dlt_user_shared: Add timeout to writev (#385)

This timeout is necessary to prevent blocking writev indefinitely. Without the timeout dlt-daemon, may block indefinitely when an app id is re-used very frequently. In that case dlt-daemon won't accept anymore new connections and further communication in any way is not possible anymore. Signed-off-by: Alexander Mohr <[email protected]>
COVESA · May 17, 2023 · 6005b92 · 6005b92
1 parent cfc2c86
commit 6005b92
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Showing 5 changed files with 78 additions and 4 deletions.
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -98,6 +98,8 @@ option(WITH_DLT_DAEMON_VSOCK_IPC "Set to ON to enable VSOCK support in daemon"
 option(WITH_DLT_LIB_VSOCK_IPC    "Set to ON to enable VSOCK support in library (DLT_IPC is not used in library)" OFF)
 
 set(DLT_VSOCK_PORT "13490" CACHE STRING "VSOCK port number for logging traffic.")
+set(DLT_WRITEV_TIMEOUT_SEC "1" CACHE STRING "Set sec timeout for writev to prevent blocking indefinitely")
+set(DLT_WRITEV_TIMEOUT_USEC "0" CACHE STRING "Set usec timeout for writev to prevent blocking indefinitely")
 
 # RPM settings
 set(GENIVI_RPM_RELEASE "1")  # ${DLT_REVISION}")
@@ -135,6 +137,8 @@ include_directories(
 )
 
 add_definitions(-D_GNU_SOURCE)
+add_definitions(-DDLT_WRITEV_TIMEOUT_SEC=${DLT_WRITEV_TIMEOUT_SEC})
+add_definitions(-DDLT_WRITEV_TIMEOUT_USEC=${DLT_WRITEV_TIMEOUT_USEC})
 
 if(NOT DLT_IPC STREQUAL "UNIX_SOCKET" AND NOT DLT_IPC STREQUAL "FIFO")
     message(FATAL_ERROR "${DLT_IPC} is not a valid value for DLT_IPC")

diff --git a/src/daemon/dlt_daemon_client.c b/src/daemon/dlt_daemon_client.c
@@ -1622,7 +1622,7 @@ void dlt_daemon_control_callsw_cinjection(int sock,
 
         /* write to FIFO */
         DltReturnValue ret =
-            dlt_user_log_out3(context->user_handle, &(userheader), sizeof(DltUserHeader),
+            dlt_user_log_out3_with_timeout(context->user_handle, &(userheader), sizeof(DltUserHeader),
                               &(usercontext), sizeof(DltUserControlMsgInjection),
                               userbuffer, (size_t) data_length_inject);
 

diff --git a/src/daemon/dlt_daemon_common.c b/src/daemon/dlt_daemon_common.c
@@ -1380,7 +1380,7 @@ int dlt_daemon_user_send_log_level(DltDaemon *daemon, DltDaemonContext *context,
 
     /* log to FIFO */
     errno = 0;
-    ret = dlt_user_log_out2(context->user_handle,
+    ret = dlt_user_log_out2_with_timeout(context->user_handle,
                             &(userheader), sizeof(DltUserHeader),
                             &(usercontext), sizeof(DltUserControlMsgLogLevel));
 
@@ -1416,7 +1416,7 @@ int dlt_daemon_user_send_log_state(DltDaemon *daemon, DltDaemonApplication *app,
     logstate.log_state = daemon->connectionState;
 
     /* log to FIFO */
-    ret = dlt_user_log_out2(app->user_handle,
+    ret = dlt_user_log_out2_with_timeout(app->user_handle,
                             &(userheader), sizeof(DltUserHeader),
                             &(logstate), sizeof(DltUserControlMsgLogState));
 

diff --git a/src/shared/dlt_user_shared.c b/src/shared/dlt_user_shared.c
@@ -71,6 +71,7 @@
 #include <errno.h>
 
 #include <sys/uio.h> /* writev() */
+#include <sys/time.h> /* timeval */
 
 #include "dlt_user_shared.h"
 #include "dlt_user_shared_cfg.h"
@@ -125,6 +126,28 @@ DltReturnValue dlt_user_log_out2(int handle, void *ptr1, size_t len1, void *ptr2
     return DLT_RETURN_OK;
 }
 
