net/net: Add SocketReadState for reuse codes

This function is from net/socket.c, move it to net.c and net.h.
Add SocketReadState to make others reuse net_fill_rstate().
suggestion from jason.

v4:
 - move 'rs->finalize = finalize' to rs_init()

v3:
 - remove SocketReadState init callback
 - put finalize callback to net_fill_rstate()

v2:
 - rename ReadState to SocketReadState
 - add SocketReadState init and finalize callback

v1:
 - init patch

Signed-off-by: Zhang Chen <zhangchen.fnst@cn.fujitsu.com>
Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

1 files changed, 70 insertions, 0 deletions

diff --git a/net/net.c b/net/net.c
index 1680b680e1..5f3e5a9ff5 100644
--- a/net/net.c
+++ b/net/net.c
@@ -1550,3 +1550,73 @@ QemuOptsList qemu_net_opts = {
         { /* end of list */ }
     },
 };
+
+void net_socket_rs_init(SocketReadState *rs,
+                        SocketReadStateFinalize *finalize)
+{
+    rs->state = 0;
+    rs->index = 0;
+    rs->packet_len = 0;
+    memset(rs->buf, 0, sizeof(rs->buf));
+    rs->finalize = finalize;
+}
+
+/*
+ * Returns
+ * 0: SocketReadState is not ready
+ * 1: SocketReadState is ready
+ * otherwise error occurs
+ */
+int net_fill_rstate(SocketReadState *rs, const uint8_t *buf, int size)
+{
+    unsigned int l;
+
+    while (size > 0) {
+        /* reassemble a packet from the network */
+        switch (rs->state) { /* 0 = getting length, 1 = getting data */
+        case 0:
+            l = 4 - rs->index;
+            if (l > size) {
+                l = size;
+            }
+            memcpy(rs->buf + rs->index, buf, l);
+            buf += l;
+            size -= l;
+            rs->index += l;
+            if (rs->index == 4) {
+                /* got length */
+                rs->packet_len = ntohl(*(uint32_t *)rs->buf);
+                rs->index = 0;
+                rs->state = 1;
+            }
+            break;
+        case 1:
+            l = rs->packet_len - rs->index;
+            if (l > size) {
+                l = size;
+            }
+            if (rs->index + l <= sizeof(rs->buf)) {
+                memcpy(rs->buf + rs->index, buf, l);
+            } else {
+                fprintf(stderr, "serious error: oversized packet received,"
+                    "connection terminated.\n");
+                rs->index = rs->state = 0;
+                return -1;
+            }
+
+            rs->index += l;
+            buf += l;
+            size -= l;
+            if (rs->index >= rs->packet_len) {
+                rs->index = 0;
+                rs->state = 0;
+                if (rs->finalize) {
+                    rs->finalize(rs);
+                }
+                return 1;
+            }
+            break;
+        }
+    }
+    return 0;
+}