Rewrite send_packet to update the eigrp header without using ibuf_seek.

There is a long term goal to remove ibuf_seek from the public ibuf API
since the function is a bit tricky to use.
OK tb@

diff --git a/usr.sbin/eigrpd/packet.c b/usr.sbin/eigrpd/packet.c
index c68ad8f..dcf97cb 100644 (file)
--- a/usr.sbin/eigrpd/packet.c
+++ b/usr.sbin/eigrpd/packet.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: packet.c,v 1.22 2023/07/03 10:34:31 claudio Exp $ */
+/*     $OpenBSD: packet.c,v 1.23 2023/12/14 10:02:27 claudio Exp $ */
 
 /*
  * Copyright (c) 2015 Renato Westphal <renato@openbsd.org>
@@ -24,6 +24,7 @@
 
 #include <arpa/inet.h>
 #include <errno.h>
+#include <stddef.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -160,26 +161,39 @@ send_packet(struct eigrp_iface *ei, struct nbr *nbr, uint32_t flags,
 {
        struct eigrp            *eigrp = ei->eigrp;
        struct iface            *iface = ei->iface;
-       struct eigrp_hdr        *eigrp_hdr;
+       struct ibuf              ebuf;
+       struct eigrp_hdr         eigrp_hdr;
 
        if (!(iface->flags & IFF_UP) || !LINK_STATE_IS_UP(iface->linkstate))
                return (-1);
 
        /* update ack number, flags and checksum */
-       if ((eigrp_hdr = ibuf_seek(buf, 0, sizeof(*eigrp_hdr))) == NULL)
-                fatalx("send_packet: buf_seek failed");
        if (nbr) {
-               eigrp_hdr->ack_num = htonl(nbr->recv_seq);
+               if (ibuf_set_n32(buf, offsetof(struct eigrp_hdr, ack_num),
+                   nbr->recv_seq) == -1)
+                       fatalx("send_packet: set of ack_num failed");
                rtp_ack_stop_timer(nbr);
        }
-       if (flags)
-               eigrp_hdr->flags |= htonl(flags);
-       
-       eigrp_hdr->chksum = 0;
-       eigrp_hdr->chksum = in_cksum(ibuf_data(buf), ibuf_size(buf));
+
+       ibuf_from_ibuf(buf, &ebuf);
+       if (ibuf_get(&ebuf, &eigrp_hdr, sizeof(eigrp_hdr)) == -1)
+               fatalx("send_packet: get hdr failed");
+
+       if (flags) {
+               flags |= ntohl(eigrp_hdr.flags);
+               if (ibuf_set_n32(buf, offsetof(struct eigrp_hdr, flags),
+                   flags) == -1)
+                       fatalx("send_packet: set of flags failed");
+       }
+
+       if (ibuf_set_n16(buf, offsetof(struct eigrp_hdr, chksum), 0) == -1)
+               fatalx("send_packet: set of chksum failed");
+       if (ibuf_set_n16(buf, offsetof(struct eigrp_hdr, chksum),
+           in_cksum(ibuf_data(buf), ibuf_size(buf))) == -1)
+               fatalx("send_packet: set of chksum failed");
 
        /* log packet being sent */
-       if (eigrp_hdr->opcode != EIGRP_OPC_HELLO) {
+       if (eigrp_hdr.opcode != EIGRP_OPC_HELLO) {
                char    buffer[64];
 
                if (nbr)
@@ -189,9 +203,9 @@ send_packet(struct eigrp_iface *ei, struct nbr *nbr, uint32_t flags,
                        snprintf(buffer, sizeof(buffer), "(multicast)");
 
                log_debug("%s: type %s iface %s %s AS %u seq %u ack %u",
-                   __func__, opcode_name(eigrp_hdr->opcode), iface->name,
-                   buffer, ntohs(eigrp_hdr->as), ntohl(eigrp_hdr->seq_num),
-                   ntohl(eigrp_hdr->ack_num));
+                   __func__, opcode_name(eigrp_hdr.opcode), iface->name,
+                   buffer, ntohs(eigrp_hdr.as), ntohl(eigrp_hdr.seq_num),
+                   ntohl(eigrp_hdr.ack_num));
        }
 
        switch (eigrp->af) {
@@ -207,9 +221,9 @@ send_packet(struct eigrp_iface *ei, struct nbr *nbr, uint32_t flags,
                fatalx("send_packet: unknown af");
        }
 
-       switch (eigrp_hdr->opcode) {
+       switch (eigrp_hdr.opcode) {
        case EIGRP_OPC_HELLO:
-               if (ntohl(eigrp_hdr->ack_num) == 0)
+               if (ntohl(eigrp_hdr.ack_num) == 0)
                        ei->eigrp->stats.hellos_sent++;
                else
                        ei->eigrp->stats.acks_sent++;