하지만 다양한 플랫폼을 지원하기 위해서 범용적인 코드를 원한다면
아래의 예제처럼 구현하기 보다는 pcap library 를 사용하기를 권합니다.
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/* Copyright (c) 2002 Information Equipment co.,LTD. All Right Reserved. Code by JaeHyuk Cho <minzkn@infoeq.co.kr> - Simple is best */ #if !defined(DEF_ifconfig_c) #define DEF_ifconfig_c "ifconfig.c" #include <stdio.h> #include <unistd.h> #include <stdlib.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <sys/ioctl.h> #include <netinet/in.h> #include <net/if.h> #include <netinet/if_ether.h> #include <arpa/inet.h> #include <netdb.h> #include <netinet/ether.h> int main(int s_Argc, char **s_Argv); int main(int s_Argc, char **s_Argv) { int s_SocketHandle; int s_RequestCount = 10; struct ifconf s_ifconfig; struct ifreq *s_ifrequest; struct sockaddr_in *s_SockAddr_In; char s_StringBuffer[1 << 10]; char *s_MyTitle; char *s_MyDevice; char *s_MyIP, *s_MyBroadcastIP, *s_MyNetmaskIP; char *s_MyHWAddr; char *s_MyFlagString; int s_MyFlags, s_MyMTU, s_MyMetric; fprintf(stdout, "MZ_ifconfig v0.0.1b - Copyright(c)InfoEQ co.,LTD - %s %s\n", __DATE__, __TIME__); fprintf(stdout, "Code by JaeHyuk Cho - <minzkn@infoeq.co.kr>\n\n"); s_SocketHandle = socket(AF_INET, SOCK_DGRAM, 0); if(s_SocketHandle >= 0) { memset((void *)&s_ifconfig, 0, sizeof(struct ifconf)); do { if(s_ifconfig.ifc_buf)free(s_ifconfig.ifc_buf); s_ifconfig.ifc_len = sizeof(struct ifreq) * s_RequestCount; s_ifconfig.ifc_buf = malloc(s_ifconfig.ifc_len); if(s_ifconfig.ifc_buf) { if(ioctl(s_SocketHandle, SIOCGIFCONF, &s_ifconfig) == 0) { if(s_ifconfig.ifc_len < (sizeof(struct ifreq) * s_RequestCount)) { s_ifrequest = s_ifconfig.ifc_req; if(s_ifrequest) { for(s_RequestCount = 0;s_RequestCount < s_ifconfig.ifc_len;s_RequestCount += sizeof(struct ifreq), s_ifrequest++) { /* ------------------------------------------------------------------------ */ s_MyDevice = strdup(s_ifrequest->ifr_name); /* ioctl(s_SocketHandle, SIOCGIFADDR, s_ifrequest); */ s_SockAddr_In = (struct sockaddr_in *)(&s_ifrequest->ifr_addr); s_MyIP = strdup(inet_ntoa(s_SockAddr_In->sin_addr)); ioctl(s_SocketHandle, SIOCGIFBRDADDR, s_ifrequest); s_SockAddr_In = (struct sockaddr_in *)&s_ifrequest->ifr_broadaddr; s_MyBroadcastIP = strdup(inet_ntoa(s_SockAddr_In->sin_addr)); ioctl(s_SocketHandle, SIOCGIFNETMASK, s_ifrequest); s_SockAddr_In = (struct sockaddr_in *)&s_ifrequest->ifr_netmask; s_MyNetmaskIP = strdup(inet_ntoa(s_SockAddr_In->sin_addr)); #if 0 if(ioctl(s_SocketHandle, SIOCGIFHWADDR, s_ifrequest) == 0) { unsigned char s_NullHWAddr[] = {0, 0, 0, 0, 0, 0}; if(memcmp(&s_ifrequest->ifr_hwaddr.sa_data[0], &s_NullHWAddr[0], sizeof(s_NullHWAddr)) == 0)strcpy(s_StringBuffer, ""); else sprintf(s_StringBuffer, "HWAddr %s", ether_ntoa((struct ether_addr *)s_ifrequest->ifr_hwaddr.sa_data)); } else strcpy(s_StringBuffer, "HWAddr <ERROR>"); #else if(ioctl(s_SocketHandle, SIOCGIFHWADDR, s_ifrequest) == 0) { sprintf(s_StringBuffer, "HWAddr %s", ether_ntoa((struct ether_addr *)s_ifrequest->ifr_hwaddr.sa_data)); } else strcpy(s_StringBuffer, "HWAddr <ERROR>"); #endif s_MyHWAddr = strdup(s_StringBuffer); if(ioctl(s_SocketHandle, SIOCGIFFLAGS, s_ifrequest) == 0)s_MyFlags = s_ifrequest->ifr_flags; else s_MyFlags = 0; strcpy(s_StringBuffer, ""); if(s_MyFlags == 0)strcpy(s_StringBuffer, "[NO FLAGS]"); else { if(s_MyFlags & IFF_UP )strcat(s_StringBuffer, "UP "); if(s_MyFlags & IFF_BROADCAST )strcat(s_StringBuffer, "BROADCAST "); if(s_MyFlags & IFF_DEBUG )strcat(s_StringBuffer, "DEBUG "); if(s_MyFlags & IFF_LOOPBACK )strcat(s_StringBuffer, "LOOPBACK "); if(s_MyFlags & IFF_POINTOPOINT )strcat(s_StringBuffer, "POINTOPOINT "); if(s_MyFlags & IFF_NOTRAILERS )strcat(s_StringBuffer, "NOTRAILERS "); if(s_MyFlags & IFF_RUNNING )strcat(s_StringBuffer, "RUNNING "); if(s_MyFlags & IFF_NOARP )strcat(s_StringBuffer, "NOARP "); if(s_MyFlags & IFF_PROMISC )strcat(s_StringBuffer, "PROMISC "); if(s_MyFlags & IFF_ALLMULTI )strcat(s_StringBuffer, "ALLMULTI "); if(s_MyFlags & IFF_SLAVE )strcat(s_StringBuffer, "SLAVE "); if(s_MyFlags & IFF_MASTER )strcat(s_StringBuffer, "MASTER "); if(s_MyFlags & IFF_MULTICAST )strcat(s_StringBuffer, "MULTICAST "); } s_MyFlagString = strdup(s_StringBuffer); s_MyTitle = strdup("Unknown"); /* Not support */ if(ioctl(s_SocketHandle, SIOCGIFMTU, s_ifrequest) == 0)s_MyMTU = s_ifrequest->ifr_mtu; else s_MyMTU = 0; if(ioctl(s_SocketHandle, SIOCGIFMETRIC, s_ifrequest) == 0)s_MyMetric = s_ifrequest->ifr_metric; else s_MyMetric = 0; /* Print. */ fprintf(stdout, "%-8s Link encap:%s %s\n" "%-8s inet addr %-15s Broadcast %-15s Netmask %-15s\n" "%-8s %s MTU:%d Metric:%d\n" "\n", s_MyDevice, s_MyTitle, s_MyHWAddr, "", s_MyIP, s_MyBroadcastIP, s_MyNetmaskIP, "", s_MyFlagString, s_MyMTU, s_MyMetric ? s_MyMetric : 1 ); /* Free. */ if(s_MyTitle )free(s_MyTitle); if(s_MyDevice )free(s_MyDevice); if(s_MyIP )free(s_MyIP); if(s_MyBroadcastIP)free(s_MyBroadcastIP); if(s_MyNetmaskIP )free(s_MyNetmaskIP); if(s_MyHWAddr )free(s_MyHWAddr); if(s_MyFlagString )free(s_MyFlagString); /* ------------------------------------------------------------------------ */ } } break; } else s_RequestCount += 10; } else break; } else break; }while(1); if(s_ifconfig.ifc_buf)free(s_ifconfig.ifc_buf); close(s_SocketHandle); } else fprintf(stderr, "Can not open socket !!!\n"); return(0); } #endif /* End of source */ |
위의 예제를 조금더 응용하여
현재 내가 보유한 여러개의 IP중에서 어떤 IP가 route를 통하는지
검출하는 간략한 예제입니다.
즉, 이것은 여러개의 IP를 가지고 있을때 이중에서 어떤것이
인터넷으로 패킷이 탈수 있는지 검출하는 것입니다.
물론 이것은 너무 간략하게 구현하려고 약간의 case 에 대해서 버그가 존재합니다. 그것은 적절히 코드를 보강하면 됩니다.
