Re: [PATCH iproute2-next v2 1/6] ipaddress: Improve print_linkinfo()

[Serhey Popovych]

David Ahern wrote:
> On 1/30/18 11:09 AM, Serhey Popovych wrote:
> 
>> diff --git a/ip/ipaddress.c b/ip/ipaddress.c
>> index 051a05f..f8fd392 100644
>> --- a/ip/ipaddress.c
>> +++ b/ip/ipaddress.c
>> @@ -948,14 +948,14 @@ int print_linkinfo_brief(const struct sockaddr_nl *who,
>>  parse_rtattr(tb, IFLA_MAX, IFLA_RTA(ifi), len);
>>  if (tb[IFLA_IFNAME] == NULL) {
>>  fprintf(stderr, "BUG: device with ifindex %d has nil ifname\n", 
>> ifi->ifi_index);
>> -name = "";
>> +name = ll_index_to_name(ifi->ifi_index);
> 
> This is one of those "should never happen checks" since the kernel
> always adds IFLA_IFNAME. Going to a cache to get a name for the index
> when the existing message is missing that attribute seems wrong. I
> realize the expectation is that the cache is empty today so if%d is
> returned, but that could change and it is the idea of consulting a cache
> that I think is wrong.
> 
> If that intention is to have a name I think it is safer to just have it
> set to if%d here (or in a helper that the cache also uses).

In my opinion in print_*() functions it is expected that cache isn't
empty. That's actually point where we benefit from cache.

I understand side effects this change may introduce and your concerns
about them. Will present small set of changes to export "if%d" template
from lib/ll_map.c for use here.

Using "" of something other, even for "should never happen" case
seems wrong to me.

> 
>>  } else {
>>  name = rta_getattr_str(tb[IFLA_IFNAME]);
>>  }
>>  
>>  if (pfilter->label &&
>>  (!pfilter->family || pfilter->family == AF_PACKET) &&
>> -fnmatch(pfilter->label, RTA_DATA(tb[IFLA_IFNAME]), 0))
>> +fnmatch(pfilter->label, name, 0))
>>  return -1;
>>  
>>  if (tb[IFLA_GROUP]) {
>> @@ -1057,6 +1057,7 @@ int print_linkinfo(const struct sockaddr_nl *who,
>>  struct ifinfomsg *ifi = NLMSG_DATA(n);
>>  struct rtattr *tb[IFLA_MAX+1];
>>  int len = n->nlmsg_len;
>> +const char *name;
>>  unsigned int m_flag = 0;
>>  
>>  if (n->nlmsg_type != RTM_NEWLINK && n->nlmsg_type != RTM_DELLINK)
>> @@ -1067,18 +1068,22 @@ int print_linkinfo(const struct sockaddr_nl *who,
>>  return -1;
>>  
>>  if (filter.ifindex && ifi->ifi_index != filter.ifindex)
>> -return 0;
>> +return -1;
>>  if (filter.up && !(ifi->ifi_flags_UP))
>> -return 0;
>> +return -1;
>>  
>>  parse_rtattr(tb, IFLA_MAX, IFLA_RTA(ifi), len);
>> -if (tb[IFLA_IFNAME] == NULL)
>> +if (tb[IFLA_IFNAME] == NULL) {
>>  fprintf(stderr, "BUG: device with ifindex %d has nil ifname\n", 
>> ifi->ifi_index);
>> +name = ll_index_to_name(ifi->ifi_index);
> 
> same here
> 
> 
>> +} else {
>> +name = rta_getattr_str(tb[IFLA_IFNAME]);
>> +}
>>  
>>  if (filter.label &&
>>  (!filter.family || filter.family == AF_PACKET) &&
>> -fnmatch(filter.label, RTA_DATA(tb[IFLA_IFNAME]), 0))
>> -return 0;
>> +fnmatch(filter.label, name, 0))
>> +return -1;
>>  
>>  if (tb[IFLA_GROUP]) {
>>  int group = rta_getattr_u32(tb[IFLA_GROUP]);
>> @@ -1105,16 +1110,7 @@ int print_linkinfo(const struct sockaddr_nl *who,
>>  print_bool(PRINT_ANY, "deleted", "Deleted ", true);
>>  
>>  print_int(PRINT_ANY, "ifindex", "%d: ", ifi->ifi_index);
>> -if (tb[IFLA_IFNAME]) {
>> -print_color_string(PRINT_ANY,
>> -   COLOR_IFNAME,
>> -   "ifname", "%s",
>> -   rta_getattr_str(tb[IFLA_IFNAME]));
>> -} else {
>> -print_null(PRINT_JSON, "ifname", NULL, NULL);
>> -print_color_null(PRINT_FP, COLOR_IFNAME,
>> - "ifname", "%s", "");
>> -}
>> +print_color_string(PRINT_ANY, COLOR_IFNAME, "ifname", "%s", name);
>>  
>>  if (tb[IFLA_LINK]) {
>>  int iflink = rta_getattr_u32(tb[IFLA_LINK]);
>>
> 




