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/* netmask.c - a netmask generator
*
* Copyright (c) 2013 Robert Stone <talby@trap.mtview.ca.us>,
* Tom Lear <tom@trap.mtview.ca.us>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#include <stdlib.h>
#include <string.h>
#include <arpa/inet.h>
#include "errors.h"
#include "netmask.h"
typedef struct {
uint64_t h;
uint64_t l;
} u128_t;
static inline u128_t u128_add(u128_t x, u128_t y, int *carry) {
/* this relies on the sum being greater than both terms of the
* addition, otherwise an overflow must have occurred. */
u128_t rv;
rv.l = x.l + y.l;
if(rv.l < x.l || rv.l < y.l)
rv.h = 1;
else
rv.h = 0;
rv.h += x.h + y.h;
if(carry) {
if(rv.h < x.h || rv.h < y.h)
*carry = 1;
else
*carry = 0;
}
return rv;
}
static inline u128_t u128_and(u128_t x, u128_t y) {
u128_t rv;
rv.h = x.h & y.h;
rv.l = x.l & y.l;
return rv;
}
static inline u128_t u128_or(u128_t x, u128_t y) {
u128_t rv;
rv.h = x.h | y.h;
rv.l = x.l | y.l;
return rv;
}
static inline u128_t u128_xor(u128_t x, u128_t y) {
u128_t rv;
rv.h = x.h ^ y.h;
rv.l = x.l ^ y.l;
return rv;
}
static inline u128_t u128_neg(u128_t v) {
u128_t rv;
rv.h = ~v.h;
rv.l = ~v.l;
return rv;
}
static inline u128_t u128_lsh(u128_t v, uint8_t d) {
u128_t rv;
rv.h = v.h << 1 | v.l >> 63;
rv.l = v.l << 1;
return rv;
}
static inline int u128_cmp(u128_t x, u128_t y) {
/* return -1, 0, 1 on sort order */
if(x.h < y.h)
return -1;
if(x.h > y.h)
return 1;
if(x.l < y.l)
return -1;
if(x.l > y.l)
return 1;
return 0;
}
static inline u128_t u128_of_s6(struct in6_addr *s6) {
u128_t rv;
rv.h = (((uint64_t)s6->s6_addr[0]) << 56) |
(((uint64_t)s6->s6_addr[1]) << 48) |
(((uint64_t)s6->s6_addr[2]) << 40) |
(((uint64_t)s6->s6_addr[3]) << 32) |
(((uint64_t)s6->s6_addr[4]) << 24) |
(((uint64_t)s6->s6_addr[5]) << 16) |
(((uint64_t)s6->s6_addr[6]) << 8) |
(((uint64_t)s6->s6_addr[7]) << 0);
rv.l = (((uint64_t)s6->s6_addr[8]) << 56) |
(((uint64_t)s6->s6_addr[9]) << 48) |
(((uint64_t)s6->s6_addr[10]) << 40) |
(((uint64_t)s6->s6_addr[11]) << 32) |
(((uint64_t)s6->s6_addr[12]) << 24) |
(((uint64_t)s6->s6_addr[13]) << 16) |
(((uint64_t)s6->s6_addr[14]) << 8) |
(((uint64_t)s6->s6_addr[15]) << 0);
return rv;
}
static inline struct in6_addr s6_of_u128(u128_t v) {
struct in6_addr s6;
s6.s6_addr[0] = 0xff & (v.h >> 56);
s6.s6_addr[1] = 0xff & (v.h >> 48);
s6.s6_addr[2] = 0xff & (v.h >> 40);
s6.s6_addr[3] = 0xff & (v.h >> 32);
s6.s6_addr[4] = 0xff & (v.h >> 24);
s6.s6_addr[5] = 0xff & (v.h >> 16);
s6.s6_addr[6] = 0xff & (v.h >> 8);
s6.s6_addr[7] = 0xff & (v.h >> 0);
s6.s6_addr[8] = 0xff & (v.l >> 56);
s6.s6_addr[9] = 0xff & (v.l >> 48);
s6.s6_addr[10] = 0xff & (v.l >> 40);
s6.s6_addr[11] = 0xff & (v.l >> 32);
s6.s6_addr[12] = 0xff & (v.l >> 24);
s6.s6_addr[13] = 0xff & (v.l >> 16);
s6.s6_addr[14] = 0xff & (v.l >> 8);
s6.s6_addr[15] = 0xff & (v.l >> 0);
return s6;
}
static inline u128_t u128_lit(uint64_t h, uint64_t l) {
u128_t rv;
rv.h = h;
rv.l = l;
return rv;
}
static inline u128_t u128_cidr(uint8_t n) {
u128_t rv;
if(n <= 0) {
rv.h = 0;
rv.l = 0;
} else if(n <= 64) {
rv.h = ~0ULL << (64 - n);
rv.l = 0;
} else if(n <= 128) {
rv.h = ~0ULL;
rv.l = ~0ULL << (128 - n);
} else {
rv.h = ~0ULL;
