[insert project logo here (125x200px max)] Navigator Home Downloads Documentation Research News Forums Project Summary CVS repository Mailinglists Help Announcement Developer Please report any errors or ommissions you find to our `Help' mailinglist, or post a message in the Forums. Copyright and Licensing Information Snap is (c) Jonathan T. Moore, 1999-2002 and licensed under the GNU General Public License (GPL). All other parts of Splash are (c) Willem de Bruijn, 2002-2003 and licensed under the BSD Open Source License. All sourcecode is made publicly available. Acknowledgement Splash and the Splash website are hosted by SourceForge.net

Splash - Documentation SNMP Plus a Lightweight API for SNAP Handling             snap_svc/snap_svc_if.c Go to the documentation of this file. /* snap service library */ /* (c) Willem de Bruijn, 2002, 2003 */ /* Licensed under the BSD License */ /* snap_svc_if library sourcefile */ /* platform includes (linux) */ #include <sys/ioctl.h> #include <sys/socket.h> #include <asm/types.h> #include <netinet/in.h> #include <net/if.h> /* libc includes */ #include <string.h> #include <arpa/inet.h> #include <unistd.h> #include <stdlib.h> #include <stdio.h> /* local includes */ #include "d_printf.h" #include "snap_svc.h" #include "snap_svc_if.h" /* global variables */ unsigned int snap_svc_if_count = 0; unsigned int snap_svc_if_maxidx = 0; struct snap_svc_ifip_item* iface_list = NULL; /* library handling functions */ void snap_external_svclib_init(){ if (snap_svc_ifip_init()) d_printf(50,"snap_svc_if : initialized\n"); else d_printf(50,"snap_svc_if : initialized with errors\n"); } void snap_external_svclib_done(){ int count; if (iface_list){ for(count=0; count == snap_svc_if_maxidx + 1; count++){ if (iface_list[count].if_name) /* if it exists */ free (iface_list[count].if_name); } free (iface_list); } d_printf(50,"snap_svc_if : closed\n"); } /* there is where functions inside the library should be listed for registration */ void snap_external_svclib_getnextfunc(char** snapsvc_name, snapsvc_func_proto* snapsvc_func, int* snapsvc_args, int* snapsvc_rets){ switch (svc_fun_counter){ case 0 : (*snapsvc_name) = strdup ("if_getifacecount"); (*snapsvc_func) = (snapsvc_func_proto) &if_get_interface_count; (*snapsvc_args) = 0; (*snapsvc_rets) = SVC_SNMP_TYPE_INT; break; case 1 : (*snapsvc_name) = strdup ("if_getifacename"); (*snapsvc_func) = (snapsvc_func_proto) &if_get_interface_name; (*snapsvc_args) = 1; (*snapsvc_rets) = SVC_SNMP_TYPE_STRING; break; case 2 : (*snapsvc_name) = strdup ("if_getiface_flag"); (*snapsvc_func) = (snapsvc_func_proto) &if_getiface; (*snapsvc_args) = 2; (*snapsvc_rets) = SVC_SNMP_TYPE_INT; break; case 3 : (*snapsvc_name) = strdup ("if_getiface_up"); (*snapsvc_func) = (snapsvc_func_proto) &if_getiface_up; (*snapsvc_args) = 1; (*snapsvc_rets) = SVC_SNMP_TYPE_INT; break; case 4 : (*snapsvc_name) = strdup ("if_setiface_flag"); (*snapsvc_func) = (snapsvc_func_proto) &if_setiface; (*snapsvc_args) = 3; (*snapsvc_rets) = SVC_SNMP_TYPE_NULL; break; case 5 : (*snapsvc_name) = strdup ("if_setiface_up"); (*snapsvc_func) = (snapsvc_func_proto) &if_setiface_up; (*snapsvc_args) = 2; (*snapsvc_rets) = SVC_SNMP_TYPE_NULL; break; case 6 : (*snapsvc_name) = strdup ("if_getnexthop"); (*snapsvc_func) = (snapsvc_func_proto) &if_getnexthop; (*snapsvc_args) = 1; (*snapsvc_rets) = SVC_SNMP_TYPE_ADDR; break; case 7 : (*snapsvc_name) = strdup ("if_getallneighbours"); (*snapsvc_func) = (snapsvc_func_proto) &if_getallneighbours; (*snapsvc_args) = 1; (*snapsvc_rets) = SVC_SNMP_TYPE_NULL; break; /* unknown handler -> return NULL as end-of-list symbol */ default : (*snapsvc_name) = NULL; (*snapsvc_func) = NULL; (*snapsvc_args) = 