refactor getaddrinfo and add support for most remaining features

this is the first phase of the "resolver overhaul" project.

conceptually, the results of getaddrinfo are a direct product of a
list of address results and a list of service results. the new code
makes this explicit by computing these lists separately and combining
the results. this adds support for services that have both tcp and udp
versions, where the caller has not specified which it wants, and
eliminates a number of duplicate code paths which were all producing
the final output addrinfo structures, but in subtly different ways,
making it difficult to implement any of the features which were
missing.

in addition to the above benefits, the refactoring allows for legacy
functions like gethostbyname to be implemented without using the
getaddrinfo function itself. such changes to the legacy functions have
not yet been made, however.

further improvements include matching of service alias names from
/etc/services (previously only the primary name was supported),
returning multiple results from /etc/hosts (previously only the first
matching line was honored), and support for the AI_V4MAPPED and AI_ALL
flags.

features which remain unimplemented are IDN translations (encoding
non-ASCII hostnames for DNS lookup) and the AI_ADDRCONFIG flag.

at this point, the DNS-based name resolving code is still based on the
old interfaces in __dns.c, albeit somewhat simpler in its use of them.
there may be some dead code which could already be removed, but
changes to this layer will be a later phase of the resolver overhaul.

1 files changed, 94 insertions, 228 deletions

diff --git a/src/network/getaddrinfo.c b/src/network/getaddrinfo.c
index 5d45be74..70b6cfda 100644
--- a/src/network/getaddrinfo.c
+++ b/src/network/getaddrinfo.c
@@ -1,249 +1,115 @@
 #include <stdlib.h>
-#include <stdio.h>
-#include <netdb.h>
-#include <netinet/in.h>
 #include <sys/socket.h>
-#include <unistd.h>
+#include <netinet/in.h>
+#include <netdb.h>
 #include <string.h>
-#include <ctype.h>
-#include "__dns.h"
-#include "stdio_impl.h"
-
-static int is_valid(const char *host)
-{
-	const unsigned char *s;
-	if (strlen(host)-1 > 254 || mbstowcs(0, host, 0) > 255) return 0;
-	for (s=(void *)host; *s>=0x80 || *s=='.' || *s=='-' || isalnum(*s); s++);
-	return !*s;
-}
-
-#if 0
-static int have_af(int family)
-{
-	struct sockaddr_in6 sin6 = { .sin6_family = family };
-	socklen_t sl = family == AF_INET
-		? sizeof(struct sockaddr_in)
-		: sizeof(struct sockaddr_in6);
-	int sock = socket(family, SOCK_STREAM, 0);
-	int have = !bind(sock, (void *)&sin6, sl);
-	close(sock);
-	return have;
-}
-#endif
-
-union sa {
-	struct sockaddr_in sin;
-	struct sockaddr_in6 sin6;
-};
-
-struct aibuf {
-	struct addrinfo ai;
-	union sa sa;
-};
-
-/* Extra slots needed for storing canonical name */
-#define EXTRA ((256+sizeof(struct aibuf)-1)/sizeof(struct aibuf))
+#include "lookup.h"
 
