Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!linus!decvax!harpo!seismo!hao!hplabs!sri-unix!RWS@mit-xx
From: RWS%mit-xx@sri-unix.UUCP
Newsgroups: net.unix-wizards
Subject: another 4.2 UDP bug fix
Message-ID: <13356@sri-arpa.UUCP>
Date: Fri, 4-Nov-83 15:31:00 EST
Article-I.D.: sri-arpa.13356
Posted: Fri Nov  4 15:31:00 1983
Date-Received: Tue, 8-Nov-83 02:36:10 EST
Lines: 28

From:  Robert W. Scheifler <RWS@mit-xx>

In udp_input(), the code
          if (udpcksum) {
                    ui->ui_next = ui->ui_prev = 0;
                    ui->ui_x1 = 0;
                    ui->ui_len = htons((u_short)len);
                    if (ui->ui_sum = in_cksum(m, len + sizeof (struct ip))) {
                              udpstat.udps_badsum++;
                              m_freem(m);
                              return;
                    }
          }
should be changed to
          if (udpcksum && ui->ui_sum) {
                    register u_short csum = ui->ui_sum;

                    ui->ui_next = ui->ui_prev = 0;
                    ui->ui_x1 = 0;
                    ui->ui_len = htons((u_short)len);
                    ui->ui_sum = 0;
                    if (csum != in_cksum(m, len + sizeof (struct ip))) {
                              udpstat.udps_badsum++;
                              m_freem(m);
                              return;
                    }
          }
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