Add communication support for xt_qtaguid(network traffic accounting) kernel module.

Change-Id: Ie0fb5b593987c53ee6f906fe6e0caab5a581d5a1
diff --git a/libcutils/qtaguid.c b/libcutils/qtaguid.c
new file mode 100644
index 0000000..517e784
--- /dev/null
+++ b/libcutils/qtaguid.c
@@ -0,0 +1,44 @@
+/* libcutils/qtaguid.c
+**
+** Copyright 2011, The Android Open Source Project
+**
+** Licensed under the Apache License, Version 2.0 (the "License");
+** you may not use this file except in compliance with the License.
+** You may obtain a copy of the License at
+**
+**     http://www.apache.org/licenses/LICENSE-2.0
+**
+** Unless required by applicable law or agreed to in writing, software
+** distributed under the License is distributed on an "AS IS" BASIS,
+** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+** See the License for the specific language governing permissions and
+** limitations under the License.
+*/
+
+#define LOG_TAG "qtaguid"
+
+#include <cutils/qtaguid.h>
+#include <cutils/log.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+extern int set_qtaguid(int sockfd, int tag, uid_t uid) {
+    char lineBuf[128];
+    int fd, cnt = 0;
+    uint64_t kTag = (uint64_t)tag << 32;
+    snprintf(lineBuf, sizeof(lineBuf), "t %d %llu %d", sockfd, kTag, uid);
+
+    LOGV("Tagging Socket with command %s\n", lineBuf);
+    /* TODO: Enable after the kernel module is fixed.
+       fd = open("/proc/net/xt_qtaguid/ctrl", O_WRONLY);
+       if (fd < 0) {
+           return -1;
+       }
+
+       cnt = write(fd, lineBuf, strlen(lineBuf));
+       close(fd);
+    */
+    return (cnt>0?0:-1);
+}