Re: [PATCH] net/tap: add support for fixed mac addresses

["Wiles, Keith" <keith.wiles@intel.com>]

> On Apr 11, 2017, at 10:09 AM, Pascal Mazon <pascal.mazon@6wind.com> wrote:
> 
> Support for a fixed MAC address for testing with the last octet
> incrementing by one for each interface defined with the new 'mac=fixed'
> string on the --vdev option. The default option is still to randomize
> the MAC address for each tap interface.
> 
> Signed-off-by: Keith Wiles <keith.wiles@intel.com>
> Signed-off-by: Pascal Mazon <pascal.mazon@6wind.com>
> ---
> 
> Hi Keith, I've made the changes I suggested.
> 
> It does as expected use a mac incremented by 1 for each new tap device,
> without a global variable for fixed_mac_type.
> 
> With the more clean "\0dtap" initialization for mac[], I do think it
> looks better, don't you?
> I agree my version with \x did little improvement to yours, and would
> be a question of style.
> What do you say of this patch?

The patch looks fine, I guess I did not want to change the function API (for some strange reason), but I agree removing the static works.

I can remove my patch and allow this one to replace it.

> 
> doc/guides/nics/tap.rst       | 13 ++++++++++++-
> drivers/net/tap/rte_eth_tap.c | 39 ++++++++++++++++++++++++++++++++++++---
> 2 files changed, 48 insertions(+), 4 deletions(-)
> 
> diff --git a/doc/guides/nics/tap.rst b/doc/guides/nics/tap.rst
> index 5c5ba5357bba..f3ee95d2897b 100644
> --- a/doc/guides/nics/tap.rst
> +++ b/doc/guides/nics/tap.rst
> @@ -46,7 +46,7 @@ These TAP interfaces can be used with Wireshark or tcpdump or Pktgen-DPDK
> along with being able to be used as a network connection to the DPDK
> application. The method enable one or more interfaces is to use the
> ``--vdev=net_tap0`` option on the DPDK application command line. Each
> -``--vdev=net_tap1`` option give will create an interface named dtap0, dtap1,
> +``--vdev=net_tap1`` option given will create an interface named dtap0, dtap1,
> and so on.
> 
> The interface name can be changed by adding the ``iface=foo0``, for example::
> @@ -58,6 +58,17 @@ needed, but the interface does not enforce that speed, for example::
> 
>    --vdev=net_tap0,iface=foo0,speed=25000
> 
> +Normally the PMD will generate a random MAC address, but when testing or with
> +a static configuration the developer may need a fixed MAC address style.
> +Using the option ``mac=fixed`` you can create a fixed known MAC address::
> +
> +   --vdev=net_tap0,mac=fixed
> +
> +The MAC address will have a fixed value with the last octet incrementing by one
> +for each interface string containing ``mac=fixed``. The MAC address is formatted
> +as 00:'d':'t':'a':'p':[00-FF]. Convert the characters to hex and you get the
> +actual MAC address: ``00:64:74:61:70:[00-FF]``.
> +
> It is possible to specify a remote netdevice to capture packets from by adding
> ``remote=foo1``, for example::
> 
> diff --git a/drivers/net/tap/rte_eth_tap.c b/drivers/net/tap/rte_eth_tap.c
> index cd82a7e09c75..2092f5d4184b 100644
> --- a/drivers/net/tap/rte_eth_tap.c
> +++ b/drivers/net/tap/rte_eth_tap.c
> @@ -1,7 +1,7 @@
> /*-
>  *   BSD LICENSE
>  *
> - *   Copyright(c) 2016 Intel Corporation. All rights reserved.
> + *   Copyright(c) 2016-2017 Intel Corporation. All rights reserved.
