426 lines
12 KiB
C
426 lines
12 KiB
C
#include <sys/socket.h>
|
|
#include <netinet/in.h>
|
|
#include <netdb.h>
|
|
#include <net/if.h>
|
|
#include <arpa/inet.h>
|
|
#include <ctype.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <fcntl.h>
|
|
#include <unistd.h>
|
|
#include <pthread.h>
|
|
#include <errno.h>
|
|
#include <resolv.h>
|
|
#include "lookup.h"
|
|
#include "stdio_impl.h"
|
|
#include "syscall.h"
|
|
|
|
static int is_valid_hostname(const char *host)
|
|
{
|
|
const unsigned char *s;
|
|
if (strnlen(host, 255)-1 >= 254 || mbstowcs(0, host, 0) == -1) return 0;
|
|
for (s=(void *)host; *s>=0x80 || *s=='.' || *s=='-' || isalnum(*s); s++);
|
|
return !*s;
|
|
}
|
|
|
|
static int name_from_null(struct address buf[static 2], const char *name, int family, int flags)
|
|
{
|
|
int cnt = 0;
|
|
if (name) return 0;
|
|
if (flags & AI_PASSIVE) {
|
|
if (family != AF_INET6)
|
|
buf[cnt++] = (struct address){ .family = AF_INET };
|
|
if (family != AF_INET)
|
|
buf[cnt++] = (struct address){ .family = AF_INET6 };
|
|
} else {
|
|
if (family != AF_INET6)
|
|
buf[cnt++] = (struct address){ .family = AF_INET, .addr = { 127,0,0,1 } };
|
|
if (family != AF_INET)
|
|
buf[cnt++] = (struct address){ .family = AF_INET6, .addr = { [15] = 1 } };
|
|
}
|
|
return cnt;
|
|
}
|
|
|
|
static int name_from_numeric(struct address buf[static 1], const char *name, int family)
|
|
{
|
|
return __lookup_ipliteral(buf, name, family);
|
|
}
|
|
|
|
static int name_from_hosts(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family)
|
|
{
|
|
char line[512];
|
|
size_t l = strlen(name);
|
|
int cnt = 0, badfam = 0, have_canon = 0;
|
|
unsigned char _buf[1032];
|
|
FILE _f, *f = __fopen_rb_ca("/etc/hosts", &_f, _buf, sizeof _buf);
|
|
if (!f) switch (errno) {
|
|
case ENOENT:
|
|
case ENOTDIR:
|
|
case EACCES:
|
|
return 0;
|
|
default:
|
|
return EAI_SYSTEM;
|
|
}
|
|
while (fgets(line, sizeof line, f) && cnt < MAXADDRS) {
|
|
char *p, *z;
|
|
|
|
if ((p=strchr(line, '#'))) *p++='\n', *p=0;
|
|
for(p=line+1; (p=strstr(p, name)) &&
|
|
(!isspace(p[-1]) || !isspace(p[l])); p++);
|
|
if (!p) continue;
|
|
|
|
/* Isolate IP address to parse */
|
|
for (p=line; *p && !isspace(*p); p++);
|
|
*p++ = 0;
|
|
switch (name_from_numeric(buf+cnt, line, family)) {
|
|
case 1:
|
|
cnt++;
|
|
break;
|
|
case 0:
|
|
continue;
|
|
default:
|
|
badfam = EAI_NONAME;
|
|
break;
|
|
}
|
|
|
|
if (have_canon) continue;
|
|
|
|
/* Extract first name as canonical name */
|
|
for (; *p && isspace(*p); p++);
|
|
for (z=p; *z && !isspace(*z); z++);
|
|
*z = 0;
|
|
if (is_valid_hostname(p)) {
|
|
have_canon = 1;
|
|
memcpy(canon, p, z-p+1);
|
|
}
|
|
}
|
|
__fclose_ca(f);
|
|
return cnt ? cnt : badfam;
|
|
}
|
|
|
|
struct dpc_ctx {
|
|
struct address *addrs;
|
|
char *canon;
|
|
int cnt;
|
|
};
|
|
|
|
#define RR_A 1
|
|
#define RR_CNAME 5
|
|
#define RR_AAAA 28
|
|
|
|
static int dns_parse_callback(void *c, int rr, const void *data, int len, const void *packet)
|
|
{
|
|
char tmp[256];
|
|
struct dpc_ctx *ctx = c;
|
|
if (ctx->cnt >= MAXADDRS) return -1;
|
|
switch (rr) {
|
|
case RR_A:
|
|
if (len != 4) return -1;
|
|
ctx->addrs[ctx->cnt].family = AF_INET;
|
|
ctx->addrs[ctx->cnt].scopeid = 0;
|
|
memcpy(ctx->addrs[ctx->cnt++].addr, data, 4);
|
|
break;
|
|
case RR_AAAA:
|
|
if (len != 16) return -1;
|
|
ctx->addrs[ctx->cnt].family = AF_INET6;
|
|
ctx->addrs[ctx->cnt].scopeid = 0;
|
|
memcpy(ctx->addrs[ctx->cnt++].addr, data, 16);
|
|
break;
|
|
case RR_CNAME:
|
|
if (__dn_expand(packet, (const unsigned char *)packet + 512,
|
|
data, tmp, sizeof tmp) > 0 && is_valid_hostname(tmp))
|
|
strcpy(ctx->canon, tmp);
|
|