0; (*snapsvc_rets) = 0; } svc_fun_counter ++; } /* ADD SERVICES BELOW */ /* declarations of snap service handlers */ /* initialize the interfaces and read IP addresses (if applicable) */ int snap_svc_ifip_init(){ int sk; struct if_nameindex *allifs; struct if_nameindex *currif; struct ifreq ifr; /* setup the socket for ioctl(..) access */ sk = socket(PF_INET, SOCK_DGRAM, 0); /* collect IFACE info from glibc functions */ if ((allifs = if_nameindex()) == NULL) { perror("if_nameindex"); } /* calculate number of interfaces and maximum interface index */ for (currif = allifs; (currif->if_index != 0) && (currif->if_name != NULL); currif++) { if (currif->if_index > snap_svc_if_maxidx) { snap_svc_if_maxidx = currif->if_index; } snap_svc_if_count++; } d_printf(40,"snap_svc_if : found %u interfaces, max index is %u\n",snap_svc_if_count, snap_svc_if_maxidx); if(snap_svc_if_maxidx <= 0){ d_printf(20,"snap_svc_if : warning : found zero or less interfaces\n"); } /* get additional IFACE info from local functions */ if (iface_list){ d_printf(40,"snap_svc_if : warning : reinitializing open iface list\n"); free (iface_list); } iface_list = (struct snap_svc_ifip_item*) calloc (snap_svc_if_maxidx + 1, sizeof(struct snap_svc_ifip_item)); for (currif = allifs;(currif->if_index != 0) && (currif->if_name != NULL); currif++) { /* incorporate data from the if_nameindex(..) call */ iface_list[currif->if_index].if_index = currif->if_index; iface_list[currif->if_index].if_name = strdup(currif->if_name); /* get data from the kernel through ioctl(..) */ strcpy(ifr.ifr_name, currif->if_name); if (ioctl(sk, SIOCGIFADDR, &ifr) < 0 ){ d_printf(20,"snap_svc_if : error while executing ioctl()\n"); iface_list[currif->if_index].addr = 0; } else iface_list[currif->if_index].addr = (*(struct sockaddr_in *)(&ifr.ifr_addr)).sin_addr.s_addr; /* show some debugging info*/ d_printf(100,"snap_svc_if : found interface [id=%u, name=%s, ip=%u.%u.%u.%u]\n", iface_list[currif->if_index].if_index, iface_list[currif->if_index].if_name, iface_list[currif->if_index].addr >> 24, iface_list[currif->if_index].addr << 8 >> 24, iface_list[currif->if_index].addr << 16 >> 24, iface_list[currif->if_index].addr << 24 >> 24); } /* free structure obtained by if_nameindex(..) call */ if_freenameindex (allifs); close (sk); return snap_svc_if_maxidx; } /* returns the number of active interfaces */ int if_get_interface_count(void* useless){ struct ifconf ifc; struct ifreq ifrs[100]; int sk; int i; sk = socket(PF_INET, SOCK_DGRAM, 0); ifc.ifc_len = sizeof(ifrs); ifc.ifc_req = ifrs; if (ioctl(sk, SIOCGIFCONF, &ifc) == -1){ d_printf(10,"error >> if_get_interfaces : ioctl failed\n"); return -1; } for (i = 0; i < ifc.ifc_len / sizeof(struct ifreq); i++) { struct ifreq *ifr = &ifrs[i]; struct sockaddr_in *addr = (struct sockaddr_in *) &ifr->ifr_addr; d_printf(100,"%2d %-8s %-15s\n", i, ifr->ifr_name, inet_ntoa(addr->sin_addr)); } close(sk); return (ifc.ifc_len / sizeof(struct ifreq)); } /* translates an interface no into a name */ char* if_get_interface_name(int dIfNo){ struct ifconf ifc; struct ifreq ifrs[100]; int sk; char* strIfName = NULL; sk = socket(PF_INET, SOCK_DGRAM, 0); ifc.ifc_len = sizeof(ifrs); ifc.ifc_req = ifrs; if (ioctl(sk, SIOCGIFCONF, &ifc) == -1){ d_printf(10,"error >> if_get_interfaces : ioctl failed\n"); return NULL; } if (dIfNo < ifc.ifc_len) strIfName = strdup(( &ifrs[dIfNo])->ifr_name ); close(sk); return (strIfName); } /* test whether a flag is toggled */ int if_getiface(const char* strIfName, int flag){ int fd; struct ifreq ifr; fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP); strcpy(ifr.ifr_name, strIfName); if (ioctl(fd, SIOCGIFFLAGS, &ifr) == -1){ d_printf(10,"error >> if_isup_interface : ioctl failed\n"); return -1; } else{ d_printf(100,"%s is %s\n", strIfName, (ifr.ifr_flags & IFF_UP) ? "up" : "down"); return (ifr.ifr_flags & flag) ? 