Added chap client support (factotum had server only). I include
chaptest.c which exercises the code. I use it in the latest cifs client
daily, but havent ported ip/ppp as I no longer use that.
-Steve

Reference: /n/sources/patch/applied/chap-client
Date: Sun Oct 31 00:48:04 CES 2004

--- /sys/src/cmd/auth/factotum/chap.c	Sun Oct 31 00:48:04 2004
+++ /sys/src/cmd/auth/factotum/chap.c	Sun Oct 31 00:48:03 2004
@@ -4,7 +4,8 @@
  * The client does not authenticate the server, hence no CAI
  *
  * Client protocol:
- *	unimplemented
+ *	write Chapchal 
+ *	read response Chapreply or MSchaprely structure
  *
  * Server protocol:
  *	read challenge: 8 bytes binary
@@ -12,14 +13,21 @@
  *	write response: Chapreply or MSchapreply structure
  */
 
+#include <ctype.h>
 #include "dat.h"
 
 enum {
 	ChapChallen = 8,
+	ChapResplen = 16,
+	MSchapResplen = 24,
 };
 
 static int dochal(State*);
 static int doreply(State*, void*, int);
+static void doLMchap(char *, uchar [ChapChallen], uchar [MSchapResplen]);
+static void doNTchap(char *, uchar [ChapChallen], uchar [MSchapResplen]);
+static void dochap(char *, int, char [ChapChallen], uchar [ChapResplen]);
+
 
 struct State
 {
@@ -30,7 +38,9 @@
 	Ticket	t;
 	Ticketreq	tr;
 	char chal[ChapChallen];
-	char	err[ERRMAX];
+	MSchapreply mcr;
+	char cr[ChapResplen];
+	char err[ERRMAX];
 	char user[64];
 	uchar secret[16];	/* for mschap */
 	int nsecret;
@@ -38,6 +48,9 @@
 
 enum
 {
+	CNeedChal,
+	CHaveResp,
+
 	SHaveChal,
 	SNeedUser,
 	SNeedResp,
@@ -49,6 +62,9 @@
 
 static char *phasenames[Maxphase] =
 {
+[CNeedChal]	"CNeedChal",
+[CHaveResp]	"CHaveResp",
+
 [SHaveChal]	"SHaveChal",
 [SNeedUser]	"SNeedUser",
 [SNeedResp]	"SNeedResp",
@@ -64,8 +80,6 @@
 
 	if((iscli = isclient(_strfindattr(fss->attr, "role"))) < 0)
 		return failure(fss, nil);
-	if(iscli)
-		return failure(fss, "%s client not supported", p->name);
 
 	s = emalloc(sizeof *s);
 	fss->phasename = phasenames;
@@ -78,15 +92,21 @@
 		s->astype = AuthMSchap;
 		s->protoname = "mschap";
 	}
-	if((ret = findp9authkey(&s->key, fss)) != RpcOk){
-		free(s);
-		return ret;
-	}
-	if(dochal(s) < 0){
-		free(s);
-		return failure(fss, nil);
+
+	if(iscli)
+		fss->phase = CNeedChal;
+	else{
+		if((ret = findp9authkey(&s->key, fss)) != RpcOk){
+			free(s);
+			return ret;
+		}
+		if(dochal(s) < 0){
+			free(s);
+			return failure(fss, nil);
+		}
+		fss->phase = SHaveChal;
 	}
-	fss->phase = SHaveChal;
+
 	fss->ps = s;
 	return RpcOk;
 }
@@ -104,11 +124,26 @@
 	free(s);
 }
 
+void
+dmpkey(char *s, void *v, int n)
+{
+	int i;
+	char *p = v;
+
+	print("%s", s);
+	for (i = 0; i < n; i++)
+		print("%02x ", *p++);
+	print("\n");
+}
+
+
 static int
 chapwrite(Fsstate *fss, void *va, uint n)
 {
-	int nreply;
+	int ret, nreply;
+	char *a, *v;
 	void *reply;
+	Key *k;
 	State *s;
 	Chapreply cr;
 	MSchapreply mcr;
@@ -116,10 +151,34 @@
 	OMSchapreply omcr;
 
 	s = fss->ps;
+	a = va;
 	switch(fss->phase){
 	default:
 		return phaseerror(fss, "write");
 
+	case CNeedChal:
+		ret = findkey(&k, fss, fss->sysuser, 0, 0, fss->attr, "%s", fss->proto->keyprompt);
+		if(ret != RpcOk)
+			return ret;
+		v = _strfindattr(k->privattr, "!password");
+		if(v == nil)
+			return failure(fss, "key has no password");
+		setattrs(fss->attr, k->attr);
+		switch(s->astype){
+		default:
+			abort();
+		case AuthMSchap:
+			doLMchap(v, (uchar *)a, (uchar *)s->mcr.LMresp);
+			doNTchap(v, (uchar *)a, (uchar *)s->mcr.NTresp);
+			break;
+		case AuthChap:
+			dochap(v, *a, a+1, (uchar *)s->cr);
+			break;
+		}
+		closekey(k);
+		fss->phase = CHaveResp;
+		return RpcOk;
+
 	case SNeedUser:
 		if(n >= sizeof s->user)
 			return failure(fss, "user name too long");
@@ -151,6 +210,9 @@
 			strecpy(omcr.uid, omcr.uid+sizeof omcr.uid, s->user);
 			reply = &omcr;
 			nreply = sizeof omcr;
+print("%s\n", omcr.uid);
+dmpkey("LM ", omcr.LMresp, 24);
+dmpkey("NT ", omcr.NTresp, 24);
 			break;
 		}
 		if(doreply(s, reply, nreply) < 0)
@@ -175,6 +237,25 @@
 	default:
 		return phaseerror(fss, "read");
 