rv.l = ~0ULL;
}
return rv;
}
static inline int cidr(u128_t u) {
uint64_t v;
int n = 0;
for(v = u.l; v > 0; v <<= 1) n++;
for(v = u.h; v > 0; v <<= 1) n++;
return n;
}
static inline int chkmask(u128_t v) {
/* this is sort of specialized */
int i;
u128_t m = u128_lit(~0ULL, ~0ULL);
for(i = 0; i < 129; i++) {
if(u128_cmp(v, m) == 0)
return 1;
m = u128_lsh(m, 1);
}
return 0;
}
struct nm {
u128_t neta;
u128_t mask;
int domain;
NM next;
};
NM nm_new_v4(struct in_addr *s) {
NM self;
union {
struct in6_addr s6;
uint32_t u32[4];
} v;
v.u32[0] = 0;
v.u32[1] = 0;
v.u32[2] = htonl(0x0000ffff);
v.u32[3] = s->s_addr;
self = nm_new_v6(&v.s6);
self->domain = AF_INET;
return self;
}
NM nm_new_v6(struct in6_addr *s6) {
NM self = (NM)malloc(sizeof(struct nm));
self->neta = u128_of_s6(s6);
self->mask = u128_cidr(128);
self->domain = AF_INET6;
self->next = (NM)0;
return self;
}
/* is "a" a subset of "b"? */
static inline int subset_of(NM a, NM b) {
return(
u128_cmp(a->mask, b->mask) >= 0 &&
u128_cmp(b->neta, u128_and(a->neta, b->mask)) == 0
);
}
/* are "a" and "b" a joinable pair? */
static inline int joinable_pair(NM a, NM b) {
return(
/* nets have the same mask */
u128_cmp(a->mask, b->mask) == 0 &&
/* but are distinct */
u128_cmp(a->neta, b->neta) != 0 &&
/* and would both be subsets of the same mask << 1 */
u128_cmp(u128_lit(0, 0), u128_and(
u128_xor(a->neta, b->neta),
u128_lsh(a->mask, 1)
)) == 0
);
}
/* this is slightly complicated because an NM can outgrow it's initial
* v4 state, but if it doesn't, we want to retain the fact that it
* was and remained v4. */
static inline int is_v4(NM self) {
struct nm v4map;
v4map.neta = u128_lit(0, 0x0000ffff00000000ULL);
v4map.mask = u128_cidr(96);
return(self->domain == AF_INET && subset_of(self, &v4map));
}
NM nm_new_ai(struct addrinfo *ai) {
NM self = NULL;
struct addrinfo *cur;
for(cur = ai; cur; cur = cur->ai_next) {
switch(cur->ai_family) {
case AF_INET:
self = nm_merge(self, nm_new_v4(&(
(struct sockaddr_in *)cur->ai_addr
)->sin_addr));
break;
case AF_INET6:
self = nm_merge(self, nm_new_v6(&(
(struct sockaddr_in6 *)cur->ai_addr
)->sin6_addr));
break;
default:
panic("unknown ai_family %d in struct addrinfo",
cur->ai_family);
}
}
return self;
}
static inline NM parse_addr(const char *str, int flags) {
struct in6_addr s6;
struct in_addr s;
if(inet_pton(AF_INET6, str, &s6))
return nm_new_v6(&s6);
if(inet_aton(str, &s))
return nm_new_v4(&s);
if(NM_USE_DNS & flags) {
struct addrinfo in, *out;
memset(&in, 0, sizeof(struct addrinfo));
in.ai_family = AF_UNSPEC;
if(getaddrinfo(str, NULL, &in, &out) == 0) {
NM self = nm_new_ai(out);
freeaddrinfo(out);
return self;
}
}
return NULL;
}
static inline int parse_mask(NM self, const char *str, int flags) {
char *p;
uint32_t v;
struct in6_addr s6;
struct in_addr s;
v = strtoul(str, &p, 0);
if(*p == '\0') {
/* read it as a CIDR value */
if(is_v4(self)) {
if(v > 32) return 0;
v += 96;
} else {
if(v > 128) return 0;
}
self->mask = u128_cidr(v);
} else if(inet_pton(AF_INET6, str, &s6)) {
self->mask = u128_of_s6(&s6);
/* flip cisco style masks */
if(u128_cmp(
u128_lit(0, 0),
u128_and(
u128_lit(1ULL << 63, 1),
u128_xor(u128_lit(0, 1), self->mask)
)
) == 0) {
self->mask = u128_neg(self->mask);