 int getaddrinfo(const char *restrict host, const char *restrict serv, const struct addrinfo *restrict hint, struct addrinfo **restrict res)
 {
-	int flags = hint ? hint->ai_flags : 0;
-	int family = hint ? hint->ai_family : AF_UNSPEC;
-	int type = hint ? hint->ai_socktype : 0;
-	int proto = hint ? hint->ai_protocol : 0;
-	unsigned long port = 0;
-	struct aibuf *buf;
-	union sa sa = {{0}};
-	unsigned char reply[1024];
-	int i, j;
-	char line[512];
-	FILE *f, _f;
-	unsigned char _buf[1024];
-	char *z;
-	int result;
-	int cnt;
-
-	if (family != AF_INET && family != AF_INET6 && family != AF_UNSPEC)
-		return EAI_FAMILY;
-
-	if (host && strlen(host)>255) return EAI_NONAME;
-	if (serv && strlen(serv)>32) return EAI_SERVICE;
-
-	if (type && !proto)
-		proto = type==SOCK_DGRAM ? IPPROTO_UDP : IPPROTO_TCP;
-	if (!type && proto)
-		type = proto==IPPROTO_UDP ? SOCK_DGRAM : SOCK_STREAM;
-
-	if (serv) {
-		if (!*serv) return EAI_SERVICE;
-		port = strtoul(serv, &z, 10);
-		if (*z) {
-			size_t servlen = strlen(serv);
-			char *end = line;
-
-			if (flags & AI_NUMERICSERV) return EAI_SERVICE;
+	struct service ports[MAXSERVS];
+	struct address addrs[MAXADDRS];
+	char canon[256], *outcanon;
+	int nservs, naddrs, nais, canon_len, i, j, k;
+	int family = AF_UNSPEC, flags = 0, proto = 0;
+	struct aibuf {
+		struct addrinfo ai;
+		union sa {
+			struct sockaddr_in sin;
+			struct sockaddr_in6 sin6;
+		} sa;
+	} *out;
+
+	if (hint) {
+		family = hint->ai_family;
+		flags = hint->ai_flags;
+		proto = hint->ai_protocol;
+
+		const int mask = AI_PASSIVE | AI_CANONNAME | AI_NUMERICHOST |
+			AI_V4MAPPED | AI_ALL | AI_ADDRCONFIG | AI_NUMERICSERV;
+		if ((flags & mask) != flags)
+			return EAI_BADFLAGS;
+
+		switch (family) {
+		case AF_INET:
+		case AF_INET6:
+		case AF_UNSPEC:
+			break;
+		default:
+			return EAI_FAMILY;
+		}
 
-			f = __fopen_rb_ca("/etc/services", &_f, _buf, sizeof _buf);
-			if (!f) return EAI_SERVICE;
-			while (fgets(line, sizeof line, f)) {
-				if (strncmp(line, serv, servlen) || !isspace(line[servlen]))
-					continue;
-				port = strtoul(line+servlen, &end, 10);
-				if (strncmp(end, proto==IPPROTO_UDP ? "/udp" : "/tcp", 4))
-					continue;
+		switch (hint->ai_socktype) {
+		case SOCK_STREAM:
+			switch (proto) {
+			case 0:
+				proto = IPPROTO_TCP;
+			case IPPROTO_TCP:
 				break;
+			default:
+				return EAI_SERVICE;
 			}
-			__fclose_ca(f);
-			if (feof(f)) return EAI_SERVICE;
-		}
-		if (port > 65535) return EAI_SERVICE;
-		port = htons(port);
-	}
-
-	if (!host) {
-		if (family == AF_UNSPEC) {
-			cnt = 2; family = AF_INET;
-		} else {
-			cnt = 1;
-		}
-		buf = calloc(sizeof *buf, cnt);
-		if (!buf) return EAI_MEMORY;
-		for (i=0; i<cnt; i++) {
-			if (i) family = AF_INET6;
-			buf[i].ai.ai_protocol = proto;
-			buf[i].ai.ai_socktype = type;
-			buf[i].ai.ai_addr = (void *)&buf[i].sa;
-			buf[i].ai.ai_addrlen = family==AF_INET6
-				? sizeof sa.sin6 : sizeof sa.sin;
-			buf[i].ai.ai_family = family;
-			buf[i].sa.sin.sin_family = family;
-			buf[i].sa.sin.sin_port = port;
-			if (i+1<cnt) buf[i].ai.ai_next = &buf[i+1].ai;
-			if (!(flags & AI_PASSIVE)) {
-				if (family == AF_INET) {
-					0[(uint8_t*)&buf[i].sa.sin.sin_addr.s_addr]=127;
-					3[(uint8_t*)&buf[i].sa.sin.sin_addr.s_addr]=1;
-				} else buf[i].sa.sin6.sin6_addr.s6_addr[15] = 1;
+			break;
+		case SOCK_DGRAM:
+			switch (proto) {
+			case 0:
+				proto = IPPROTO_UDP;
+			case IPPROTO_UDP:
+				break;
+			default:
+				return EAI_SERVICE;
 			}
+		case 0:
+			break;
+		default:
+			return EAI_SOCKTYPE;
 		}
-		*res = &buf->ai;
-		return 0;
-	}
-
-	if (!*host) return EAI_NONAME;
-
-	/* Try as a numeric address */
-	if (__ipparse(&sa, family, host) >= 0) {
-		buf = calloc(sizeof *buf, 1+EXTRA);
-		if (!buf) return EAI_MEMORY;
-		family = sa.sin.sin_family;
-		buf->ai.ai_protocol = proto;
-		buf->ai.ai_socktype = type;
-		buf->ai.ai_addr = (void *)&buf->sa;
-		buf->ai.ai_addrlen = family==AF_INET6 ? sizeof sa.sin6 : sizeof sa.sin;
-		buf->ai.ai_family = family;
-		buf->ai.ai_canonname = (char *)host;
-		buf->sa = sa;
-		buf->sa.sin.sin_port = port;
-		*res = &buf->ai;
-		return 0;
 	}
 
