ipc: socket accept()

src/ipc/connection.c

@@ -72,7 +72,7 @@ int listen(Thread *t, int sd, int backlog) {
 
     if(backlog > 0) sock->backlogMax = backlog;
     else sock->backlogMax = SOCKET_DEFAULT_BACKLOG;
-    
+
     sock->backlog = calloc(backlog, sizeof(SocketDescriptor *));
     if(!sock->backlog) {
         socketRelease();
@@ -83,3 +83,62 @@ int listen(Thread *t, int sd, int backlog) {
     socketRelease();
     return 0;
 }
+
+/* accept(): accepts an incoming socket connection
+ * this function does NOT block at the kernel level - the syscall dispatcher
+ * will take care of blocking if the socket is not set to be non-blocking
+ * params: t - calling thread, NULL for kernel threads
+ * params: sd - socket descriptor
+ * params: addr - buffer to store peer's address
+ * params: len - length of the buffer on input, length of data stored on output
+ * returns: positive socket descriptor on success, negative error code on fail
+ */
+
+int accept(Thread *t, int sd, struct sockaddr *addr, socklen_t *len) {
+    Process *p;
+    if(t) p = getProcess(t->pid);
+    else p = getProcess(getPid());
+    if(!p) return -ESRCH;
+
+    if(!p->io[sd].valid || !p->io[sd].data || (p->io[sd].type != IO_SOCKET))
+        return -ENOTSOCK;
+
+    SocketDescriptor *listener = (SocketDescriptor *)p->io[sd].data;
+    if(!listener->listener || !listener->backlog || !listener->backlogMax)
+        return -EINVAL;         // socket is not listening
+
+    if(!listener->backlogCount)
+        return -EWOULDBLOCK;    // socket has no incoming queue
+
+    socketLock();
+
+    // create a new connected socket
+    IODescriptor *iod = NULL;
+    int connectedSocket = openIO(p, (void **) &iod);
+    if((connectedSocket < 0) || !iod) {
+        socketRelease();
+        return -EMFILE;
+    }
+
+    iod->type = IO_SOCKET;
+    iod->flags = p->io[sd].flags;
+    iod->data = calloc(1, sizeof(SocketDescriptor));
+    if(!iod->data) {
+        socketRelease();
+        closeIO(p, iod);
+        return -ENOMEM;
+    }
+
+    // copy the self address
+    SocketDescriptor *self = (SocketDescriptor *)iod->data;
+    memcpy(&self->address, &listener->address, sizeof(struct sockaddr));
+    self->type = listener->type;
+    self->protocol = listener->protocol;
+
+    // and assign the peer address
+    self->peer = listener->backlog[0];  // TODO: is this always FIFO?
+    memmove(&listener->backlog[0], &listener->backlog[1], (listener->backlogMax - 1) * sizeof(SocketDescriptor *));
+
+    socketRelease();
+    return connectedSocket;
+}