Clean up IMSI decoding

diff --git a/drivers/isimodem/sim.c b/drivers/isimodem/sim.c
index b035e67..3ba0dff 100644 (file)
--- a/drivers/isimodem/sim.c
+++ b/drivers/isimodem/sim.c
@@ -135,9 +135,9 @@ static bool imsi_resp_cb(GIsiClient *client, const void *restrict data,
        ofono_sim_imsi_cb_t cb = cbd->cb;
 
        char imsi[SIM_MAX_IMSI_LENGTH + 1];
-       int index = 0;
        size_t i = 0;
-       size_t imsi_len = 0;
+       size_t j = 0;
+       size_t octets = 0;
 
        if(!msg) {
                DBG("ISI client error: %d", g_isi_client_error(client));
@@ -150,25 +150,26 @@ static bool imsi_resp_cb(GIsiClient *client, const void *restrict data,
        if (msg[1] != READ_IMSI || msg[2] != SIM_SERV_OK)
                goto error;
 
-       imsi_len = msg[3];
-       if (imsi_len == 0 || imsi_len > len)
+       octets = msg[3];
+       if (octets != 8 || octets > len)
                goto error;
        
        msg += 4;
 
        /* Ignore the low-order semi-octet of the first byte */
-       imsi[0] = ((msg[0] & 0xF0) >> 4) + '0';
-       for (i = 1, index = 1; i < imsi_len; i++) {
+       imsi[j] = ((msg[i] & 0xF0) >> 4) + '0';
+
+       for (i++, j++; i < octets && j < SIM_MAX_IMSI_LENGTH; i++) {
 
                char nibble;
-               imsi[index++] = (msg[i] & 0x0F) + '0';
+               imsi[j++] = (msg[i] & 0x0F) + '0';
 
                nibble = (msg[i] & 0xF0) >> 4;
                if (nibble != 0x0F)
-                       imsi[index++] = nibble + '0';
+                       imsi[j++] = nibble + '0';
        }
 
-       imsi[index] = '\0';
+       imsi[j] = '\0';
        CALLBACK_WITH_SUCCESS(cb, imsi, cbd->data);
        goto out;