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net_switch: build secret_hash header as a separate component

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The prior code did a memmove over the packet data, and in cases where
a packet is completely full (large transfers under an MTU 1500, for
instance), it would corrupt the data packet and nothing got
transferred.

In its place, teach the code to build up the secret_hash header as a
separate component and send a larger packet (by 32 bytes).  The
original packet remains intact and will get received by the intended
target this way.
This commit is contained in:
Mike Swanson
2026-02-10 01:58:35 -08:00
parent bc17da04d1
commit 2d9374190c
1 changed files with 17 additions and 18 deletions
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35
src/network/net_switch.c
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@@ -386,19 +386,14 @@ net_switch_thread(void *priv)
if (!(net_cards_conf[netswitch->card->card_num].link_state & NET_LINK_DOWN)) {
for (int i = 0; i < packets; i++) {
int orig_len = netswitch->pkt_tx_v[i].len;
int send_len = orig_len + 32;
int send_len = orig_len + sizeof(netswitch->secret_hash);
if (send_len > NET_MAX_FRAME) {
netswitch_log("Network Switch: packet too large to add header (%d bytes)\n",
orig_len);
continue;
}
/* Prepend secret hash data */
memmove(netswitch->pkt_tx_v[i].data + 32,
netswitch->pkt_tx_v[i].data,
orig_len);
memcpy(netswitch->pkt_tx_v[i].data, netswitch->secret_hash, 32);
/* Build header with secret hash */
uint8_t augmented[sizeof(netswitch->secret_hash) + NET_MAX_FRAME];
uint8_t *hdr = augmented;
memcpy(hdr, netswitch->secret_hash, sizeof(netswitch->secret_hash));
memcpy(augmented + sizeof(netswitch->secret_hash),
netswitch->pkt_tx_v[i].data, orig_len);
#define MAC_FORMAT "(%02X:%02X:%02X:%02X:%02X:%02X -> %02X:%02X:%02X:%02X:%02X:%02X)"
#define MAC_FORMAT_ARGS(p) (p)[38], (p)[39], (p)[40], (p)[41], (p)[42], (p)[43], (p)[32], (p)[33], (p)[34], (p)[35], (p)[36], (p)[37]
@@ -407,8 +402,7 @@ net_switch_thread(void *priv)
/* Send through all known host interfaces. */
for (net_switch_hostaddr_t *hostaddr = netswitch->hostaddrs; hostaddr; hostaddr = hostaddr->next)
sendto(hostaddr->socket_tx,
(char *) netswitch->pkt_tx_v[i].data, send_len, 0,
sendto(hostaddr->socket_tx, augmented, send_len, 0,
&hostaddr->addr_tx.sa, sizeof(hostaddr->addr_tx.sa));
}
}
@@ -432,16 +426,21 @@ net_switch_thread(void *priv)
}
if (pfd[NET_EVENT_RX].revents & POLLIN) {
#endif
len = recv(netswitch->socket_rx, (char *) netswitch->pkt.data, NET_MAX_FRAME, 0);
if (len < 44) {
len = recv(netswitch->socket_rx, (char *) netswitch->pkt.data, NET_MAX_FRAME + sizeof(netswitch->secret_hash), 0);
if (len < sizeof(netswitch->secret_hash) + 12) {
netswitch_log("Network Switch: recv error (%d)\n", len);
continue;
}
if (memcmp(netswitch->pkt.data, netswitch->secret_hash, 32) != 0) {
if (memcmp(netswitch->pkt.data, netswitch->secret_hash, sizeof(netswitch->secret_hash)) != 0) {
/* This packet contains a different secret hash, ignore it. */
continue;
} else {
memmove(netswitch->pkt.data, netswitch->pkt.data + 32, len - 32);
memmove(netswitch->pkt.data,
netswitch->pkt.data + sizeof(netswitch->secret_hash),
len - sizeof(netswitch->secret_hash));
len = len - sizeof(netswitch->secret_hash);
netswitch->pkt.len = len;
}
if ((AS_U64(netswitch->pkt.data[6]) & le64_to_cpu(0xffffffffffffULL)) == netswitch->mac_addr_u64) {