揭开unix网络之纱8- ioctl获得网络接口.doc

揭开unix网络之纱8- ioctl获得网络接口1 概述需处理网络接口的许多程序沿用的初始步骤之一就是从内核获取配置在系统中的所有接口。本任务由SIOCGIFCONF请求完成，它使用ifconf结构，ifconf又使用ifreq结构。1.1 Ifconfig结构struct ifconfint ifc_len;unioncaddr_t ifcu_buf;struct ifreq* ifcu_req;ifc_ifcu;#define ifc_buf ifc_ifcu.ifcu_buf#define ifc_req ifc_ifcu.ifcu_req#define IFNAMSIZ 16Struct ifreqChar ifr_nameIFNAMSIZ;UnionStruct sockaddr ifru_addr;Struct sockaddr ifru_dstaddr;Struct sockaddr ifru_broadaddr;Short ifru_flags;Int ifru_metric;Caddr_t ifru_data;ifr_ifru;#define ifr_addr ifr_ifru.ifru_addr#define ifr_dstaddr ifr_ifru.ifru_dstaddr#define ifr_broadaddr ifr_ifru.ifru_broadaddr#define ifr_flags ifr_ifru.ifru_flags#define ifr_metric ifr_ifru.ifru_metric#define ifr_data ifr_ifru.ifru_data2 Unp_ifi.h#ifndef _UNP_IFI_H#define _UNP_IFI_H#include #define IFI_NAME 16 /*same as IFNAMSIZ in */#define IFI_HADDR 8 /*allow for 64-bit EUI-64 in future*/struct ifi_infochar ifi_nameIFI_NAME; /*interface name,null-terminated*/short ifi_index; /*interface index*/short ifi_mtu; /*interface MTU*/u_char ifi_haddrIFI_HADDR; /*hardware address*/u_short ifi_hlen; /*#bytes in hardware address: 0,6,8*/short ifi_flags; /*IFF_XXX constants from */short ifi_myflags; /*our own IFI_XXX flags*/struct sockaddr *ifi_addr; /*primary address*/struct sockaddr *ifi_brdaddr; /*broadcast address*/struct sockaddr *ifi_dstaddr; /*destination address*/struct ifi_info *ifi_next; /*next of these structures*/;#define IFI_ALIAS 1 /*ifi_addr is an alias*/*function prototypes*/struct ifi_info *get_ifi_info(int,int);void free_ifi_info(struct ifi_info *);#endif3 get_ifi_info#include #include #include #include #include #include #include #include #include #include #include #include #define max(a,b)using namespace std;/将地址转换为字符串，不在这里讨论char *sock_ntop_host(const struct sockaddr *sa, socklen_t salen) static char str128;/* Unix domain is largest */switch (sa-sa_family) case AF_INET: struct sockaddr_in*sin = (struct sockaddr_in *) sa;if (inet_ntop(AF_INET, &sin-sin_addr, str, sizeof(str) = NULL)return(NULL);return(str);#ifdefIPV6case AF_INET6: struct sockaddr_in6*sin6 = (struct sockaddr_in6 *) sa;if (inet_ntop(AF_INET6, &sin6-sin6_addr, str, sizeof(str) = NULL)return(NULL);return(str);#endif#ifdefAF_UNIXcase AF_UNIX: struct sockaddr_un*unp = (struct sockaddr_un *) sa;/* OK to have no pathname bound to the socket: happens on * every connect() unless client calls bind() first. */if (unp-sun_path0 = 0)strcpy(str, (no pathname bound);elsesnprintf(str, sizeof(str), %s, unp-sun_path);return(str);#endif#ifdefHAVE_SOCKADDR_DL_STRUCTcase AF_LINK: struct sockaddr_dl*sdl = (struct sockaddr_dl *) sa;if (sdl-sdl_nlen 0)snprintf(str, sizeof(str), %*s, sdl-sdl_nlen, &sdl-sdl_data0);elsesnprintf(str, sizeof(str), AF_LINK, index=%d, sdl-sdl_index);return(str);#endifdefault:snprintf(str, sizeof(str), sock_ntop_host: unknown AF_xxx: %d, len %d, sa-sa_family, salen);return(str); return (NULL);/关键struct ifi_info* get_ifi_info(int family,int doaliases)/unp_ifi.h文件中定义struct ifi_info *ifi,*ifihead,*ifipnext;int sockfd,len,lastlen,flags,myflags,idx=0,hlen=0;char *ptr,*buf,lastnameIFNAMSIZ,*cptr,*haddr,*sdlname;/中定义struct ifconf ifc;struct ifreq *ifr,ifrcopy;/地址struct sockaddr_in *sinptr;struct sockaddr_in6 *sin6ptr;/创建socket套接字，数据报sockfd = socket(AF_INET,SOCK_DGRAM,0);lastlen=0;len=100*sizeof(struct ifreq);/取出网络接口信息for(;)/开辟100 