ref: 7fe8f299454bc2238a549e7dad31c0956aed26a9
parent: f0f00c4644ec29bc528c2b47e9ec4e284f72cccc
author: Ori Bernstein <[email protected]>
date: Tue Oct 29 12:04:15 EDT 2013
Start generating DNS queries.
--- a/libstd/resolve.myr
+++ b/libstd/resolve.myr
@@ -1,7 +1,9 @@
use "alloc.use"
+use "die.use"
use "endian.use"
use "error.use"
use "fmt.use"
+use "slcp.use"
use "sys.use"
use "types.use"
@@ -25,6 +27,16 @@
const resolve : (host : byte[:] -> hostinfo#)
;;
+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
@@ -54,17 +66,18 @@
var s
var status
- s = socket(Afinet, Sockstream, 0)
+ s = socket(Afinet, Sockdgram, 0)
if s < 0
put("Warning: Failed to open socket: %l\n", s)-> -1
;;
/* hardcode Google DNS for now */
+ sa.fam = Afinet
sa.port = hosttonet(53)
sa.addr = 0x08080808
status = connect(s, (&sa) castto(sockaddr#), sizeof(sockaddr_in))
if status < 0
- put("Warning: Failed to connect to server: %l\n", s)+ put("Warning: Failed to connect to server: %l\n", status)-> -1
;;
-> s
@@ -71,8 +84,96 @@
}
const dnsquery = {srv, host+ tquery(srv, host)
+ rquery(srv)
put("Unimplemented query: srv=%z, host=%s\n", srv, host)-> false
+}
+
+const Qr : uint16 = 1 << 0
+const Aa : uint16 = 1 << 4
+const Tc : uint16 = 1 << 5
+const Rd : uint16 = 1 << 6
+const Ra : uint16 = 1 << 7
+
+var nextid = 0
+const tquery = {srv, host+ var pkt : byte[512] /* big enough */
+ var off
+
+ /* header */
+ off = 0
+ off += pack16(pkt[:], off, nextid++) /* id */
+ off += pack16(pkt[:], off, Qr|Ra|Rd) /* flags */
+ off += pack16(pkt[:], off, 1) /* qdcount */
+ off += pack16(pkt[:], off, 0) /* ancount */
+ off += pack16(pkt[:], off, 0) /* nscount */
+ off += pack16(pkt[:], off, 0) /* arcount */
+
+ /* query */
+ off += packname(pkt[:], off, host) /* host */
+ off += pack16(pkt[:], off, 0x1) /* qtype: a record */
+ off += pack16(pkt[:], off, 0x1) /* qclass: inet4 */
+
+ write(srv, pkt[:off])
+}
+
+const rquery = {srv+ var pktbuf : byte[1024]
+ var n
+
+ n = read(srv, pktbuf[:])
+ if n < 0
+ put("Warning: Failed to read from %z: %i\n", srv, n)+ ;;
+ put("pkt: [len = %z]: %s\n", n, pktbuf[:n])+}
+
+const pack16 = {buf, off, v+ buf[off] = (v & 0xff00) >> 8 castto(byte)
+ buf[off+1] = (v & 0x00ff) castto(byte)
+ -> sizeof(uint16) /* we always write one uint16 */
+}
+
+/*
+const unpack16 = {buf, off+ var v
+
+ v = (buf[off] castto(uint16)) << 8
+ v |= (buf[off + 1] castto(uint16))
+ -> (v, sizeof(uint16))
+}
+*/
+
+const packname = {buf, off, host+ var i
+ var start
+ var seglen
+ var lastseg
+
+ start = off
+ lastseg = 0
+ for i = 0; i < host.len; i++
+ if host[i] == ('.' castto(byte))+ off += addseg(buf, off, host[lastseg:lastseg+seglen])
+ lastseg = seglen + 1
+ seglen = 0
+ ;;
+ seglen++
+ ;;
+ if host[host.len - 1] != ('.' castto(byte))+ off += addseg(buf, off, host[lastseg:lastseg + seglen])
+ ;;
+ off += addseg(buf, off, "") /* null terminating segment */
+ put("size: %z\n", off - start)+ -> off - start
+}
+
+const addseg = {buf, off, str+ put("Adding seg %s\n", str)+ buf[0] = str.len castto(byte)
+ slcp(buf[off + 1 : off + str.len + 1], str)
+ -> str.len
}
const valid = {host : byte[:]