Date: Fri, 16 Feb 2001 03:32:52 +0900 (JST) From: daisu-mi@is.aist-nara.ac.jp To: FreeBSD-gnats-submit@freebsd.org Subject: kern/25117: ICMP Destination Port Unreachable Error Message is wrong. Message-ID: <200102151832.DAA12798@iplab.aist-nara.ac.jp>
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>Number: 25117
>Category: kern
>Synopsis: ICMP Destination Port Unreachable Error Message is wrong.
>Confidential: no
>Severity: non-critical
>Priority: medium
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: change-request
>Submitter-Id: current-users
>Arrival-Date: Thu Feb 15 10:30:00 PST 2001
>Closed-Date:
>Last-Modified:
>Originator: Daisuke Miyamoto
>Release: FreeBSD 4.2-RELEASE i386
>Organization:
Computer Language Labo / Nara Institute of Science and Technology
>Environment:
Pentium2 300MHz and 15GB HDD and 128MB RAM. (any environments)
>Description:
ICMP Destination Port Unreachable Error Message was wrong. This ICMP
Datagram does NOT contain the checksum value of the original UDP datagram.
It is ocurred filled in original UDP datagram by 0 when calculate UDP
checksum. Does it agree with RFC ? Does it only help NMAP to detect OS ?
>How-To-Repeat:
Anytime.
>Fix:
--- sys/netinet/udp_usrreq.c.orig Thu Nov 2 02:08:50 2000
+++ sys/netinet/udp_usrreq.c Wed Jan 17 00:20:25 2001
@@ -162,6 +162,8 @@
struct ip save_ip;
struct sockaddr *append_sa;
+ u_short osum;
+
udpstat.udps_ipackets++;
/*
@@ -214,6 +216,7 @@
/*
* Checksum extended UDP header and data.
*/
+ osum = uh->uh_sum;
if (uh->uh_sum) {
if (m->m_pkthdr.csum_flags & CSUM_DATA_VALID) {
if (m->m_pkthdr.csum_flags & CSUM_PSEUDO_HDR)
@@ -234,6 +237,9 @@
return;
}
}
+
+ /* restore original datagram */
+ uh->uh_sum = osum;
if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
in_broadcast(ip->ip_dst, m->m_pkthdr.rcvif)) {
>Release-Note:
>Audit-Trail:
>Unformatted:
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