// group ipv4/ipv6 list from stdout into subnets // each line must contain either ip or ip/bitcount // valid ip/bitcount and ip1-ip2 are passed through without modification // ips are groupped into subnets // can be compiled in mingw. msvc not supported because of absent getopt #include #include #include #include #include #ifdef _WIN32 #undef _WIN32_WINNT #define _WIN32_WINNT 0x600 #include #include #include #else #include #include #include #endif #include #include "qsort.h" #define ALLOC_STEP 16384 // minimum subnet fill percent is PCTMULT/PCTDIV (for example 3/4) #define DEFAULT_PCTMULT 3 #define DEFAULT_PCTDIV 4 // subnet search range in "zero bit count" // means search start from /(32-ZCT_MAX) to /(32-ZCT_MIN) #define DEFAULT_V4_ZCT_MAX 10 // /22 #define DEFAULT_V4_ZCT_MIN 2 // /30 #define DEFAULT_V6_ZCT_MAX 72 // /56 #define DEFAULT_V6_ZCT_MIN 64 // /64 // must be no less than N ipv6 in subnet #define DEFAULT_V6_THRESHOLD 5 static int ucmp(const void * a, const void * b, void *arg) { if (*(uint32_t*)a < *(uint32_t*)b) return -1; else if (*(uint32_t*)a > *(uint32_t*)b) return 1; else return 0; } static uint32_t mask_from_bitcount(uint32_t zct) { return zct<32 ? ~((1 << zct) - 1) : 0; } // make presorted array unique. return number of unique items. // 1,1,2,3,3,0,0,0 (ct=8) => 1,2,3,0 (ct=4) static uint32_t unique(uint32_t *pu, uint32_t ct) { uint32_t i, j, u; for (i = j = 0; j < ct; i++) { u = pu[j++]; for (; j < ct && pu[j] == u; j++); pu[i] = u; } return i; } #if defined(__GNUC__) && !defined(__llvm__) __attribute__((optimize ("no-strict-aliasing"))) #endif static int cmp6(const void * a, const void * b, void *arg) { // this function is critical for sort performance // on big endian systems cpu byte order is equal to network byte order // no conversion required. it's possible to improve speed by using big size compares // on little endian systems byte conversion also gives better result than byte comparision // 64-bit archs often have cpu command to reverse byte order // assume that a and b are properly aligned #if defined(__BYTE_ORDER__) && ((__BYTE_ORDER__==__ORDER_BIG_ENDIAN__) || (__BYTE_ORDER__==__ORDER_LITTLE_ENDIAN__)) uint64_t aa,bb; #if __BYTE_ORDER__==__ORDER_LITTLE_ENDIAN__ aa = __builtin_bswap64(((uint64_t*)((struct in6_addr *)a)->s6_addr)[0]); bb = __builtin_bswap64(((uint64_t*)((struct in6_addr *)b)->s6_addr)[0]); #else aa = ((uint64_t*)((struct in6_addr *)a)->s6_addr)[0]; bb = ((uint64_t*)((struct in6_addr *)b)->s6_addr)[0]; #endif if (aa < bb) return -1; else if (aa > bb) return 1; else { #if __BYTE_ORDER__==__ORDER_LITTLE_ENDIAN__ aa = __builtin_bswap64(((uint64_t*)((struct in6_addr *)a)->s6_addr)[1]); bb = __builtin_bswap64(((uint64_t*)((struct in6_addr *)b)->s6_addr)[1]); #else aa = ((uint64_t*)((struct in6_addr *)a)->s6_addr)[1]; bb = ((uint64_t*)((struct in6_addr *)b)->s6_addr)[1]; #endif return aa < bb ? -1 : aa > bb ? 