commit 0238eb8f3612515f4374381b593dd79116169330

Author: John Dennis <jdennis@redhat.com>

Date:   Thu Aug 2 16:21:33 2018 -0400

    fix concatkdf failures on big endian architectures

    Several of the elements used to compute the digest in ECDH-ES key

    agreement computation are represented in binary form as a 32-bit

    integer length followed by that number of octets.  the length

    field. The 32-bit length integer is represented in big endian

    format (the 8 most significant bits are in the first octet.).

    The conversion to a 4 byte big endian integer was being computed

    in a manner that only worked on little endian architectures. The

    function htonl() returns a 32-bit integer whose octet sequence given

    the address of the integer is big endian. There is no need for any

    further manipulation.

    The existing code used bit shifting on a 32-bit value. In C bit

    shifting is endian agnostic for multi-octet values, a right shift

    moves most significant bits toward least significant bits. The result

    of a bit shift of a multi-octet value on either big or little

    archictures will always be the same provided you "view" it as the same

    data type (e.g. 32-bit integer). But indexing the octets of that

    mulit-octet value will be different depending on endianness, hence the

    assembled octets differed depending on endianness.

    Issue: #77

    Signed-off-by: John Dennis <jdennis@redhat.com>

diff --git a/src/concatkdf.c b/src/concatkdf.c

index ec064ab..59b845a 100644

--- a/src/concatkdf.c

+++ b/src/concatkdf.c

@@ -29,15 +29,9 @@

 ////////////////////////////////////////////////////////////////////////////////

 static uint8_t *_apply_uint32(const uint32_t value, uint8_t *buffer)

 {

-    const uint32_t formatted = htonl(value);

-    const uint8_t data[4] = {

-        (formatted >> 0) & 0xff,

-        (formatted >> 8) & 0xff,

-        (formatted >> 16) & 0xff,

-        (formatted >> 24) & 0xff

-    };

-    memcpy(buffer, data, 4);

+    const uint32_t big_endian_int32 = htonl(value);

+    memcpy(buffer, &big_endian_int32, 4);

     return buffer + 4;

 }

diff --git a/test/check_concatkdf.c b/test/check_concatkdf.c

index e4325fc..41d0f1c 100644

--- a/test/check_concatkdf.c

+++ b/test/check_concatkdf.c

@@ -60,14 +60,9 @@ _create_otherinfo_header_finish:

 static bool _cmp_uint32(uint8_t **actual, uint32_t expected)

 {

-    uint32_t value = htonl(expected);

-    uint8_t expectedData[] = {

-        (value >> 0) & 0xff,

-        (value >> 8) & 0xff,

-        (value >> 16) & 0xff,

-        (value >> 24) & 0xff

-    };

-    bool result = (0 == memcmp(*actual, expectedData, 4));

+    uint32_t big_endian_int32 = htonl(expected);

+

+    bool result = (0 == memcmp(*actual, &big_endian_int32, 4));

     (*actual) += 4;

     return result;

 }