-	if (flags & AI_NUMERICHOST) return EAI_NONAME;
+	nservs = __lookup_serv(ports, serv, proto, flags);
+	if (nservs < 0) return nservs;
 
-	f = __fopen_rb_ca("/etc/hosts", &_f, _buf, sizeof _buf);
-	if (f) while (fgets(line, sizeof line, f)) {
-		char *p;
-		size_t l = strlen(host);
+	naddrs = __lookup_name(addrs, canon, host, family, flags);
+	if (naddrs < 0) return naddrs;
 
-		if ((p=strchr(line, '#'))) *p++='\n', *p=0;
-		for(p=line+1; (p=strstr(p, host)) &&
-			(!isspace(p[-1]) || !isspace(p[l])); p++);
-		if (!p) continue;
-		__fclose_ca(f);
-
-		/* Isolate IP address to parse */
-		for (p=line; *p && !isspace(*p); p++);
-		*p++ = 0;
-		if (__ipparse(&sa, family, line) < 0) return EAI_NONAME;
-
-		/* Allocate and fill result buffer */
-		buf = calloc(sizeof *buf, 1+EXTRA);
-		if (!buf) return EAI_MEMORY;
-		family = sa.sin.sin_family;
-		buf->ai.ai_protocol = proto;
-		buf->ai.ai_socktype = type;
-		buf->ai.ai_addr = (void *)&buf->sa;
-		buf->ai.ai_addrlen = family==AF_INET6 ? sizeof sa.sin6 : sizeof sa.sin;
-		buf->ai.ai_family = family;
-		buf->sa = sa;
-		buf->sa.sin.sin_port = port;
-
-		/* Extract first name as canonical name */
-		for (; *p && isspace(*p); p++);
-		buf->ai.ai_canonname = (void *)(buf+1);
-		snprintf(buf->ai.ai_canonname, 256, "%s", p);
-		for (p=buf->ai.ai_canonname; *p && !isspace(*p); p++);
-		*p = 0;
-		if (!is_valid(buf->ai.ai_canonname))
-			buf->ai.ai_canonname = 0;
-
-		*res = &buf->ai;
-		return 0;
-	}
-	if (f) __fclose_ca(f);
+	nais = nservs * naddrs;
+	canon_len = strlen(canon);
+	out = calloc(1, nais * sizeof(*out) + canon_len + 1);
+	if (!out) return EAI_MEMORY;
 
-#if 0
-	f = __fopen_rb_ca("/etc/resolv.conf", &_f, _buf, sizeof _buf);
-	if (f) while (fgets(line, sizeof line, f)) {
-		if (!isspace(line[10]) || (strncmp(line, "search", 6)
-			&& strncmp(line, "domain", 6))) continue;
+	if (canon_len) {
+		outcanon = (void *)&out[nais];
+		memcpy(outcanon, canon, canon_len+1);
+	} else {
+		outcanon = 0;
 	}
-	if (f) __fclose_ca(f);
-#endif
 
