Kernel+LibC+UserspaceEmulator: Add SO_TIMESTAMP, and cmsg definitions

When SO_TIMESTAMP is set as an option on a SOCK_DGRAM socket, then
recvmsg() will return a SCM_TIMESTAMP control message that
contains a struct timeval with the system time that was current
when the socket was received.

Kernel/Net/Socket.cpp

@@ -133,6 +133,17 @@ KResult Socket::setsockopt(int level, int option, Userspace<const void*> user_va
     case SO_KEEPALIVE:
         // FIXME: Obviously, this is not a real keepalive.
         return KSuccess;
+    case SO_TIMESTAMP:
+        if (user_value_size != sizeof(int))
+            return KResult(-EINVAL);
+        if (!copy_from_user(&m_timestamp, static_ptr_cast<const int*>(user_value)))
+            return KResult(-EFAULT);
+        if (m_timestamp && (domain() != AF_INET || type() == SOCK_STREAM)) {
+            // FIXME: Support SO_TIMESTAMP for more protocols?
+            m_timestamp = 0;
+            return KResult(-ENOTSUP);
+        }
+        return KSuccess;
     default:
         dbg() << "setsockopt(" << option << ") at SOL_SOCKET not implemented.";
         return KResult(-ENOPROTOOPT);
@@ -196,6 +207,15 @@ KResult Socket::getsockopt(FileDescription&, int level, int option, Userspace<vo
 
             return KResult(-EFAULT);
         }
+    case SO_TIMESTAMP:
+        if (size < sizeof(int))
+            return KResult(-EINVAL);
+        if (!copy_to_user(static_ptr_cast<int*>(value), &m_timestamp))
+            return KResult(-EFAULT);
+        size = sizeof(int);
+        if (!copy_to_user(value_size, &size))
+            return KResult(-EFAULT);
+        return KSuccess;
     default:
         dbg() << "getsockopt(" << option << ") at SOL_SOCKET not implemented.";
         return KResult(-ENOPROTOOPT);

Kernel/Net/Socket.h

@@ -135,6 +135,8 @@ public:
     bool has_send_timeout() const { return m_send_timeout.tv_sec || m_send_timeout.tv_usec; }
     const timeval& send_timeout() const { return m_send_timeout; }
 
+    bool wants_timestamp() const { return m_timestamp; }
+
 protected:
     Socket(int domain, int type, int protocol);
 
@@ -172,6 +174,7 @@ private:
 
     timeval m_receive_timeout { 0, 0 };
     timeval m_send_timeout { 0, 0 };
+    int m_timestamp { 0 };
 
     NonnullRefPtrVector<Socket> m_pending;
 };

Kernel/Syscalls/socket.cpp

@@ -264,6 +264,23 @@ ssize_t Process::sys$recvmsg(int sockfd, Userspace<struct msghdr*> user_msg, int
         msg_flags |= MSG_TRUNC;
     }
 
+    if (socket.wants_timestamp()) {
+        struct {
+            cmsghdr cmsg;
+            timeval timestamp;
+        } cmsg_timestamp;
+        socklen_t control_length = sizeof(cmsg_timestamp);
+        if (msg.msg_controllen < control_length) {
+            msg_flags |= MSG_CTRUNC;
+        } else {
+            cmsg_timestamp = { { control_length, SOL_SOCKET, SCM_TIMESTAMP }, timestamp };
+            if (!copy_to_user(msg.msg_control, &cmsg_timestamp, control_length))
+                return -EFAULT;
+        }
+        if (!copy_to_user(&user_msg.unsafe_userspace_ptr()->msg_controllen, &control_length))
+            return -EFAULT;
+    }
+
     if (!copy_to_user(&user_msg.unsafe_userspace_ptr()->msg_flags, &msg_flags))
         return -EFAULT;
 

Kernel/UnixTypes.h

@@ -458,6 +458,7 @@ struct pollfd {
 #define SHUT_RDWR 3
 
 #define MSG_TRUNC 0x1
+#define MSG_CTRUNC 0x2
 #define MSG_DONTWAIT 0x40
 
 #define SOL_SOCKET 1
@@ -471,6 +472,11 @@ enum {
     SO_REUSEADDR,
     SO_BINDTODEVICE,
     SO_KEEPALIVE,
+    SO_TIMESTAMP,
+};
+
+enum {
+    SCM_TIMESTAMP,
 };
 
 #define IPPROTO_IP 0
@@ -556,6 +562,12 @@ struct iovec {
     size_t iov_len;
 };
 
+struct cmsghdr {
+    socklen_t cmsg_len;
+    int cmsg_level;
+    int cmsg_type;
+};
+
 struct msghdr {
     void* msg_name;
     socklen_t msg_namelen;