break;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static int name_from_dns(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family, const struct resolvconf *conf)
|
|
{
|
|
unsigned char qbuf[2][280], abuf[2][512];
|
|
const unsigned char *qp[2] = { qbuf[0], qbuf[1] };
|
|
unsigned char *ap[2] = { abuf[0], abuf[1] };
|
|
int qlens[2], alens[2];
|
|
int i, nq = 0;
|
|
struct dpc_ctx ctx = { .addrs = buf, .canon = canon };
|
|
static const struct { int af; int rr; } afrr[2] = {
|
|
{ .af = AF_INET6, .rr = RR_A },
|
|
{ .af = AF_INET, .rr = RR_AAAA },
|
|
};
|
|
|
|
for (i=0; i<2; i++) {
|
|
if (family != afrr[i].af) {
|
|
qlens[nq] = __res_mkquery(0, name, 1, afrr[i].rr,
|
|
0, 0, 0, qbuf[nq], sizeof *qbuf);
|
|
if (qlens[nq] == -1)
|
|
return EAI_NONAME;
|
|
qbuf[nq][3] = 0; /* don't need AD flag */
|
|
nq++;
|
|
}
|
|
}
|
|
|
|
if (__res_msend_rc(nq, qp, qlens, ap, alens, sizeof *abuf, conf) < 0)
|
|
return EAI_SYSTEM;
|
|
|
|
for (i=0; i<nq; i++) {
|
|
if (alens[i] < 4 || (abuf[i][3] & 15) == 2) return EAI_AGAIN;
|
|
if ((abuf[i][3] & 15) == 3) return 0;
|
|
if ((abuf[i][3] & 15) != 0) return EAI_FAIL;
|
|
}
|
|
|
|
for (i=0; i<nq; i++)
|
|
__dns_parse(abuf[i], alens[i], dns_parse_callback, &ctx);
|
|
|
|
if (ctx.cnt) return ctx.cnt;
|
|
return EAI_NONAME;
|
|
}
|
|
|
|
static int name_from_dns_search(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family)
|
|
{
|
|
char search[256];
|
|
struct resolvconf conf;
|
|
size_t l, dots;
|
|
char *p, *z;
|
|
|
|
if (__get_resolv_conf(&conf, search, sizeof search) < 0) return -1;
|
|
|
|
/* Count dots, suppress search when >=ndots or name ends in
|
|
* a dot, which is an explicit request for global scope. */
|
|
for (dots=l=0; name[l]; l++) if (name[l]=='.') dots++;
|
|
if (dots >= conf.ndots || name[l-1]=='.') *search = 0;
|
|
|
|
/* Strip final dot for canon, fail if multiple trailing dots. */
|
|
if (name[l-1]=='.') l--;
|
|
if (!l || name[l-1]=='.') return EAI_NONAME;
|
|
|
|
/* This can never happen; the caller already checked length. */
|
|
if (l >= 256) return EAI_NONAME;
|
|
|
|
/* Name with search domain appended is setup in canon[]. This both
|
|
* provides the desired default canonical name (if the requested
|
|
* name is not a CNAME record) and serves as a buffer for passing
|
|
* the full requested name to name_from_dns. */
|
|
memcpy(canon, name, l);
|
|
canon[l] = '.';
|
|
|
|
for (p=search; *p; p=z) {
|
|
for (; isspace(*p); p++);
|
|
for (z=p; *z && !isspace(*z); z++);
|
|
if (z==p) break;
|
|
if (z-p < 256 - l - 1) {
|
|
memcpy(canon+l+1, p, z-p);
|
|
canon[z-p+1+l] = 0;
|
|
int cnt = name_from_dns(buf, canon, canon, family, &conf);
|
|
if (cnt) return cnt;
|
|
}
|
|
}
|
|
|
|
canon[l] = 0;
|
|
return name_from_dns(buf, canon, name, family, &conf);
|
|
}
|
|
|
|
static const struct policy {
|
|
unsigned char addr[16];
|
|
unsigned char len, mask;
|
|
unsigned char prec, label;
|
|
} defpolicy[] = {
|
|
{ "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\1", 15, 0xff, 50, 0 },
|
|
{ "\0\0\0\0\0\0\0\0\0\0\xff\xff", 11, 0xff, 35, 4 },
|
|
{ "\x20\2", 1, 0xff, 30, 2 },
|
|
{ "\x20\1", 3, 0xff, 5, 5 },
|
|
{ "\xfc", 0, 0xfe, 3, 13 },
|
|
#if 0
|
|
/* These are deprecated and/or returned to the address
|
|
* pool, so despite the RFC, treating them as special
|
|
* is probably wrong. */
|
|
{ "", 11, 0xff, 1, 3 },
|
|
{ "\xfe\xc0", 1, 0xc0, 1, 11 },
|
|
{ "\x3f\xfe", 1, 0xff, 1, 12 },
|
|
#endif
|
|
/* Last rule must match all addresses to stop loop. */
|
|
{ "", 0, 0, 40, 1 },
|
|
};
|
|
|
|
static const struct policy *policyof(const struct in6_addr *a)
|
|
{
|
|
int i;
|
|
for (i=0; ; i++) {
|
|
if (memcmp(a->s6_addr, defpolicy[i].addr, defpolicy[i].len))
|
|
continue;
|
|