1 : 0; } #else // fallback case for (uint8_t i = 0; i < sizeof(((struct in6_addr *)0)->s6_addr); i++) { if (((struct in6_addr *)a)->s6_addr[i] < ((struct in6_addr *)b)->s6_addr[i]) return -1; else if (((struct in6_addr *)a)->s6_addr[i] > ((struct in6_addr *)b)->s6_addr[i]) return 1; } return 0; #endif } // make presorted array unique. return number of unique items. static uint32_t unique6(struct in6_addr *pu, uint32_t ct) { uint32_t i, j, k; for (i = j = 0; j < ct; i++) { for (k = j++; j < ct && !memcmp(pu + j, pu + k, sizeof(struct in6_addr)); j++); pu[i] = pu[k]; } return i; } static void mask_from_bitcount6_make(uint32_t zct, struct in6_addr *a) { if (zct >= 128) memset(a->s6_addr,0x00,16); else { int32_t n = (127 - zct) >> 3; memset(a->s6_addr,0xFF,n); memset(a->s6_addr+n,0x00,16-n); a->s6_addr[n] = ~((1 << (zct & 7)) - 1); } } static struct in6_addr ip6_mask[129]; static void mask_from_bitcount6_prepare(void) { for (int zct=0;zct<=128;zct++) mask_from_bitcount6_make(zct, ip6_mask+zct); } static inline const struct in6_addr *mask_from_bitcount6(uint32_t zct) { return ip6_mask+zct; } /* // this is "correct" solution for strict aliasing feature // but I don't like this style of coding // write what I don't mean to force smart optimizer to do what it's best // it produces better code sometimes but not on all compilers/versions/archs // sometimes it even generates real memcpy calls (mips32,arm32) // so I will not do it static void ip6_and(const struct in6_addr *a, const struct in6_addr *b, struct in6_addr *result) { uint64_t a_addr[2], b_addr[2]; memcpy(a_addr, a->s6_addr, 16); memcpy(b_addr, b->s6_addr, 16); a_addr[0] &= b_addr[0]; a_addr[1] &= b_addr[1]; memcpy(result->s6_addr, a_addr, 16); } */ // YES, from my point of view C should work as a portable assembler. It must do what I instruct it to do. // that's why I disable strict aliasing for this function. I observed gcc can miscompile with O2/O3 setting if inlined and not coded "correct" // result = a & b // assume that a and b are properly aligned #if defined(__GNUC__) && !defined(__llvm__) __attribute__((optimize ("no-strict-aliasing"))) #endif static void ip6_and(const struct in6_addr * restrict a, const struct in6_addr * restrict b, struct in6_addr * restrict result) { #ifdef __SIZEOF_INT128__ // gcc and clang have 128 bit int types on some 64-bit archs. take some advantage *((unsigned __int128*)result->s6_addr) = *((unsigned __int128*)a->s6_addr) & *((unsigned __int128*)b->s6_addr); #else ((uint64_t*)result->s6_addr)[0] = ((uint64_t*)a->s6_addr)[0] & ((uint64_t*)b->s6_addr)[0]; ((uint64_t*)result->s6_addr)[1] = ((uint64_t*)a->s6_addr)[1] & ((uint64_t*)b->s6_addr)[1]; #endif } static void rtrim(char *s) { if (s) for (char *p = s + strlen(s) - 1; p >= s && (*p == '\n' || *p == '\r'); p--) *p = '\0'; } static struct params_s { bool ipv6; uint32_t pctmult, pctdiv; // for v4 uint32_t zct_min, zct_max; // for v4 and v6 uint32_t v6_threshold; // for v6 } params; static void exithelp(void) { printf( " -4\t\t\t\t; ipv4 list (default)\n" " -6\t\t\t\t; ipv6 list\n" " --prefix-length=min[-max]\t; consider prefix lengths from 'min' to 'max'. examples : 22-30 (ipv4), 56-64 (ipv6)\n" " --v4-threshold=mul/div\t\t; ipv4 only : include subnets with more than mul/div ips. example : 3/4\n" " --v6-threshold=N\t\t; ipv6 only : include subnets with more than N v6 ips. example : 5\n" ); exit(1); } static void parse_params(int argc, char *argv[]) { int option_index = 0; int v, i; uint32_t plen1=-1, plen2=-1; memset(¶ms, 0, sizeof(params)); params.pctmult = DEFAULT_PCTMULT; params.pctdiv = DEFAULT_PCTDIV; params.v6_threshold = DEFAULT_V6_THRESHOLD; const struct option long_options[] = { { "help",no_argument,0,0 },// optidx=0 { "h",no_argument,0,0 },// optidx=1 { "4",no_argument,0,0 },// optidx=2 { "6",no_argument,0,0 },// optidx=3 { "prefix-length",required_argument,0,0 },// optidx=4 { "v4-threshold",required_argument,0,0 },// optidx=5 { "v6-threshold",required_argument,0,0 },// optidx=6 { NULL,0,NULL,0 } }; while ((v = getopt_long_only(argc, argv, "", long_options, &option_index)) != -1) { if (v) exithelp(); switch (option_index) { case 0: case 1: exithelp(); break; case 2: params.ipv6 = false; break; case 3: params.ipv6 = true; break; case 4: i = sscanf(optarg,"%u-%u",&plen1,&plen2); if (i == 1) plen2 = plen1; if (i<=0 || plen2=params.pctdiv) { fprintf(stderr, "invalid parameter for v4-threshold : %s\n", optarg); exit(1); } break; case 6: i = sscanf(optarg, "%u", ¶ms.v6_threshold); if (i != 1 || params.v6_threshold<1) { fprintf(stderr, "invalid parameter for v6-threshold : %s\n", optarg); exit(1); } break; } } if (plen1 != -1 && ((!params.ipv6 && (plen1>31 || plen2>31)) || (params.ipv6 && (plen1>127 || plen2>127)))) { fprintf(stderr, "invalid parameter for prefix-length\n"); exit(1); } params.zct_min = params.ipv6 ? plen2==-1 ? DEFAULT_V6_ZCT_MIN : 128-plen2 : plen2==-1 ? DEFAULT_V4_ZCT_MIN : 32-plen2; params.zct_max = params.ipv6 ? plen1==-1 ? DEFAULT_V6_ZCT_MAX : 128-plen1 : plen1==-1 ? DEFAULT_V4_ZCT_MAX : 32-plen1; } int main(int argc, char **argv) { char str[256],d; uint32_t ipct = 0, iplist_size = 0, pos = 0, p, zct, ip_ct, pos_end; parse_params(argc, argv); if (params.ipv6) // ipv6 { char *s; struct in6_addr a, *iplist = NULL, *iplist_new; while (fgets(str, sizeof(str), stdin)) { rtrim(str); d = 0; if ((s = strchr(str, '/')) || (s = strchr(str, '-'))) { d = *s; *s = '\0'; } if (inet_pton(AF_INET6, str, &a)) { if (d=='/') { // we have subnet ip6/y // output it as is if (sscanf(s + 1, "%u", &zct)==1 && zct!=128) { if (zct<128) printf("%s/%u\n", str, zct); continue; } } else if (d=='-') { if (inet_pton(AF_INET6, s+1, &a)) printf("%s-%s\n", str, s+1); continue; } if (ipct >= iplist_size) { iplist_size += ALLOC_STEP; iplist_new = (struct in6_addr*)(iplist ? realloc(iplist, sizeof(*iplist)*iplist_size) : malloc(sizeof(*iplist)*iplist_size)); if (!iplist_new) { free(iplist); fprintf(stderr, "out of memory\n"); return 100; } iplist = iplist_new; } iplist[ipct++] = a; } } gnu_quicksort(iplist, ipct, sizeof(*iplist), cmp6, NULL); ipct = unique6(iplist, ipct); mask_from_bitcount6_prepare(); /* for(uint32_t i=0;i= params.zct_min; zct--) { mask = mask_from_bitcount6(zct); ip6_and(iplist + pos, mask, &ip_start); for (p = pos + 1, ip_ct = 1; p < ipct; p++, ip_ct++) { ip6_and(iplist + p, mask, &ip); if (memcmp(&ip_start, &ip, sizeof(ip))) break; } if (ip_ct == 1) break; if (ip_ct >= params.v6_threshold) { // network found. but is there smaller network with