First stab at a host key cache on the Mac.

[originally from svn r5260]

mac/mac.c

@@ -696,6 +696,7 @@ void verify_ssh_host_key(void *frontend, char *host, int port, char *keytype,
 {
     Str255 stuff;
     Session *s = frontend;
+    int ret;
 
     /*
      * This function is horribly wrong.  For one thing, the alert
@@ -703,23 +704,40 @@ void verify_ssh_host_key(void *frontend, char *host, int port, char *keytype,
      * Aqua.  Also, PuTTY might be in the background, in which case we
      * should use the Notification Manager to wake up the user.  In
      * any case, we shouldn't hold up processing of other connections'
-     * data just because this one's waiting for the user.  It should
-     * also handle a host key cache, of course, and see the note below
-     * about closing the connection.  All in all, a bit of a mess
-     * really.
+     * data just because this one's waiting for the user. Also see the
+     * note below about closing the connection.  All in all, a bit of
+     * a mess really.
      */
 
-    stuff[0] = sprintf((char *)(&stuff[1]),
-		       "The server's key fingerprint is: %s\n"
-		       "Continue connecting?", fingerprint);
-    ParamText(stuff, NULL, NULL, NULL);
+    /* Verify the key against the cache */
+
+    ret = verify_host_key(host, port, keytype, keystr);
+
+    if (ret == 0)		       /* success - key matched OK */
+	return;
+    if (ret == 2) {		       /* key was different */
+	stuff[0] = sprintf((char *)(&stuff[1]),
+			   "WARNING - POTENTIAL SECURITY BREACH\n",
+			   "The key fingerprint is: %s\n"
+			   "Continue connecting?", fingerprint);
+	ParamText(stuff, NULL, NULL, NULL);
+    }
+    if (ret == 1) {                     /* key was absent */
+	stuff[0] = sprintf((char *)(&stuff[1]),
+			   "The server's key fingerprint is: %s\n"
+			   "Continue connecting?", fingerprint);
+	ParamText(stuff, NULL, NULL, NULL);
+    }
+
     if (CautionAlert(wQuestion, NULL) == 2) {
 	/*
 	 * User chose "Cancel".  Unfortunately, if I tear the
 	 * connection down here, Bad Things happen when I return.  I
 	 * think this function should actually return something
 	 * telling the SSH code to abandon the connection.
-	 */
+	 */	
+    } else {
+	store_host_key(host, port, keytype, keystr);
     }
 }
 

mac/mac.h

@@ -21,6 +21,7 @@
 #define INTERNAL_CREATOR FOUR_CHAR_CODE('pTTI')
 #define SESS_TYPE	FOUR_CHAR_CODE('Sess')
 #define SEED_TYPE	FOUR_CHAR_CODE('Seed')
+#define HKYS_TYPE       FOUR_CHAR_CODE('Hkys')
 
 struct mac_gestalts {
     long sysvers;
@@ -167,6 +168,8 @@ extern OSErr get_putty_dir(Boolean makeit, short *pVRefNum, long *pDirID);
 extern OSErr get_session_dir(Boolean makeit, short *pVRefNum, long *pDirID);
 extern void *open_settings_r_fsp(FSSpec *);
 extern void *open_settings_w_fsp(FSSpec *);
+extern int verify_host_key(const char *, int, const char *, const char*);
+extern void store_host_key(const char *, int, const char *, const char*);
 /* from macucs.c */
 extern void init_ucs(Session *);
 /* from macnet.c */

mac/macstore.c

@@ -1,4 +1,4 @@
-/* $Id: macstore.c,v 1.19 2003/04/01 18:10:25 simon Exp $ */
+/* $Id$ */
 
 /*
  * macstore.c: Macintosh-specific impementation of the interface
@@ -602,6 +602,122 @@ void write_random_seed(void *data, int len)
     return;
 }
 