+DltReturnValue dlt_user_log_out2_with_timeout(int handle, void *ptr1, size_t len1, void *ptr2, size_t len2)
+{
+    if (handle < 0)
+        /* Invalid handle */
+        return DLT_RETURN_ERROR;
+
+    fd_set fds;
+    FD_ZERO(&fds);
+    FD_SET(handle, &fds);
+
+    struct timeval tv = { DLT_WRITEV_TIMEOUT_SEC, DLT_WRITEV_TIMEOUT_USEC };
+    if (select(handle+1, NULL, &fds, NULL, &tv) < 0) {
+        return DLT_RETURN_ERROR;
+    }
+
+    if (FD_ISSET(handle, &fds)) {
+        return dlt_user_log_out2(handle, ptr1, len1, ptr2, len2);
+    } else {
+        return DLT_RETURN_ERROR;
+    }
+}
+
 DltReturnValue dlt_user_log_out3(int handle, void *ptr1, size_t len1, void *ptr2, size_t len2, void *ptr3, size_t len3)
 {
     struct iovec iov[3];
@@ -175,4 +198,26 @@ DltReturnValue dlt_user_log_out3(int handle, void *ptr1, size_t len1, void *ptr2
     }
 
     return DLT_RETURN_OK;
-}
+}
+
+DltReturnValue dlt_user_log_out3_with_timeout(int handle, void *ptr1, size_t len1, void *ptr2, size_t len2, void *ptr3, size_t len3)
+{
+    if (handle < 0)
+        /* Invalid handle */
+        return DLT_RETURN_ERROR;
+
+    fd_set fds;
+    FD_ZERO(&fds);
+    FD_SET(handle, &fds);
+
+    struct timeval tv = { DLT_WRITEV_TIMEOUT_SEC, DLT_WRITEV_TIMEOUT_USEC };
+    if (select(handle+1, NULL, &fds, NULL, &tv) < 0) {
+        return DLT_RETURN_ERROR;
+    }
+
+    if (FD_ISSET(handle, &fds)) {
+        return dlt_user_log_out3(handle, ptr1, len1, ptr2, len2, ptr3, len3);
+    } else {
+        return DLT_RETURN_ERROR;
+    }
+}
diff --git a/src/shared/dlt_user_shared.h b/src/shared/dlt_user_shared.h
@@ -211,6 +211,17 @@ int dlt_user_check_userheader(DltUserHeader *userheader);
  */
 DltReturnValue dlt_user_log_out2(int handle, void *ptr1, size_t len1, void *ptr2, size_t len2);
 
+/**
+ * Atomic write to file descriptor, using vector of 2 elements  with a timeout of 1s
+ * @param handle file descriptor
+ * @param ptr1 generic pointer to first segment of data to be written
+ * @param len1 length of first segment of data to be written
+ * @param ptr2 generic pointer to second segment of data to be written
+ * @param len2 length of second segment of data to be written
+ * @return Value from DltReturnValue enum
+ */
+DltReturnValue dlt_user_log_out2_with_timeout(int handle, void *ptr1, size_t len1, void *ptr2, size_t len2);
+
 /**
  * Atomic write to file descriptor, using vector of 3 elements
  * @param handle file descriptor
@@ -224,4 +235,18 @@ DltReturnValue dlt_user_log_out2(int handle, void *ptr1, size_t len1, void *ptr2
  */
 DltReturnValue dlt_user_log_out3(int handle, void *ptr1, size_t len1, void *ptr2, size_t len2, void *ptr3, size_t len3);
 
+/**
+ * Atomic write to file descriptor, using vector of 3 elements with a timeout of 1s
+ * @param handle file descriptor
+ * @param ptr1 generic pointer to first segment of data to be written
+ * @param len1 length of first segment of data to be written
+ * @param ptr2 generic pointer to second segment of data to be written
+ * @param len2 length of second segment of data to be written
+ * @param ptr3 generic pointer to third segment of data to be written
+ * @param len3 length of third segment of data to be written
+ * @return Value from DltReturnValue enum
+ */
+DltReturnValue dlt_user_log_out3_with_timeout(int handle, void *ptr1, size_t len1, void *ptr2, size_t len2, void *ptr3, size_t len3);
+
+
 #endif /* DLT_USER_SHARED_H */