kern: Implement skeleton for POSIX sockets

- Adds POSIX socket()
- Adds POSIX listen()
- Adds vnode socket type
- Adds tmpfs socket awareness

Much work is to be done but this commit provides a solid skeleton
to be built upon.

Signed-off-by: Ian Moffett <ian@osmora.org>

4 files changed, 91 insertions, 1 deletions

diff --git a/src/sys/include/compat/unix/syscall.h b/src/sys/include/compat/unix/syscall.h
index 42dc4c0..38419af 100644
--- a/src/sys/include/compat/unix/syscall.h
+++ b/src/sys/include/compat/unix/syscall.h
@@ -31,6 +31,7 @@
 #define _UNIX_SYSCALL_H_ 1
 
 #include <sys/proc.h>
+#include <sys/socket.h>
 #include <sys/param.h>
 #include <sys/mount.h>
 #include <sys/syscall.h>
@@ -95,7 +96,9 @@ scret_t(*g_unix_sctab[])(struct syscall_args *) = {
     [SYS_dmsio] = sys_dmsio,
     [SYS_read] = sys_read,
     [SYS_close] = sys_close,
-    [SYS_lseek] = sys_lseek
+    [SYS_lseek] = sys_lseek,
+    [SYS_socket] = sys_socket,
+    [SYS_listen] = sys_listen
 };
 
 #endif  /* !_NEED_UNIX_SCTAB */
diff --git a/src/sys/include/os/vnode.h b/src/sys/include/os/vnode.h
index 31cfb0c..8cdcded 100644
--- a/src/sys/include/os/vnode.h
+++ b/src/sys/include/os/vnode.h
@@ -44,12 +44,14 @@ struct vop;
  * @VTYPE_NONE: Vnode is yet to be assigned a type
  * @VTYPE_FILE: Vnode references a file
  * @VTYPE_DIR:  Vnode references a directory
+ * @VTYPE_SOCK: Vnode references a socket
  * @__N_VTYPE:  Number of valid nodes on the system
  */
 typedef enum {
     VTYPE_NONE,
     VTYPE_FILE,
     VTYPE_DIR,
+    VTYPE_SOCK,
     __N_VTYPE
 } vtype_t;
 
diff --git a/src/sys/include/sys/socket.h b/src/sys/include/sys/socket.h
new file mode 100644
index 0000000..0ca041f
--- /dev/null
+++ b/src/sys/include/sys/socket.h
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and L5 engineers
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the project nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _SYS_SOCKET_H_
+#define _SYS_SOCKET_H_ 1
+
+#include <sys/types.h>
+#include <sys/syscall.h>
+
+/* Address family defines */
+#define AF_UNIX     0x00        /* Local comms / IPC */
+#define AF_LOCAL    AF_UNIX     /* AF_UNIX alias */
+
+/* Socket type defines */
+#define SOCK_STREAM  0x00
+#define SOCK_DGRAM   0x01
+
+/*
+ * Get a socket as a file descriptor
+ *
+ * @domain: Socket domain (AF_*)
+ * @type: Socket type SOCK_*
+ *
+ * Returns file descriptor on success, otherwise
+ * a less than zero value on failure
+ */
+int socket(int domain, int type, int protocol);
+
+/*
+ * @socket: Socket to listen on
+ * @backlog: Max connections
+ */
+int listen(int socket, int backlog);
+
+#if defined(_KERNEL)
+
+/*
+ * Kernel representation of a socket
+ *
+ * @backlog: Maximum connections (< 0 means socket not active)
+ */
+struct ksocket {
+    int backlog;
+};
+
+/*
+ * Socket syscall
+ */
+scret_t sys_socket(struct syscall_args *scargs);
+
+/*
+ * Listen syscall
+ */
+scret_t sys_listen(struct syscall_args *scargs);
+
+#endif  /* _KERNEL */
+#endif  /* !_SYS_SOCKET_H_ */
diff --git a/src/sys/include/sys/syscall.h b/src/sys/include/sys/syscall.h
index c97d5ea..2ca712f 100644
--- a/src/sys/include/sys/syscall.h
+++ b/src/sys/include/sys/syscall.h
@@ -59,6 +59,8 @@
 #define SYS_read        0x0E    /* read a file descriptor */
 #define SYS_close       0x0F    /* close a file */
 #define SYS_lseek       0x10    /* seek to end of file */
+#define SYS_socket      0x11    /* get a socket fd */
+#define SYS_listen      0x12    /* listen on a socket */
 
 typedef __ssize_t scret_t;
 typedef __ssize_t scarg_t;