commit ea9f048761d0b9a2ab6310bffa07351f0b04d8c5 Author: Olaf Kirch Date: Tue Sep 2 12:11:15 2008 -0400 Always make IPv6 sockets V6ONLY Assume you have a netconfig file looking like this: udp tpi_clts v inet udp - - udp6 tpi_clts v inet6 udp - - ... a call to svc_tli_create(... &someaddr, "udp") will fail to create an IPv6 server socket. The problem is that on Linux, passive IPv6 sockets will also accept packets/connections from IPv4, and will simply map the sender's address to an IPv6 mapped IPv4 address. So if you want to bind both a UDPv4 and UDPv6 socket to the same port, this will fail with EADDRINUSE. The way to avoid this behavior is to change the socket to V6ONLY, which tells the kernel to avoid the autmatic mapping. The change proposed in the patch below does this. I *think* this is a good place to do this, as it will also fix applications that do not use svc_tli_create() - such as rpcbind, which creates the sockets on its own using __rpc_nconf2fd. I think this also improves portability, as BSD code assumes BSD behavior, where this mapping does not occur either. Signed-off-by: Olaf Kirch Signed-off-by: Steve Dickson diff --git a/src/rpc_generic.c b/src/rpc_generic.c index 583aff0..ff4ba16 100644 --- a/src/rpc_generic.c +++ b/src/rpc_generic.c @@ -525,11 +525,18 @@ int __rpc_nconf2fd(const struct netconfig *nconf) { struct __rpc_sockinfo si; + int fd; if (!__rpc_nconf2sockinfo(nconf, &si)) return 0; - return socket(si.si_af, si.si_socktype, si.si_proto); + if ((fd = socket(si.si_af, si.si_socktype, si.si_proto)) >= 0 && + si.si_af == AF_INET6) { + int val = 1; + + setsockopt(fd, SOL_IPV6, IPV6_V6ONLY, &val, sizeof(val)); + } + return fd; } int