Change -K semantics: timeout *during handshake*, not afterwards

 - the TLS tunnel itself should be transparent so it has no business
shutting down the connection no matter how long the app takes
 - there's still an undetectable situation on some kernels where
EOF doesn't get transmitted from the network, and the engine is in
the handshake, and it can't do anything but wait forever. A timeout
is useful here: dawg, your peer is never going to send any more data,
you should just give up.
 - if the situation happens after the handshake, the *app* should
have a timeout and die. The tunnel will follow suit.
 - libtls has a blocking tls_handshake() blackbox, we cannot give it
a timeout. Too bad, use bearssl.

9 files changed, 38 insertions, 29 deletions

diff --git a/doc/s6-tlsc-io.html b/doc/s6-tlsc-io.html
index 2f02841..d4c1b7e 100644
--- a/doc/s6-tlsc-io.html
+++ b/doc/s6-tlsc-io.html
@@ -195,10 +195,12 @@ connection without using <tt>close_notify</tt>. This is the default. </li>
  <li> <tt>-k&nbsp;<em>servername</em></tt>&nbsp;: use Server Name
 Indication, and send <em>servername</em>. The default is not to
 use SNI, which may be a security risk. </li>
- <li> <tt>-K&nbsp;<em>kimeout</em></tt>&nbsp;: close the connection
-if <em>kimeout</em> milliseconds elapse without any data being
-received from either side. The default is 0, which means
-infinite timeout (never kill the connection). </li>
+ <li> <tt>-K&nbsp;<em>kimeout</em></tt>&nbsp;: if the peer fails
+to send data for <em>kimeout</em> milliseconds during the handshake,
+close the connection. The default is 0, which means infinite timeout
+(never kill the connection). This option is ignored by the
+<tt>libtls</tt> backend, which does not have a way to interrupt
+the handshake after a timeout. </li>
  <li> <tt>-d&nbsp;<em>notif</em></tt>&nbsp;: handshake notification.
 <em>notif</em> must be a file descriptor open for writing. When the
 TLS handshake has completed, some data (terminated by two null
diff --git a/doc/s6-tlsc.html b/doc/s6-tlsc.html
index c2e7521..5ff3431 100644
--- a/doc/s6-tlsc.html
+++ b/doc/s6-tlsc.html
@@ -121,10 +121,12 @@ connection without using <tt>close_notify</tt>. This is the default. </li>
  <li> <tt>-k&nbsp;<em>servername</em></tt>&nbsp;: use Server Name
 Indication, and send <em>servername</em>. The default is not to
 use SNI, which may be a security risk. </li>
- <li> <tt>-K&nbsp;<em>kimeout</em></tt>&nbsp;: close the connection
-if <em>kimeout</em> milliseconds elapse without any data being
-received from either side. The default is 0, which means
-infinite timeout (never kill the connection). </li>
+ <li> <tt>-K&nbsp;<em>kimeout</em></tt>&nbsp;: if the peer fails
+to send data for <em>kimeout</em> milliseconds during the handshake,
+close the connection. The default is 0, which means infinite timeout
+(never kill the connection). This option is ignored by the
+<tt>libtls</tt> backend, which does not have a way to interrupt
+the handshake after a timeout. </li>
  <li> <tt>-6&nbsp;<em>fdr</em></tt>&nbsp;: expect an open file
 descriptor numbered <em>fdr</em> to read network (ciphertext)
 data from. Make sure <em>prog</em> also reads its data
diff --git a/doc/s6-tlsd-io.html b/doc/s6-tlsd-io.html
index 6aad7dc..00f7cd4 100644
--- a/doc/s6-tlsd-io.html
+++ b/doc/s6-tlsd-io.html
@@ -190,10 +190,12 @@ and break the connection when receiving a local EOF. </li>
 connection without using <tt>close_notify</tt>. This is the default. </li>
  <li> <tt>-Y</tt>&nbsp;: Do not send a client certificate. This is the default. </li>
  <li> <tt>-y</tt>&nbsp;: Send a client certificate. </li>
- <li> <tt>-K&nbsp;<em>kimeout</em></tt>&nbsp;: close the connection
-if <em>kimeout</em> milliseconds elapse without any data being
-received from either side. The default is 0, which means
-infinite timeout (never kill the connection). </li>
+ <li> <tt>-K&nbsp;<em>kimeout</em></tt>&nbsp;: if the peer fails
+to send data for <em>kimeout</em> milliseconds during the handshake,
+close the connection. The default is 0, which means infinite timeout
+(never kill the connection). This option is ignored by the
+<tt>libtls</tt> backend, which does not have a way to interrupt
+the handshake after a timeout. </li>
  <li> <tt>-d&nbsp;<em>notif</em></tt>&nbsp;: handshake notification.
 <em>notif</em> must be a file descriptor open for writing. When the
 TLS handshake has completed, some data (terminated by two null
diff --git a/doc/s6-tlsd.html b/doc/s6-tlsd.html
index beeedda..579c63c 100644
--- a/doc/s6-tlsd.html
+++ b/doc/s6-tlsd.html
@@ -129,10 +129,12 @@ connection without using <tt>close_notify</tt>. This is the default. </li>
  <li> <tt>-y</tt>&nbsp;: Require a mandatory client certificate.
 The default, with neither the <tt>-Y</tt> nor the <tt>-y</tt> option,
 is not to require a client certificate at all. </li>
- <li> <tt>-K&nbsp;<em>kimeout</em></tt>&nbsp;: close the connection
-if <em>kimeout</em> milliseconds elapse without any data being
-received from either side. The default is 0, which means
-infinite timeout (never kill the connection). </li>
+ <li> <tt>-K&nbsp;<em>kimeout</em></tt>&nbsp;: if the peer fails
+to send data for <em>kimeout</em> milliseconds during the handshake,
+close the connection. The default is 0, which means infinite timeout
+(never kill the connection). This option is ignored by the
+<tt>libtls</tt> backend, which does not have a way to interrupt
+the handshake after a timeout. </li>
 </ul>
 
