From ce6a93cc1846955e39f121c2a2e169b299fc23b0 Mon Sep 17 00:00:00 2001
From: Wouter Verhelst <w@uter.be>
Date: Tue, 27 Jul 2010 07:34:04 -0400
Subject: [PATCH] Use a different magic

Use a different magic, to avoid old clients accidentally using the
well-known port and hanging.
---
 nbd-client.c |   12 ++++++++----
 nbd-server.c |    6 +++---
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/nbd-client.c b/nbd-client.c
index 6e5225d..63202d2 100644
--- a/nbd-client.c
+++ b/nbd-client.c
@@ -139,14 +139,14 @@ void negotiate(int sock, u64 *rsize64, u32 *flags, char* name) {
 	if (read(sock, &magic, sizeof(magic)) < 0)
 		err("Failed/2: %m");
 	magic = ntohll(magic);
-	if (magic != cliserv_magic)
-		err("Not enough cliserv_magic");
-	printf(".");
 	if(name) {
 		uint32_t opt;
 		uint64_t namesize;
 		uint64_t reserved = 0;
 
+		if (magic != opts_magic)
+			err("Not enough opts_magic");
+		printf(".");
 		if(read(sock, &tmp, sizeof(uint16_t)) < 0) {
 			err("Failed reading flags: %m");
 		}
@@ -164,6 +164,10 @@ void negotiate(int sock, u64 *rsize64, u32 *flags, char* name) {
 		namesize = ntohll(namesize);
 		write(sock, &namesize, sizeof(namesize));
 		write(sock, name, strlen(name));
+	} else {
+		if (magic != cliserv_magic)
+			err("Not enough cliserv_magic");
+		printf(".");
 	}
 
 	if (read(sock, &size64, sizeof(size64)) < 0)
@@ -264,7 +268,7 @@ void usage(char* errmsg, ...) {
 	} else {
 		fprintf(stderr, "nbd-client version %s\n", PACKAGE_VERSION);
 	}
-	fprintf(stderr, "Usage: nbd-client host port nbd_device [-block-size|-b block size] [-timeout|-t timeout] [-swap|-s] [-sdp|-S] [-persist|-p] [-nofork|-n]\n");
+	fprintf(stderr, "Usage: nbd-client host port nbd_device [-block-size|-b block size] [-timeout|-t timeout] [-swap|-s] [-sdp|-S] [-persist|-p] [-nofork|-n] [-name|-N name]\n");
 	fprintf(stderr, "Or   : nbd-client -d nbd_device\n");
 	fprintf(stderr, "Or   : nbd-client -c nbd_device\n");
 	fprintf(stderr, "Or   : nbd-client -h|--help\n");
diff --git a/nbd-server.c b/nbd-server.c
index f07a29f..b92170a 100644
--- a/nbd-server.c
+++ b/nbd-server.c
@@ -1218,6 +1218,7 @@ CLIENT* negotiate(int net, CLIENT *client, GArray* servers) {
 	uint64_t size_host;
 	uint32_t flags = NBD_FLAG_HAS_FLAGS;
 	uint16_t smallflags = 0;
+	uint64_t magic;
 
 	memset(zeros, '\0', sizeof(zeros));
 	if(!client || !client->modern) {
@@ -1226,8 +1227,8 @@ CLIENT* negotiate(int net, CLIENT *client, GArray* servers) {
 			if(client)
 				exit(EXIT_FAILURE);
 		}
-		cliserv_magic = htonll(cliserv_magic);
-		if (write(net, &cliserv_magic, sizeof(cliserv_magic)) < 0) {
+		magic = htonll(opts_magic);
+		if (write(net, &magic, sizeof(magic)) < 0) {
 			err_nonfatal("Negotiation failed: %m");
 			if(client)
 				exit(EXIT_FAILURE);
@@ -1235,7 +1236,6 @@ CLIENT* negotiate(int net, CLIENT *client, GArray* servers) {
 	}
 	if(!client) {
 		uint64_t reserved;
-		uint64_t magic;
 		uint32_t opt;
 		uint64_t namelen;
 		char* name;
-- 
1.7.10.4