}
self->domain = AF_INET6;
} else if(self->domain == AF_INET && inet_aton(str, &s)) {
v = htonl(s.s_addr);
if(v & 1 && ~v >> 31) /* flip cisco style masks */
v = ~v;
/* since mask is currently all 1s, mask ^ ~m will
* set the low 32. */
self->mask = u128_xor(self->mask, u128_lit(0, ~v));
} else {
return 0;
}
if(!chkmask(self->mask))
return 0;
/* apply mask to neta */
self->neta = u128_and(self->neta, self->mask);
return 1;
}
/* widen the mask as much as possible without including addresses below
* neta or above max. return one if more ranges are needed to complete
* the span or zero if this nm includes max. */
static inline int nm_widen(NM self, u128_t max, u128_t *last) {
u128_t mask, neta, bcst;
int cmp = u128_cmp(self->neta, max);
while(cmp < 0) {
/* attempt widening by one bit */
mask = u128_lsh(self->mask, 1);
neta = u128_and(self->neta, mask);
bcst = u128_or(self->neta, u128_neg(mask));
/* check ranges */
if(u128_cmp(neta, self->neta) < 0)
break;
cmp = u128_cmp(bcst, max);
if(cmp > 0)
break;
/* successful attempt */
self->mask = mask;
*last = bcst;
status("widen %016llx %016llx/%d", self->neta.h, self->neta.l, cidr(self->mask));
if(cmp == 0)
break;
}
return cmp;
}
static inline void nm_order(NM *low, NM *high) {
if(u128_cmp((*low)->neta, (*high)->neta) > 0) {
NM tmp = *low;
*low = *high;
*high = tmp;
}
}
/* convert first and last into a list from first to last. (both these
* should be single addresses, not lists.) */
static inline NM nm_seq(NM first, NM last) {
/* if first is higher than last, swap them (legacy) */
nm_order(&first, &last);
NM cur = first;
u128_t pos = cur->neta;
u128_t one = u128_lit(0, 1);
u128_t max = last->neta;
int domain = is_v4(first) && is_v4(last) ? AF_INET : AF_INET6;
free(last);
while(nm_widen(cur, max, &pos)) {
cur->next = (NM)malloc(sizeof(struct nm));
cur = cur->next;
cur->neta = u128_add(pos, one, NULL);
cur->mask = u128_cidr(128);
cur->domain = domain;
cur->next = NULL;
}
return first;
}
NM nm_new_str(const char *str, int flags) {
char *p, buf[2048];
NM self;
if((p = strchr(str, '/'))) { /* mask separator */
strncpy(buf, str, p - str);
buf[p - str] = '\0';
self = parse_addr(buf, flags);
if(!self)
return NULL;
if(!parse_mask(self, p + 1, flags)) {
free(self);
return NULL;
}
return self;
} else if((p = strchr(str, ','))) { /* new range character */
NM top;
int add;
strncpy(buf, str, p - str);
buf[p - str] = '\0';
self = parse_addr(buf, flags);
if(!self)
return NULL;
if(p[1] == '+')
add = 1;
else
add = 0;
top = parse_addr(p + add + 1, flags);
if(!top) {
free(self);
return NULL;
}
if(add) {
int carry;
if(is_v4(top))
top->neta.l &= 0xffffffffULL;
top->neta = u128_add(self->neta, top->neta, &carry);
if(carry) {
free(self);
free(top);
return NULL;
}
}
return nm_seq(self, top);
} else if((self = parse_addr(str, flags))) {
return self;
} else if((p = strchr(str, ':'))) { /* old range character (sloppy) */
NM top;
int add;
strncpy(buf, str, p - str);
buf[p - str] = '\0';
self = parse_addr(buf, flags);
if(!self)
return NULL;
if(p[1] == '+') {
add = 1;
if(p[2] == '-') {
/* this is a pretty special reverse compatibility
* situation. N:+-5" would actually emit the range from
* N-5 to N because strtoul() hilariously accepts