+	case CHaveResp:
+		switch(s->astype){
+		default:
+			abort();
+		case AuthMSchap:
+			if(*n > sizeof(MSchapreply))
+				*n = sizeof(MSchapreply);
+			memmove(va, &s->mcr, *n);
+			break;
+		case AuthChap:
+			if(*n > ChapResplen)
+				*n = ChapResplen;
+			memmove(va, s->cr, ChapResplen);
+			break;
+		}
+		fss->phase = Established;
+		fss->haveai = 0;
+		return RpcOk;
+
 	case SHaveChal:
 		if(*n > sizeof s->chal)
 			*n = sizeof s->chal;
@@ -273,6 +354,8 @@
 .write=	chapwrite,
 .read=	chapread,
 .close=	chapclose,
+.addkey= replacekey,
+.keyprompt= "!password?"
 };
 
 Proto mschap = {
@@ -281,5 +364,86 @@
 .write=	chapwrite,
 .read=	chapread,
 .close=	chapclose,
+.addkey= replacekey,
+.keyprompt= "!password?"
 };
+
+static void
+hash(uchar pass[16], uchar c8[ChapChallen], uchar p24[MSchapResplen])
+{
+	int i;
+	uchar p21[21];
+	ulong schedule[32];
+
+	memset(p21, 0, sizeof p21 );
+	memmove(p21, pass, 16);
+
+	for(i=0; i<3; i++) {
+		key_setup(p21+i*7, schedule);
+		memmove(p24+i*8, c8, 8);
+		block_cipher(schedule, p24+i*8, 0);
+	}
+}
+
+static void
+doNTchap(char *pass, uchar chal[ChapChallen], uchar reply[MSchapResplen])
+{
+	int i, n;
+	uchar *w, unipass[256];
+	uchar digest[MD4dlen];
+
+	Rune r;
+
+	// Standard says unlimited length, experience says 128 max
+	if ((n = strlen(pass)) > 128)
+		n = 128;
+
+	memset(unipass, 0, sizeof unipass);
+	for(i=0, w=unipass; i < n; i++) {
+		pass += chartorune(&r, pass);
+		*w++ = r & 0xff;
+		*w++ = r >> 8;
+	}
+
+	memset(digest, 0, sizeof digest);
+	md4(unipass, w - unipass, digest, nil);
+	hash(digest, chal, reply);
+}
+
+static void
+doLMchap(char *pass, uchar chal[ChapChallen], uchar reply[MSchapResplen])
+{
+	int i;
+	ulong schedule[32];
+	uchar p14[15], p16[16];
+	uchar s8[8] = {0x4b, 0x47, 0x53, 0x21, 0x40, 0x23, 0x24, 0x25};
+
+	// Spec says space padded, experience says otherwise
+	memset(p14, 0, sizeof p14 -1);
+	p14[sizeof p14 - 1] = '\0';
+
+	// NT4 requires uppercase, Win XP doesn't care
+	for (i = 0; pass[i]; i++)
+		p14[i] = islower(pass[i])? toupper(pass[i]): pass[i];
+
+	for(i=0; i<2; i++) {
+		key_setup(p14+i*7, schedule);
+		memmove(p16+i*8, s8, 8);
+		block_cipher(schedule, p16+i*8, 0);
+	}
+
+	hash(p16, chal, reply);
+}
+
+static void
+dochap(char *pass, int id, char chal[ChapChallen], uchar resp[ChapResplen])
+{
+	char buf[1+ChapChallen+MAXNAMELEN+1];
+	int n = strlen(pass);
+
+	*buf = id;
+	strcpy(buf+1, pass);
+	memmove(buf+1+n, chal, ChapChallen);
+	md5((uchar*)buf, 1+n+ChapChallen, resp, nil);
+}
 
