server: hookup agent-msg-filter discard-all functionality

This ensures that if the client or agent connects to the client-agent
"tunnel" while the other side is halfway through sending a multi part
message, the rest of the message gets discarded, and the connecting
party starts getting data at the beginning of the next message.

1 files changed, 22 insertions, 30 deletions

diff --git a/server/reds.c b/server/reds.c
index b1a97e62..f04680d0 100644
--- a/server/reds.c
+++ b/server/reds.c
@@ -171,8 +171,6 @@ typedef struct VDIPortState {
     AgentMsgFilter read_filter;
 
     VDIChunkHeader vdi_chunk_header;
-
-    int client_agent_started;
 } VDIPortState;
 
 #ifdef RED_STATISTICS
@@ -576,8 +574,12 @@ static void reds_reset_vdp()
         ring_add(&state->read_bufs, &state->current_read_buf->link);
         state->current_read_buf = NULL;
     }
-    agent_msg_filter_init(&state->read_filter, agent_copypaste, FALSE);
-    state->client_agent_started = FALSE;
+    /* Reset read filter to start with clean state when the agent reconnects */
+    agent_msg_filter_init(&state->read_filter, agent_copypaste, TRUE);
+    /* Throw away pending chunks from the current (if any) and future
+       messages written by the client */
+    state->write_filter.result = AGENT_MSG_FILTER_DISCARD;
+    state->write_filter.discard_all = TRUE;
 }
 
 int reds_main_channel_connected()
@@ -595,8 +597,14 @@ void reds_disconnect()
     reds->disconnecting = TRUE;
     reds->link_id = 0;
 
+    /* Reset write filter to start with clean state on client reconnect */
     agent_msg_filter_init(&reds->agent_state.write_filter, agent_copypaste,
-                          FALSE);
+                          TRUE);
+    /* Throw away pending chunks from the current (if any) and future
+       messages read from the agent */
+    reds->agent_state.read_filter.result = AGENT_MSG_FILTER_DISCARD;
+    reds->agent_state.read_filter.discard_all = TRUE;
+
     if (reds->agent_state.connected) {
         SpiceCharDeviceInterface *sif;
         sif = SPICE_CONTAINEROF(vdagent->base.sif, SpiceCharDeviceInterface, base);
@@ -604,7 +612,6 @@ void reds_disconnect()
         if (sif->state) {
             sif->state(vdagent, reds->agent_state.connected);
         }
-        reds->agent_state.client_agent_started = FALSE;
     }
 
     reds_shatdown_channels();
@@ -833,14 +840,8 @@ static void dispatch_vdi_port_data(int port, VDIReadBuf *buf)
             reds_agent_remove();
             return;
         }
-
-        if (reds->agent_state.connected) {
-            main_channel_push_agent_data(reds->main_channel, buf->data, buf->len,
-                                         vdi_read_buf_release, buf);
-        } else {
-            red_printf("throwing away, no client: %d", buf->len);
-            ring_add(&state->read_bufs, &buf->link);
-        }
+        main_channel_push_agent_data(reds->main_channel, buf->data, buf->len,
+                                     vdi_read_buf_release, buf);
         break;
     }
     case VDP_SERVER_PORT:
@@ -1012,7 +1013,7 @@ void reds_fill_channels(SpiceMsgChannels *channels_info)
 
 void reds_on_main_agent_start()
 {
-    reds->agent_state.client_agent_started = TRUE;
+    reds->agent_state.write_filter.discard_all = FALSE;
 }
 
 void reds_on_main_agent_data(void *message, size_t size)
@@ -1041,17 +1042,6 @@ void reds_on_main_agent_data(void *message, size_t size)
         return;
     }
 
-    if (!vdagent) {
-        add_token();
-        return;
-    }
-
-    if (!reds->agent_state.client_agent_started) {
-        red_printf("SPICE_MSGC_MAIN_AGENT_DATA race");
-        add_token();
-        return;
-    }
-
     if (!(ring_item = ring_get_head(&reds->agent_state.external_bufs))) {
         red_printf("no agent free bufs");
         reds_disconnect();
@@ -1115,7 +1105,7 @@ void reds_marshall_migrate_data_item(SpiceMarshaller *m, MainMigrateData *data)
     data->version = MAIN_CHANNEL_MIG_DATA_VERSION;
 
     data->agent_connected = !!state->connected;
-    data->client_agent_started = state->client_agent_started;
+    data->client_agent_started = !state->write_filter.discard_all;
     data->num_client_tokens = state->num_client_tokens;
     data->send_tokens = ~0;
 
@@ -1350,7 +1340,7 @@ void reds_on_main_receive_migrate_data(MainMigrateData *data, uint8_t *end)
         return;
     }
 
-    state->client_agent_started = data->client_agent_started;
+    state->write_filter.discard_all = !data->client_agent_started;
 
     pos = (uint8_t *)(data + 1);
 
@@ -1573,6 +1563,7 @@ static void reds_handle_main_link(RedLinkInfo *link)
         SpiceCharDeviceInterface *sif;
         sif = SPICE_CONTAINEROF(vdagent->base.sif, SpiceCharDeviceInterface, base);
         reds->agent_state.connected = 1;
+        reds->agent_state.read_filter.discard_all = FALSE;
         if (sif->state) {
             sif->state(vdagent, reds->agent_state.connected);
         }
@@ -3180,6 +3171,7 @@ static void attach_to_red_agent(SpiceCharDeviceInstance *sin)
     }
     sif = SPICE_CONTAINEROF(vdagent->base.sif, SpiceCharDeviceInterface, base);
     state->connected = 1;
+    state->read_filter.discard_all = FALSE;
     if (sif->state) {
         sif->state(vdagent, state->connected);
     }
@@ -3417,8 +3409,8 @@ static void init_vd_agent_resources()
     ring_init(&state->internal_bufs);
     ring_init(&state->write_queue);
     ring_init(&state->read_bufs);
-    agent_msg_filter_init(&state->write_filter, agent_copypaste, FALSE);
-    agent_msg_filter_init(&state->read_filter, agent_copypaste, FALSE);
+    agent_msg_filter_init(&state->write_filter, agent_copypaste, TRUE);
+    agent_msg_filter_init(&state->read_filter, agent_copypaste, TRUE);
 
     state->read_state = VDI_PORT_READ_STATE_READ_HADER;
     state->recive_pos = (uint8_t *)&state->vdi_chunk_header;