1 : 0; } } /* test whether an interface is up */ int if_getiface_up(const char* strIfName){ return if_getiface(strIfName, IFF_UP); } /* set an interface flag */ /* flags are defined in linux/if.h */ int if_setiface(const char* strIfName, int flag, int state){ int fd; struct ifreq ifr; fd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP); strcpy(ifr.ifr_name, strIfName); if (ioctl(fd, SIOCGIFFLAGS, &ifr) == -1){ d_printf(10,"error >> if_isup_interface : ioctl failed\n"); return -1; } if (state) ifr.ifr_flags |= flag; else ifr.ifr_flags ^= flag; /* XOR operator : set bit to zero */ if (ioctl(fd, SIOCSIFFLAGS, &ifr) == -1){ d_printf(10,"error >> if_isup_interface : ioctl failed\n"); return -1; } else{ d_printf(100,"%s is %s\n", strIfName, (ifr.ifr_flags & IFF_UP) ? "up" : "down"); return if_getiface_up(strIfName); } } /* set the interface up/down flag */ int if_setiface_up(const char* strIfName, int state){ return if_setiface(strIfName, IFF_UP, state); } /* ADVANCED : get low-level packet routing information (uses route access through /proc/net/route) we use a simple round-robin scheme for stateless network traversal. Calculate the incoming iface from the ip, find the next ip interface - forgetting localhost - and return this as a result. second, an oilstain spread of packets has been facilitated if_getallneighbours(..) resembles the algorithm discussed above, but extends it by returning all other (non localhost) devices. For this a single returnvalue cannot suffice, therefore we resorted to using the struct svc_returnstruct defined in snap_svc.h */ /* find the next interface by index in iface_table */ unsigned int if_getnextiface(unsigned int iface_idx){ unsigned int iface_nextidx=0; unsigned short bFound = 0; iface_nextidx = iface_idx + 1; do { if (iface_nextidx > snap_svc_if_maxidx) iface_nextidx = 0; /* drop empty items and the local address */ if (iface_list[iface_nextidx].addr != 0 && iface_list[iface_nextidx].addr != htonl((127 << 24) + 1)) bFound = 1; d_printf(200,"snap_sv_if_getoutiface : found addr %u.%u.%u.%u at index %u\n",iface_list[iface_nextidx].addr << 24>>24, iface_list[iface_nextidx].addr << 16 >>24, iface_list[iface_nextidx].addr << 8 >>24, iface_list[iface_nextidx].addr >>24, iface_nextidx); if (!bFound) iface_nextidx++; } while (!bFound && iface_nextidx != iface_idx+1); /* if nextidx=idx+1 we've searched the entire structure and have to use the previous interface*/ return iface_nextidx; } /* search the iface list for the incoming ip address */ unsigned int if_getifaceidx(uint32_t ip){ int iface_counter=0; unsigned int iface_idx = 0; do { d_printf(200,"snap_svc_if_getifaceidx : comparing %u.%u.%u.%u with %u.%u.%u.%u\n",ip << 24 >> 24,ip << 16 >> 24 ,ip << 8 >> 24 ,ip >> 24 ,iface_list[iface_counter].addr << 24 >>24, iface_list[iface_counter].addr << 16 >>24, iface_list[iface_counter].addr << 8 >>24, iface_list[iface_counter].addr >>24); if (ip == iface_list[iface_counter].addr) iface_idx = iface_list[iface_counter].if_index; iface_counter++; } while (!iface_idx && iface_counter <= snap_svc_if_maxidx); return iface_idx; } /* select a new interface based on a given ip */ char* if_getoutiface(uint32_t incoming_ip){ unsigned int iface_idx = 0, iface_nextidx = 0; char* outgoing_name = NULL; /* safety check */ if (!incoming_ip) snap_svc_ifip_init(); /* get iface from incoming ip. drop if IP is not one of our local addresses */ iface_idx = if_getifaceidx(incoming_ip); if (!iface_idx) return NULL; /* get the next interface */ iface_nextidx = if_getnextiface(iface_idx); outgoing_name = iface_list[iface_nextidx].if_name; d_printf(100,"snap_svc_if_getoutiface : found hop with index %u and name %s\n",iface_nextidx,outgoing_name); return outgoing_name; } /* find an ip that is linked to the given interface */ uint32_t if_gethopfromiface(char* if_outname){ /* scan the routetable for an appropriate destination if it is a subnet then add a 1 to create a host this trick works when we use FORW,SEND,etc. *NOT* DFORW,DSEND,etc. */ char buf[1024]; FILE *f; uint32_t outgoing_ip=0; /* simple test */ if (! if_outname){ d_printf(40,"snap_svc_if_gethopfromiface : didn't receive an iface name... skipping\n"); return 0; } f = fopen("/proc/net/route","r"); if (f == NULL) { fprintf(stderr,"snap_svc_if_getnexthop : unable to open /proc/net/route\n"); exit(1); } /* count number of routes */ while(! outgoing_ip && fgets(buf,sizeof(buf),f)) { if (!strncmp(if_outname,buf,strlen(if_outname))){ outgoing_ip = strtol(&buf[strlen(if_outname)], NULL, 16); if ((outgoing_ip >> 24) == 0) outgoing_ip += 0x01000000; /* add .01 if dest is a network address */ d_printf(50,"snap_svc_if_getnexthop : found destination %u.%u.%u.%u over iface %s\n",outgoing_ip << 24 >> 24,outgoing_ip << 16 >> 24,outgoing_ip << 8 >> 24,outgoing_ip >> 24,if_outname); } } return outgoing_ip; } /* a wrapper for two previous functions */ uint32_t if_getnexthop(uint32_t incoming_ip){ char* if_outname = if_getoutiface(incoming_ip); if (!if_outname) return (1 << 24); /* send to the standard route + 1 (0,0,0,1) in network byte order */ else return if_gethopfromiface(if_outname); } /* return all neighbours through the returnstruct mechanism */ void if_getallneighbours(uint32_t incoming_ip){ unsigned int iface_idx=0; unsigned int iface_saveidx=0; unsigned int iface_nextidx=0; uint32_t uAddress; unsigned int iface_count=0; iface_idx=if_getifaceidx(incoming_ip); iface_saveidx = iface_idx; d_printf(100,"snap_svc_getallneighbours : packet entered from interface %u, discarding\n",iface_saveidx); /* find all interfaces*/ do { /* find the next interface */ iface_nextidx = if_getnextiface(iface_idx); if (iface_nextidx != iface_idx && iface_list[iface_nextidx].addr){ /* only process interfaces other than the incoming iface */ iface_count++; iface_idx = iface_nextidx; /* move the `current' pointer */ } } while (iface_nextidx != iface_saveidx); d_printf(100,"snap_svc_if_getallneighbours : found %u items\n",iface_count); /* initialize the returnstruct */ snap_external_svclib_free_local_returnstruct(); svc_return = (struct svc_returnstruct*) calloc (1,sizeof(struct svc_returnstruct)); svc_return->length = iface_count; svc_return->list = (struct svc_returnitem*) calloc (iface_count,sizeof(struct svc_returnitem)); /* find the interfaces again and now place them inside the struct */ iface_saveidx = iface_idx; do { /* find the next interface */ iface_nextidx = if_getnextiface(iface_idx); if (iface_nextidx != iface_saveidx && iface_list[iface_nextidx].addr){ /* only process interfaces other than the incoming iface */ uAddress=if_gethopfromiface(iface_list[iface_nextidx].if_name); d_printf(50,"snap_svc_if_getallneighbours : found destination %u.%u.%u.%u over iface %s\n",uAddress << 24 >> 24,uAddress << 16 >> 24,uAddress << 8 >> 24,uAddress >> 24,iface_list[iface_nextidx].if_name); /* write the value */ svc_return->list[iface_count-1].type = SVC_SNMP_TYPE_ADDR; svc_return->list[iface_count-1].data = calloc (1, sizeof(uint32_t)); memmove(svc_return->list[iface_count-1].data,&uAddress,sizeof(uint32_t)); iface_count--; iface_idx = iface_nextidx; /* move the `current' pointer */ } } while (iface_nextidx != iface_saveidx && iface_count); /*NB second test shouldn't be an issue*/ }