sstp: add ppposeq transport to avoid userspace HDLC framingsstp-ppposeq

A pty is a byte stream, so the tty flip buffer merges frames written
back to back and sstp has to re-delimit them with async HDLC escaping
and a CRC-16 FCS. On a 1452-byte payload that is ~3600 ns per frame,
most of it spent on the FCS.

PPPOSEQ is a pppox protocol whose socket is the ppp endpoint itself,
so one datagram is one frame and no framing is needed at all. The
same payload takes ~380 ns per frame, about 9 times less. Requires
kernel 2.6.37, the first with PX_MAX_PROTO 3, whose remaining slot
it claims.
Supported kernels are from 2.6.37 to 7.2.

The new ppp-mode option selects the transport; auto, the default,
falls back to async when the module is unavailable, so hosts with
prebuilt kernels are unaffected.

PPP_SYNC is removed, being disabled and unfixable over a pty: frame
boundaries cannot be recovered from the stream, and coalescing cannot
be prevented since frames arrive from the network stack.

1 files changed, 26 insertions, 6 deletions

diff --git a/.github/workflows/run-tests.yml b/.github/workflows/run-tests.yml
index 71b3820b..9cd47a00 100644
--- a/.github/workflows/run-tests.yml
+++ b/.github/workflows/run-tests.yml
@@ -127,7 +127,8 @@ jobs:
         run: >
           ssh -i ssh-key -p2222 user@localhost "cd accel-ppp &&
           mkdir build && cd build &&
-          cmake -DBUILD_IPOE_DRIVER=TRUE -DBUILD_VLAN_MON_DRIVER=TRUE -DCMAKE_INSTALL_PREFIX=/usr 
+          cmake -DBUILD_IPOE_DRIVER=TRUE -DBUILD_VLAN_MON_DRIVER=TRUE -DBUILD_PPPOSEQ_DRIVER=TRUE 
+          -DCMAKE_INSTALL_PREFIX=/usr 
           -DKDIR=/usr/src/linux-headers-\`uname -r\` 
           -DLUA=TRUE -DSHAPER=TRUE -DRADIUS=TRUE .. &&
           make && sudo make install"
@@ -167,6 +168,12 @@ jobs:
           sudo insmod build/drivers/vlan_mon/driver/vlan_mon.ko &&
           lsmod | grep vlan_mon"
 
+      - name: Insert ppposeq kernel module
+        run: >
+          ssh -i ssh-key -p2222 user@localhost "cd accel-ppp &&
+          sudo modprobe pppox && sudo insmod build/drivers/ppposeq/driver/ppposeq.ko &&
+          lsmod | grep ppposeq"
+
       - name: Run tests (all)
         timeout-minutes: 5
         run: >
@@ -265,7 +272,8 @@ jobs:
         run: >
           ssh -i ssh-key -p2222 alpine@localhost "cd accel-ppp &&
           mkdir build && cd build &&
-          cmake -DBUILD_IPOE_DRIVER=TRUE -DBUILD_VLAN_MON_DRIVER=TRUE -DCMAKE_INSTALL_PREFIX=/usr 
+          cmake -DBUILD_IPOE_DRIVER=TRUE -DBUILD_VLAN_MON_DRIVER=TRUE -DBUILD_PPPOSEQ_DRIVER=TRUE 
+          -DCMAKE_INSTALL_PREFIX=/usr 
           -DKDIR=/usr/src/linux-headers-\`uname -r\` 
           -DLUA=TRUE -DSHAPER=TRUE -DRADIUS=TRUE .. &&
           make && doas make install"
@@ -305,6 +313,12 @@ jobs:
           doas insmod build/drivers/vlan_mon/driver/vlan_mon.ko &&
           lsmod | grep vlan_mon"
 
+      - name: Insert ppposeq kernel module
+        run: >
+          ssh -i ssh-key -p2222 alpine@localhost "cd accel-ppp &&
+          doas modprobe pppox && doas insmod build/drivers/ppposeq/driver/ppposeq.ko &&
+          lsmod | grep ppposeq"
+
       - name: Run tests (all)
         timeout-minutes: 5
         run: >
@@ -360,7 +374,8 @@ jobs:
       - name: cmake
         working-directory: ./build
         run: >
-          cmake -DBUILD_IPOE_DRIVER=TRUE -DBUILD_VLAN_MON_DRIVER=TRUE -DCMAKE_INSTALL_PREFIX=/usr 
+          cmake -DBUILD_IPOE_DRIVER=TRUE -DBUILD_VLAN_MON_DRIVER=TRUE -DBUILD_PPPOSEQ_DRIVER=TRUE 
+          -DCMAKE_INSTALL_PREFIX=/usr 
           -DKDIR=/usr/src/linux-headers-`uname -r` 
           -DLUA=TRUE -DSHAPER=TRUE -DRADIUS=TRUE ..
 
@@ -368,13 +383,15 @@ jobs:
         working-directory: ./build
         run: make && sudo make install
 
-      - name: Insert and check kernel modules (ipoe and vlan-mon)
+      - name: Insert and check kernel modules (ipoe, vlan-mon, ppposeq)
         # if: ${{ false }}
         run: |
           sudo insmod build/drivers/vlan_mon/driver/vlan_mon.ko
           sudo insmod build/drivers/ipoe/driver/ipoe.ko
+          sudo modprobe pppox && sudo insmod build/drivers/ppposeq/driver/ppposeq.ko
           lsmod | grep ipoe
           lsmod | grep vlan_mon
+          lsmod | grep ppposeq
 
       - name: Run tests
         timeout-minutes: 5
@@ -424,7 +441,8 @@ jobs:
       - name: cmake (with coverage)
         working-directory: ./build
         run: >
-          cmake -DBUILD_IPOE_DRIVER=TRUE -DBUILD_VLAN_MON_DRIVER=TRUE -DCMAKE_INSTALL_PREFIX=/usr 
+          cmake -DBUILD_IPOE_DRIVER=TRUE -DBUILD_VLAN_MON_DRIVER=TRUE -DBUILD_PPPOSEQ_DRIVER=TRUE 
+          -DCMAKE_INSTALL_PREFIX=/usr 
           -DKDIR=/usr/src/linux-headers-`uname -r` 
           -DLUA=TRUE -DSHAPER=TRUE -DRADIUS=TRUE 
           -DCMAKE_C_FLAGS="--coverage -O0" ..
@@ -433,13 +451,15 @@ jobs:
         working-directory: ./build
         run: make && sudo make install
 
-      - name: Insert and check kernel modules (ipoe and vlan-mon)
+      - name: Insert and check kernel modules (ipoe, vlan-mon, ppposeq)
         # if: ${{ false }}
         run: |
           sudo insmod build/drivers/vlan_mon/driver/vlan_mon.ko
           sudo insmod build/drivers/ipoe/driver/ipoe.ko
+          sudo modprobe pppox && sudo insmod build/drivers/ppposeq/driver/ppposeq.ko
           lsmod | grep ipoe
           lsmod | grep vlan_mon
+          lsmod | grep ppposeq
 
       - name: Run tests (for coverage report) (fail is ok)
         timeout-minutes: 5