kernel/net: send nothing on a connection the peer has reset

kernel/net: stop the TCP timers when the peer resets the connection
kernel/net: mark a TCP socket disconnected when the peer resets it
2026-09-30 10:14:21 +03:00 · 2026-09-30 10:14:21 +03:00 · 2026-09-30 10:14:20 +03:00 · 2026-09-30 10:14:19 +03:00
5 changed files with 32 additions and 72 deletions
@@ -463,7 +463,7 @@ proc kernel_alloc stdcall, size:dword
        and     eax, -PAGE_SIZE;
        mov     [size], eax
        and     eax, eax
-        jz      .err0
+        jz      .err
        mov     ebx, eax
        shr     ebx, 12
        mov     [pages_count], ebx
@@ -509,13 +509,6 @@ proc kernel_alloc stdcall, size:dword
        pop     ebx
        ret
 .err:
-        mov     eax, [lin_addr]
-        test    eax, eax
-        jz      .err0
-        mov     ecx, [pages_count]
-        call    release_pages
-        stdcall free_kernel_space, [lin_addr]
-.err0:
        xor     eax, eax
        pop     edi
        pop     ebx
@@ -1397,9 +1397,7 @@ proc create_ring_buffer stdcall, size:dword, flags:dword
        mov     [page_tabs + edi], eax
        mov     [page_tabs + edi + edx], eax
        invlpg  [ebx]
-        add     ebx, [size]
-        invlpg  [ebx]                   ; the mirror half
-        sub     ebx, [size]
+        invlpg  [ebx+0x10000]
        add     eax, 0x1000
        add     ebx, 0x1000
        add     edi, 4
@@ -1418,62 +1416,6 @@ proc create_ring_buffer stdcall, size:dword, flags:dword
        ret
 endp

-; Same as create_ring_buffer, but from non-contiguous pages.
-; Not for DMA. Free with kernel_free.
-align 4
-proc create_ring_buffer_sparse stdcall, size:dword, flags:dword
-           locals
-             buf_ptr  dd ?
-           endl
-
-        mov     eax, [size]
-        test    eax, eax
-        jz      .fail
-
-        add     eax, eax
-        stdcall alloc_kernel_space, eax
-        test    eax, eax
-        jz      .fail
-        mov     [buf_ptr], eax
-
-        push    ebx esi edi
-        mov     ebx, eax                ; page being mapped
-        mov     esi, [size]             ; distance to its mirror
-        mov     edi, esi
-        shr     edi, 12                 ; pages left
-  .page:
-        call    alloc_page
-        test    eax, eax
-        jz      .mm_fail
-        or      eax, [flags]
-        mov     edx, ebx
-        shr     edx, 12
-        mov     [page_tabs + edx*4], eax
-        invlpg  [ebx]
-        lea     edx, [ebx + esi]
-        shr     edx, 12
-        mov     [page_tabs + edx*4], eax
-        invlpg  [ebx + esi]
-        add     ebx, PAGE_SIZE
-        dec     edi
-        jnz     .page
-
-        mov     eax, [buf_ptr]
-        pop     edi esi ebx
-        ret
-
-  .mm_fail:
-        mov     eax, [buf_ptr]
-        mov     ecx, [size]
-        shr     ecx, 11                 ; both halves, in pages
-        call    release_pages
-        stdcall free_kernel_space, [buf_ptr]
-        pop     edi esi ebx
-        xor     eax, eax
-  .fail:
-        ret
-endp
-

 align 4
 proc print_mem
@@ -198,10 +198,6 @@ ends

 SOCKET_STRUCT_SIZE      = 4096          ; in bytes

-if sizeof.STREAM_SOCKET > SOCKET_STRUCT_SIZE
-  err "STREAM_SOCKET does not fit in SOCKET_STRUCT_SIZE"
-end if
-
 SOCKET_QUEUE_SIZE       = 10            ; maximum number of incoming packets queued for 1 socket
 ; the incoming packet queue for sockets is placed in the socket struct itself, at this location from start
 SOCKET_QUEUE_LOCATION   = (SOCKET_STRUCT_SIZE - SOCKET_QUEUE_SIZE*sizeof.socket_queue_entry - sizeof.queue)
@@ -1072,6 +1068,11 @@ socket_send_tcp:

        DEBUGF  DEBUG_NETWORK_VERBOSE, "SOCKET_send: TCP\n"

+; Connection closed or reset by peer?
+
+        test    [eax + SOCKET.state], SS_CANTSENDMORE
+        jnz     .cantsendmore
+
        push    eax
        add     eax, STREAM_SOCKET.snd
        call    socket_ring_write
@@ -1086,6 +1087,16 @@ socket_send_tcp:
        mov     [esp + SYSCALL_STACK.ebx], eax
        ret

+  .cantsendmore:
+        mov     ebx, [eax + SOCKET.errorcode]
+        test    ebx, ebx
+        jnz     @f
+        mov     ebx, ENOTCONN
+       @@:
+        mov     [esp + SYSCALL_STACK.ebx], ebx
+        mov     dword[esp + SYSCALL_STACK.eax], -1
+        ret
+

 align 4
 socket_send_ip:
@@ -1651,7 +1662,7 @@ socket_ring_create:
        mov     esi, eax

        push    edx
-        stdcall create_ring_buffer_sparse, SOCKET_BUFFER_SIZE, PG_SWR
+        stdcall create_ring_buffer, SOCKET_BUFFER_SIZE, PG_SWR
        pop     edx
        test    eax, eax
        jz      .fail
@@ -864,6 +864,10 @@ endl
        mov     [ebx + TCP_SOCKET.t_state], TCPS_CLOSED
        inc     [TCPS_drops]

+; Stop the timers, wake up the application
+        mov     eax, ebx
+        call    tcp_cancel_timers
+        call    socket_is_disconnected

        jmp     .drop

@@ -63,6 +63,15 @@ endl

  .not_idle:
  .again:
+; Connection was reset by peer, send nothing
+        cmp     [eax + TCP_SOCKET.t_state], TCPS_CLOSED
+        jne     @f
+        mov     ebx, [eax + SOCKET.state]
+        and     ebx, SS_CANTSENDMORE + SS_ISDISCONNECTING
+        cmp     ebx, SS_CANTSENDMORE
+        je      .nothing_to_send
+  @@:
+
        mov     [temp_bits], 0

 ; Calculate offset
@@ -306,6 +315,7 @@ endl
 ;----------------------------
 ; No reason to send a segment

+  .nothing_to_send:
        DEBUGF  DEBUG_NETWORK_VERBOSE, "TCP_output: No reason to send a segment\n"

        pusha
Author	SHA1	Message	Date
Leency	6fc8e7596f	kernel/net: send nothing on a connection the peer has reset Check kernel codestyle / Check kernel codestyle (pull_request) Successful in 33s Details Test PR / Build (en_US) (pull_request) Successful in 3m35s Details Test PR / Build (es_ES) (pull_request) Successful in 3m32s Details Test PR / Build (ru_RU) (pull_request) Successful in 3m6s Details	2026-09-30 10:14:21 +03:00
Leency	8a4662a4c1	kernel/net: stop the TCP timers when the peer resets the connection	2026-09-30 10:14:21 +03:00
Leency	78d8a28f6c	kernel/net: mark a TCP socket disconnected when the peer resets it .econnreset only set t_state = CLOSED, so SS_CANTSENDMORE stayed clear: send still succeeded and wiped ECONNRESET. Now it fails with ECONNRESET and a blocked recv wakes up.	2026-09-30 10:14:20 +03:00
Leency	8d0f70c92d	kernel/net: fail socket_send on a connection the peer has closed socket_send_tcp took the data into the transmit ring, cleared the socket's errorcode and only then called tcp_output, and it never looked at SS_CANTSENDMORE. After tcp_drop/tcp_close (a RST or FIN from the peer) had run socket_is_disconnected, a send therefore "succeeded" until the ring was full and then returned 0 bytes with errorcode 0 -- byte for byte the answer a healthy socket gives while the kernel drains the ring. An application writing a large request never learned the connection was dead; NetSurf on the 2009 QEMU/slirp sat 20 s per upload at ~100 KB of 25 MB with nothing to distinguish it from a slow uplink. Return -1 with the error the drop recorded (ECONNRESET, ...), or ENOTCONN when nothing was recorded, when SS_CANTSENDMORE is set.	2026-09-30 10:14:19 +03:00