if ((a->s6_addr[defpolicy[i].len] & defpolicy[i].mask)
|
|
!= defpolicy[i].addr[defpolicy[i].len])
|
|
continue;
|
|
return defpolicy+i;
|
|
}
|
|
}
|
|
|
|
static int labelof(const struct in6_addr *a)
|
|
{
|
|
return policyof(a)->label;
|
|
}
|
|
|
|
static int scopeof(const struct in6_addr *a)
|
|
{
|
|
if (IN6_IS_ADDR_MULTICAST(a)) return a->s6_addr[1] & 15;
|
|
if (IN6_IS_ADDR_LINKLOCAL(a)) return 2;
|
|
if (IN6_IS_ADDR_LOOPBACK(a)) return 2;
|
|
if (IN6_IS_ADDR_SITELOCAL(a)) return 5;
|
|
return 14;
|
|
}
|
|
|
|
static int prefixmatch(const struct in6_addr *s, const struct in6_addr *d)
|
|
{
|
|
/* FIXME: The common prefix length should be limited to no greater
|
|
* than the nominal length of the prefix portion of the source
|
|
* address. However the definition of the source prefix length is
|
|
* not clear and thus this limiting is not yet implemented. */
|
|
unsigned i;
|
|
for (i=0; i<128 && !((s->s6_addr[i/8]^d->s6_addr[i/8])&(128>>(i%8))); i++);
|
|
return i;
|
|
}
|
|
|
|
#define DAS_USABLE 0x40000000
|
|
#define DAS_MATCHINGSCOPE 0x20000000
|
|
#define DAS_MATCHINGLABEL 0x10000000
|
|
#define DAS_PREC_SHIFT 20
|
|
#define DAS_SCOPE_SHIFT 16
|
|
#define DAS_PREFIX_SHIFT 8
|
|
#define DAS_ORDER_SHIFT 0
|
|
|
|
static int addrcmp(const void *_a, const void *_b)
|
|
{
|
|
const struct address *a = _a, *b = _b;
|
|
return b->sortkey - a->sortkey;
|
|
}
|
|
|
|
int __lookup_name(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family, int flags)
|
|
{
|
|
int cnt = 0, i, j;
|
|
|
|
*canon = 0;
|
|
if (name) {
|
|
/* reject empty name and check len so it fits into temp bufs */
|
|
size_t l = strnlen(name, 255);
|
|
if (l-1 >= 254)
|
|
return EAI_NONAME;
|
|
memcpy(canon, name, l+1);
|
|
}
|
|
|
|
/* Procedurally, a request for v6 addresses with the v4-mapped
|
|
* flag set is like a request for unspecified family, followed
|
|
* by filtering of the results. */
|
|
if (flags & AI_V4MAPPED) {
|
|
if (family == AF_INET6) family = AF_UNSPEC;
|
|
else flags -= AI_V4MAPPED;
|
|
}
|
|
|
|
/* Try each backend until there's at least one result. */
|
|
cnt = name_from_null(buf, name, family, flags);
|
|
if (!cnt) cnt = name_from_numeric(buf, name, family);
|
|
if (!cnt && !(flags & AI_NUMERICHOST)) {
|
|
cnt = name_from_hosts(buf, canon, name, family);
|
|
if (!cnt) cnt = name_from_dns_search(buf, canon, name, family);
|
|
}
|
|
if (cnt<=0) return cnt ? cnt : EAI_NONAME;
|
|
|
|
/* Filter/transform results for v4-mapped lookup, if requested. */
|
|
if (flags & AI_V4MAPPED) {
|
|
if (!(flags & AI_ALL)) {
|
|
/* If any v6 results exist, remove v4 results. */
|
|
for (i=0; i<cnt && buf[i].family != AF_INET6; i++);
|
|
if (i<cnt) {
|
|
for (j=0; i<cnt; i++) {
|
|
if (buf[i].family == AF_INET6)
|
|
buf[j++] = buf[i];
|
|
}
|
|
cnt = i = j;
|
|
}
|
|
}
|
|
/* Translate any remaining v4 results to v6 */
|
|
for (i=0; i<cnt; i++) {
|
|
if (buf[i].family != AF_INET) continue;
|
|
memcpy(buf[i].addr+12, buf[i].addr, 4);
|
|
memcpy(buf[i].addr, "\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
|
|
buf[i].family = AF_INET6;
|
|
}
|
|
}
|
|
|
|
/* No further processing is needed if there are fewer than 2
|
|
* results or if there are only IPv4 results. */
|
|
if (cnt<2 || family==AF_INET) return cnt;
|
|
for (i=0; i<cnt; i++) if (buf[i].family != AF_INET) break;
|
|
if (i==cnt) return cnt;
|
|
|
|
int cs;
|
|
pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
|
|
|
|
/* The following implements a subset of RFC 3484/6724 destination
|
|
* address selection by generating a single 31-bit sort key for
|
|
* each address. Rules 3, 4, and 7 are omitted for having
|
|
* excessive runtime and code size cost and dubious benefit.
