feat(e2e): hardware-free REU-less HTTPS e2e in VICE + fix(tls): post-ServerHello drain

Makefile

@@ -35,6 +35,11 @@ IP65_BUILD   := ip65-build
 IP65_BIN     := $(IP65_BUILD)/ip65-c64.bin
 
 CA65FLAGS := -I src -I src/inc -I src/crypto/shared -I src/net/$(BACKEND) -I build --debug-info
+# Optional HTTPS target-port override (src/boot.s defaults to 443).
+# `make HTTPS_PORT=4433` lets a test rig's TLS listener bind unprivileged.
+ifdef HTTPS_PORT
+CA65FLAGS += -D HTTPS_PORT=$(HTTPS_PORT)
+endif
 # Lazy (=) so the USE_NISTCURVES_ONCHIP_COMB block below can retarget
 # CFG to the cfg variant after this line.
 LD65FLAGS = -C $(CFG) -Ln build/labels.txt -m build/c64-https.map --dbgfile build/c64-https.dbg

src/boot.s

@@ -3,6 +3,14 @@
 
         .include "constants.inc"
 
+        ; HTTPS target port. Overridable at build time for test rigs
+        ; whose TLS listener cannot bind the privileged default (e.g.
+        ; `make HTTPS_PORT=4433` for the unprivileged macOS/VICE e2e).
+        ; The default MUST stay 443 and the default build byte-identical.
+        .ifndef HTTPS_PORT
+        HTTPS_PORT = 443
+        .endif
+
         ; ---- exports: entry + print helpers ----
         .export start
         .export main_loop
@@ -521,9 +529,9 @@ do_https_get:
         lda #1
         sta http_path_len
 
-        lda #<443
+        lda #<HTTPS_PORT
         sta http_port
-        lda #>443
+        lda #>HTTPS_PORT
         sta http_port+1
 
         ; --- copy hostname into tls_hostname for SNI ---
@@ -556,9 +564,9 @@ do_https_get:
         ldy #>dns_ok_msg
         jsr print_string
 
-        ; --- TCP connect port 443 ---
-        lda #<443               ; port low byte
-        ldx #>443               ; port high byte
+        ; --- TCP connect on HTTPS_PORT (default 443) ---
+        lda #<HTTPS_PORT        ; port low byte
+        ldx #>HTTPS_PORT        ; port high byte
         jsr net_tcp_connect
         bcc @tcp_ok
 

src/tls13.s

@@ -453,6 +453,39 @@ tls_recv_server_hello:
         lda #$05
         sta tls_recv_progress
 
+        ; Drain frames already at the NIC and ACK them BEFORE the
+        ; multi-minute ECDHE stall. The server's post-SH flight is on
+        ; the wire/in the chip by now (it splits at the 512 B default
+        ; MSS because ip65's SYN carries no MSS option); without this
+        ; drain the tail sits unACKed while we compute, and impatient
+        ; peers drop the connection (macOS: hard drop after 13
+        ; retransmits ≈ 54 s on a LAN — the C64 then verifies the whole
+        ; buffered flight offline and dies SENDING client Finished into
+        ; an RST'd socket). Draining here leaves zero unACKed data
+        ; across every later crypto stall; idle connections survive.
+        ; Safe: SH is fully parsed above, and net_poll only appends to
+        ; the TCP ring — it never touches tls_rec_buf. Bounded 8x250
+        ; polls (~10-20 s at 1 MHz — trivial vs the 20 min verify, and
+        ; long enough to cover the peer's first retransmission of the
+        ; flight tail if it wasn't at the NIC yet when we got here).
+        ldy #8
+@sh_drain_outer:
+        ldx #250
+@sh_drain:
+        tya
+        pha
+        txa
+        pha
+        jsr net_poll
+        pla
+        tax
+        pla
+        tay
+        dex
+        bne @sh_drain
+        dey
+        bne @sh_drain_outer
+
         ; compute ECDH shared secret now that tls_server_pubkey is populated
         jsr tls_ecdh_compute_shared
         clc