the same ip_ct ? dont do carpet bombing if possible, use smaller subnets if (!ip_ct_best || ip_ct == ip_ct_best) { ip_ct_best = ip_ct; zct_best = zct; pos_end = p; } else break; } } if (zct_best) // network was found ip6_and(iplist + pos, mask_from_bitcount6(zct_best), &ip_start); else ip_start = iplist[pos], pos_end = pos + 1; // network not found, use single ip inet_ntop(AF_INET6, &ip_start, str, sizeof(str)); printf(zct_best ? "%s/%u\n" : "%s\n", str, 128 - zct_best); pos = pos_end; } free(iplist); } else // ipv4 { uint32_t u1,u2,u3,u4, u11,u22,u33,u44, ip; uint32_t *iplist = NULL, *iplist_new, i; while (fgets(str, sizeof(str), stdin)) { if ((i = sscanf(str, "%u.%u.%u.%u-%u.%u.%u.%u", &u1, &u2, &u3, &u4, &u11, &u22, &u33, &u44)) >= 8 && !(u1 & 0xFFFFFF00) && !(u2 & 0xFFFFFF00) && !(u3 & 0xFFFFFF00) && !(u4 & 0xFFFFFF00) && !(u11 & 0xFFFFFF00) && !(u22 & 0xFFFFFF00) && !(u33 & 0xFFFFFF00) && !(u44 & 0xFFFFFF00)) { printf("%u.%u.%u.%u-%u.%u.%u.%u\n", u1, u2, u3, u4, u11, u22, u33, u44); } else if ((i = sscanf(str, "%u.%u.%u.%u/%u", &u1, &u2, &u3, &u4, &zct)) >= 4 && !(u1 & 0xFFFFFF00) && !(u2 & 0xFFFFFF00) && !(u3 & 0xFFFFFF00) && !(u4 & 0xFFFFFF00)) { if (i == 5 && zct != 32) { // we have subnet x.x.x.x/y // output it as is if valid, ignore otherwise if (zct < 32) printf("%u.%u.%u.%u/%u\n", u1, u2, u3, u4, zct); } else { ip = u1 << 24 | u2 << 16 | u3 << 8 | u4; if (ipct >= iplist_size) { iplist_size += ALLOC_STEP; iplist_new = (uint32_t*)(iplist ? realloc(iplist, sizeof(*iplist)*iplist_size) : malloc(sizeof(*iplist)*iplist_size)); if (!iplist_new) { free(iplist); fprintf(stderr, "out of memory\n"); return 100; } iplist = iplist_new; } iplist[ipct++] = ip; } } } gnu_quicksort(iplist, ipct, sizeof(*iplist), ucmp, NULL); ipct = unique(iplist, ipct); while (pos < ipct) { uint32_t mask, ip_start, ip_end, subnet_ct; uint32_t ip_ct_best = 0, zct_best = 0; // find smallest network with maximum ip coverage with no less than mul/div percent addresses for (zct = params.zct_max; zct >= params.zct_min; zct--) { mask = mask_from_bitcount(zct); ip_start = iplist[pos] & mask; subnet_ct = ~mask + 1; if (iplist[pos] > (ip_start + subnet_ct*(params.pctdiv - params.pctmult) / params.pctdiv)) continue; // ip is higher than (1-PCT). definitely coverage is not enough. skip searching ip_end = ip_start | ~mask; for (p=pos+1, ip_ct=1; p < ipct && iplist[p] <= ip_end; p++) ip_ct++; // count ips within subnet range if (ip_ct == 1) break; if (ip_ct >= (subnet_ct*params.pctmult / params.pctdiv)) { // network found. but is there smaller network with the same ip_ct ? dont do carpet bombing if possible, use smaller subnets if (!ip_ct_best || ip_ct == ip_ct_best) { ip_ct_best = ip_ct; zct_best = zct; pos_end = p; } else break; } } if (zct_best) ip_start = iplist[pos] & mask_from_bitcount(zct_best); else ip_start = iplist[pos], pos_end = pos + 1; // network not found, use single ip u1 = ip_start >> 24; u2 = (ip_start >> 16) & 0xFF; u3 = (ip_start >> 8) & 0xFF; u4 = ip_start & 0xFF; printf(zct_best ? "%u.%u.%u.%u/%u\n" : "%u.%u.%u.%u\n", u1, u2, u3, u4, 32 - zct_best); pos = pos_end; } free(iplist); } return 0; }