host_key_verifier.hpp

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// SPDX-License-Identifier: LGPL-2.1-or-later
#pragma once
 
#include <sshpp/config.hpp>
 
#include <sshpp/export.hpp>
#include <sshpp/fwd.hpp>
#include <sshpp/key.hpp>
#include <sshpp/known_hosts.hpp>
 
#include <cstdint>
#include <functional>
#include <string>
#include <string_view>
#include <vector>
 
namespace sshpp {
 
struct InsecureOptIn { explicit InsecureOptIn() = default; };
inline InsecureOptIn i_understand_this_is_insecure() { return InsecureOptIn{}; }
 
class SSHPP_API HostKeyVerifier {
public:
    struct Context {
        std::string_view host;
        std::uint16_t    port;
        KnownHostsStatus status;
        const Key&       presented_key;
        Fingerprint      sha256;
        Session&         session;
    };
    enum class Decision { accept, accept_and_remember, reject };
 
    virtual ~HostKeyVerifier() = default;
    virtual Decision verify(const Context&) const = 0;
};
 
class SSHPP_API StrictHostKeyPolicy final : public HostKeyVerifier {
public:
    Decision verify(const Context&) const override;
};
 
class SSHPP_API TofuHostKeyPolicy final : public HostKeyVerifier {
public:
    Decision verify(const Context&) const override;
};
 
class SSHPP_API AcceptAnyHostKeyPolicy final : public HostKeyVerifier {
public:
    explicit AcceptAnyHostKeyPolicy(InsecureOptIn) {}
    Decision verify(const Context&) const override;
};
 
class SSHPP_API PinnedHostKeyPolicy final : public HostKeyVerifier {
public:
    explicit PinnedHostKeyPolicy(std::vector<Fingerprint> fps) : pins_(std::move(fps)) {}
    Decision verify(const Context&) const override;
 
private:
    std::vector<Fingerprint> pins_;
};
 
class SSHPP_API CallbackHostKeyPolicy final : public HostKeyVerifier {
public:
    explicit CallbackHostKeyPolicy(std::function<Decision(const Context&)> cb) : cb_(std::move(cb)) {}
    Decision verify(const Context& ctx) const override { return cb_(ctx); }
 
private:
    std::function<Decision(const Context&)> cb_;
};
 
} // namespace sshpp
 
#if SSHPP_HEADER_ONLY
#include <sshpp/detail/host_key_verifier.ipp>
#endif