net: add new method Sock::GetSockName() that wraps getsockname()

This will help to increase `Sock` usage and make more code mockable.

Author: vasild

src/test/fuzz/util.cpp

@@ -206,6 +206,20 @@ int FuzzedSock::SetSockOpt(int, int, const void*, socklen_t) const
     return 0;
 }
 
+int FuzzedSock::GetSockName(sockaddr* name, socklen_t* name_len) const
+{
+    constexpr std::array getsockname_errnos{
+        ECONNRESET,
+        ENOBUFS,
+    };
+    if (m_fuzzed_data_provider.ConsumeBool()) {
+        SetFuzzedErrNo(m_fuzzed_data_provider, getsockname_errnos);
+        return -1;
+    }
+    *name_len = m_fuzzed_data_provider.ConsumeData(name, *name_len);
+    return 0;
+}
+
 bool FuzzedSock::Wait(std::chrono::milliseconds timeout, Event requested, Event* occurred) const
 {
     constexpr std::array wait_errnos{

src/test/fuzz/util.h

@@ -69,6 +69,8 @@ class FuzzedSock : public Sock
 
     int SetSockOpt(int level, int opt_name, const void* opt_val, socklen_t opt_len) const override;
 
+    int GetSockName(sockaddr* name, socklen_t* name_len) const override;
+
     bool Wait(std::chrono::milliseconds timeout, Event requested, Event* occurred = nullptr) const override;
 
     bool WaitMany(std::chrono::milliseconds timeout, EventsPerSock& events_per_sock) const override;

src/test/util/net.h

@@ -152,6 +152,12 @@ class StaticContentsSock : public Sock
 
     int SetSockOpt(int, int, const void*, socklen_t) const override { return 0; }
 
+    int GetSockName(sockaddr* name, socklen_t* name_len) const override
+    {
+        std::memset(name, 0x0, *name_len);
+        return 0;
+    }
+
     bool Wait(std::chrono::milliseconds timeout,
               Event requested,
               Event* occurred = nullptr) const override

src/util/sock.cpp

@@ -111,6 +111,11 @@ int Sock::SetSockOpt(int level, int opt_name, const void* opt_val, socklen_t opt
     return setsockopt(m_socket, level, opt_name, static_cast<const char*>(opt_val), opt_len);
 }
 
+int Sock::GetSockName(sockaddr* name, socklen_t* name_len) const
+{
+    return getsockname(m_socket, name, name_len);
+}
+
 bool Sock::Wait(std::chrono::milliseconds timeout, Event requested, Event* occurred) const
 {
     // We need a `shared_ptr` owning `this` for `WaitMany()`, but don't want

src/util/sock.h

@@ -126,6 +126,13 @@ class Sock
                                          const void* opt_val,
                                          socklen_t opt_len) const;
 
+    /**
+     * getsockname(2) wrapper. Equivalent to
+     * `getsockname(this->Get(), name, name_len)`. Code that uses this
+     * wrapper can be unit tested if this method is overridden by a mock Sock implementation.
+     */
+    [[nodiscard]] virtual int GetSockName(sockaddr* name, socklen_t* name_len) const;
+
     using Event = uint8_t;
 
     /**