proxy utils: check network interfaces only once
proxy utils: check network interfaces only once

Signed-off-by: Andrew Sy Kim <216147b618cb827f522f086e90f58ea14ddeaac5@gmail.com>

MHBauer/kubernetes,ingvagabund/kubernetes,olivierlemasle/kubernetes,brendandburns/kubernetes,MikeSpreitzer/kubernetes,du2016/kubernetes,bparees/kubernetes,iterion/kubernetes,idvoretskyi/kubernetes,fanzhangio/kubernetes,linux-on-ibm-z/kubernetes,xlgao-zju/kubernetes,thockin/kubernetes,brendandburns/kubernetes,li-ang/kubernetes,nckturner/kubernetes,xychu/kubernetes,cofyc/kubernetes,bparees/kubernetes,mengqiy/kubernetes,Acidburn0zzz/kubernetes,csrwng/kubernetes,ravisantoshgudimetla/kubernetes,xlgao-zju/kubernetes,kitt1987/kubernetes,matthyx/kubernetes,hex108/kubernetes,tengqm/kubernetes,mfojtik/kubernetes,ping035627/kubernetes,zhouhaibing089/kubernetes,wanghaoran1988/kubernetes,verb/kubernetes,mikedanese/kubernetes,idvoretskyi/kubernetes,gnufied/kubernetes,mengqiy/kubernetes,tomzhang/kubernetes,aledbf/kubernetes,rafax/kubernetes,luxas/kubernetes,chestack/kubernetes,ravisantoshgudimetla/kubernetes,tcnghia/kubernetes,jackfrancis/kubernetes,x13n/kubernetes,Lion-Wei/kubernetes,stevesloka/kubernetes,deads2k/kubernetes,fanzhangio/kubernetes,coolsvap/kubernetes,mYmNeo/kubernetes,tpepper/kubernetes,saad-ali/kubernetes,klaus1982/kubernetes,mengqiy/kubernetes,tallclair/kubernetes,thockin/kubernetes,shyamjvs/kubernetes,johscheuer/kubernetes,zhangmingld/kubernetes,rrati/kubernetes,tomzhang/kubernetes,chestack/kubernetes,fabriziopandini/kubernetes,mosoft521/kubernetes,enj/kubernetes,nikhita/kubernetes,mikedanese/kubernetes,liggitt/kubernetes,krmayankk/kubernetes,mahak/kubernetes,stevesloka/kubernetes,xlgao-zju/kubernetes,openshift/kubernetes,dims/kubernetes,jsafrane/kubernetes,lojies/kubernetes,ravisantoshgudimetla/kubernetes,nak3/kubernetes,roberthbailey/kubernetes,rrati/kubernetes,micahhausler/kubernetes,jackfrancis/kubernetes,soltysh/kubernetes,mfojtik/kubernetes,chrislovecnm/kubernetes,monopole/kubernetes,MHBauer/kubernetes,alejandroEsc/kubernetes,weiwei04/kubernetes,li-ang/kubernetes,jagosan/kubernetes,openshift/kubernetes,mikedanese/kubernetes,feiskyer/kubernetes,tallclair/kubernetes,lojies/kubernetes,verult/kubernetes,weiwei04/kubernetes,liggitt/kubernetes,ravisantoshgudimetla/kubernetes,BenTheElder/kubernetes,jsafrane/kubernetes,tomzhang/kubernetes,pires/kubernetes,sdminonne/kubernetes,humblec/kubernetes,wanghaoran1988/kubernetes,joelsmith/kubernetes,MikeSpreitzer/kubernetes,tomzhang/kubernetes,rnaveiras/kubernetes,ravilr/kubernetes,dims/kubernetes,kevin-wangzefeng/kubernetes,deads2k/kubernetes,enj/kubernetes,yujuhong/kubernetes,MHBauer/kubernetes,ingvagabund/kubernetes,aledbf/kubernetes,dlorenc/kubernetes,saad-ali/kubernetes,iterion/kubernetes,verult/kubernetes,GulajavaMinistudio/kubernetes,jdef/kubernetes,kevin-wangzefeng/kubernetes,linux-on-ibm-z/kubernetes,PiotrProkop/kubernetes,k82cn/kubernetes,micahhausler/kubernetes,k82cn/kubernetes,hex108/kubernetes,mosoft521/kubernetes,tpepper/kubernetes,fabriziopandini/kubernetes,tomzhang/kubernetes,andrewsykim/kubernetes,tcnghia/kubernetes,coolsvap/kubernetes,wongma7/kubernetes,fgimenez/kubernetes,lojies/kubernetes,mikebrow/kubernetes,johscheuer/kubernetes,kubernetes/kubernetes,ii/kubernetes,MHBauer/