Merge #21630: fuzz: split FuzzedSock interface and implementation

549c82ad3a34a885ecca37a5f04c36dfbaa95d17 fuzz: use ConsumeBool() instead of !ConsumeBool() (Vasil Dimov)
29ae1c13a59187119f5b2a38b54dbbec936d8f87 fuzz: split FuzzedSock interface and implementation (Vasil Dimov)
9668e43d8e757c0185b900eb6ee6891a0ba41666 fuzz: make FuzzedSock::Wait() sometimes simulate an occurred event (Vasil Dimov)
0c90ff1429deaa556c0509c13cdd5aef5df9c0d4 fuzz: set errno from FuzzedSock::Wait() if it simulates a failure (Vasil Dimov)
5198a02de4e7a1b0efe28c6095745ce59f7f98c4 style: remove extra white space (Vasil Dimov)

Pull request description:

  * split FuzzedSock interface and implementation
  * make FuzzedSock::Wait() sometimes simulate an occurred event
  * set errno from FuzzedSock::Wait() if it simulates a failure

  (this is a followup from https://github.com/bitcoin/bitcoin/pull/21617)

ACKs for top commit:
  practicalswift:
    cr ACK 549c82ad3a34a885ecca37a5f04c36dfbaa95d17: patch looks correct and touches only `src/test/fuzz/`
  MarcoFalke:
    re-ACK 549c82ad3a34a885ecca37a5f04c36dfbaa95d17 only change is rebase 🎬

Tree-SHA512: 8ba965a8319074ad2ef840219c35c77e37cc79f00fb3926f20ccbf5f58e9616f5a3ac96434ad33996b47d292fa760d5d00a529001ac0d1d254262e5df93f616f

2 files changed, 193 insertions, 166 deletions

diff --git a/src/test/fuzz/util.cpp b/src/test/fuzz/util.cpp
index cf5244e314..b8d846a995 100644
--- a/src/test/fuzz/util.cpp
+++ b/src/test/fuzz/util.cpp
@@ -7,15 +7,196 @@
 #include <util/rbf.h>
 #include <version.h>
 
-bool FuzzedSock::Wait(std::chrono::milliseconds timeout, Event requested, Event* occurred ) const
+FuzzedSock::FuzzedSock(FuzzedDataProvider& fuzzed_data_provider)
+    : m_fuzzed_data_provider{fuzzed_data_provider}
 {
-    if (!m_fuzzed_data_provider.ConsumeBool()) {
+    m_socket = fuzzed_data_provider.ConsumeIntegralInRange<SOCKET>(INVALID_SOCKET - 1, INVALID_SOCKET);
+}
+
+FuzzedSock::~FuzzedSock()
+{
+    // 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& FuzzedSock::operator=(Sock&& other)
+{
+    assert(false && "Move of Sock into FuzzedSock not allowed.");
+    return *this;
+}
+
+void FuzzedSock::Reset()
+{
+    m_socket = INVALID_SOCKET;
+}
+
+ssize_t FuzzedSock::Send(const void* data, size_t len, int flags) const
+{
+    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 FuzzedSock::Recv(void* buf, size_t len, int flags) const
+{
+    // 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();
+}
+
+int FuzzedSock::Connect(const sockaddr*, socklen_t) const
+{
+    // 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 FuzzedSock::GetSockOpt(int level, int opt_name, void* opt_val, socklen_t* opt_len) const
+{
+    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;
+}
+
+bool FuzzedSock::Wait(std::chrono::milliseconds timeout, Event requested, Event* occurred) const
+{
+    constexpr std::array wait_errnos{
+        EBADF,
+        EINTR,
+        EINVAL,
+    };
+    if (m_fuzzed_data_provider.ConsumeBool()) {
+        SetFuzzedErrNo(m_fuzzed_data_provider, wait_errnos);
         return false;
     }
-    if (occurred) *occurred = 0;
+    if (occurred != nullptr) {
+        *occurred = m_fuzzed_data_provider.ConsumeBool() ? requested : 0;
+    }
     return true;
 }
 
+bool FuzzedSock::IsConnected(std::string& errmsg) const
+{
+    if (m_fuzzed_data_provider.ConsumeBool()) {
+        return true;
+    }
+    errmsg = "disconnected at random by the fuzzer";
+    return false;
+}
+
 void FillNode(FuzzedDataProvider& fuzzed_data_provider, CNode& node, bool init_version) noexcept
 {
     const ServiceFlags remote_services = ConsumeWeakEnum(fuzzed_data_provider, ALL_SERVICE_FLAGS);
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)