From 3ad7de225efce3e76530f56bee8a8f7a75ea0f3c Mon Sep 17 00:00:00 2001
From: Vasil Dimov <vd@FreeBSD.org>
Date: Tue, 13 Apr 2021 16:31:04 +0200
Subject: [PATCH] net: add new method Sock::Bind() that wraps bind()

This will help to increase `Sock` usage and make more code mockable.
---
 src/net.cpp            |  3 +--
 src/test/fuzz/util.cpp | 20 ++++++++++++++++++++
 src/test/fuzz/util.h   |  2 ++
 src/test/util/net.h    |  2 ++
 src/util/sock.cpp      |  5 +++++
 src/util/sock.h        |  6 ++++++
 6 files changed, 36 insertions(+), 2 deletions(-)

diff --git a/src/net.cpp b/src/net.cpp
index bee8710062b..0bf0f58828b 100644
--- a/src/net.cpp
+++ b/src/net.cpp
@@ -2396,8 +2396,7 @@ bool CConnman::BindListenPort(const CService& addrBind, bilingual_str& strError,
 #endif
     }
 
-    if (::bind(sock->Get(), (struct sockaddr*)&sockaddr, len) == SOCKET_ERROR)
-    {
+    if (sock->Bind(reinterpret_cast<struct sockaddr*>(&sockaddr), len) == SOCKET_ERROR) {
         int nErr = WSAGetLastError();
         if (nErr == WSAEADDRINUSE)
             strError = strprintf(_("Unable to bind to %s on this computer. %s is probably already running."), addrBind.ToString(), PACKAGE_NAME);
diff --git a/src/test/fuzz/util.cpp b/src/test/fuzz/util.cpp
index 2514636d6ef..c5694b0b06d 100644
--- a/src/test/fuzz/util.cpp
+++ b/src/test/fuzz/util.cpp
@@ -160,6 +160,26 @@ int FuzzedSock::Connect(const sockaddr*, socklen_t) const
     return 0;
 }
 
+int FuzzedSock::Bind(const sockaddr*, socklen_t) const
+{
+    // Have a permanent error at bind_errnos[0] because when the fuzzed data is exhausted
+    // SetFuzzedErrNo() will always set the global errno to bind_errnos[0]. We want to
+    // avoid this method returning -1 and setting errno to a temporary error (like EAGAIN)
+    // repeatedly because proper code should retry on temporary errors, leading to an
+    // infinite loop.
+    constexpr std::array bind_errnos{
+        EACCES,
+        EADDRINUSE,
+        EADDRNOTAVAIL,
+        EAGAIN,
+    };
+    if (m_fuzzed_data_provider.ConsumeBool()) {
+        SetFuzzedErrNo(m_fuzzed_data_provider, bind_errnos);
+        return -1;
+    }
+    return 0;
+}
+
 std::unique_ptr<Sock> FuzzedSock::Accept(sockaddr* addr, socklen_t* addr_len) const
 {
     constexpr std::array accept_errnos{
diff --git a/src/test/fuzz/util.h b/src/test/fuzz/util.h
index 6c918446334..f0f9e506984 100644
--- a/src/test/fuzz/util.h
+++ b/src/test/fuzz/util.h
@@ -64,6 +64,8 @@ public:
 
     int Connect(const sockaddr*, socklen_t) const override;
 
+    int Bind(const sockaddr*, socklen_t) const override;
+
     std::unique_ptr<Sock> Accept(sockaddr* addr, socklen_t* addr_len) const override;
 
     int GetSockOpt(int level, int opt_name, void* opt_val, socklen_t* opt_len) const override;
diff --git a/src/test/util/net.h b/src/test/util/net.h
index 20c45058a1a..11202f0c389 100644
--- a/src/test/util/net.h
+++ b/src/test/util/net.h
@@ -127,6 +127,8 @@ public:
 
     int Connect(const sockaddr*, socklen_t) const override { return 0; }
 
+    int Bind(const sockaddr*, socklen_t) const override { return 0; }
+
     std::unique_ptr<Sock> Accept(sockaddr* addr, socklen_t* addr_len) const override
     {
         if (addr != nullptr) {
diff --git a/src/util/sock.cpp b/src/util/sock.cpp
index 2029d70a374..89d7a1a7ec4 100644
--- a/src/util/sock.cpp
+++ b/src/util/sock.cpp
@@ -74,6 +74,11 @@ int Sock::Connect(const sockaddr* addr, socklen_t addr_len) const
     return connect(m_socket, addr, addr_len);
 }
 
+int Sock::Bind(const sockaddr* addr, socklen_t addr_len) const
+{
+    return bind(m_socket, addr, addr_len);
+}
+
 std::unique_ptr<Sock> Sock::Accept(sockaddr* addr, socklen_t* addr_len) const
 {
 #ifdef WIN32
diff --git a/src/util/sock.h b/src/util/sock.h
index 75104828578..6a7840f4e22 100644
--- a/src/util/sock.h
+++ b/src/util/sock.h
@@ -97,6 +97,12 @@ public:
      */
     [[nodiscard]] virtual int Connect(const sockaddr* addr, socklen_t addr_len) const;
 
+    /**
+     * bind(2) wrapper. Equivalent to `bind(this->Get(), addr, addr_len)`. Code that uses this
+     * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
+     */
+    [[nodiscard]] virtual int Bind(const sockaddr* addr, socklen_t addr_len) const;
+
     /**
      * accept(2) wrapper. Equivalent to `std::make_unique<Sock>(accept(this->Get(), addr, addr_len))`.
      * Code that uses this wrapper can be unit tested if this method is overridden by a mock Sock