Separation of decoding User Data Header from decoding 7 bit message

It is preparation for supporting 8 bit and 16 bit encoding. Moving out
this code from decode_7bit_field() allows to reuse it in caller
function where other than 7 bit decoding will take place.

Signed-off-by: SÅ‚awomir Demeszko <s.demeszko@wireless-instruments.com>

diff --git a/commands-wms.c b/commands-wms.c
index 5f159cefa707cee4ebbfc88fbd0e2d2f3e63f617..9760d856780bf4b846059d34dd6e942ab18f7f95 100644 (file)
--- a/commands-wms.c
+++ b/commands-wms.c
@@ -158,13 +158,13 @@ pdu_decode_7bit_str(char *dest, const unsigned char *data, int data_len, int bit
        return len;
 }
 
-static void decode_udh(const unsigned char *data)
+static int decode_udh(const unsigned char *data)
 {
        const unsigned char *end;
-       unsigned int type, len;
+       unsigned int type, len, udh_len;
 
-       len = *(data++);
-       end = data + len;
+       udh_len = *(data++);
+       end = data + udh_len;
        while (data < end) {
                const unsigned char *val;
 
@@ -185,29 +185,15 @@ static void decode_udh(const unsigned char *data)
                        break;
                }
        }
+
+       return udh_len + 1;
 }
 
-static void decode_7bit_field(char *name, const unsigned char *data, int data_len, bool udh)
+static void decode_7bit_field(char *name, const unsigned char *data, int data_len, int bit_offset)
 {
-       const unsigned char *udh_start;
-       char *dest;
-       int pos_offset = 0;
-
-       if (udh) {
-               int len = data[0] + 1;
-
-               udh_start = data;
-               data += len;
-               data_len -= len;
-               pos_offset = len % 7;
-       }
-
-       dest = blobmsg_alloc_string_buffer(&status, name, 3 * (data_len * 8 / 7) + 2);
-       pdu_decode_7bit_str(dest, data, data_len, pos_offset);
+       char *dest = blobmsg_alloc_string_buffer(&status, name, 3 * (data_len * 8 / 7) + 2);
+       pdu_decode_7bit_str(dest, data, data_len, bit_offset);
        blobmsg_add_string_buffer(&status);
-
-       if (udh)
-               decode_udh(udh_start);
 }
 
 static char *pdu_add_semioctet(char *str, char val)
@@ -375,8 +361,20 @@ static void cmd_wms_get_message_cb(struct qmi_dev *qmi, struct qmi_request *req,
                data += 7;
        }
 
-       cur_len = *(data++);
-       decode_7bit_field("text", data, end - data, !!(first & 0x40));
+       data++;
+       int bit_offset = 0;
+
+       /* User Data Header */
+       if (first & 0x40) {
+               int udh_len = decode_udh(data);
+               data += udh_len;
+               bit_offset = udh_len % 7;
+               }
+
+       if (data >= end)
+               goto error;
+
+       decode_7bit_field("text", data, end - data, bit_offset);
        blobmsg_close_table(&status, c);
 
        return;