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
3 changed files with 29 additions and 0 deletions
@@ -1068,6 +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
@@ -1082,6 +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:
@@ -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