* negative numbers and the original code never detected
* overflow and things just happened to work out. */
struct in_addr s;
char *endp;
uint32_t v = self->neta.l + strtoul(p + 2, &endp, 0);
if(*endp == '\0') {
s.s_addr = htonl(v);
top = nm_new_v4(&s);
if(!top) {
free(self);
return NULL;
}
return nm_seq(self, top);
}
}
} else {
add = 0;
}
top = parse_addr(p + add + 1, flags);
if(!top) {
free(self);
return NULL;
}
if(add) {
int carry;
if(is_v4(top))
top->neta.l &= 0xffffffffULL;
top->neta = u128_add(self->neta, top->neta, &carry);
if(carry) {
free(self);
free(top);
return NULL;
}
}
return nm_seq(self, top);
} else {
return NULL;
}
}
NM nm_merge(NM dst, NM src) {
/* both lists are ordered and non-overlapping. Knit them into a
* single ordered, non-overlapping list. */
NM tmp;
NM *pos = &dst; /* double indirect pointer simplifies list insertion
logic. */
while(src) {
if(*pos == NULL) {
/* remains of src go to tail of dst */
tmp = src;
src = *pos;
*pos = tmp;
} else if(subset_of(src, *pos)) {
status("found %016llx %016llx/%d a subset of %016llx %016llx/%d", src->neta.h, src->neta.l, cidr(src->mask), (*pos)->neta.h, (*pos)->neta.l, cidr((*pos)->mask));
/* drop src elt on the floor */
if(src->domain != AF_INET) /* may need to promote domain */
(*pos)->domain = src->domain;
tmp = src;
src = src->next;
free(tmp);
} else if(subset_of(*pos, src)) {
/* src seems larger, merge the other direction instead */
tmp = src;
src = *pos;
*pos = tmp;
} else if(joinable_pair(src, *pos)) {
status("joinable %016llx %016llx/%d and %016llx %016llx/%d", src->neta.h, src->neta.l, cidr(src->mask), (*pos)->neta.h, (*pos)->neta.l, cidr((*pos)->mask));
/* pull the dst elt */
tmp = *pos;
*pos = (*pos)->next;
if(src->domain == AF_INET)
src->domain = tmp->domain;
free(tmp);
/* widen the src elt */
src->mask = u128_lsh(src->mask, 1);
src->neta = u128_and(src->neta, src->mask);
/* and merge it back into the src tail */
tmp = src->next;
src->next = NULL;
src = nm_merge(src, tmp);
/* now the dst scan needs to start over to find preceding
* join candidates. */
pos = &dst;
/* TODO: there should be a cheaper way to do this than an
* effective double recursion, but the possibility of joins
* cascading backwards makes this difficult */
} else if(u128_cmp(src->neta, (*pos)->neta) < 0) {
/* src elt goes here in dst list. if top src elt were
* spliced into dst, it may duplicate later elts in dst.
* swap tails instead because src is well formed. */
tmp = src;
src = *pos;
*pos = tmp;
} else {
/* move down the dst list */
pos = &(*pos)->next;
}
}
return dst;
}
void nm_walk(NM self, void (*cb)(int, nm_addr *, nm_addr *)) {
int domain;
nm_addr neta, mask;
while(self) {
neta.s6 = s6_of_u128(self->neta);
mask.s6 = s6_of_u128(self->mask);
if(is_v4(self)) {
domain = AF_INET;
neta.s.s_addr = htonl(
neta.s6.s6_addr[12] << 24 |
neta.s6.s6_addr[13] << 16 |
neta.s6.s6_addr[14] << 8 |
neta.s6.s6_addr[15] << 0);
mask.s.s_addr = htonl(
mask.s6.s6_addr[12] << 24 |
mask.s6.s6_addr[13] << 16 |
mask.s6.s6_addr[14] << 8 |
mask.s6.s6_addr[15] << 0);
} else {
domain = AF_INET6;
}
cb(domain, &neta, &mask);
self = self->next;
}
}
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