net: clean up usbnet_receive()

The USB network interface has two code paths depending on whether or not
RNDIS mode is enabled.  Refactor usbnet_receive() so that there is a
common path throughout the function instead of duplicating everything
across if (is_rndis(s)) ... else ... code paths.

Clean up coding style and 80 character line wrap along the way.

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>

hw/usb/dev-network.c

@@ -1250,20 +1250,27 @@ static int usb_net_handle_data(USBDevice *dev, USBPacket *p)
 static ssize_t usbnet_receive(NetClientState *nc, const uint8_t *buf, size_t size)
 {
     USBNetState *s = DO_UPCAST(NICState, nc, nc)->opaque;
-    struct rndis_packet_msg_type *msg;
+    uint8_t *in_buf = s->in_buf;
+    size_t total_size = size;
 
     if (is_rndis(s)) {
-        msg = (struct rndis_packet_msg_type *) s->in_buf;
         if (s->rndis_state != RNDIS_DATA_INITIALIZED) {
             return -1;
         }
-        if (size + sizeof(struct rndis_packet_msg_type) > sizeof(s->in_buf))
-            return -1;
+        total_size += sizeof(struct rndis_packet_msg_type);
+    }
+    if (total_size > sizeof(s->in_buf)) {
+        return -1;
+    }
 
+    if (is_rndis(s)) {
+        struct rndis_packet_msg_type *msg;
+
+        msg = (struct rndis_packet_msg_type *)in_buf;
         memset(msg, 0, sizeof(struct rndis_packet_msg_type));
         msg->MessageType = cpu_to_le32(RNDIS_PACKET_MSG);
-        msg->MessageLength = cpu_to_le32(size + sizeof(struct rndis_packet_msg_type));
-        msg->DataOffset = cpu_to_le32(sizeof(struct rndis_packet_msg_type) - 8);
+        msg->MessageLength = cpu_to_le32(size + sizeof(*msg));
+        msg->DataOffset = cpu_to_le32(sizeof(*msg) - 8);
         msg->DataLength = cpu_to_le32(size);
         /* msg->OOBDataOffset;
          * msg->OOBDataLength;
@@ -1273,14 +1280,11 @@ static ssize_t usbnet_receive(NetClientState *nc, const uint8_t *buf, size_t siz
          * msg->VcHandle;
          * msg->Reserved;
          */
-        memcpy(msg + 1, buf, size);
-        s->in_len = size + sizeof(struct rndis_packet_msg_type);
-    } else {
-        if (size > sizeof(s->in_buf))
-            return -1;
-        memcpy(s->in_buf, buf, size);
-        s->in_len = size;
+        in_buf += sizeof(*msg);
     }
+
+    memcpy(in_buf, buf, size);
+    s->in_len = total_size;
     s->in_ptr = 0;
     return size;
 }