net: move CloseSocket() from netbase to util/sock

Move `CloseSocket()` (and `NetworkErrorString()` which it uses) from
`netbase.{h,cpp}` to newly added `src/util/sock.{h,cpp}`.

This is necessary in order to use `CloseSocket()` from a newly
introduced Sock class (which will live in `src/util/sock.{h,cpp}`).
`sock.{h,cpp}` cannot depend on netbase because netbase will depend
on it.

2 files changed, 82 insertions, 0 deletions

diff --git a/src/util/sock.cpp b/src/util/sock.cpp
new file mode 100644
index 0000000000..35eca4afb1
--- /dev/null
+++ b/src/util/sock.cpp
@@ -0,0 +1,64 @@
+// Copyright (c) 2020-2021 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <compat.h>
+#include <logging.h>
+#include <tinyformat.h>
+#include <util/sock.h>
+
+#include <codecvt>
+#include <cwchar>
+#include <locale>
+#include <string>
+
+#ifdef WIN32
+std::string NetworkErrorString(int err)
+{
+    wchar_t buf[256];
+    buf[0] = 0;
+    if(FormatMessageW(FORMAT_MESSAGE_FROM_SYSTEM | FORMAT_MESSAGE_IGNORE_INSERTS | FORMAT_MESSAGE_MAX_WIDTH_MASK,
+            nullptr, err, MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
+            buf, ARRAYSIZE(buf), nullptr))
+    {
+        return strprintf("%s (%d)", std::wstring_convert<std::codecvt_utf8_utf16<wchar_t>,wchar_t>().to_bytes(buf), err);
+    }
+    else
+    {
+        return strprintf("Unknown error (%d)", err);
+    }
+}
+#else
+std::string NetworkErrorString(int err)
+{
+    char buf[256];
+    buf[0] = 0;
+    /* Too bad there are two incompatible implementations of the
+     * thread-safe strerror. */
+    const char *s;
+#ifdef STRERROR_R_CHAR_P /* GNU variant can return a pointer outside the passed buffer */
+    s = strerror_r(err, buf, sizeof(buf));
+#else /* POSIX variant always returns message in buffer */
+    s = buf;
+    if (strerror_r(err, buf, sizeof(buf)))
+        buf[0] = 0;
+#endif
+    return strprintf("%s (%d)", s, err);
+}
+#endif
+
+bool CloseSocket(SOCKET& hSocket)
+{
+    if (hSocket == INVALID_SOCKET)
+        return false;
+#ifdef WIN32
+    int ret = closesocket(hSocket);
+#else
+    int ret = close(hSocket);
+#endif
+    if (ret) {
+        LogPrintf("Socket close failed: %d. Error: %s\n", hSocket, NetworkErrorString(WSAGetLastError()));
+    }
+    hSocket = INVALID_SOCKET;
+    return ret != SOCKET_ERROR;
+}
diff --git a/src/util/sock.h b/src/util/sock.h
new file mode 100644
index 0000000000..0d48235043
--- /dev/null
+++ b/src/util/sock.h
@@ -0,0 +1,18 @@
+// Copyright (c) 2020-2021 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_UTIL_SOCK_H
+#define BITCOIN_UTIL_SOCK_H
+
+#include <compat.h>
+
+#include <string>
+
+/** Return readable error string for a network error code */
+std::string NetworkErrorString(int err);
+
+/** Close socket and set hSocket to INVALID_SOCKET */
+bool CloseSocket(SOCKET& hSocket);
+
+#endif // BITCOIN_UTIL_SOCK_H