X-Git-Url: http://nsz.repo.hu/git/?a=blobdiff_plain;f=src%2Fnetwork%2Flookup_name.c;h=be0c0bdd9b919db77680645616de517c27021af6;hb=0a7b4323b0f2b944dbd47a813c0c6e6813e7fd67;hp=68b172b4fa5e7300babd2ef363437bedea9da596;hpb=2abb70c302efe46dfd8fd9e1d64fa00f1376f428;p=musl

diff --git a/src/network/lookup_name.c b/src/network/lookup_name.c
index 68b172b4..be0c0bdd 100644
--- a/src/network/lookup_name.c
+++ b/src/network/lookup_name.c
@@ -7,6 +7,10 @@
 #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"
@@ -14,7 +18,7 @@
 static int is_valid_hostname(const char *host)
 {
 	const unsigned char *s;
-	if (strnlen(host, 254)-1 >= 253 || mbstowcs(0, host, 0) == -1) return 0;
+	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;
 }
@@ -46,10 +50,17 @@ static int name_from_hosts(struct address buf[static MAXADDRS], char canon[stati
 {
 	char line[512];
 	size_t l = strlen(name);
-	int cnt = 0;
+	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) return 0;
+	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;
 
@@ -61,53 +72,67 @@ static int name_from_hosts(struct address buf[static MAXADDRS], char canon[stati
 		/* Isolate IP address to parse */
 		for (p=line; *p && !isspace(*p); p++);
 		*p++ = 0;
-		if (name_from_numeric(buf+cnt, line, family))
+		switch (name_from_numeric(buf+cnt, line, family)) {
+		case 1:
 			cnt++;
+			break;
+		case 0:
+			continue;
+		default:
+			badfam = EAI_NODATA;
+			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)) memcpy(canon, p, z-p+1);
+		if (is_valid_hostname(p)) {
+			have_canon = 1;
+			memcpy(canon, p, z-p+1);
+		}
 	}
 	__fclose_ca(f);
-	return cnt;
+	return cnt ? cnt : badfam;
 }
 
 struct dpc_ctx {
 	struct address *addrs;
 	char *canon;
 	int cnt;
+	int rrtype;
 };
 
-int __dns_parse(const unsigned char *, int, int (*)(void *, int, const void *, int, const void *), void *);
-int __dn_expand(const unsigned char *, const unsigned char *, const unsigned char *, char *, int);
-int __res_mkquery(int, const char *, int, int, const unsigned char *, int, const unsigned char*, unsigned char *, int);
-int __res_msend(int, const unsigned char *const *, const int *, unsigned char *const *, int *, int);
-
 #define RR_A 1
 #define RR_CNAME 5
 #define RR_AAAA 28
 
+#define ABUF_SIZE 768
+
 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 0;
 	switch (rr) {
 	case RR_A:
+		if (rr != ctx->rrtype) return 0;
 		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 (rr != ctx->rrtype) return 0;
 		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,
+		if (__dn_expand(packet, (const unsigned char *)packet + ABUF_SIZE,
 		    data, tmp, sizeof tmp) > 0 && is_valid_hostname(tmp))
 			strcpy(ctx->canon, tmp);
 		break;
@@ -115,35 +140,168 @@ static int dns_parse_callback(void *c, int rr, const void *data, int len, const
 	return 0;
 }
 
-static int name_from_dns(struct address buf[static MAXADDRS], char canon[static 256], const char *name, int family)
+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];
+	unsigned char qbuf[2][280], abuf[2][ABUF_SIZE];
 	const unsigned char *qp[2] = { qbuf[0], qbuf[1] };
 	unsigned char *ap[2] = { abuf[0], abuf[1] };
-	int qlens[2], alens[2];
+	int qlens[2], alens[2], qtypes[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 },
+	};
 
-	if (family != AF_INET6) {
-		qlens[nq] = __res_mkquery(0, name, 1, RR_A, 0, 0, 0,
-			qbuf[nq], sizeof *qbuf);
-		nq++;
-	}
-	if (family != AF_INET) {
-		qlens[nq] = __res_mkquery(0, name, 1, RR_AAAA, 0, 0, 0,
-			qbuf[nq], sizeof *qbuf);
-		nq++;
+	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 0;
+			qtypes[nq] = afrr[i].rr;
+			qbuf[nq][3] = 0; /* don't need AD flag */
+			/* Ensure query IDs are distinct. */
+			if (nq && qbuf[nq][0] == qbuf[0][0])
+				qbuf[nq][0]++;
+			nq++;
+		}
 	}
 
-	if (__res_msend(nq, qp, qlens, ap, alens, sizeof *abuf) < 0) return EAI_SYSTEM;
+	if (__res_msend_rc(nq, qp, qlens, ap, alens, sizeof *abuf, conf) < 0)
+		return EAI_SYSTEM;
 
-	for (i=0; i<nq; i++)
+	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=nq-1; i>=0; i--) {
+		ctx.rrtype = qtypes[i];
 		__dns_parse(abuf[i], alens[i], dns_parse_callback, &ctx);
+	}
 
 	if (ctx.cnt) return ctx.cnt;
-	if (alens[0] < 4 || (abuf[0][3] & 15) == 2) return EAI_AGAIN;
-	if ((abuf[0][3] & 15) == 3) return EAI_NONAME;
-	return EAI_FAIL;
+	return EAI_NODATA;
+}
+
+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)
@@ -152,8 +310,9 @@ int __lookup_name(struct address buf[static MAXADDRS], char canon[static 256], c
 
 	*canon = 0;
 	if (name) {
-		size_t l;
-		if ((l = strnlen(name, 254))-1 >= 253)
+		/* 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);
 	}
@@ -171,7 +330,7 @@ int __lookup_name(struct address buf[static MAXADDRS], char canon[static 256], c
 	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(buf, canon, name, family);
+		if (!cnt) cnt = name_from_dns_search(buf, canon, name, family);
 	}
 	if (cnt<=0) return cnt ? cnt : EAI_NONAME;
 
@@ -197,5 +356,81 @@ int __lookup_name(struct address buf[static MAXADDRS], char canon[static 256], c
 		}
 	}
 
+	/* 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;
 }