From cef9e0825b9ba15a2feac07d82bfd0889732b151 Mon Sep 17 00:00:00 2001
From: jewelcodes <omarmelghoul01@gmail.com>
Date: Sat, 7 Sep 2024 11:13:43 -0400
Subject: [PATCH] syscalls: added socket syscalls

---
 src/include/kernel/syscalls.h |   2 +-
 src/syscalls/dispatch.c       | 103 ++++++++++++++++++++++++++++++++++
 2 files changed, 104 insertions(+), 1 deletion(-)

diff --git a/src/include/kernel/syscalls.h b/src/include/kernel/syscalls.h
index 2f5d7d6..09b3400 100644
--- a/src/include/kernel/syscalls.h
+++ b/src/include/kernel/syscalls.h
@@ -11,7 +11,7 @@
 #include <stdbool.h>
 #include <kernel/sched.h>
 
-#define MAX_SYSCALL                     12       // for now
+#define MAX_SYSCALL                     37       // for now
 
 typedef struct SyscallRequest {
     bool busy, queued, unblock;
diff --git a/src/syscalls/dispatch.c b/src/syscalls/dispatch.c
index d680fb2..e1a5ffd 100644
--- a/src/syscalls/dispatch.c
+++ b/src/syscalls/dispatch.c
@@ -6,7 +6,11 @@
  */
 
 #include <stdint.h>
+#include <stdbool.h>
+#include <errno.h>
+#include <platform/mmap.h>
 #include <kernel/sched.h>
+#include <kernel/socket.h>
 #include <kernel/syscalls.h>
 #include <kernel/logger.h>
 
@@ -14,6 +18,26 @@
  * their behavior. This ensures the exposed functionality is always as close
  * as possible to the Unix specification */
 
+/* syscallVerifyPointer(): ensure user programs don't violate memory permissions
+ * params: req - syscall request
+ * params: base - base pointer
+ * params: len - length of the structure at the point
+ * returns: true if safe, false if unsafe, user program terminated as well
+ */
+
+bool syscallVerifyPointer(SyscallRequest *req, uintptr_t base, uintptr_t len) {
+    uintptr_t end = base + len;
+    if(base < USER_BASE_ADDRESS || end > USER_LIMIT_ADDRESS) {
+        KWARN("killing tid %d for memory access violation at 0x%X (%d)\n", req->thread->tid, base, len);
+        terminateThread(req->thread, -1, false);
+        return false;
+    }
+
+    return true;
+}
+
+/* Group 1: Scheduler */
+
 void syscallDispatchExit(SyscallRequest *req) {
     exit(req->thread, req->params[0]);
 }
@@ -66,6 +90,56 @@ void syscallDispatchMSleep(SyscallRequest *req) {
     req->ret = msleep(req->thread, req->params[0]);
 }
 
+/* TODO: Group 2: File System */
+
+/* Group 3: Interprocess Communication */
+
+void syscallDispatchSocket(SyscallRequest *req) {
+    req->ret = socket(req->thread, req->params[0], req->params[1], req->params[2]);
+    req->unblock = true;
+}
+
+void syscallDispatchConnect(SyscallRequest *req) {
+    if(syscallVerifyPointer(req, req->params[1], req->params[2])) {
+        req->ret = connect(req->thread, req->params[0], (const struct sockaddr *)req->params[1], req->params[2]);
+        req->unblock = true;
+    }
+}
+
+void syscallDispatchBind(SyscallRequest *req) {
+    if(syscallVerifyPointer(req, req->params[1], req->params[2])) {
+        req->ret = bind(req->thread, req->params[0], (const struct sockaddr *)req->params[1], req->params[2]);
+        req->unblock = true;
+    }
+}
+
+void syscallDispatchListen(SyscallRequest *req) {
+    req->ret = listen(req->thread, req->params[0], req->params[1]);
+    req->unblock = true;
+}
+
+void syscallDispatchAccept(SyscallRequest *req) {
+    int status;
+    if(!req->params[1]) {
+        status = accept(req->thread, req->params[0], NULL, NULL);
+    } else {
+        if(syscallVerifyPointer(req, req->params[1], sizeof(const struct sockaddr)) &&
+        syscallVerifyPointer(req, req->params[2], sizeof(socklen_t))) {
+            status = accept(req->thread, req->params[0], (struct sockaddr *)req->params[1], (socklen_t *)req->params[2]);
+        }
+    }
+
+    if(status == -EWOULDBLOCK || status == -EAGAIN) {
+        // return without unblocking if necessary
+        Process *p = getProcess(req->thread->pid);
+        if(!(p->io[req->params[0]].flags & O_NONBLOCK))
+            req->unblock = false;
+    } else {
+        req->ret = status;
+        req->unblock = true;
+    }
+}
+
 void (*syscallDispatchTable[])(SyscallRequest *) = {
     /* group 1: scheduler functions */
     syscallDispatchExit,        // 0 - exit()
@@ -81,4 +155,33 @@ void (*syscallDispatchTable[])(SyscallRequest *) = {
     NULL,                       // 10 - setuid()
     NULL,                       // 11 - setgid()
     syscallDispatchMSleep,      // 12 - msleep()
+
+    /* group 2: file system manipulation */
+    NULL,                       // 13 - open()
+    NULL,                       // 14 - close()
+    NULL,                       // 15 - read()
+    NULL,                       // 16 - write()
+    NULL,                       // 17 - stat()
+    NULL,                       // 18 - lseek()
+    NULL,                       // 19 - chown()
+    NULL,                       // 20 - chmod()
+    NULL,                       // 21 - link()
+    NULL,                       // 22 - unlink()
+    NULL,                       // 23 - mknod()
+    NULL,                       // 24 - mkdir()
+    NULL,                       // 25 - rmdir()
+    NULL,                       // 26 - utime()
+    NULL,                       // 27 - chroot()
+    NULL,                       // 28 - mount()
+    NULL,                       // 29 - umount()
+    NULL,                       // 30 - fnctl()
+
+    /* group 3: interprocess communication */
+    syscallDispatchSocket,      // 31 - socket()
+    syscallDispatchConnect,     // 32 - connect()
+    syscallDispatchBind,        // 33 - bind()
+    syscallDispatchListen,      // 34 - listen()
+    syscallDispatchAccept,      // 35 - accept()
+    NULL,                       // 36 - recv()
+    NULL,                       // 37 - send()
 };