fuzz: split FuzzedSock interface and implementation

Move the `FuzzedSock`'s implementation from `src/test/fuzz/util.h` to
`src/test/fuzz/util.cpp`.

A separate interface and implementation make the code more readable for
consumers who don't need to (better not) know the implementation
details.

1 files changed, 9 insertions, 163 deletions

diff --git a/src/test/fuzz/util.h b/src/test/fuzz/util.h
index a3feddc21d..8f4f87fbdc 100644
--- a/src/test/fuzz/util.h
+++ b/src/test/fuzz/util.h
@@ -575,179 +575,25 @@ class FuzzedSock : public Sock
     mutable std::optional<uint8_t> m_peek_data;
 
 public:
-    explicit FuzzedSock(FuzzedDataProvider& fuzzed_data_provider) : m_fuzzed_data_provider{fuzzed_data_provider}
-    {
-          m_socket = fuzzed_data_provider.ConsumeIntegralInRange<SOCKET>(INVALID_SOCKET - 1, INVALID_SOCKET);
-    }
+    explicit FuzzedSock(FuzzedDataProvider& fuzzed_data_provider);
 
-    ~FuzzedSock() override
-    {
-        // Sock::~Sock() will be called after FuzzedSock::~FuzzedSock() and it will call
-        // Sock::Reset() (not FuzzedSock::Reset()!) which will call CloseSocket(m_socket).
-        // Avoid closing an arbitrary file descriptor (m_socket is just a random very high number which
-        // theoretically may concide with a real opened file descriptor).
-        Reset();
-    }
+    ~FuzzedSock() override;
 
-    FuzzedSock& operator=(Sock&& other) override
-    {
-        assert(false && "Move of Sock into FuzzedSock not allowed.");
-        return *this;
-    }
+    FuzzedSock& operator=(Sock&& other) override;
 
-    void Reset() override
-    {
-        m_socket = INVALID_SOCKET;
-    }
+    void Reset() override;
 
-    ssize_t Send(const void* data, size_t len, int flags) const override
-    {
-        constexpr std::array send_errnos{
-            EACCES,
-            EAGAIN,
-            EALREADY,
-            EBADF,
-            ECONNRESET,
-            EDESTADDRREQ,
-            EFAULT,
-            EINTR,
-            EINVAL,
-            EISCONN,
-            EMSGSIZE,
-            ENOBUFS,
-            ENOMEM,
-            ENOTCONN,
-            ENOTSOCK,
-            EOPNOTSUPP,
-            EPIPE,
-            EWOULDBLOCK,
-        };
-        if (m_fuzzed_data_provider.ConsumeBool()) {
-            return len;
-        }
-        const ssize_t r = m_fuzzed_data_provider.ConsumeIntegralInRange<ssize_t>(-1, len);
-        if (r == -1) {
-            SetFuzzedErrNo(m_fuzzed_data_provider, send_errnos);
-        }
-        return r;
-    }
+    ssize_t Send(const void* data, size_t len, int flags) const override;
 
