Re: [PATCH 1/1] tidbits: net-udp: solicit new client for server mode

[Philippe Gerum <rpm@xenomai.org>]

Philippe Gerum <rpm@xenomai.org> writes:

> Hannes Diethelm <hannes.diethelm@gmail.com> writes:
>
>> This fixes random EINPROGRESS at init or during runtime.
>>
>> Also correct whitespaces and make stdout more consistent.
>>
>> Signed-off-by: Hannes Diethelm <hannes.diethelm@gmail.com>
>> ---
>>  tidbits/oob-net-udp.c | 58 +++++++++++++++++++++++++++++++++++++------
>>  1 file changed, 50 insertions(+), 8 deletions(-)
>>
>> diff --git a/tidbits/oob-net-udp.c b/tidbits/oob-net-udp.c
>> index 11b8459..7af834f 100644
>> --- a/tidbits/oob-net-udp.c
>> +++ b/tidbits/oob-net-udp.c
>> @@ -50,12 +50,12 @@ static void usage(void)
>>  }
>>  
>>  static void print_addr(char* text, struct sockaddr_in *addr){
>> -    char ip_str[INET_ADDRSTRLEN+1];
>> -    inet_ntop(AF_INET, &(addr->sin_addr), ip_str, sizeof(ip_str));
>> -    evl_printf("%s--------\n", text);
>> -    evl_printf("IP-Address: %s\n", ip_str);
>> -    evl_printf("Port:       %d\n", ntohs(addr->sin_port));
>> -    evl_printf("Family:     %d\n", addr->sin_family);
>> +	char ip_str[INET_ADDRSTRLEN+1];
>> +	inet_ntop(AF_INET, &(addr->sin_addr), ip_str, sizeof(ip_str));
>> +	evl_printf("== %s\n", text);
>> +	evl_printf("   ip-address: %s\n", ip_str);
>> +	evl_printf("   port:       %d\n", ntohs(addr->sin_port));
>> +	evl_printf("   family:     %d\n", addr->sin_family);
>>  }
>>  
>>  static void sender(int s, const char *text, int mcount,
>> @@ -226,6 +226,8 @@ static void client(int s, const char *text, int mcount,
>>  	free(tbuf);
>>  }
>>  
>> +#define SERVER_ADDR_LIST_SIZE 64
>> +
>>  static void server(int s, const char *text, int mcount,
>>  		struct sockaddr_in *addr, int iter)
>>  {
>> @@ -236,6 +238,9 @@ static void server(int s, const char *text, int mcount,
>>  	ssize_t ret;
>>  	char *tbuf;
>>  	char rbuf[16384];
>> +	in_addr_t addr_list[SERVER_ADDR_LIST_SIZE]={};
>                                                   ^ missing whitespaces
>> +	size_t addr_list_fill=0;
>> +	bool solicit_done;
>>  
>>  	tlen = (strlen(text) + 1) * mcount;
>>  	tbuf = malloc(tlen);
>> @@ -276,6 +281,39 @@ static void server(int s, const char *text, int mcount,
>>  			evl_printf(" (TRUNCATED)");
>>  		evl_printf(": %.*s\n", (int)ret, rbuf);
>>  
>> +		/*
>> +		 * We need to call evl_net_solicit for each new
>> +		 * client once before sending data. This will break
>> +		 * realtime for the first response.
>> +		 * If this is not done and the ARP address is not
>> +		 * yet in cache or garbage-collected, oob_sendmsg
>> +		 * will return EINPROGRESS on start or during runtime.
>> +		 */
>
> We can happily send redundant solicit requests to the core, no need to
> filter out cached addresses, evl_net_solicit() will do the right thing.
>

Except that doing so would always demote the caller to the in-band
stage, which may not be what you want. The fact that we'd need to
maintain a cache in apps in order to figure out whether solicitation
should be done shows a shortcoming in the core, users should not have to
do this dance.

We should have an oob call for probing the route+arp caches with
ipv4. I'll look into this asap.

-- 
Philippe.