bpf: move random padding into function

hack3ric · Oct 8, 2024 · cb3649c · cb3649c
1 parent 713fdbe
commit cb3649c
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Showing 3 changed files with 6 additions and 5 deletions.
diff --git a/bpf/egress.c b/bpf/egress.c
@@ -129,8 +129,7 @@ int egress_handler(struct __sk_buff* skb) {
   if (likely(conn->state == CONN_ESTABLISHED)) {
     seq = conn->seq;
     ack_seq = conn->ack_seq;
-    padding =
-      conn->settings.padding == PADDING_RANDOM ? (seq + ack_seq) % 11 : conn->settings.padding;
+    padding = conn_padding(conn, seq, ack_seq);
     conn->seq += payload_len + padding;
   } else {
     if (conn->state == CONN_IDLE) {

diff --git a/bpf/ingress.c b/bpf/ingress.c
@@ -305,9 +305,7 @@ int ingress_handler(struct xdp_md* xdp) {
   }
   if (will_drop) return XDP_DROP;
 
-  __u32 padding = conn->settings.padding == PADDING_RANDOM
-                    ? (ntohl(tcp->seq) + ntohl(tcp->ack_seq)) % 11
-                    : conn->settings.padding;
+  __u32 padding = conn_padding(conn, ntohl(tcp->seq), ntohl(tcp->ack));
   size_t reserve_len = TCP_UDP_HEADER_DIFF + padding;
   if (ipv4) {
     __be16 old_len = ipv4->tot_len;

diff --git a/common/defs.h b/common/defs.h
@@ -307,6 +307,10 @@ static __always_inline __u32 conn_cooldown_display(struct connection* conn) {
   return conn->initiator ? conn_cooldown(conn) : 0;
 }
 
+static __always_inline __u32 conn_padding(struct connection* conn, __u32 seq, __u32 ack_seq) {
+  return conn->settings.padding == PADDING_RANDOM ? (seq + ack_seq) % 11 : conn->settings.padding;
+}
+
 static __always_inline int time_diff_sec(__u64 a, __u64 b) {
   if (a <= b) return 0;
   if ((a - b) % SECOND < SECOND / 2)