getifaddr.c: prefer non-reserved over reserved addresses in `getifaddr()`
When iterating interface addresses obtained via `getifaddrs()`, don't stop at the first found IPv4 address but continue checking all IPv4 addresses and prefer to use a non-reserved one in case an interface has both reserved (private) and non-reserved (public) addresses assigned. After this fix, miniupnpd on OpenWrt is able to properly detect the external IP address of an external interface with both a private RFC1918 and a public IP assigned regardless of whether `getifaddrs()` happens to return the private or the public IPv4 address first. Signed-off-by: Jo-Philipp Wich <jo@mein.io>
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@ -101,6 +101,7 @@ getifaddr(const char * ifname, char * buf, int len,
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/* Works for all address families (both ip v4 and ip v6) */
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struct ifaddrs * ifap;
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struct ifaddrs * ife;
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struct ifaddrs * candidate = NULL;
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if(!ifname || ifname[0]=='\0')
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return -1;
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@ -119,14 +120,10 @@ getifaddr(const char * ifname, char * buf, int len,
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switch(ife->ifa_addr->sa_family)
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{
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case AF_INET:
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if(buf)
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{
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inet_ntop(ife->ifa_addr->sa_family,
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&((struct sockaddr_in *)ife->ifa_addr)->sin_addr,
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buf, len);
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}
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if(addr) *addr = ((struct sockaddr_in *)ife->ifa_addr)->sin_addr;
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if(mask) *mask = ((struct sockaddr_in *)ife->ifa_netmask)->sin_addr;
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if(!candidate ||
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(addr_is_reserved(&((struct sockaddr_in *)candidate->ifa_addr)->sin_addr) &&
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!addr_is_reserved(&((struct sockaddr_in *)ife->ifa_addr)->sin_addr)))
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candidate = ife;
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break;
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/*
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case AF_INET6:
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@ -136,6 +133,17 @@ getifaddr(const char * ifname, char * buf, int len,
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*/
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}
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}
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if(candidate)
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{
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if(buf)
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{
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inet_ntop(candidate->ifa_addr->sa_family,
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&((struct sockaddr_in *)candidate->ifa_addr)->sin_addr,
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buf, len);
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}
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if(addr) *addr = ((struct sockaddr_in *)candidate->ifa_addr)->sin_addr;
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if(mask) *mask = ((struct sockaddr_in *)candidate->ifa_netmask)->sin_addr;
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}
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freeifaddrs(ifap);
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#endif
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return 0;
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