NSS3
+    };
+    virtual std::unique_ptr<VerificationInterface> createVerificationHandler(std::vector<unsigned char> &&pkcs7) = 0;
+    virtual std::unique_ptr<SigningInterface> createSigningHandler(const std::string &certID, HashAlgorithm digestAlgTag) = 0;
+    virtual std::vector<std::unique_ptr<X509CertificateInfo>> getAvailableSigningCertificates() = 0;
+    virtual ~Backend();
+    Backend() = default;
+    Backend(const Backend &other) = delete;
+    Backend &operator=(const Backend &other) = delete;
+};
+
+class POPPLER_PRIVATE_EXPORT Factory
+{
+public:
+    // Sets the user preferred backend
+    static void setPreferredBackend(Backend::Type backend);
+    // Gets the current active backend
+    // prioritized from 1) setPreferredBackend,
+    //                  2) POPPLER_SIGNATURE_BACKEND
+    //                  3) Compiled in default
+    static Backend::Type getActive();
+    static std::vector<Backend::Type> getAvailable();
+    static std::unique_ptr<Backend> createActive();
+    static std::unique_ptr<Backend> create(Backend::Type);
+    static std::optional<Backend::Type> typeFromString(std::string_view string);
+    Factory() = delete;
+    /// backend specific settings
+
+private:
+    static std::optional<Backend::Type> preferredBackend;
+};
+
+}
+
+#endif // SIGNATUREBACKEND_H