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.

DevTools/UserspaceEmulator/Emulator.cpp

@@ -490,10 +490,10 @@ int Emulator::virt$setsockopt(FlatPtr params_addr)
     Syscall::SC_setsockopt_params params;
     mmu().copy_from_vm(&params, params_addr, sizeof(params));
 
-    if (params.option == SO_RCVTIMEO) {
+    if (params.option == SO_RCVTIMEO || params.option == SO_TIMESTAMP) {
         auto host_value_buffer = ByteBuffer::create_zeroed(params.value_size);
         mmu().copy_from_vm(host_value_buffer.data(), (FlatPtr)params.value, params.value_size);
-        int rc = setsockopt(params.sockfd, params.level, SO_RCVTIMEO, host_value_buffer.data(), host_value_buffer.size());
+        int rc = setsockopt(params.sockfd, params.level, params.option, host_value_buffer.data(), host_value_buffer.size());
         if (rc < 0)
             return -errno;
         return rc;

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;

Libraries/LibC/sys/socket.h

@@ -62,10 +62,17 @@ __BEGIN_DECLS
 #define IPPROTO_UDP 17
 
 #define MSG_TRUNC 0x1
+#define MSG_CTRUNC 0x2
 #define MSG_DONTWAIT 0x40
 
 typedef uint16_t sa_family_t;
 
+struct cmsghdr {
+    socklen_t cmsg_len;
+    int cmsg_level;
+    int cmsg_type;
+};
+
 struct msghdr {
     void* msg_name;
     socklen_t msg_namelen;
@@ -99,6 +106,7 @@ enum {
     SO_REUSEADDR,
     SO_BINDTODEVICE,
     SO_KEEPALIVE,
+    SO_TIMESTAMP,
 };
 #define SO_RCVTIMEO SO_RCVTIMEO
 #define SO_SNDTIMEO SO_SNDTIMEO
@@ -108,6 +116,12 @@ enum {
 #define SO_REUSEADDR SO_REUSEADDR
 #define SO_BINDTODEVICE SO_BINDTODEVICE
 #define SO_KEEPALIVE SO_KEEPALIVE
+#define SO_TIMESTAMP SO_TIMESTAMP
+
+enum {
+    SCM_TIMESTAMP,
+};
+#define SCM_TIMESTAMP SCM_TIMESTAMP
 
 struct sockaddr_storage {
     union {
@@ -135,4 +149,30 @@ int getpeername(int sockfd, struct sockaddr*, socklen_t*);
 int sendfd(int sockfd, int fd);
 int recvfd(int sockfd);
 
+// These three are non-POSIX, but common:
+#define CMSG_ALIGN(x) (((x) + sizeof(void*) - 1) & ~(sizeof(void*) - 1))
+#define CMSG_SPACE(x) (CMSG_ALIGN(sizeof(struct cmsghdr)) + CMSG_ALIGN(x))
+#define CMSG_LEN(x) (CMSG_ALIGN(sizeof(struct cmsghdr)) + (x))
+
+static inline struct cmsghdr* CMSG_FIRSTHDR(struct msghdr* msg)
+{
+    if (msg->msg_controllen < sizeof(struct cmsghdr))
+        return 0;
+    return (struct cmsghdr*)msg->msg_control;
+}
+
+static inline struct cmsghdr* CMSG_NXTHDR(struct msghdr* msg, struct cmsghdr* cmsg)
+{
+    struct cmsghdr* next = (struct cmsghdr*)((char*)cmsg + CMSG_ALIGN(cmsg->cmsg_len));
+    unsigned offset = (char*)next - (char*)msg->msg_control;
+    if (msg->msg_controllen < offset + sizeof(struct cmsghdr))
+        return NULL;
+    return next;
+}
+
+static inline void* CMSG_DATA(struct cmsghdr* cmsg)
+{
+    return (void*)(cmsg + 1);
+}
+
 __END_DECLS