Re: [PATCH v5 12/18] pesto: Expose list of pifs to pesto and optionally display

On Wed, 29 Apr 2026 15:17:34 +1000 David Gibson wrote:

On Sun, Apr 26, 2026 at 09:45:14AM -0400, Jon Maloy wrote:

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On 2026-04-21 02:25, David Gibson wrote:

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Extend the dynamic update protocol to expose the pif indices and names from a running passt/pasta to the pesto tool. pesto records that data and, if requested with a new --show flag, prints it out.

Signed-off-by: David Gibson --- Makefile | 1 + common.h | 2 + conf.c | 41 ++++++++++++++++ pesto.c | 132 ++++++++++++++++++++++++++++++++++++++++++++++++++++ pesto.h | 19 +++++++- pif.h | 4 +- serialise.c | 4 ++ serialise.h | 1 + util.h | 2 - 9 files changed, 200 insertions(+), 6 deletions(-)

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diff --git a/pesto.h b/pesto.h index 92d4df3a..ac4c2b58 100644 --- a/pesto.h +++ b/pesto.h @@ -17,18 +17,33 @@ /* Version 0 is reserved for unreleased / unsupported experimental versions */ #define PESTO_PROTOCOL_VERSION 0 +/* Maxmimum size of a pif name, including \0 */ +#define PIF_NAME_SIZE (128) +#define PIF_NONE 0 + /** * struct pesto_hello - Server introduction message - * @magic: PESTO_SERVER_MAGIC - * @version: Version number + * @magic: PESTO_SERVER_MAGIC + * @version: Version number + * @pif_name_size: Server's value for PIF_NAME_SIZE */ struct pesto_hello { char magic[8]; uint32_t version; + uint32_t pif_name_size; } __attribute__ ((__packed__)); static_assert(sizeof(PESTO_SERVER_MAGIC) == sizeof(((struct pesto_hello *)0)->magic), "PESTO_SERVER_MAGIC has wrong size"); +/** + * struct pesto_pif_info - Message with basic metadata about a pif + * @resv_: Alignment gap (must be 0)

You forgot to remove this one.

Oops, yes.

Fixed in v6.

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+ * @name: Name (\0 terminated) + */ +struct pesto_pif_info { + char name[PIF_NAME_SIZE]; +} __attribute__ ((__packed__)); + #endif /* PESTO_H */ diff --git a/pif.h b/pif.h index 90dd3a32..d7708603 100644 --- a/pif.h +++ b/pif.h @@ -11,6 +11,7 @@ #include +#include "pesto.h" #include "epoll_type.h" union inany_addr; @@ -24,7 +25,7 @@ union sockaddr_inany; */ enum pif_type { /* Invalid or not present pif */ - PIF_NONE = 0, + PIF_NONE_ = PIF_NONE,

This looks a bit weird.

Yes, but it seemed less weird that the other approaches I could think of to do what I needed. The key point here is that the specific value of PIF_NONE is locked as part of the configuration protocol. The values of all other pif indices are (intentionally) passt internal and should not be known by the client.

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As fara as I can see this one is never used.

Yes, that's correct.

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If it is important that PIF_NONE is zero and PIF_HOST is 1,

It's important that PIF_NONE is zero. It's not important that PIF_HOST is 1.

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you could just do:

enum pif_type {

PIF_HOST = 1,

PIF_TAP, PIF_SPLICE,

PIF_NUM_TYPES, };

I could, but I think this makes the connection between the public PIF_NONE and the private PIF_* less obvious.

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or #define PESTO_PIF_END 0 in pesto.h and leave this one as is.

I could - indeed an earlier draft did essentially this. Hoewver, that wouldn't enforce that PIF_NONE is equal to the terminator value, which it should be.

Left as it was in v6. -- Stefano