|
|
* So far the label/precedence table cannot be customized. */
|
|
for (i=0; i<cnt; i++) {
|
|
int family = buf[i].family;
|
|
int key = 0;
|
|
struct sockaddr_in6 sa6 = { 0 }, da6 = {
|
|
.sin6_family = AF_INET6,
|
|
.sin6_scope_id = buf[i].scopeid,
|
|
.sin6_port = 65535
|
|
};
|
|
struct sockaddr_in sa4 = { 0 }, da4 = {
|
|
.sin_family = AF_INET,
|
|
.sin_port = 65535
|
|
};
|
|
void *sa, *da;
|
|
socklen_t salen, dalen;
|
|
if (family == AF_INET6) {
|
|
memcpy(da6.sin6_addr.s6_addr, buf[i].addr, 16);
|
|
da = &da6; dalen = sizeof da6;
|
|
sa = &sa6; salen = sizeof sa6;
|
|
} else {
|
|
memcpy(sa6.sin6_addr.s6_addr,
|
|
"\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
|
|
memcpy(da6.sin6_addr.s6_addr+12, buf[i].addr, 4);
|
|
memcpy(da6.sin6_addr.s6_addr,
|
|
"\0\0\0\0\0\0\0\0\0\0\xff\xff", 12);
|
|
memcpy(da6.sin6_addr.s6_addr+12, buf[i].addr, 4);
|
|
memcpy(&da4.sin_addr, buf[i].addr, 4);
|
|
da = &da4; dalen = sizeof da4;
|
|
sa = &sa4; salen = sizeof sa4;
|
|
}
|
|
const struct policy *dpolicy = policyof(&da6.sin6_addr);
|
|
int dscope = scopeof(&da6.sin6_addr);
|
|
int dlabel = dpolicy->label;
|
|
int dprec = dpolicy->prec;
|
|
int prefixlen = 0;
|
|
int fd = socket(family, SOCK_DGRAM|SOCK_CLOEXEC, IPPROTO_UDP);
|
|
if (fd >= 0) {
|
|
if (!connect(fd, da, dalen)) {
|
|
key |= DAS_USABLE;
|
|
if (!getsockname(fd, sa, &salen)) {
|
|
if (family == AF_INET) memcpy(
|
|
sa6.sin6_addr.s6_addr+12,
|
|
&sa4.sin_addr, 4);
|
|
if (dscope == scopeof(&sa6.sin6_addr))
|
|
key |= DAS_MATCHINGSCOPE;
|
|
if (dlabel == labelof(&sa6.sin6_addr))
|
|
key |= DAS_MATCHINGLABEL;
|
|
prefixlen = prefixmatch(&sa6.sin6_addr,
|
|
&da6.sin6_addr);
|
|
}
|
|
}
|
|
close(fd);
|
|
}
|
|
key |= dprec << DAS_PREC_SHIFT;
|
|
key |= (15-dscope) << DAS_SCOPE_SHIFT;
|
|
key |= prefixlen << DAS_PREFIX_SHIFT;
|
|
key |= (MAXADDRS-i) << DAS_ORDER_SHIFT;
|
|
buf[i].sortkey = key;
|
|
}
|
|
qsort(buf, cnt, sizeof *buf, addrcmp);
|
|
|
|
pthread_setcancelstate(cs, 0);
|
|
|
|
return cnt;
|
|
}
|