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More work on DNS resolver.

--- a/libstd/resolve.myr

+++ b/libstd/resolve.myr

@@ -12,37 +12,34 @@

 		`Badhost

 		`Badsrv

 		`Badquery

+		`Badresp

 	;;

+	type netaddr = union

+		`Ipv4	byte[4]

+		`Ipv6	byte[16]

+	;;

+

 	type hostinfo = struct

-		flags	: uint32

 		fam	: sockfam

 		stype	: socktype

+		ttl	: uint32

+		addr	: netaddr

+	/*

 		proto	: uint32

+		flags	: uint32

 		addr	: sockaddr[:]

 		canon	: byte[:]

 		next	: hostinfo#

+	*/

 	;;

-	const resolve	: (host : byte[:]	-> hostinfo#)

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

 ;;

-type dnshdr = struct

-	id	: uint16

-	/* {qr:1|op:4|aa:1|tc:1|rd:1|ra:1|z:3|rcode:4} */

-	flags	: uint16  

-	qdcnt	: uint16

-	ancnt	: uint16

-	nscnt	: uint16

-	arcnt	: uint16

-;;

-

 const resolve = {host : byte[:]

-	var hinf

-

-	hinf = zalloc()

-	dnsresolve(host)

-	-> hinf

+	/* FIXME: read /etc/hosts */

+	-> dnsresolve(host)

 }

 const dnsresolve = {host : byte[:]

@@ -55,10 +52,7 @@

 	if (nsrv = dnsconnect()) < 0

 		-> `Failure (`Badsrv)

 	;;

-	if !dnsquery(nsrv, host)

-		-> `Failure (`Badquery)

-	;;

-	-> `Success true

+	-> dnsquery(nsrv, host)

 }

 const dnsconnect = {

@@ -71,7 +65,8 @@

 		put("Warning: Failed to open socket: %l\n", s)

 		-> -1

 	;;

-	/* hardcode Google DNS for now */

+	/* 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 */

@@ -84,10 +79,13 @@

 }

 const dnsquery = {srv, host

-	tquery(srv, host)

-	rquery(srv)

-	put("Unimplemented query: srv=%z, host=%s\n", srv, host)

-	-> false

+	var id

+	var r

+

+	id = tquery(srv, host)

+	r = rquery(srv, id)

+	put("Got hosts. Returning\n")

+	-> r

 }

 const Qr : uint16 = 1 << 0

@@ -96,14 +94,15 @@

 const Rd : uint16 = 1 << 7

 const Ra : uint16 = 1 << 8

-var nextid = 42

+var nextid : uint16 = 42

 const tquery = {srv, host

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

 	var off : size

+	put("Sending request for %s\n", host)

 	/* header */

 	off = 0

-	off += pack16(pkt[:], off, nextid++)	/* id */

+	off += pack16(pkt[:], off, nextid)	/* id */

 	off += pack16(pkt[:], off, Ra)	/* flags */

 	off += pack16(pkt[:], off, 1)	/* qdcount */

 	off += pack16(pkt[:], off, 0)	/* ancount */

@@ -115,11 +114,11 @@

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

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

-	write(1, pkt[:off])

 	write(srv, pkt[:off])

+	-> nextid++

 }

-const rquery = {srv

+const rquery = {srv, id

 	var pktbuf : byte[1024]

 	var pkt

 	var n

@@ -130,10 +129,56 @@

 		put("Warning: Failed to read from %z: %i\n", srv, n)

 	;;

 	pkt = pktbuf[:n]

+	put("Got response:\n");

 	dumpresponse(pkt)

+	-> hosts(pkt, id)

 }

+const hosts = {pkt, id : uint16

+	var off

+	var v

+	var q

+	var a

+	var i

+	var hinf : hostinfo[:]

+	off = 0

+	/* parse header */

+	(v, off) = unpack16(pkt, off)	/* id */

+	if v != id

+		-> `Failure (`Badresp)

+	;;

+	put("Unpacking flags")

+	(v, off) = unpack16(pkt, off)	/* flags */

+	(q, off) = unpack16(pkt, off)	/* qdcount */

+	(a, off) = unpack16(pkt, off)	/* ancount */

+	(v, off) = unpack16(pkt, off)	/* nscount */

+	(v, off) = unpack16(pkt, off)	/* arcount */

+

+	/* skip past query records */

+	for i = 0; i < q; i++

+		put("Skipping query record")

+		off = skipname(pkt, off)	/* name */

+		(v, off) = unpack16(pkt, off)	/* type */

+		(v, off) = unpack16(pkt, off)	/* class */

+	;;

+

+	/* parse answer records */

+	hinf = slalloc(a castto(size))

+	for i = 0; i < a; i++

+		off = skipname(pkt, off)	/* name */

+		(v, off) = unpack16(pkt, off)	/* type */

+		(v, off) = unpack16(pkt, off)	/* class */

+		(hinf[i].ttl, off) = unpack32(pkt, off)	/* ttl */

+		(v, off) = unpack16(pkt, off)	/* rdatalen */

+		/* the thing we're interested in: our IP address */

+		hinf[i].addr = `Ipv4 [pkt[off], pkt[off+1], pkt[off+2], pkt[off+3]]

+		off += 4;

+	;;

+	-> `Success hinf

+}

+

+

 const dumpresponse = {pkt

 	var nquery

 	var nans

@@ -141,13 +186,8 @@

 	var v

 	var i

-	put("packet size = %z\n", pkt.len)

 	(v, off) = unpack16(pkt, 0)

-	put("hdr.id = %w\n", v)

 	(v, off) = unpack16(pkt, off)

-	put("hdr.rawflag = %i\n", (((v castto(uint32)) & 0xf000) >> 12))

-	put("hdr.flag = [Qr = %t, Aa = %t, Tc = %t, Rd = %t, Ra = %t]\n", (v&Qr) == 0, (v&Aa) == 0, (v&Tc) == 0, (v&Rd)==0, (v&Ra)==0)

-	put("hdr.rcode = %w\n", (v >> 11) & 0xf)

 	(nquery, off) = unpack16(pkt, off)

 	put("hdr.qdcount = %w\n", nquery)

 	(nans, off) = unpack16(pkt, off)

@@ -203,6 +243,21 @@

 	-> off

 }

+const skipname = {pkt, off

+	var sz

+

+	for sz = pkt[off] castto(size); sz != 0; sz = pkt[off] castto(size)

+		/* ptr is 2 bytes */

+		if sz & 0xC0 == 0xC0

+			-> off + 2

+		else

+			off += sz + 1

+		;;

+	;;

+	-> off + 1

+}

+

+

 const printname = {pkt, off

 	var sz

@@ -231,6 +286,16 @@

 	v = (buf[off] castto(uint16)) << 8

 	v |= (buf[off + 1] castto(uint16))

 	-> (v, off+sizeof(uint16))

+}

+

+const unpack32 = {buf, off

+	var v

+

+	v = (buf[off] castto(uint32)) << 24

+	v |= (buf[off+1] castto(uint32)) << 32

+	v |= (buf[off+2] castto(uint32)) << 8

+	v |= (buf[off+3] castto(uint32))

+	-> (v, off+sizeof(uint32))

 }

 const packname = {buf, off : size, host