On Sat, 2023-01-28 at 14:43 -0800, Richard Cochran wrote:
> Signed-off-by: Richard Cochran <richardcoch...@gmail.com>
> ---
> tlv.c | 58
> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> tlv.h | 26 ++++++++++++++++++++++++++
> 2 files changed, 84 insertions(+)
>
> diff --git a/tlv.c b/tlv.c
> index 2e421ed..212414f 100644
> --- a/tlv.c
> +++ b/tlv.c
> @@ -77,6 +77,22 @@ static uint16_t flip16(void *p)
> return v;
> }
>
> +static void host2net32_unaligned(void *p)
> +{
> + int32_t v;
> + memcpy(&v, p, sizeof(v));
> + v = htonl(v);
> + memcpy(p, &v, sizeof(v));
> +}
> +
> +static void net2host32_unaligned(void *p)
> +{
> + int32_t v;
> + memcpy(&v, p, sizeof(v));
> + v = ntohl(v);
> + memcpy(p, &v, sizeof(v));
> +}
> +
> static int64_t host2net64_unaligned(void *p)
> {
> int64_t v;
> @@ -111,6 +127,43 @@ static bool tlv_array_invalid(struct TLV *tlv,
> size_t base_size, size_t item_siz
> return (tlv->length == expected_length) ? false : true;
> }
>
> +static int alttime_offset_post_recv(struct tlv_extra *extra)
> +{
> + struct TLV *tlv = extra->tlv;
> + struct alternate_time_offset_indicator_tlv *atoi =
> + (struct alternate_time_offset_indicator_tlv *) tlv;
> +
> + if (tlv->length < sizeof(struct
> alternate_time_offset_indicator_tlv) +
> + atoi->displayName.length - sizeof(struct TLV)) {
> + return -EBADMSG;
> + }
> +
> + NTOHS(atoi->type);
> + NTOHS(atoi->length);
> + /* Message alignment broken by design. */
> + net2host32_unaligned(&atoi->currentOffset);
> + net2host32_unaligned(&atoi->jumpSeconds);
> + flip16(&atoi->timeOfNextJump.seconds_msb);
> + net2host32_unaligned(&atoi->timeOfNextJump.seconds_lsb);
> +
> + return 0;
> +}
> +
> +static void alttime_offset_pre_send(struct tlv_extra *extra)
> +{
> + struct alternate_time_offset_indicator_tlv *atoi;
> +
> + atoi = (struct alternate_time_offset_indicator_tlv *) extra-
> >tlv;
> +
> + HTONS(atoi->type);
> + HTONS(atoi->length);
> + /* Message alignment broken by design. */
> + host2net32_unaligned(&atoi->currentOffset);
> + host2net32_unaligned(&atoi->jumpSeconds);
> + flip16(&atoi->timeOfNextJump.seconds_msb);
> + host2net32_unaligned(&atoi->timeOfNextJump.seconds_lsb);
> +}
> +
> static int mgt_post_recv(struct management_tlv *m, uint16_t
> data_len,
> struct tlv_extra *extra)
> {
> @@ -1035,6 +1088,8 @@ int tlv_post_recv(struct tlv_extra *extra)
> }
> break;
> case TLV_ALTERNATE_TIME_OFFSET_INDICATOR:
> + result = alttime_offset_post_recv(extra);
> + break;
> case TLV_AUTHENTICATION_2008:
> case TLV_AUTHENTICATION_CHALLENGE:
> case TLV_SECURITY_ASSOCIATION_UPDATE:
> @@ -1098,7 +1153,10 @@ void tlv_pre_send(struct TLV *tlv, struct
> tlv_extra *extra)
> unicast_negotiation_pre_send(tlv);
> break;
> case TLV_PATH_TRACE:
> + break;
> case TLV_ALTERNATE_TIME_OFFSET_INDICATOR:
> + alttime_offset_pre_send(extra);
> + break;
> case TLV_AUTHENTICATION_2008:
> case TLV_AUTHENTICATION_CHALLENGE:
> case TLV_SECURITY_ASSOCIATION_UPDATE:
> diff --git a/tlv.h b/tlv.h
> index 3dbce4f..a1a7dbc 100644
> --- a/tlv.h
> +++ b/tlv.h
> @@ -175,6 +175,32 @@ struct grant_unicast_xmit_tlv {
> uint8_t flags;
> } PACKED;
>
> +struct alternate_time_offset_indicator_tlv {
> + Enumeration16 type;
> + UInteger16 length;
> + UInteger8 keyField;
> + /* Message alignment broken by design. */
> + Integer32 currentOffset;
> + Integer32 jumpSeconds;
> + struct {
> + uint16_t seconds_msb; /* 16 bits + */
> + uint32_t seconds_lsb; /* 32 bits = 48 bits*/
> + } PACKED timeOfNextJump;
> + struct PTPText displayName;
> +} PACKED;
> +
> +struct alternate_time_offset_properties {
> + UInteger8 keyField;
> + /* Message alignment broken by design. */
> + Integer32 currentOffset;
> + Integer32 jumpSeconds;
> + struct {
> + uint16_t seconds_msb; /* 16 bits + */
> + uint32_t seconds_lsb; /* 32 bits = 48 bits*/
> + } PACKED timeOfNextJump;
> + uint8_t pad;
> +} PACKED;
> +
> struct management_tlv {
> Enumeration16 type;
> UInteger16 length;
I understand the idea in general.
And I understand the files in the TLVs are unaligned.
But Does htonl() and ntohl() have problem with alignment?
Or the point was using pointers?
Please add a short explanation for the solution.
The explanation on "alignment break by design" is very clear :-)
Erez
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