kubernetes,feiskyer/kubernetes,fabriziopandini/kubernetes,monopole/kubernetes,monopole/kubernetes,Lion-Wei/kubernetes,linux-on-ibm-z/kubernetes,ii/kubernetes,nak3/kubernetes,mkumatag/kubernetes,ravilr/kubernetes,luxas/kubernetes,sanjeevm0/kubernetes,tomzhang/kubernetes,liggitt/kubernetes,rrati/kubernetes,mYmNeo/kubernetes,jdef/kubernetes,jessfraz/kubernetes,jdef/kubernetes,spzala/kubernetes,jessfraz/kubernetes,kevin-wangzefeng/kubernetes,joelsmith/kubernetes,andrewrynhard/kubernetes,GulajavaMinistudio/kubernetes,dixudx/kubernetes,feiskyer/kubernetes,JacobTanenbaum/kubernetes,warmchang/kubernetes,csrwng/kubernetes,andrewrynhard/kubernetes,zhouhaibing089/kubernetes,dlorenc/kubernetes,cmluciano/kubernetes,idvoretskyi/kubernetes,andrewsykim/kubernetes,BenTheElder/kubernetes,bparees/kubernetes,mosoft521/kubernetes,jsafrane/kubernetes,krmayankk/kubernetes,carlory/kubernetes,iameli/kubernetes,fgimenez/kubernetes,PiotrProkop/kubernetes,jdef/kubernetes,tomzhang/kubernetes,PI-Victor/kubernetes,ingvagabund/kubernetes,warmchang/kubernetes,matthyx/kubernetes,zhangmingld/kubernetes,xychu/kubernetes,pires/kubernetes,jsafrane/kubernetes,fanzhangio/kubernetes,fgimenez/kubernetes,kevensen/kubernetes,k82/kubernetes,verult/kubernetes,pires/kubernetes,linux-on-ibm-z/kubernetes,iterion/kubernetes,tcnghia/kubernetes,alejandroEsc/kubernetes,zhangmingld/kubernetes,spzala/kubernetes,dereknex/kubernetes,weiwei04/kubernetes,dims/kubernetes,xlgao-zju/kubernetes,verult/kubernetes,aledbf/kubernetes,kevensen/kubernetes,nckturner/kubernetes,brendandburns/kubernetes,krmayankk/kubernetes,csrwng/kubernetes,andrewsykim/kubernetes,cofyc/kubernetes,ping035627/kubernetes,xlgao-zju/kubernetes,du2016/kubernetes,tengqm/kubernetes,matthyx/kubernetes,cblecker/kubernetes,tengqm/kubernetes,mosoft521/kubernetes,Lion-Wei/kubernetes,krmayankk/kubernetes,kitt1987/kubernetes,mahak/kubernetes,tengqm/kubernetes,erwinvaneyk/kubernetes,GulajavaMinistudio/kubernetes,soltysh/kubernetes,erwinvaneyk/kubernetes,andrewrynhard/kubernetes,zhouhaibing089/kubernetes,zhouhaibing089/kubernetes,kubernetes/kubernetes,monopole/kubernetes,verb/kubernetes,idvoretskyi/kubernetes,PiotrProkop/kubernetes,rafax/kubernetes,micahhausler/kubernetes,krmayankk/kubernetes,coolsvap/kubernetes,saad-ali/kubernetes,JacobTanenbaum/kubernetes,JacobTanenbaum/kubernetes,GulajavaMinistudio/kubernetes,kpgriffith/kubernetes,andrewrynhard/kubernetes,wanghaoran1988/kubernetes,mikedanese/kubernetes,stevesloka/kubernetes,tallclair/kubernetes,hex108/kubernetes,klaus1982/kubernetes,brendandburns/kubernetes,pires/kubernetes,matthyx/kubernetes,yarntime/kubernetes,mkumatag/kubernetes,mahak/kubernetes,micahhausler/kubernetes,cblecker/kubernetes,tallclair/kubernetes,cofyc/kubernetes,saad-ali/kubernetes,mikebrow/kubernetes,iameli/kubernetes,luxas/kubernetes,olivierlemasle/kubernetes,openshift/kubernetes,gnufied/kubernetes,rnaveiras/kubernetes,humblec/kubernetes,wongma7/kubernetes,sdminonne/kubernetes,ravilr/kubernetes,ingvagabund/kubernetes,joelsmith/kubernetes,mikebrow/kubernetes,x13n/kubernetes,x13n/kubernetes,erwinvaneyk/kubernetes,aledbf/kubernetes,li-ang/kubernetes,dlorenc/kubernetes,luxas/kubernetes,yujuhong/kubernetes,csrwng/kubernetes,matthyx/kubernetes,PI-Victor/kubernetes,rrati/kubernetes,hex108/kubernetes,mengqiy/kubernetes,roberthbailey/kubernetes,ravisantoshgudimetla/kubernetes,x13n/kubernetes,MHBauer/kubernetes,rrati/kubernetes,Clarifai/kubernetes,mkumatag/kubernetes,chrislovecnm/kubernetes,fgimenez/kubernetes,MikeSpreitzer/kubernetes,fanzhangio/kubernetes,yujuhong/kubernetes,liggitt/kubernetes,nak3/kubernetes,tengqm/kubernetes,bparees/kubernetes,ii/kubernetes,aledbf/kubernetes,saad-ali/kubernetes,jingxu97/kubernetes,yarntime/kubernetes,mkumatag/kubernetes,sanjeevm0/kubernetes,luxas/kubernetes,Acidburn0zzz/kubernetes,warmchang/kubernetes,du2016/kubernetes,lojies/kubernetes,kevensen/kubernetes,iameli/kubernetes,carlory/kubernetes,chestack/kubernetes,andrewrynhard/kubernetes,weiwei04/kubernetes,kitt1987/kubernetes,nak3/kubernetes,nikhita/kubernetes,deads2k/kubernetes,nak3/kubernetes,kitt1987/kubernetes,JacobTanenbaum/kubernetes,kitt1987/kubernetes,li-ang/kubernetes,GulajavaMinistudio/kubernetes,cofyc/kubernetes,pires/kubernetes,nikhita/kubernetes,Clarifai/kubernetes,verb/kubernetes,jagosan/kubernetes,fgimenez/kubernetes,iameli/kubernetes,tcnghia/kubernetes,krmayankk/kubernetes,jackfrancis/kubernetes,mikedanese/kubernetes,dixudx/kubernetes,yujuhong/kubernetes,jessfraz/kubernetes,alejandroEsc/kubernetes,tpepper/kubernetes,k82/kubernetes,sdminonne/kubernetes,warmchang/kubernetes,olivierlemasle/kubernetes,weiwei04/kubernetes,nckturner/kubernetes,yarntime/kubernetes,joelsmith/kubernetes,mfojtik/kubernetes,ingvagabund/kubernetes,soltysh/kubernetes,kpgriffith/kubernetes,mkumatag/kubernetes,carlory/kubernetes,Acidburn0zzz/kubernetes,luxas/kubernetes,x13n/kubernetes,liggitt/kubernetes,tpepper/kubernetes,verult/kubernetes,jsafrane/kubernetes,shyamjvs/kubernetes,wanghaoran1988/kubernetes,monopole/kubernetes,cmluciano/kubernetes,sanjeevm0/kubernetes,x13n/kubernetes,kevin-wangzefeng/kubernetes,gnufied/kubernetes,Clarifai/kubernetes,pires/kubernetes,jessfraz/kubernetes,deads2k/kubernetes,cofyc/kubernetes,andrewsykim/kubernetes,dereknex/kubernetes,bparees/kubernetes,jackfrancis/kubernetes,ravilr/kubernetes,PI-Victor/kubernetes,shyamjvs/kubernetes,coolsvap/kubernetes,cmluciano/kubernetes,enj/kubernetes,micahhausler/kubernetes,k82/kubernetes,xychu/kubernetes,ping035627/kubernetes,dereknex/kubernetes,PI-Victor/kubernetes,jagosan/kubernetes,brendandburns/kubernetes,rnaveiras/kubernetes,PI-Victor/kubernetes,jagosan/kubernetes,idvoretskyi/kubernetes,MikeSpreitzer/kubernetes,dims/kubernetes,Lion-Wei/kubernetes,jackfrancis/kubernetes,jessfraz/kubernetes,nikhita/kubernetes,mengqiy/kubernetes,MikeSpreitzer/kubernetes,xychu/kubernetes,sanjeevm0/kubernetes,du2016/kubernetes,alejandroEsc/kubernetes,nckturner/kubernetes,cmluciano/kubernetes,dims/kubernetes,johscheuer/kubernetes,mahak/kubernetes,humblec/kubernetes,k82/kubernetes,PiotrProkop/kubernetes,thockin/kubernetes,olivierlemasle/kubernetes,mikebrow/kubernetes,tallclair/kubernetes,dixudx/kubernetes,chrislovecnm/kubernetes,johscheuer/kubernetes,iterion/kubernetes,JacobTanenbaum/kubernetes,weiwei04/kubernetes,verb/kubernetes,fabriziopandini/kubernetes,wanghaoran1988/kubernetes,du2016/kubernetes,iterion/kubernetes,thockin/kubernetes,Lion-Wei/kubernetes,xlgao-zju/kubernetes,xychu/kubernetes,klaus1982/kubernetes,feiskyer/kubernetes,kubernetes/kubernetes,zhangmingld/kubernetes,iameli/kubernetes