Re: [dpdk-dev] [PATCH v2] net/pcap: rx_iface_in stream type support

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 6/5/2018 10:39 AM, ido goshen wrote:
> Support rx of in direction packets only
> Useful for apps that also tx to eth_pcap ports in order not to see them
> echoed back in as rx when out direction is also captured

Can you please explain the problem a little more?
If you are using rx_iface and tx_iface arguments you should have different pcap
handlers for Rx and Tx and you shouldn't be getting Tx packets in Rx handler.

> 
> Signed-off-by: ido goshen <ido@cgstowernetworks.com>
> ---
> v2: clean checkpatch warning
> 
>  drivers/net/pcap/rte_eth_pcap.c | 36 ++++++++++++++++++++++++++++++++----

doc/guides/nics/pcap_ring.rst also needs to be updated with this new arg, but
please wait to clarify the above comment, to figure out if this patch really
necessary, before updating that document.

>  1 file changed, 32 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/pcap/rte_eth_pcap.c b/drivers/net/pcap/rte_eth_pcap.c
> index 6bd4a7d..132f469 100644
> --- a/drivers/net/pcap/rte_eth_pcap.c
> +++ b/drivers/net/pcap/rte_eth_pcap.c
> @@ -26,6 +26,7 @@
>  #define ETH_PCAP_RX_PCAP_ARG  "rx_pcap"
>  #define ETH_PCAP_TX_PCAP_ARG  "tx_pcap"
>  #define ETH_PCAP_RX_IFACE_ARG "rx_iface"
> +#define ETH_PCAP_RX_IFACE_IN_ARG "rx_iface_in"
>  #define ETH_PCAP_TX_IFACE_ARG "tx_iface"
>  #define ETH_PCAP_IFACE_ARG    "iface"
>  
> @@ -83,6 +84,7 @@ struct pmd_devargs {
>  	ETH_PCAP_RX_PCAP_ARG,
>  	ETH_PCAP_TX_PCAP_ARG,
>  	ETH_PCAP_RX_IFACE_ARG,
> +	ETH_PCAP_RX_IFACE_IN_ARG,
>  	ETH_PCAP_TX_IFACE_ARG,
>  	ETH_PCAP_IFACE_ARG,
>  	NULL
> @@ -726,6 +728,22 @@ struct pmd_devargs {
>  	return 0;
>  }
>  
> +static inline int
> +set_iface_direction(const char *iface, const char *key, pcap_t *pcap)
> +{
> +	if (strcmp(key, ETH_PCAP_RX_IFACE_IN_ARG) == 0) {

set_iface_direction() can be more generic function, instead of checking the key
here, it can be done the functions calls this.

Also can be possible to make even more generic, this function only sets
direction as PCAP_D_IN, you can get in/out as input to function.

> +		if (pcap_setdirection(pcap, PCAP_D_IN) < 0) {
> +			PMD_LOG(ERR,
> +				"Setting %s pcap direction IN failed - %s\n",
> +				 iface,
> +				 pcap_geterr(pcap));
> +			return -1;
> +		}
> +		PMD_LOG(INFO, "Setting %s pcap direction IN\n", iface);
> +	}
> +	return 0;
> +}
> +
>  /*
>   * Opens a NIC for reading packets from it
>   */
> @@ -740,11 +758,12 @@ struct pmd_devargs {
>  	for (i = 0; i < rx->num_of_queue; i++) {
>  		if (open_single_iface(iface, &pcap) < 0)
>  			return -1;
> +		if (set_iface_direction(iface, key, pcap) < 0)
> +			return -1;
>  		rx->queue[i].pcap = pcap;
>  		rx->queue[i].name = iface;
>  		rx->queue[i].type = key;
>  	}
> -
>  	return 0;
>  }
>  
> @@ -963,17 +982,25 @@ struct pmd_devargs {
>  		is_rx_pcap = 1;
>  	else
>  		pcaps.num_of_queue = rte_kvargs_count(kvlist,
> -				ETH_PCAP_RX_IFACE_ARG);
> +				ETH_PCAP_RX_IFACE_ARG) +
> +				rte_kvargs_count(kvlist,
> +						ETH_PCAP_RX_IFACE_IN_ARG);
>  
>  	if (pcaps.num_of_queue > RTE_PMD_PCAP_MAX_QUEUES)
>  		pcaps.num_of_queue = RTE_PMD_PCAP_MAX_QUEUES;
>  
> -	if (is_rx_pcap)
> +	if (is_rx_pcap) {
>  		ret = rte_kvargs_process(kvlist, ETH_PCAP_RX_PCAP_ARG,
>  				&open_rx_pcap, &pcaps);
> -	else
> +	} else {
>  		ret = rte_kvargs_process(kvlist, ETH_PCAP_RX_IFACE_ARG,
>  				&open_rx_iface, &pcaps);
> +		if (ret == 0)
> +			ret = rte_kvargs_process(kvlist,
> +					ETH_PCAP_RX_IFACE_IN_ARG,
> +					&open_rx_iface,
> +					&pcaps);

I guess there is an assumption here ETH_PCAP_RX_IFACE_ARG and
ETH_PCAP_RX_IFACE_IN_ARG are mutually exclusive. What if user uses both?
Anything to protect against this, or any information to prevent this usage?

> +	}
>  
>  	if (ret < 0)
>  		goto free_kvlist;
> @@ -1046,6 +1073,7 @@ struct pmd_devargs {
>  	ETH_PCAP_RX_PCAP_ARG "=<string> "
>  	ETH_PCAP_TX_PCAP_ARG "=<string> "
>  	ETH_PCAP_RX_IFACE_ARG "=<ifc> "
> +	ETH_PCAP_RX_IFACE_IN_ARG "=<ifc> "
>  	ETH_PCAP_TX_IFACE_ARG "=<ifc> "
>  	ETH_PCAP_IFACE_ARG "=<ifc>");
>  
>