static int s_build_canonical_payload()

in source/aws_signing.c [1476:1566]

• 68 lines of code
• 17 McCabe index (conditional complexity)

static int s_build_canonical_payload(struct aws_signing_state_aws *state) {
    const struct aws_signable *signable = state->signable;
    struct aws_allocator *allocator = state->allocator;
    struct aws_byte_buf *payload_hash_buffer = &state->payload_hash;

    AWS_ASSERT(payload_hash_buffer->len == 0);

    struct aws_byte_buf body_buffer;
    AWS_ZERO_STRUCT(body_buffer);
    struct aws_byte_buf digest_buffer;
    AWS_ZERO_STRUCT(digest_buffer);

    struct aws_hash *hash = NULL;

    int result = AWS_OP_ERR;
    if (state->config.signed_body_value.len == 0) {
        /* No value provided by user, so we must calculate it */
        hash = aws_sha256_new(allocator);
        if (hash == NULL) {
            return AWS_OP_ERR;
        }

        if (aws_byte_buf_init(&body_buffer, allocator, BODY_READ_BUFFER_SIZE) ||
            aws_byte_buf_init(&digest_buffer, allocator, AWS_SHA256_LEN)) {
            goto on_cleanup;
        }

        struct aws_input_stream *payload_stream = NULL;
        if (aws_signable_get_payload_stream(signable, &payload_stream)) {
            goto on_cleanup;
        }

        if (payload_stream != NULL) {
            if (aws_input_stream_seek(payload_stream, 0, AWS_SSB_BEGIN)) {
                goto on_cleanup;
            }

            struct aws_stream_status payload_status;
            AWS_ZERO_STRUCT(payload_status);

            while (!payload_status.is_end_of_stream) {
                /* reset the temporary body buffer; we can calculate the hash in window chunks */
                body_buffer.len = 0;
                if (aws_input_stream_read(payload_stream, &body_buffer)) {
                    goto on_cleanup;
                }

                if (body_buffer.len > 0) {
                    struct aws_byte_cursor body_cursor = aws_byte_cursor_from_buf(&body_buffer);
                    aws_hash_update(hash, &body_cursor);
                }

                if (aws_input_stream_get_status(payload_stream, &payload_status)) {
                    goto on_cleanup;
                }
            }

            /* reset the input stream for sending */
            if (aws_input_stream_seek(payload_stream, 0, AWS_SSB_BEGIN)) {
                goto on_cleanup;
            }
        }

        if (aws_hash_finalize(hash, &digest_buffer, 0)) {
            goto on_cleanup;
        }

        struct aws_byte_cursor digest_cursor = aws_byte_cursor_from_buf(&digest_buffer);
        if (aws_hex_encode_append_dynamic(&digest_cursor, payload_hash_buffer)) {
            goto on_cleanup;
        }
    } else {
        /* Use value provided in config */
        if (aws_byte_buf_append_dynamic(payload_hash_buffer, &state->config.signed_body_value)) {
            goto on_cleanup;
        }
    }

    result = AWS_OP_SUCCESS;

on_cleanup:

    aws_byte_buf_clean_up(&digest_buffer);
    aws_byte_buf_clean_up(&body_buffer);

    if (hash) {
        aws_hash_destroy(hash);
    }

    return result;
}