fireq的空间buf=(char*)malloc(len);ifc.ifc_len=len;ifc.ifc_buf=buf;if(ioctl(sockfd,SIOCGIFCONF,&ifc)0)if(errno != EINVAL | lastlen != 0)coutioctl errorendl;exit(0);elseif(ifc.ifc_len = lastlen);break;lastlen=ifc.ifc_len;len+=10*(sizeof(struct ifreq);free(buf);ifihead=NULL;ifipnext=&ifihead;lastname0=0;sdlname=NULL;for(ptr=buf;ptrifr_addr.sa_len);#elseswitch(ifr-ifr_addr.sa_family)#ifdefIPV6case AF_INET6:len=sizeof(struct sockaddr_in6);break;#endifcase AF_INET:default:len=sizeof(struct sockaddr);break;#endifptr+=sizeof(ifr-ifr_name)+len;#ifdef HAVE_SOCKADDR_DL_STRUCTif(ifr-ifr_addr.sa_family=AF_LINE)struct sockaddr_dl *sdl=(struct sockaddr_dl*)&ifr-ifr_addr;sdlname=ifr-ifr_name;idx=sdl-sdl_index;haddr=sdl-sdl_data + sdl-sdl_nlen;hlen=sdl-sdl_alen;#endifif(ifr-ifr_addr.sa_family != family)continue;myflags=0;if(cptr=strchr(ifr-ifr_name,:)!=NULL)*cptr=0;if(strncmp(lastname,ifr-ifr_name,IFNAMSIZ) =0)if(doaliases=0)continue;myflags=IFI_ALIAS;memcpy(lastname,ifr-ifr_name,IFNAMSIZ);ifrcopy = *ifr;ioctl(sockfd,SIOCGIFFLAGS,&ifrcopy);flags=ifrcopy.ifr_flags;if(flags & IFF_UP)=0)continue;ifi=(ifi_info*)calloc(1,sizeof(struct ifi_info);*ifipnext=ifi;ifipnext=&ifi-ifi_next;ifi-ifi_flags=flags;ifi-ifi_myflags=myflags;#if defined(SIOCGIFMTU) & defined(HAVE_STRUCT_IFREQ_IFR_MTU)ioctl(sockfd,SIOCGIFMTU,&ifrcopy);ifi-ifi_mtu=ifrcopy.ifr_mtu;#else ifi-ifi_mtu=0;#endifmemcpy(ifi-ifi_name,ifr-ifr_name,IFI_NAME);ifi-ifi_nameIFI_NAME-1=0;if(sdlname=NULL | strcmp(sdlname,ifr-ifr_name) != 0)idx=hlen=0;ifi-ifi_index=idx;ifi-ifi_hlen=hlen;if(ifi-ifi_hlen IFI_HADDR)ifi-ifi_hlen=IFI_HADDR;if(hlen)memcpy(ifi-ifi_haddr,haddr,ifi-ifi_hlen);switch(ifr-ifr_addr.sa_family)case AF_INET:sinptr=(struct sockaddr_in*)&ifr-ifr_addr;ifi-ifi_addr=(struct sockaddr*)calloc(1,sizeof(struct sockaddr_in);memcpy(ifi-ifi_addr,sinptr,sizeof(struct sockaddr_in);#ifdef SIOCGIFBRDADDRif(flags & IFF_BROADCAST)ioctl(sockfd,SIOCGIFBRDADDR,&ifrcopy);sinptr=(struct sockaddr_in*)&ifrcopy.ifr_broadaddr;ifi-ifi_brdaddr=(struct sockaddr*)calloc(1,sizeof(struct sockaddr_in);memcpy(ifi-ifi_brdaddr,sinptr,sizeof(struct sockaddr_in);#endif#ifdefSIOCGIFDSTADDRif(flags & IFF_POINTOPOINT)ioctl(sockfd,SIOCGIFDSTADDR,&ifrcopy);sin6ptr=(struct sockaddr_in6*)&ifrcopy.ifr_dstaddr;ifi-ifi_dstaddr=(struct sockaddr*)calloc(1,sizeof(struct sockaddr_in6);memcpy(ifi-ifi_dstaddr,sin6ptr,sizeof(struct sockaddr_in6);#endifbreak;default:break;free(buf);return(ifihead);void free_ifi_info(struct ifi_info *ifihead)struct ifi_info *ifi,*ifinext;for(ifi = ifihead;ifi != NULL;ifi=ifinext)if(ifi-ifi_addr != NULL)free(ifi-ifi_addr);if(ifi-ifi_dstaddr != NULL)free(ifi-ifi_brdaddr);if(ifi-ifi_dstaddr != NULL)free(ifi-ifi_dstaddr);ifinext=ifi-ifi_next;free(ifi);int main(int argc,char* argv)struct ifi_info *ifi,*ifihead;struct sockaddr* sa;u_char *ptr;int i,family,doaliases;if(argc != 3)coutusage: prifinfo endl;exit(0);if(strcmp(argv1,inet4)=0)family=AF_INET;else if(strcmp(argv1,inet6)=0)family=AF_INET6;elsecoutinvalid ifi_next)printf(%s: ,ifi-ifi_name);if(ifi-ifi_index != 0)printf(%d) ,ifi-ifi_index);printf(ifi_flags & IFF_UP) printf(UP );if(ifi-ifi_flags & IFF_BROADCAST) printf(BCAST );if(ifi-ifi_flags & IFF_MULTICAST) printf(MCAST );if(ifi-ifi_flags & IFF_LOOPBACK) printf(LOOP );if(ifi-ifi_flags & IFF_POINTOPOINT) printf(P2P );printf(n);if(i=ifi-ifi_hlen) 0)ptr=ifi-ifi_haddr;doprintf(%s%x, (i = ifi-ifi_hlen) ? : :,*ptr+);while(-i0);printf(n);if(ifi-ifi_mtu != 0)printf( MTU: %dn,ifi-ifi_mtu);if(