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Add support for different record types in DNS

--- a/libstd/resolve.myr

+++ b/libstd/resolve.myr

@@ -21,6 +21,27 @@

 use "utf.use"

 pkg std =

+	type rectype = uint16

+

+	const DnsA	: rectype = 1  /* host address */

+	const DnsNS	: rectype = 2  /* authoritative name server */

+	const DnsMD	: rectype = 3  /* mail destination (Obsolete - use MX) */

+	const DnsMF	: rectype = 4  /* mail forwarder (Obsolete - use MX) */

+	const DnsCNAME	: rectype = 5  /* canonical name for an alias */

+	const DnsSOA	: rectype = 6  /* marks the start of a zone of authority */

+	const DnsMB	: rectype = 7  /* mailbox domain name (EXPERIMENTAL) */

+	const DnsMG	: rectype = 8  /* mail group member (EXPERIMENTAL) */

+	const DnsMR	: rectype = 9  /* mail rename domain name (EXPERIMENTAL) */

+	const DnsNULL	: rectype = 10 /* null RR (EXPERIMENTAL) */

+	const DnsWKS	: rectype = 11 /* well known service description */

+	const DnsPTR	: rectype = 12 /* domain name pointer */

+	const DnsHINFO	: rectype = 13 /* host information */

+	const DnsMINFO	: rectype = 14 /* mailbox or mail list information */

+	const DnsMX	: rectype = 15 /* mail exchange */

+	const DnsTXT	: rectype = 16 /* text strings */

+	const DnsAAAA	: rectype = 28 /* ipv6 host address */

+

+

 	type resolveerr = union

 		`Badhost

 		`Badsrv

@@ -34,15 +55,15 @@

 		ttl	: uint32

 		addr	: netaddr

 	/*

-		proto	: uint32

 		flags	: uint32

 		addr	: sockaddr[:]

 		canon	: byte[:]

-		next	: hostinfo#

 	*/

 	;;

 	const resolve	: (host : byte[:]	-> error(hostinfo[:], resolveerr))

+	const resolvemx	: (host : byte[:]	-> error(hostinfo[:], resolveerr))

+	const resolverec	: (host : byte[:], t : rectype	-> error(hostinfo[:], resolveerr))

 ;;

 const Hostfile = "/etc/hosts"

@@ -54,12 +75,20 @@

 var inited	: bool = false

-const resolve = {host : byte[:] -> error(hostinfo[:], resolveerr)

+const resolve = {host

+	-> resolverec(host, DnsA)

+}

+

+const resolvemx = {host

+	-> resolverec(host, DnsMX)

+}

+

+const resolverec = {host, t

 	match hostfind(host)

 	| `Some hinf:

 		-> `Success slpush([][:], hinf)

 	| `None:

-		-> dnsresolve(host)

+		-> dnsresolve(host, DnsA)

 	;;

 }

@@ -181,8 +210,7 @@

 }

-const dnsresolve = {host : byte[:]

-	/*var hosts*/

+const dnsresolve = {host, t

 	var nsrv

 	if !valid(host)

@@ -191,7 +219,7 @@

 	for ns in nameservers

 		nsrv = dnsconnect(ns)

 		if nsrv >= 0

-			-> dnsquery(nsrv, host)

+			-> dnsquery(nsrv, host, t)

 		;;

 	;;

 	-> `Failure (`Badsrv)

@@ -199,7 +227,7 @@

 const dnsconnect = {ns

 	match ns

-	| `Ipv4 addr:	-> dnsconnectv4(ns)

+	| `Ipv4 addr:	-> dnsconnectv4(addr)

 	| `Ipv6 addr:	die("don't support ipv6 yet\n")

 	;;

 }

@@ -213,11 +241,9 @@

 	if s < 0

 		-> -1

 	;;

-	/* hardcode Google DNS for now.

-	FIXME: parse /etc/resolv.conf */

 	sa.fam = Afinet

-	sa.port = hosttonet(53) /* port 53 */

-	sa.addr = [8,8,8,8]	/* 8.8.8.8 */

+	sa.port = hosttonet(53)

+	sa.addr = addr

 	status = connect(s, (&sa) castto(sockaddr#), sizeof(sockaddr_in))

 	if status < 0

 		-> -1

@@ -225,11 +251,11 @@

 	-> s

 }

-const dnsquery = {srv, host

+const dnsquery = {srv, host, t

 	var id

 	var r

-	id = tquery(srv, host)

+	id = tquery(srv, host, t)

 	r = rquery(srv, id)

 	-> r

 }

@@ -241,7 +267,7 @@

 const Ra : uint16 = 1 << 8

 var nextid : uint16 = 42

-const tquery = {srv, host

+const tquery = {srv, host, t

 	var pkt : byte[512] /* big enough */

 	var off : size

@@ -256,7 +282,7 @@

 	/* query */

 	off += packname(pkt[:], off, host)	/* host */

-	off += pack16(pkt[:], off, 0x1) /* qtype: a record */

+	off += pack16(pkt[:], off, t castto(uint16)) /* qtype: a record */

 	off += pack16(pkt[:], off, 0x1) /* qclass: inet4 */

 	write(srv, pkt[:off])

@@ -417,21 +443,18 @@

 const packname = {buf, off : size, host

 	var i

 	var start

-	var seglen, lastseg

+	var last

 	start = off

-	seglen = 0

-	lastseg = 0

+	last = 0

 	for i = 0; i < host.len; i++

-		seglen++

 		if host[i] == ('.' castto(byte))

-			off += addseg(buf, off, host[lastseg:lastseg+seglen-1])

-			lastseg = seglen

-			seglen = 0

+			off += addseg(buf, off, host[last:i])

+			last = i + 1

 		;;

 	;;

 	if host[host.len - 1] != ('.' castto(byte))

-		off += addseg(buf, off, host[lastseg:lastseg + seglen])

+		off += addseg(buf, off, host[last:])

 	;;

 	off += addseg(buf, off, "") /* null terminating segment */

 	-> off - start