-    ssize_t Recv(void* buf, size_t len, int flags) const override
-    {
-        // Have a permanent error at recv_errnos[0] because when the fuzzed data is exhausted
-        // SetFuzzedErrNo() will always return the first element and we want to avoid Recv()
-        // returning -1 and setting errno to EAGAIN repeatedly.
-        constexpr std::array recv_errnos{
-            ECONNREFUSED,
-            EAGAIN,
-            EBADF,
-            EFAULT,
-            EINTR,
-            EINVAL,
-            ENOMEM,
-            ENOTCONN,
-            ENOTSOCK,
-            EWOULDBLOCK,
-        };
-        assert(buf != nullptr || len == 0);
-        if (len == 0 || m_fuzzed_data_provider.ConsumeBool()) {
-            const ssize_t r = m_fuzzed_data_provider.ConsumeBool() ? 0 : -1;
-            if (r == -1) {
-                SetFuzzedErrNo(m_fuzzed_data_provider, recv_errnos);
-            }
-            return r;
-        }
-        std::vector<uint8_t> random_bytes;
-        bool pad_to_len_bytes{m_fuzzed_data_provider.ConsumeBool()};
-        if (m_peek_data.has_value()) {
-            // `MSG_PEEK` was used in the preceding `Recv()` call, return `m_peek_data`.
-            random_bytes.assign({m_peek_data.value()});
-            if ((flags & MSG_PEEK) == 0) {
-                m_peek_data.reset();
-            }
-            pad_to_len_bytes = false;
-        } else if ((flags & MSG_PEEK) != 0) {
-            // New call with `MSG_PEEK`.
-            random_bytes = m_fuzzed_data_provider.ConsumeBytes<uint8_t>(1);
-            if (!random_bytes.empty()) {
-                m_peek_data = random_bytes[0];
-                pad_to_len_bytes = false;
-            }
-        } else {
-            random_bytes = m_fuzzed_data_provider.ConsumeBytes<uint8_t>(
-                m_fuzzed_data_provider.ConsumeIntegralInRange<size_t>(0, len));
-        }
-        if (random_bytes.empty()) {
-            const ssize_t r = m_fuzzed_data_provider.ConsumeBool() ? 0 : -1;
-            if (r == -1) {
-                SetFuzzedErrNo(m_fuzzed_data_provider, recv_errnos);
-            }
-            return r;
-        }
-        std::memcpy(buf, random_bytes.data(), random_bytes.size());
-        if (pad_to_len_bytes) {
-            if (len > random_bytes.size()) {
-                std::memset((char*)buf + random_bytes.size(), 0, len - random_bytes.size());
-            }
-            return len;
-        }
-        if (m_fuzzed_data_provider.ConsumeBool() && std::getenv("FUZZED_SOCKET_FAKE_LATENCY") != nullptr) {
-            std::this_thread::sleep_for(std::chrono::milliseconds{2});
-        }
-        return random_bytes.size();
-    }
+    ssize_t Recv(void* buf, size_t len, int flags) const override;
 
-    int Connect(const sockaddr*, socklen_t) const override
-    {
-        // Have a permanent error at connect_errnos[0] because when the fuzzed data is exhausted
-        // SetFuzzedErrNo() will always return the first element and we want to avoid Connect()
-        // returning -1 and setting errno to EAGAIN repeatedly.
-        constexpr std::array connect_errnos{
-            ECONNREFUSED,
-            EAGAIN,
-            ECONNRESET,
-            EHOSTUNREACH,
-            EINPROGRESS,
-            EINTR,
-            ENETUNREACH,
-            ETIMEDOUT,
-        };
-        if (m_fuzzed_data_provider.ConsumeBool()) {
-            SetFuzzedErrNo(m_fuzzed_data_provider, connect_errnos);
-            return -1;
-        }
-        return 0;
-    }
+    int Connect(const sockaddr*, socklen_t) const override;
 
-    int GetSockOpt(int level, int opt_name, void* opt_val, socklen_t* opt_len) const override
-    {
-        constexpr std::array getsockopt_errnos{
-            ENOMEM,
-            ENOBUFS,
-        };
-        if (m_fuzzed_data_provider.ConsumeBool()) {
-            SetFuzzedErrNo(m_fuzzed_data_provider, getsockopt_errnos);
-            return -1;
-        }
-        if (opt_val == nullptr) {
-            return 0;
-        }
-        std::memcpy(opt_val,
-                    ConsumeFixedLengthByteVector(m_fuzzed_data_provider, *opt_len).data(),
-                    *opt_len);
-        return 0;
-    }
+    int GetSockOpt(int level, int opt_name, void* opt_val, socklen_t* opt_len) const override;
 
     bool Wait(std::chrono::milliseconds timeout, Event requested, Event* occurred = nullptr) const override;
 
-    bool IsConnected(std::string& errmsg) const override
-    {
-        if (m_fuzzed_data_provider.ConsumeBool()) {
-            return true;
-        }
-        errmsg = "disconnected at random by the fuzzer";
-        return false;
-    }
+    bool IsConnected(std::string& errmsg) const override;
 };
 
 [[nodiscard]] inline FuzzedSock ConsumeSock(FuzzedDataProvider& fuzzed_data_provider)