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/* Copyright (c) 2002 Information Equipment co.,LTD. All Right Reserved. Code by JaeHyuk Cho <minzkn@infoeq.co.kr> - Simple is best */ #include <stdio.h> #include <unistd.h> #include <stdlib.h> #include <string.h> #include <sys/types.h> #include <sys/socket.h> #include <sys/ioctl.h> #include <netinet/in.h> #include <net/if.h> #include <netinet/if_ether.h> #include <arpa/inet.h> #include <netdb.h> #include <unistd.h> #include <fcntl.h> int main(int s_Argc, char **s_Argv); int main(int s_Argc, char **s_Argv) { const char *c_Proc_Route = "/proc/net/route"; int s_SocketHandle, s_Handle, s_ReadBytes, s_RequestCount = 10; struct ifconf s_ifconfig; struct ifreq *s_ifrequest; struct sockaddr_in *s_SockAddr_In; char *s_MyDevice; char *s_MyIP, *s_MyBroadcastIP, *s_MyNetmaskIP, *s_RouteIP, *s_RouteName; char s_Buffer[ 32 << 10 ]; s_RouteIP = s_RouteName = (char *)0; s_Handle = open(c_Proc_Route, O_RDONLY); if(s_Handle >= 0) { s_ReadBytes = read(s_Handle, &s_Buffer[0], sizeof(s_Buffer) - 1); close(s_Handle); if(s_ReadBytes > 0) { unsigned long s_Destination, s_Gateway, s_Flags, s_RefCnt, s_Use, s_Metric, s_Mask; char *s_TraceBuffer; int s_Index; s_Buffer[ s_ReadBytes ] = '\0'; s_Index = 0; s_TraceBuffer = (char *)(&s_Buffer[s_Index]); do { s_RouteName = (char *)0; if(s_Buffer[s_Index] == '\0' || s_Buffer[s_Index] == '\n') { s_Buffer[s_Index] = '\0'; s_RouteName = s_TraceBuffer; while((*s_TraceBuffer) != ' ' && (*s_TraceBuffer) != '\t' && (*s_TraceBuffer) != '\0')s_TraceBuffer++; *(s_TraceBuffer++) = '\0'; while(((*s_TraceBuffer) == ' ' || (*s_TraceBuffer) == '\t') && (*s_TraceBuffer) != '\0')s_TraceBuffer++; if(sscanf(s_TraceBuffer, "%lx%lx%lX%lu%lu%lu%lx", &s_Destination, &s_Gateway, &s_Flags, &s_RefCnt, &s_Use, &s_Metric, &s_Mask) == 7) { if(s_Destination == 0lu) { /* fprintf(stdout, "Default route [%s:%s]\n", s_RouteName, s_TraceBuffer); */ break; } /* else fprintf(stdout, "Normal route [%s:%s]\n", s_RouteName, s_TraceBuffer); */ } /* else fprintf(stdout, "Non line [%s:%s]\n", s_RouteName, s_TraceBuffer); */ s_Index++; s_TraceBuffer = (char *)(&s_Buffer[s_Index]); } else if(s_Buffer[s_Index] == '\r')s_Buffer[s_Index++] = ' '; else s_Index++; }while(s_Index < s_ReadBytes); } } else fprintf(stderr, "Can not open \"%s\"\n", c_Proc_Route); if(s_RouteName == (char *)0) { return(-1); } s_SocketHandle = socket(AF_INET, SOCK_DGRAM, 0); if(s_SocketHandle >= 0) { memset((void *)&s_ifconfig, 0, sizeof(struct ifconf)); do { if(s_ifconfig.ifc_buf)free(s_ifconfig.ifc_buf); s_ifconfig.ifc_len = sizeof(struct ifreq) * s_RequestCount; s_ifconfig.ifc_buf = malloc(s_ifconfig.ifc_len); if(s_ifconfig.ifc_buf) { if(ioctl(s_SocketHandle, SIOCGIFCONF, &s_ifconfig) == 0) { if(s_ifconfig.ifc_len < (sizeof(struct ifreq) * s_RequestCount)) { s_ifrequest = s_ifconfig.ifc_req; if(s_ifrequest) { for(s_RequestCount = 0;s_RequestCount < s_ifconfig.ifc_len;s_RequestCount += sizeof(struct ifreq), s_ifrequest++) { s_MyDevice = strdup(s_ifrequest->ifr_name); ioctl(s_SocketHandle, SIOCGIFADDR, s_ifrequest); s_SockAddr_In = (struct sockaddr_in *)(&s_ifrequest->ifr_addr); s_MyIP = strdup(inet_ntoa(s_SockAddr_In->sin_addr)); ioctl(s_SocketHandle, SIOCGIFBRDADDR, s_ifrequest); s_SockAddr_In = (struct sockaddr_in *)&s_ifrequest->ifr_broadaddr; s_MyBroadcastIP = strdup(inet_ntoa(s_SockAddr_In->sin_addr)); ioctl(s_SocketHandle, SIOCGIFNETMASK, s_ifrequest); s_SockAddr_In = (struct sockaddr_in *)&s_ifrequest->ifr_netmask; s_MyNetmaskIP = strdup(inet_ntoa(s_SockAddr_In->sin_addr)); if(strcmp(s_MyDevice, "lo") != 0 && strcmp(s_RouteName, s_MyDevice) == 0)fprintf(stdout, "%s %s\n", s_MyDevice, s_MyIP); if(s_MyDevice )free(s_MyDevice); if(s_MyIP )free(s_MyIP); if(s_MyBroadcastIP)free(s_MyBroadcastIP); if(s_MyNetmaskIP )free(s_MyNetmaskIP); } } break; } else s_RequestCount += 10; } else break; } else break; }while(1); if(s_ifconfig.ifc_buf)free(s_ifconfig.ifc_buf); close(s_SocketHandle); } else fprintf(stderr, "Can not open socket !!!\n"); return(0); } /* End of source */ |
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