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Re: [PATCH iproute2-next v2 1/6] ipaddress: Improve print_linkinfo()

[David Ahern]

On 1/30/18 11:09 AM, Serhey Popovych wrote:

> diff --git a/ip/ipaddress.c b/ip/ipaddress.c
> index 051a05f..f8fd392 100644
> --- a/ip/ipaddress.c
> +++ b/ip/ipaddress.c
> @@ -948,14 +948,14 @@ int print_linkinfo_brief(const struct sockaddr_nl *who,
>   parse_rtattr(tb, IFLA_MAX, IFLA_RTA(ifi), len);
>   if (tb[IFLA_IFNAME] == NULL) {
>   fprintf(stderr, "BUG: device with ifindex %d has nil ifname\n", 
> ifi->ifi_index);
> - name = "";
> + name = ll_index_to_name(ifi->ifi_index);

This is one of those "should never happen checks" since the kernel
always adds IFLA_IFNAME. Going to a cache to get a name for the index
when the existing message is missing that attribute seems wrong. I
realize the expectation is that the cache is empty today so if%d is
returned, but that could change and it is the idea of consulting a cache
that I think is wrong.

If that intention is to have a name I think it is safer to just have it
set to if%d here (or in a helper that the cache also uses).

>   } else {
>   name = rta_getattr_str(tb[IFLA_IFNAME]);
>   }
>  
>   if (pfilter->label &&
>   (!pfilter->family || pfilter->family == AF_PACKET) &&
> - fnmatch(pfilter->label, RTA_DATA(tb[IFLA_IFNAME]), 0))
> + fnmatch(pfilter->label, name, 0))
>   return -1;
>  
>   if (tb[IFLA_GROUP]) {
> @@ -1057,6 +1057,7 @@ int print_linkinfo(const struct sockaddr_nl *who,
>   struct ifinfomsg *ifi = NLMSG_DATA(n);
>   struct rtattr *tb[IFLA_MAX+1];
>   int len = n->nlmsg_len;
> + const char *name;
>   unsigned int m_flag = 0;
>  
>   if (n->nlmsg_type != RTM_NEWLINK && n->nlmsg_type != RTM_DELLINK)
> @@ -1067,18 +1068,22 @@ int print_linkinfo(const struct sockaddr_nl *who,
>   return -1;
>  
>   if (filter.ifindex && ifi->ifi_index != filter.ifindex)
> - return 0;
> + return -1;
>   if (filter.up && !(ifi->ifi_flags_UP))
> - return 0;
> + return -1;
>  
>   parse_rtattr(tb, IFLA_MAX, IFLA_RTA(ifi), len);
> - if (tb[IFLA_IFNAME] == NULL)
> + if (tb[IFLA_IFNAME] == NULL) {
>   fprintf(stderr, "BUG: device with ifindex %d has nil ifname\n", 
> ifi->ifi_index);
> + name = ll_index_to_name(ifi->ifi_index);

same here


> + } else {
> + name = rta_getattr_str(tb[IFLA_IFNAME]);
> + }
>  
>   if (filter.label &&
>   (!filter.family || filter.family == AF_PACKET) &&
> - fnmatch(filter.label, RTA_DATA(tb[IFLA_IFNAME]), 0))
> - return 0;
> + fnmatch(filter.label, name, 0))
> + return -1;
>  
>   if (tb[IFLA_GROUP]) {
>   int group = rta_getattr_u32(tb[IFLA_GROUP]);
> @@ -1105,16 +1110,7 @@ int print_linkinfo(const struct sockaddr_nl *who,
>   print_bool(PRINT_ANY, "deleted", "Deleted ", true);
>  
>   print_int(PRINT_ANY, "ifindex", "%d: ", ifi->ifi_index);
> - if (tb[IFLA_IFNAME]) {
> - print_color_string(PRINT_ANY,
> -COLOR_IFNAME,
> -"ifname", "%s",
> -rta_getattr_str(tb[IFLA_IFNAME]));
> - } else {
> - print_null(PRINT_JSON, "ifname", NULL, NULL);
> - print_color_null(PRINT_FP, COLOR_IFNAME,
> -  "ifname", "%s", "");
> - }
> + print_color_string(PRINT_ANY, COLOR_IFNAME, "ifname", "%s", name);
>  
>   if (tb[IFLA_LINK]) {
>   int iflink = rta_getattr_u32(tb[IFLA_LINK]);
> 