--- /sys/src/cmd/auth/factotum/chaptest.c	Thu Jan  1 00:00:00 1970
+++ /sys/src/cmd/auth/factotum/chaptest.c	Sun Oct 31 00:48:04 2004
@@ -0,0 +1,172 @@
+#include <u.h>
+#include <libc.h>
+#include <mp.h>
+#include <libsec.h>
+#include <auth.h>
+#include <ctype.h>
+
+char *
+strupr(char *s)
+{
+	char *p;
+	for (p = s; *p; p++)
+		if (islower(*p))
+			*p = toupper(*p);
+	return s;
+}
+
+		
+/* NT LM 0.12 challenge/response from cifs2.txt, §2.10 -- belongs in Factotum */
+static void
+hash(uchar pass[16], uchar c8[8], uchar p24[24])
+{
+	int i;
+	uchar p21[21];
+	ulong schedule[32];
+
+	memset(p21, 0, sizeof p21 );
+	memmove(p21, pass, 16);
+
+	for(i=0; i<3; i++) {
+		key_setup(p21+i*7, schedule);
+		memmove(p24+i*8, c8, 8);
+		block_cipher(schedule, p24+i*8, 0);
+	}
+}
+
+void
+doNTreply(char *pass, uchar chal[8], uchar reply[24])
+{
+	int i, n;
+	uchar *w, unipass[256];
+	uchar digest[MD4dlen];
+
+	Rune r;
+
+	// Standard says unlimited length, experience says 128 max
+	if ((n = strlen(pass)) > 128)
+		n = 128;
+
+	memset(unipass, 0, sizeof unipass);
+	for(i=0, w=unipass; i < n; i++) {
+		pass += chartorune(&r, pass);
+		*w++ = r & 0xff;
+		*w++ = r >> 8;
+	}
+
+	memset(digest, 0, sizeof digest);
+	md4(unipass, w - unipass, digest, nil);
+	hash(digest, chal, reply);
+}
+
+void
+doLMreply(char *pass, uchar chal[8], uchar reply[24])
+{
+	int i;
+	ulong schedule[32];
+	uchar p14[15], p16[16];
+	uchar s8[8] = {0x4b, 0x47, 0x53, 0x21, 0x40, 0x23, 0x24, 0x25};
+
+	memset(p14, 0, sizeof p14 -1);		// Spec says space padded, experience says otherwise
+	p14[sizeof p14 - 1] = '\0';
+	memmove(p14, pass, strlen(pass));
+	strupr((char *)p14);			// NT4 requires uppercase, Win XP doesn't care
+
+	for(i=0; i<2; i++) {
+		key_setup(p14+i*7, schedule);
+		memmove(p16+i*8, s8, 8);
+		block_cipher(schedule, p16+i*8, 0);
+	}
+
+	hash(p16, chal, reply);
+}
+
+dmpkey(char *s, void *v, int n)
+{
+	int i;
+	char *p = v;
+
+	print("%s", s);
+	for (i = 0; i < n; i++)
+		print("%02x ", *p++);
+	print("\n");
+}
+
+void
+dochap(char *pass, int id, char chal[8], uchar resp[16])
+{
+	char buf[1+8+255+1];
+	int n = strlen(pass);
+
+	*buf = id;
+	strcpy(buf+1, pass);
+	memmove(buf+1+n, chal, 8);
+	md5((uchar*)buf, 1+n+8, resp, nil);
+}
+
+
+
+void
+main(int argc, char *argv[])
+{
+	int n, i;
+	UserPasswd *up;
+	Chapreply chapchal;
+	MSchapreply mcr;
+	char *user;
+	uchar lm[64], nt[64], chal[64], chap[64], resp[64];
+
+	if (argc != 3){
+		fprint(2, "usage: %s user challange\n", argv[0]);
+		exits("usage");
+	}
+
+	user = argv[1];
+	strncpy((char *)chal, argv[2], sizeof(chal));
+
+	if ((up = auth_getuserpasswd(auth_getkey, "proto=pass service=cifs user=%s", user)) == nil)
+		sysfatal("auth_getuserpasswd failed %r");
+
+	doLMreply(up->passwd, chal, lm);
+	doNTreply(up->passwd, chal, nt);
+
+	if((n = auth_respond(chal, sizeof(chal), user, strlen(user), &mcr, sizeof(mcr), auth_getkey,
+		    "proto=mschap role=client service=cifs user=%s", up->user)) == -1)
+			sysfatal("auth_respond failed %r");
+
+
+	if (memcmp(mcr.NTresp, nt, 24)){
+		fprint(2, "FAILED\n");
+		dmpkey("my nt:", nt, 24);
+		dmpkey("ft nt:", mcr.NTresp, 24);
+	}
+	else
+		fprint(2, "MSCHAP NT ok\n");
+
+	if (memcmp(mcr.LMresp, lm, 24)){
+		fprint(2, "FAILED\n");
+		dmpkey("my nt:", lm, 24);
+		dmpkey("ft nt:", mcr.LMresp, 24);
+	}
+	else
+		fprint(2, "MSCHAP LM ok\n");
+
+	/*********************/
+
+	chapchal.id = 123;
+	strncpy(chapchal.resp, (char *)chal, 8);
+
+	if((n = auth_respond(&chapchal, sizeof(chapchal), user, strlen(user), &resp, sizeof(resp), auth_getkey,
+		    "proto=chap role=client service=cifs user=%s", up->user)) == -1)
+			sysfatal("auth_respond failed %r");
+
+	dochap(up->passwd, chapchal.id, chapchal.resp, chap);
+
+	if (memcmp(chap, resp, 16)){
+		fprint(2, "FAILED\n");
+		dmpkey("my chap:", chap, 16);
+		dmpkey("ft chap:", resp, 16);
+	}
+	else
+		fprint(2, "CHAP ok\n");
+}