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      1 /*
      2  * Copyright (C) 2009 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef __KEYSTORE_GET_H__
     18 #define __KEYSTORE_GET_H__
     19 
     20 #include <stdio.h>
     21 #include <stdint.h>
     22 #include <unistd.h>
     23 #include <sys/types.h>
     24 #include <sys/socket.h>
     25 
     26 #include <cutils/sockets.h>
     27 
     28 #define KEYSTORE_MESSAGE_SIZE 65535
     29 
     30 #ifdef __cplusplus
     31 extern "C" {
     32 #endif
     33 
     34 /* This function is provided for native components to get values from keystore.
     35  * Users are required to link against libcutils. Keys and values are 8-bit safe.
     36  * The first two arguments are the key and its length. The third argument
     37  * specifies the buffer to store the retrieved value, which must be an array of
     38  * KEYSTORE_MESSAGE_SIZE bytes. This function returns the length of the value or
     39  * -1 if an error happens. */
     40 static int keystore_get(const char *key, int length, char *value)
     41 {
     42     uint8_t bytes[2] = {length >> 8, length};
     43     uint8_t code = 'g';
     44     int sock;
     45 
     46     if (length < 0 || length > KEYSTORE_MESSAGE_SIZE) {
     47         return -1;
     48     }
     49     sock = socket_local_client("keystore", ANDROID_SOCKET_NAMESPACE_RESERVED,
     50                                SOCK_STREAM);
     51     if (sock == -1) {
     52         return -1;
     53     }
     54     if (send(sock, &code, 1, 0) == 1 && send(sock, bytes, 2, 0) == 2 &&
     55         send(sock, key, length, 0) == length && shutdown(sock, SHUT_WR) == 0 &&
     56         recv(sock, &code, 1, 0) == 1 && code == /* NO_ERROR */ 1 &&
     57         recv(sock, &bytes[0], 1, 0) == 1 && recv(sock, &bytes[1], 1, 0) == 1) {
     58         int offset = 0;
     59         length = bytes[0] << 8 | bytes[1];
     60         while (offset < length) {
     61             int n = recv(sock, &value[offset], length - offset, 0);
     62             if (n <= 0) {
     63                 length = -1;
     64                 break;
     65             }
     66             offset += n;
     67         }
     68     } else {
     69         length = -1;
     70     }
     71 
     72     close(sock);
     73     return length;
     74 }
     75 
     76 #ifdef __cplusplus
     77 }
     78 #endif
     79 
     80 #endif
     81