commit bc112b0e7feece62ce98708092306639a8a53cce
Author: Wayne Davison <wayned@samba.org>
Date:   Mon Oct 30 09:11:16 2017 -0700

    Use full MD4 len for archaic protocol auth.

diff --git a/authenticate.c b/authenticate.c
index a106b0f..519429d 100644
--- a/authenticate.c
+++ b/authenticate.c
@@ -22,7 +22,6 @@
 #include "itypes.h"
 
 extern int read_only;
-extern int protocol_version;
 extern char *password_file;
 
 /***************************************************************************
@@ -75,6 +74,8 @@ static void gen_challenge(const char *addr, char *challenge)
 	sum_init(-1, 0);
 	sum_update(input, sizeof input);
 	len = sum_end(digest);
+	if (len == 2) /* The archaic checksum is 2 bytes, but sum_end() filled in the full MD4 checksum for us. */
+		len = MD4_DIGEST_LEN;
 
 	base64_encode(digest, len, challenge, 0);
 }
@@ -90,6 +91,8 @@ static void generate_hash(const char *in, const char *challenge, char *out)
 	sum_update(in, strlen(in));
 	sum_update(challenge, strlen(challenge));
 	len = sum_end(buf);
+	if (len == 2) /* The archaic checksum is 2 bytes, but sum_end() filled in the full MD4 checksum for us. */
+		len = MD4_DIGEST_LEN;
 
 	base64_encode(buf, len, out, 0);
 }
@@ -238,11 +241,6 @@ char *auth_server(int f_in, int f_out, int module, const char *host,
 	if (!users || !*users)
 		return "";
 
-	if (protocol_version < 21) { /* Don't allow a weak checksum for the password. */
-		rprintf(FERROR, "ERROR: protocol version is too old!\n");
-		exit_cleanup(RERR_PROTOCOL);
-	}
-
 	gen_challenge(addr, challenge);
 
 	io_printf(f_out, "%s%s\n", leader, challenge);
diff --git a/checksum.c b/checksum.c
index c119f97..741ad7d 100644
--- a/checksum.c
+++ b/checksum.c
@@ -86,6 +86,8 @@ int csum_len_for_type(int cst)
 		return MD4_DIGEST_LEN;
 	  case CSUM_MD5:
 		return MD5_DIGEST_LEN;
+	  default: /* paranoia to prevent missing case values */
+		exit_cleanup(RERR_UNSUPPORTED);
 	}
 	return 0;
 }
@@ -181,6 +183,8 @@ void get_checksum2(char *buf, int32 len, char *sum)
 		mdfour_result(&m, (uchar *)sum);
 		break;
 	  }
+	  default: /* paranoia to prevent missing case values */
+		exit_cleanup(RERR_UNSUPPORTED);
 	}
 }
 
@@ -275,6 +279,8 @@ void sum_init(int csum_type, int seed)
 		break;
 	  case CSUM_NONE:
 		break;
+	  default: /* paranoia to prevent missing case values */
+		exit_cleanup(RERR_UNSUPPORTED);
 	}
 }
 
@@ -322,6 +328,8 @@ void sum_update(const char *p, int32 len)
 		break;
 	  case CSUM_NONE:
 		break;
+	  default: /* paranoia to prevent missing case values */
+		exit_cleanup(RERR_UNSUPPORTED);
 	}
 }
 
@@ -349,6 +357,8 @@ int sum_end(char *sum)
 	  case CSUM_NONE:
 		*sum = '\0';
 		break;
+	  default: /* paranoia to prevent missing case values */
+		exit_cleanup(RERR_UNSUPPORTED);
 	}
 
 	return csum_len_for_type(cursum_type);