-	/* Perform one or more DNS queries for host */
-	memset(reply, 0, sizeof reply);
-	result = __dns_query(reply, host, family, 0);
-	if (result < 0) return result;
-
-	cnt = __dns_count_addrs(reply, result);
-	if (cnt <= 0) return EAI_NONAME;
-
-	buf = calloc(sizeof *buf, cnt+EXTRA);
-	if (!buf) return EAI_MEMORY;
-
-	i = 0;
-	if (family != AF_INET6) {
-		j = __dns_get_rr(&buf[i].sa.sin.sin_addr, sizeof *buf, 4, cnt-i, reply, RR_A, 0);
-		while (j--) buf[i++].sa.sin.sin_family = AF_INET;
-	}
-	if (family != AF_INET) {
-		j = __dns_get_rr(&buf[i].sa.sin6.sin6_addr, sizeof *buf, 16, cnt-i, reply, RR_AAAA, 0);
-		while (j--) buf[i++].sa.sin.sin_family = AF_INET6;
-	}
-	if (result>1) {
-		j = __dns_get_rr(&buf[i].sa.sin.sin_addr, sizeof *buf, 4, cnt-i, reply+512, RR_A, 0);
-		while (j--) buf[i++].sa.sin.sin_family = AF_INET;
-		j = __dns_get_rr(&buf[i].sa.sin6.sin6_addr, sizeof *buf, 16, cnt-i, reply+512, RR_AAAA, 0);
-		while (j--) buf[i++].sa.sin.sin_family = AF_INET6;
-	}
-
-	if (__dns_get_rr((void *)&buf[cnt], 0, 256, 1, reply, RR_CNAME, 1) <= 0)
-		strcpy((void *)&buf[cnt], host);
-
-	for (i=0; i<cnt; i++) {
-		buf[i].ai.ai_protocol = proto;
-		buf[i].ai.ai_socktype = type;
-		buf[i].ai.ai_addr = (void *)&buf[i].sa;
-		buf[i].ai.ai_addrlen = buf[i].sa.sin.sin_family==AF_INET6
-			? sizeof sa.sin6 : sizeof sa.sin;
-		buf[i].ai.ai_family = buf[i].sa.sin.sin_family;
-		buf[i].sa.sin.sin_port = port;
-		buf[i].ai.ai_next = &buf[i+1].ai;
-		buf[i].ai.ai_canonname = (void *)&buf[cnt];
+	for (k=i=0; i<naddrs; i++) for (j=0; j<nservs; j++, k++) {
+		out[k].ai = (struct addrinfo){
+			.ai_family = addrs[i].family,
+			.ai_socktype = ports[j].proto == IPPROTO_TCP
+				? SOCK_STREAM : SOCK_DGRAM,
+			.ai_protocol = ports[j].proto,
+			.ai_addrlen = addrs[i].family == AF_INET
+				? sizeof(struct sockaddr_in)
+				: sizeof(struct sockaddr_in6),
+			.ai_addr = (void *)&out[k].sa,
+			.ai_canonname = outcanon,
+			.ai_next = &out[k+1].ai };
+		switch (addrs[i].family) {
+		case AF_INET:
+			out[k].sa.sin.sin_family = AF_INET;
+			out[k].sa.sin.sin_port = htons(ports[j].port);
+			memcpy(&out[k].sa.sin.sin_addr, &addrs[i].addr, 4);
+			break;
+		case AF_INET6:
+			out[k].sa.sin6.sin6_family = AF_INET6;
+			out[k].sa.sin6.sin6_port = htons(ports[j].port);
+			memcpy(&out[k].sa.sin6.sin6_addr, &addrs[i].addr, 16);
+			break;			
+		}
 	}
-	buf[cnt-1].ai.ai_next = 0;
-	*res = &buf->ai;
-
+	out[nais-1].ai.ai_next = 0;
+	*res = &out->ai;
 	return 0;
 }