From: Martin Schwenke <martin@meltin.net>
Date: Fri, 17 Aug 2018 02:30:19 +0000 (+1000)
Subject: ctdb-common: Avoid magic numbers when building TCP packets
X-Git-Tag: tdb-1.3.17~1967
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8fcf1af559f2a716ebcfb8277668d6539fd432f0;p=thirdparty%2Fsamba.git

ctdb-common: Avoid magic numbers when building TCP packets

Most packet sizes and offsets are multiples of 32-bit words.  The IPv6
payload length is in octets.  The IPv6 version is the top 4 bits of
the relevant field.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>
---

diff --git a/ctdb/common/system_socket.c b/ctdb/common/system_socket.c
index 7f08b817084..41037ce1ec6 100644
--- a/ctdb/common/system_socket.c
+++ b/ctdb/common/system_socket.c
@@ -528,7 +528,7 @@ static int tcp4_build(uint8_t *buf,
 	memset(ip4pkt, 0, l);
 
 	ip4pkt->ip.ip_v     = 4;
-	ip4pkt->ip.ip_hl    = sizeof(ip4pkt->ip)/4;
+	ip4pkt->ip.ip_hl    = sizeof(ip4pkt->ip)/sizeof(uint32_t);
 	ip4pkt->ip.ip_len   = htons(sizeof(ip4pkt));
 	ip4pkt->ip.ip_ttl   = 255;
 	ip4pkt->ip.ip_p     = IPPROTO_TCP;
@@ -545,7 +545,7 @@ static int tcp4_build(uint8_t *buf,
 	if (rst) {
 		ip4pkt->tcp.th_flags |= TH_RST;
 	}
-	ip4pkt->tcp.th_off   = sizeof(ip4pkt->tcp)/4;
+	ip4pkt->tcp.th_off   = sizeof(ip4pkt->tcp)/sizeof(uint32_t);
 	/* this makes it easier to spot in a sniffer */
 	ip4pkt->tcp.th_win   = htons(1234);
 	ip4pkt->tcp.th_sum   = ip_checksum((uint16_t *)&ip4pkt->tcp,
@@ -582,8 +582,8 @@ static int tcp6_build(uint8_t *buf,
 	ip6pkt = (void *)buf;
 	memset(ip6pkt, 0, l);
 
-	ip6pkt->ip6.ip6_vfc  = 0x60;
-	ip6pkt->ip6.ip6_plen = htons(20);
+	ip6pkt->ip6.ip6_vfc  = 6 << 4;
+	ip6pkt->ip6.ip6_plen = htons(sizeof(struct tcphdr));
 	ip6pkt->ip6.ip6_nxt  = IPPROTO_TCP;
 	ip6pkt->ip6.ip6_hlim = 64;
 	ip6pkt->ip6.ip6_src  = src->sin6_addr;
@@ -598,7 +598,7 @@ static int tcp6_build(uint8_t *buf,
 	if (rst) {
 		ip6pkt->tcp.th_flags |= TH_RST;
 	}
-	ip6pkt->tcp.th_off    = sizeof(ip6pkt->tcp)/4;
+	ip6pkt->tcp.th_off    = sizeof(ip6pkt->tcp)/sizeof(uint32_t);
 	/* this makes it easier to spot in a sniffer */
 	ip6pkt->tcp.th_win   = htons(1234);
 	ip6pkt->tcp.th_sum   = ip6_checksum((uint16_t *)&ip6pkt->tcp,