On Friday, 18 October 2024 23:47:13 CEST Noah Peterson wrote:
> Modify the batctl ping utility to accept both integer and floating-point
> values for the interval between sending pings. This enhancement allows
> specifying intervals with millisecond precision.

You use nanosleep - so this would be nanoseconds. But it is unlikely that we 
would be able to send in this precise interval. So maybe rename it it 
subsecond.

> 
> For example:
> `sudo batctl ping aa:bb:cc:dd:ee:ff -i 0.5`
> 
> Also, improve error handling for invalid interval arguments.
> 
> Signed-off-by: Noah Peterson <[email protected]>
> ---
>  ping.c | 35 +++++++++++++++++++++++++++--------
>  1 file changed, 27 insertions(+), 8 deletions(-)
> 
> diff --git a/ping.c b/ping.c
> index 3681e7e..104b17c 100644
> --- a/ping.c
> +++ b/ping.c
> @@ -16,6 +16,7 @@
>  #include <signal.h>
>  #include <fcntl.h>
>  #include <string.h>
> +#include <limits.h>
>  #include <math.h>
>  #include <stddef.h>
>  #include <stdint.h>

#include <time.h> missing after <sys/time.h>.

> @@ -65,14 +66,15 @@ static int ping(struct state *state, int argc, char 
> **argv)
>       struct bat_host *bat_host, *rr_host;
>       ssize_t read_len;
>       int ret = EXIT_FAILURE, res, optchar, found_args = 1;
> -     int loop_count = -1, loop_interval = 0, timeout = 1, rr = 0, i;
> +     int loop_count = -1, timeout = 1, rr = 0, i;
>       unsigned int seq_counter = 0, packets_out = 0, packets_in = 0, 
> packets_loss;
> -     char *dst_string, *mac_string, *rr_string;
> -     double time_delta;
> +     char *dst_string, *mac_string, *rr_string, *end, *loop_interval = NULL;
> +     double time_delta, ping_interval = 0.0;
>       float min = 0.0, max = 0.0, avg = 0.0, mdev = 0.0;
>       uint8_t last_rr_cur = 0, last_rr[BATADV_RR_LEN][ETH_ALEN];
>       size_t packet_len;
>       int disable_translate_mac = 0;
> +     struct timespec req;
>  
>       while ((optchar = getopt(argc, argv, "hc:i:t:RT")) != -1) {
>               switch (optchar) {
> @@ -86,9 +88,7 @@ static int ping(struct state *state, int argc, char **argv)
>                       ping_usage();
>                       return EXIT_SUCCESS;
>               case 'i':
> -                     loop_interval = strtol(optarg, NULL , 10);
> -                     if (loop_interval < 1)
> -                             loop_interval = 1;
> +                     loop_interval = strdup(optarg);

Why are you duplicating this string?

>                       found_args += ((*((char*)(optarg - 1)) == optchar ) ? 1 
> : 2);
>                       break;
>               case 't':
> @@ -135,6 +135,25 @@ static int ping(struct state *state, int argc, char 
> **argv)
>               }
>       }
>  
> +     if (loop_interval) {
> +             errno = 0;
> +             ping_interval = strtod(loop_interval, &end);
> +             free(loop_interval);
> +
> +             if (errno || end != (loop_interval + strlen(loop_interval))) {

Use after-free of loop_interval

> +                     fprintf(stderr, "Error - invalid ping interval '%s'\n", 
> (ULONG_MAX / 1000000 - 1.0));

You can't print a double as string. Please use %f, %e or %g to print a double 
value.

But the text actually suggest that you didn't want to print the calculated 
value in the first place

> +                     goto out;
> +             } else if (ping_interval >= (ULONG_MAX / 1000000 - 1.0)) {

Similar to the previously calculated value - this doesn't make a lot of sense. 
You are dividing ULONG_MAX by 1e6 but we have no place where we handle 
something related to Msecs or usecs. tv_sec is in time_t and not related to 
ULONG_MAX / 1e6.

I can also not explain the -1.0 (at the moment). I first thought this was a 
bad attempt to floor the ping interval - but this would be on the wrong side 
of the comparison and there is actually a function for that. And since the 
ULONG_MAX / 1e6 seems to be random, I am unable to find the reason for this.

> +                     fprintf(stderr, "Error - ping interval too large\n");
> +                     goto out;
> +             } else {
> +                     ping_interval = fmax(ping_interval, 0.001);
> +             }
> +
> +             req.tv_sec = (long) (ping_interval);

time_t not long

> +               req.tv_nsec = fmod(ping_interval, 1.0) * 1000000000l;

I think this would be a good place to use modf to split integral and 
fractional part.

Kind regards,
        Sven

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