umbim: fix invalid mbim message string encoding

Strings in mbim messages have to follow these formatting rules:
 - 4 byte alignment, padded if not.
 - utf-16 little endian.

Fixes:
 - mbim connect fails with more than 1 string parameter (apn/user/pass)
   when they are not 4 byte aligned.

Signed-off-by: Daniel Danzberger <daniel@dd-wrt.com>

diff --git a/mbim-msg.c b/mbim-msg.c
index 5ec04f4e6c91ed1da99ca68ee2df33b22eaadb97..8f21aa90b49d0f1fc7885073523b3a30c59e6d00 100644 (file)
--- a/mbim-msg.c
+++ b/mbim-msg.c
@@ -53,8 +53,10 @@ mbim_add_payload(uint8_t len)
 int
 mbim_encode_string(struct mbim_string *str, char *in)
 {
-       int l = strlen(in);
-       int s = mbim_add_payload(l * 2);
+       const int l = strlen(in);
+       const int utf16_len = l * 2;
+       const int pad_len = utf16_len % 4;
+       const int s = mbim_add_payload(utf16_len + pad_len);
        uint8_t *p = &payload_buffer[s];
        int i;
 
@@ -62,14 +64,14 @@ mbim_encode_string(struct mbim_string *str, char *in)
                return -1;
 
        str->offset = htole32(s);
-       str->length = htole32(l * 2);
+       str->length = htole32(utf16_len);
+
        for (i = 0; i < l; i++)
                p[i * 2] = in[i];
 
        return 0;
 }
 
-
 char *
 mbim_get_string(struct mbim_string *str, char *in)
 {