,dereknex/kubernetes,chrislovecnm/kubernetes,rafax/kubernetes,chrislovecnm/kubernetes,Acidburn0zzz/kubernetes,hex108/kubernetes,lojies/kubernetes,jdef/kubernetes,sanjeevm0/kubernetes,mYmNeo/kubernetes,andrewsykim/kubernetes,yarntime/kubernetes,enj/kubernetes,saad-ali/kubernetes,rnaveiras/kubernetes,wongma7/kubernetes,ii/kubernetes,roberthbailey/kubernetes,wongma7/kubernetes,k82/kubernetes,chrislovecnm/kubernetes,jdef/kubernetes,deads2k/kubernetes,stevesloka/kubernetes,roberthbailey/kubernetes,thockin/kubernetes,dixudx/kubernetes,dereknex/kubernetes,tcnghia/kubernetes,kevensen/kubernetes,alejandroEsc/kubernetes,kpgriffith/kubernetes,andrewsykim/kubernetes,chestack/kubernetes,sdminonne/kubernetes,carlory/kubernetes,fabriziopandini/kubernetes,wongma7/kubernetes,tcnghia/kubernetes,kubernetes/kubernetes,kubernetes/kubernetes,BenTheElder/kubernetes,zhouhaibing089/kubernetes,erwinvaneyk/kubernetes,jingxu97/kubernetes,PI-Victor/kubernetes,Acidburn0zzz/kubernetes,nak3/kubernetes,fanzhangio/kubernetes,BenTheElder/kubernetes,shyamjvs/kubernetes,spzala/kubernetes,mikebrow/kubernetes,rnaveiras/kubernetes,jingxu97/kubernetes,tomzhang/kubernetes,PiotrProkop/kubernetes,mYmNeo/kubernetes,li-ang/kubernetes,ingvagabund/kubernetes,cblecker/kubernetes,k82cn/kubernetes,cmluciano/kubernetes,dlorenc/kubernetes,cmluciano/kubernetes,kevensen/kubernetes,cblecker/kubernetes,Clarifai/kubernetes,kpgriffith/kubernetes,openshift/kubernetes,mfojtik/kubernetes,dlorenc/kubernetes,linux-on-ibm-z/kubernetes,zhangmingld/kubernetes,kpgriffith/kubernetes,roberthbailey/kubernetes,Acidburn0zzz/kubernetes,ping035627/kubernetes,mYmNeo/kubernetes,verb/kubernetes,tallclair/kubernetes,olivierlemasle/kubernetes,tomzhang/kubernetes,nikhita/kubernetes,sdminonne/kubernetes,joelsmith/kubernetes,tpepper/kubernetes,jingxu97/kubernetes,jingxu97/kubernetes,stevesloka/kubernetes,Clarifai/kubernetes,Clarifai/kubernetes,fanzhangio/kubernetes,ravilr/kubernetes,feiskyer/kubernetes,soltysh/kubernetes,hex108/kubernetes,zhangmingld/kubernetes,ii/kubernetes,ping035627/kubernetes,johscheuer/kubernetes,csrwng/kubernetes,yarntime/kubernetes,humblec/kubernetes,joelsmith/kubernetes,wanghaoran1988/kubernetes,cblecker/kubernetes,sanjeevm0/kubernetes,shyamjvs/kubernetes,rafax/kubernetes,johscheuer/kubernetes,spzala/kubernetes,yujuhong/kubernetes,idvoretskyi/kubernetes,verult/kubernetes,xychu/kubernetes,andrewrynhard/kubernetes,mfojtik/kubernetes,carlory/kubernetes,spzala/kubernetes,warmchang/kubernetes,BenTheElder/kubernetes,dlorenc/kubernetes,klaus1982/kubernetes,Lion-Wei/kubernetes,kevin-wangzefeng/kubernetes,k82cn/kubernetes,mYmNeo/kubernetes,dereknex/kubernetes,mfojtik/kubernetes,fgimenez/kubernetes,cofyc/kubernetes,openshift/kubernetes,yujuhong/kubernetes,coolsvap/kubernetes,mahak/kubernetes,stevesloka/kubernetes,JacobTanenbaum/kubernetes,ravisantoshgudimetla/kubernetes,chestack/kubernetes,kpgriffith/kubernetes,soltysh/kubernetes,jagosan/kubernetes,mosoft521/kubernetes,yarntime/kubernetes,k82cn/kubernetes,tpepper/kubernetes,enj/kubernetes,gnufied/kubernetes,coolsvap/kubernetes,humblec/kubernetes,gnufied/kubernetes,brendandburns/kubernetes,nckturner/kubernetes,dixudx/kubernetes,iterion/kubernetes,erwinvaneyk/kubernetes,erwinvaneyk/kubernetes,MHBauer/kubernetes,kitt1987/kubernetes