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Fix shown IP address belonging to wrong interface

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The following commit:

  6a75ea9 Show IP address when address has a label

introduced a way to show the IP address of an interface when a label is
associated to the IP.

When a label is associated to an IP, the structure returned by
getifaddrs() has the label concatenated to the interface name in the
.ifa_name field as in the following example:

    struct ifaddrs ifaddr = {
       .ifa_name = "eth0:mylabel",
    };

As a consequence, using a strict comparison between the interface name
and the .ifa_name field yields a falsy result. However, checking if the
.ifa_name starts with the interface name (e.g. eth0) does not work
either because other network interfaces can have a name which starts
with eth0.

This commit solves the issue by stripping out the optional label from
the .ifa_name field before making a strict comparison with the interface
name.

Fix #283

Signed-off-by: Olivier Gayot <olivier.gayot@sigexec.com>
This commit is contained in:
Olivier Gayot 2018-06-04 19:59:15 +02:00
parent 99a6fb5e49
commit 451ff9be0b
1 changed files with 31 additions and 2 deletions
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33
src/print_ip_addr.c
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@ -12,6 +12,31 @@
#include "i3status.h"
/*
* Return a copy of the .ifa_name field passed as argument where the optional
* IP label, if present, is removed.
*
* example:
* - strip_optional_label("eth0") => "eth0"
* - strip_optional_label("eth0:label") => "eth0"
*
* The memory for the returned string is obtained with malloc(3), and can be
* freed with free(3).
*
*
*/
static char *strip_optional_label(const char *ifa_name) {
char *copy = sstrdup(ifa_name);
char *ptr = strchr(copy, ':');
if (ptr) {
*ptr = '\0';
}
return copy;
}
/*
* Return the IP address for the given interface or "no IP" if the
* interface is up and running but hasn't got an IP address yet
@ -29,7 +54,6 @@ const char *get_ip_addr(const char *interface, int family) {
struct ifaddrs *ifaddr, *addrp;
bool found = false;
int interface_len = strlen(interface);
getifaddrs(&ifaddr);
@ -38,7 +62,12 @@ const char *get_ip_addr(const char *interface, int family) {
/* Skip until we are at the input family address of interface */
for (addrp = ifaddr; addrp != NULL; addrp = addrp->ifa_next) {
if (strncmp(addrp->ifa_name, interface, interface_len) != 0) {
/* Strip the label if present in the .ifa_name field. */
char *stripped_ifa_name = strip_optional_label(addrp->ifa_name);
bool name_matches = strcmp(stripped_ifa_name, interface) != 0;
free(stripped_ifa_name);
if (name_matches) {
/* The interface does not have the right name, skip it. */
continue;
}