[PATCH iproute2-next v2 1/6] ipaddress: Improve print_linkinfo()

[Serhey Popovych]

There are few places to improve:

  1) return -1 when entry is filtered instead of zero, which means
 accept entry: ipaddress_list_flush_or_save() the only user of this

  2) use ll_index_to_name() as last resort to translate name to index:
 it will return name in the form "if%d" in case of failure

  3) replace open coded access to IFLA_IFNAME attribute data by
 RTA_DATA() with rta_getattr_str()

  4) simplify ifname printing since name is never NULL, thanks to (2).

Signed-off-by: Serhey Popovych 
---
 ip/ipaddress.c |   30 +-
 1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/ip/ipaddress.c b/ip/ipaddress.c
index 051a05f..f8fd392 100644
--- a/ip/ipaddress.c
+++ b/ip/ipaddress.c
@@ -948,14 +948,14 @@ int print_linkinfo_brief(const struct sockaddr_nl *who,
parse_rtattr(tb, IFLA_MAX, IFLA_RTA(ifi), len);
if (tb[IFLA_IFNAME] == NULL) {
fprintf(stderr, "BUG: device with ifindex %d has nil ifname\n", 
ifi->ifi_index);
-   name = "";
+   name = ll_index_to_name(ifi->ifi_index);
} else {
name = rta_getattr_str(tb[IFLA_IFNAME]);
}
 
if (pfilter->label &&
(!pfilter->family || pfilter->family == AF_PACKET) &&
-   fnmatch(pfilter->label, RTA_DATA(tb[IFLA_IFNAME]), 0))
+   fnmatch(pfilter->label, name, 0))
return -1;
 
if (tb[IFLA_GROUP]) {
@@ -1057,6 +1057,7 @@ int print_linkinfo(const struct sockaddr_nl *who,
struct ifinfomsg *ifi = NLMSG_DATA(n);
struct rtattr *tb[IFLA_MAX+1];
int len = n->nlmsg_len;
+   const char *name;
unsigned int m_flag = 0;
 
if (n->nlmsg_type != RTM_NEWLINK && n->nlmsg_type != RTM_DELLINK)
@@ -1067,18 +1068,22 @@ int print_linkinfo(const struct sockaddr_nl *who,
return -1;
 
if (filter.ifindex && ifi->ifi_index != filter.ifindex)
-   return 0;
+   return -1;
if (filter.up && !(ifi->ifi_flags_UP))
-   return 0;
+   return -1;
 
parse_rtattr(tb, IFLA_MAX, IFLA_RTA(ifi), len);
-   if (tb[IFLA_IFNAME] == NULL)
+   if (tb[IFLA_IFNAME] == NULL) {
fprintf(stderr, "BUG: device with ifindex %d has nil ifname\n", 
ifi->ifi_index);
+   name = ll_index_to_name(ifi->ifi_index);
+   } else {
+   name = rta_getattr_str(tb[IFLA_IFNAME]);
+   }
 
if (filter.label &&
(!filter.family || filter.family == AF_PACKET) &&
-   fnmatch(filter.label, RTA_DATA(tb[IFLA_IFNAME]), 0))
-   return 0;
+   fnmatch(filter.label, name, 0))
+   return -1;
 
if (tb[IFLA_GROUP]) {
int group = rta_getattr_u32(tb[IFLA_GROUP]);
@@ -1105,16 +1110,7 @@ int print_linkinfo(const struct sockaddr_nl *who,
print_bool(PRINT_ANY, "deleted", "Deleted ", true);
 
print_int(PRINT_ANY, "ifindex", "%d: ", ifi->ifi_index);
-   if (tb[IFLA_IFNAME]) {
-   print_color_string(PRINT_ANY,
-  COLOR_IFNAME,
-  "ifname", "%s",
-  rta_getattr_str(tb[IFLA_IFNAME]));
-   } else {
-   print_null(PRINT_JSON, "ifname", NULL, NULL);
-   print_color_null(PRINT_FP, COLOR_IFNAME,
-"ifname", "%s", "");
-   }
+   print_color_string(PRINT_ANY, COLOR_IFNAME, "ifname", "%s", name);
 
if (tb[IFLA_LINK]) {
int iflink = rta_getattr_u32(tb[IFLA_LINK]);
-- 
1.7.10.4