>  *   All rights reserved.
>  *
>  *   Redistribution and use in source and binary forms, with or without
> @@ -71,6 +71,8 @@
> #define ETH_TAP_IFACE_ARG       "iface"
> #define ETH_TAP_SPEED_ARG       "speed"
> #define ETH_TAP_REMOTE_ARG      "remote"
> +#define ETH_TAP_MAC_ARG         "mac"
> +#define ETH_TAP_MAC_FIXED       "fixed"
> 
> #define FLOWER_KERNEL_VERSION KERNEL_VERSION(4, 2, 0)
> #define FLOWER_VLAN_KERNEL_VERSION KERNEL_VERSION(4, 9, 0)
> @@ -81,6 +83,7 @@ static const char *valid_arguments[] = {
> 	ETH_TAP_IFACE_ARG,
> 	ETH_TAP_SPEED_ARG,
> 	ETH_TAP_REMOTE_ARG,
> +	ETH_TAP_MAC_ARG,
> 	NULL
> };
> 
> @@ -1131,7 +1134,8 @@ tap_kernel_support(struct pmd_internals *pmd)
> }
> 
> static int
> -eth_dev_tap_create(const char *name, char *tap_name, char *remote_iface)
> +eth_dev_tap_create(const char *name, char *tap_name, char *remote_iface,
> +		   int fixed_mac_type)
> {
> 	int numa_node = rte_socket_id();
> 	struct rte_eth_dev *dev = NULL;
> @@ -1229,6 +1233,13 @@ eth_dev_tap_create(const char *name, char *tap_name, char *remote_iface)
> 		}
> 		rte_memcpy(&pmd->eth_addr, ifr.ifr_hwaddr.sa_data,
> 			   ETHER_ADDR_LEN);
> +	} else if (fixed_mac_type) {
> +		/* fixed mac = 00:64:74:61:70:<iface_idx> */
> +		static int iface_idx;
> +		char mac[ETHER_ADDR_LEN] = "\0dtap";
> +
> +		mac[ETHER_ADDR_LEN - 1] = iface_idx++;
> +		rte_memcpy(&pmd->eth_addr, mac, ETHER_ADDR_LEN);
> 	} else {
> 		eth_random_addr((uint8_t *)&pmd->eth_addr);
> 	}
> @@ -1285,6 +1296,17 @@ set_remote_iface(const char *key __rte_unused,
> 	return 0;
> }
> 
> +static int
> +set_mac_type(const char *key __rte_unused,
> +	     const char *value,
> +	     void *extra_args)
> +{
> +	if (value &&
> +	    !strncasecmp(ETH_TAP_MAC_FIXED, value, strlen(ETH_TAP_MAC_FIXED)))
> +		*(int *)extra_args = 1;
> +       return 0;
> +}
> +
> /* Open a TAP interface device.
>  */
> static int
> @@ -1295,6 +1317,7 @@ rte_pmd_tap_probe(const char *name, const char *params)
> 	int speed;
> 	char tap_name[RTE_ETH_NAME_MAX_LEN];
> 	char remote_iface[RTE_ETH_NAME_MAX_LEN];
> +	int fixed_mac_type = 0;
> 
> 	speed = ETH_SPEED_NUM_10G;
> 	snprintf(tap_name, sizeof(tap_name), "%s%d",
> @@ -1332,6 +1355,15 @@ rte_pmd_tap_probe(const char *name, const char *params)
> 				if (ret == -1)
> 					goto leave;
> 			}
> +
> +			if (rte_kvargs_count(kvlist, ETH_TAP_MAC_ARG) == 1) {
> +				ret = rte_kvargs_process(kvlist,
> +							 ETH_TAP_MAC_ARG,
> +							 &set_mac_type,
> +							 &fixed_mac_type);
> +				if (ret == -1)
> +					goto leave;
> +			}
> 		}
> 	}
> 	pmd_link.link_speed = speed;
> @@ -1339,7 +1371,7 @@ rte_pmd_tap_probe(const char *name, const char *params)
> 	RTE_LOG(NOTICE, PMD, "Initializing pmd_tap for %s as %s\n",
> 		name, tap_name);
> 
> -	ret = eth_dev_tap_create(name, tap_name, remote_iface);
> +	ret = eth_dev_tap_create(name, tap_name, remote_iface, fixed_mac_type);
> 
> leave:
> 	if (ret == -1) {
> @@ -1397,4 +1429,5 @@ RTE_PMD_REGISTER_ALIAS(net_tap, eth_tap);
> RTE_PMD_REGISTER_PARAM_STRING(net_tap,
> 			      ETH_TAP_IFACE_ARG "=<string> "
> 			      ETH_TAP_SPEED_ARG "=<int> "
> +			      ETH_TAP_MAC_ARG "=" ETH_TAP_MAC_FIXED " "
> 			      ETH_TAP_REMOTE_ARG "=<string>");
> -- 
> 2.12.0.306.g4a9b9b3
> 

Regards,
Keith