+int verify_host_key(const char *hostname, int port,
+		    const char *keytype, const char *key)
+{
+    short puttyVRefNum;
+    long puttyDirID;
+    OSErr error;
+    FSSpec keyfile;
+    short refnum;
+    char *resname;
+    Str255 presname;
+    char *resvalue;
+    Handle reshandle;
+    int len, compare;
+
+    if (get_putty_dir(kCreateFolder, &puttyVRefNum, &puttyDirID) != noErr)
+	return 1;
+
+    error = FSMakeFSSpec(puttyVRefNum, puttyDirID, "\pSSH Host Keys",
+			 &keyfile);
+    if (error == fnfErr) {
+	/* Keys file doesn't exist yet, so we can't match the key */
+	return 1;
+    }
+
+    refnum = FSpOpenResFile(&keyfile, fsRdPerm);
+
+    if (refnum == -1) {
+	/* We couldn't open the resource fork, so we can't match the key */
+	return 1;
+    }
+
+    UseResFile(refnum);
+
+    resname = dupprintf("%s@%d:%s", keytype, port, hostname);
+    c2pstrcpy(presname, resname);
+    reshandle = Get1NamedResource(FOUR_CHAR_CODE('TEXT'), presname);
+    if (ResError() != noErr) {
+	/* Couldn't open the specific resource */
+	return 1;
+    }
+
+    len = GetHandleSize(reshandle);
+    resvalue = snewn(len+1, char);
+    memcpy(resvalue, *reshandle, len);
+    resvalue[len]='\0';
+    ReleaseResource(reshandle);
+    CloseResFile(refnum);
+
+    compare = strncmp(resvalue, key, strlen(resvalue));
+    sfree(resname);
+    sfree(resvalue);
+
+    if (compare) {
+	/* Key different */
+	return 2;
+    } else {
+	/* Key matched */
+	return 0;
+    }
+}
+
+void store_host_key(const char *hostname, int port,
+		    const char *keytype, const char *key)
+{
+    short puttyVRefNum;
+    long puttyDirID;
+    OSErr error;
+    FSSpec keyfile;
+    short keyrefnum;
+    char *resname;
+    Str255 presname;
+    Handle resvalue;
+    int id;
+
+    /* Open the host key file */
+
+    if (get_putty_dir(~kCreateFolder, &puttyVRefNum, &puttyDirID) != noErr)
+	goto out;
+
+    error = FSMakeFSSpec(puttyVRefNum, puttyDirID, "\pSSH Host Keys",
+			 &keyfile);
+    if (error == fnfErr) {
+	/* It doesn't exist, so create it */
+	FSpCreateResFile(&keyfile, INTERNAL_CREATOR, HKYS_TYPE, smRoman);
+	keyrefnum = FSpOpenResFile(&keyfile, fsWrPerm);
+	if (ResError() == noErr) {
+	    copy_resource('STR', -16397); /* XXX: wtf is this? */
+	    CloseResFile(keyrefnum);
+	}
+    } else if (error != noErr) goto out;
+
+    keyrefnum = FSpOpenResFile(&keyfile, fsWrPerm);
+    if (keyrefnum == -1) goto out;
+
+    UseResFile(keyrefnum);
+    resname = dupprintf("%s@%d:%s", keytype, port, hostname);
+    c2pstrcpy(presname, resname);
+    
+    error = PtrToHand(key, &resvalue, strlen(key));
+    if (error != noErr) goto out;
+
+    id = Unique1ID(FOUR_CHAR_CODE('TEXT'));
+    if (ResError() != noErr) goto out;
+    AddResource(resvalue, FOUR_CHAR_CODE('TEXT'), id, presname);
+    if (ResError() != noErr) goto out;
+
+    CloseResFile(keyrefnum);
+    return;
+
+  out:
+    fatalbox("Writing host key failed (%d)", error);
+    sfree(resname);
+}
+  
+
+
 /*
  * Emacs magic:
  * Local Variables: