From: Theo Buehler <tb@theobuehler.org>
Subject: Re: bgpd: include NOTIFICATION data in logging if verbose
To: tech@openbsd.org
Date: Tue, 9 Sep 2025 13:55:59 +0200

On Tue, Sep 09, 2025 at 01:43:53PM +0200, Claudio Jeker wrote:
> Sometimes it is helpful to see a hexdump of the additional notification
> data sent since it may provide the needed info to better understand why
> the notification was triggered.
> 
> This diff adds this extra logging for UPDATE if verbose is on.

I think the offset in hexdumps is usually printed as hex, but if
decimal is what helps you here, sure

ok tb

> -- 
> :wq Claudio
> 
> Index: logmsg.c
> ===================================================================
> RCS file: /cvs/src/usr.sbin/bgpd/logmsg.c,v
> diff -u -p -r1.15 logmsg.c
> --- logmsg.c	21 Aug 2025 15:15:25 -0000	1.15
> +++ logmsg.c	9 Sep 2025 11:33:36 -0000
> @@ -128,6 +128,27 @@ log_statechange(struct peer *peer, enum 
>  	    eventnames[event]);
>  }
>  
> +static const char *
> +tohex(const unsigned char *in, size_t len)
> +{
> +	const char hex[] = "0123456789ABCDEF";
> +	static char out[(16 + 1) * 3];
> +	size_t i, o = 0;
> +
> +	if (len > 16)
> +		len = 16;
> +	for (i = 0; i < len; i++) {
> +		out[o++] = hex[in[i] >> 4];
> +		out[o++] = hex[in[i] & 0xf];
> +		out[o++] = ' ';
> +		if (i == 7)
> +			out[o++] = ' ';
> +	}
> +	out[o - 1] = '\0';
> +
> +	return out;
> +}
> +
>  void
>  log_notification(const struct peer *peer, uint8_t errcode, uint8_t subcode,
>      const struct ibuf *data, const char *dir)
> @@ -135,7 +156,7 @@ log_notification(const struct peer *peer
>  	struct ibuf	 ibuf;
>  	char		*p;
>  	const char	*suberrname = NULL;
> -	int		 uk = 0;
> +	int		 uk = 0, dump = 0;
>  
>  	if (data != NULL)
>  		ibuf_from_ibuf(&ibuf, data);
> @@ -176,6 +197,7 @@ log_notification(const struct peer *peer
>  			uk = 1;
>  		else
>  			suberrname = suberr_update_names[subcode];
> +		dump = 1;
>  		break;
>  	case ERR_CEASE:
>  		if (subcode >= sizeof(suberr_cease_names) / sizeof(char *) ||
> @@ -238,6 +260,23 @@ log_notification(const struct peer *peer
>  			logit(LOG_ERR, "%s: %s notification: %s, %s",
>  			    p, dir, errnames[errcode], suberrname);
>  	}
> +
> +	if (dump && log_getverbose() && ibuf_size(&ibuf) > 0) {
> +		size_t off = 0;
> +		logit(LOG_INFO, "%s: notification data", p);
> +		while (ibuf_size(&ibuf) > 0) {
> +			unsigned char buf[16];
> +			size_t len = sizeof(buf);
> +			if (ibuf_size(&ibuf) < len)
> +				len = ibuf_size(&ibuf);
> +			if (ibuf_get(&ibuf, buf, len) == -1) {
> +				break;
> +			}
> +			logit(LOG_INFO, "   %5zu: %s", off, tohex(buf, len));
> +			off += len;
> +		}
> +	}
> +
>  	free(p);
>  }
>  
>