 <h2> Notes </h2>
diff --git a/src/include/s6-networking/stls.h b/src/include/s6-networking/stls.h
index e4ef28a..65bb950 100644
--- a/src/include/s6-networking/stls.h
+++ b/src/include/s6-networking/stls.h
@@ -8,7 +8,6 @@
 #include <tls.h>
 
 #include <skalibs/gccattributes.h>
-#include <skalibs/tai.h>
 
 #define STLS_BUFSIZE (16384 + 325 + 1)
 
@@ -16,7 +15,7 @@
  /* Engine */
 
 extern int stls_send_environment (struct tls *, int) ;
-extern void stls_run (struct tls *, int *, tain_t const *, uint32_t, unsigned int) gccattr_noreturn ;
+extern void stls_run (struct tls *, int *, uint32_t, unsigned int) gccattr_noreturn ;
 
 
  /* s6-tlsc-io and s6-tlsd-io */
diff --git a/src/sbearssl/sbearssl_run.c b/src/sbearssl/sbearssl_run.c
index 6a350a9..e097698 100644
--- a/src/sbearssl/sbearssl_run.c
+++ b/src/sbearssl/sbearssl_run.c
@@ -29,7 +29,7 @@ void sbearssl_run (br_ssl_engine_context *ctx, int *fds, tain_t const *tto, uint
 
   for (;;)
   {
-    tain_t deadline ;
+    tain_t deadline = tain_infinite_relative ;
     unsigned int j = 0 ;
     unsigned int state = br_ssl_engine_current_state(ctx) ;
     int r ;
@@ -76,9 +76,13 @@ void sbearssl_run (br_ssl_engine_context *ctx, int *fds, tain_t const *tto, uint
     }
     else xindex[3] = 4 ;
 
-    if ((xindex[0] == 4 && xindex[1] == 4 && xindex[3] == 4 && handshake_done) || !j) break ;
+    if (xindex[0] == 4 && xindex[1] == 4 && xindex[3] == 4)
+    {
+      if (!j || handshake_done) break ;
+      deadline = *tto ;
+    }
 
-    tain_add_g(&deadline, fds[0] >= 0 && fds[2] >= 0 && state & (BR_SSL_SENDAPP | BR_SSL_RECVREC) ? tto : &tain_infinite_relative) ;
+    tain_add_g(&deadline, &deadline) ;
     r = iopause_g(x, j, &deadline) ;
     if (r < 0) strerr_diefu1sys(111, "iopause") ;
     else if (!r) break ;
diff --git a/src/stls/stls_run.c b/src/stls/stls_run.c
index e8305bf..559ebe9 100644
--- a/src/stls/stls_run.c
+++ b/src/stls/stls_run.c
@@ -9,7 +9,6 @@
 #include <skalibs/error.h>
 #include <skalibs/buffer.h>
 #include <skalibs/strerr2.h>
-#include <skalibs/tai.h>
 #include <skalibs/iopause.h>
 #include <skalibs/djbunix.h>
 
@@ -112,7 +111,7 @@ static void closeit (struct tls *ctx, int *fds, int brutal)
   fd_close(fds[3]) ; fds[3] = -1 ;
 }
 
-void stls_run (struct tls *ctx, int *fds, tain_t const *tto, uint32_t options, unsigned int verbosity)
+void stls_run (struct tls *ctx, int *fds, uint32_t options, unsigned int verbosity)
 {
   tlsbuf_t b[2] = { { .blockedonother = 0 }, { .blockedonother = 0 } } ;
   iopause_fd x[4] ;
@@ -129,12 +128,9 @@ void stls_run (struct tls *ctx, int *fds, tain_t const *tto, uint32_t options, u
 
   for (;;)
   {
-    tain_t deadline ;
     unsigned int j = 0 ;
     int r ;
 
-    tain_add_g(&deadline, fds[0] >= 0 && fds[2] >= 0 && buffer_isempty(&b[0].b) && buffer_isempty(&b[1].b) ? tto : &tain_infinite_relative) ;
-
 
    /* poll() preparation */
 
@@ -175,7 +171,7 @@ void stls_run (struct tls *ctx, int *fds, tain_t const *tto, uint32_t options, u
 
    /* poll() */
 
-    r = iopause_g(x, j, &deadline) ;
+    r = iopause_g(x, j, 0) ;
     if (r < 0) strerr_diefu1sys(111, "iopause") ;
     else if (!r) break ;
 
diff --git a/src/tls/s6-tlsc-io.c b/src/tls/s6-tlsc-io.c
index f6a0210..8629a8d 100644
--- a/src/tls/s6-tlsc-io.c
+++ b/src/tls/s6-tlsc-io.c
@@ -31,7 +31,8 @@ static inline void doit (int *fds, tain_t const *tto, uint32_t preoptions, uint3
       strerr_diefu1sys(111, "write post-handshake data") ;
     fd_close(notif) ;
   }
-  stls_run(ctx, fds, tto, options, verbosity) ;
+  (void)tto ;
+  stls_run(ctx, fds, options, verbosity) ;
 }
 
 #else
diff --git a/src/tls/s6-tlsd-io.c b/src/tls/s6-tlsd-io.c
index 75bd1e4..b6621dd 100644
--- a/src/tls/s6-tlsd-io.c
+++ b/src/tls/s6-tlsd-io.c
@@ -31,7 +31,8 @@ static inline void doit (int *fds, tain_t const *tto, uint32_t preoptions, uint3
       strerr_diefu1sys(111, "write post-handshake data") ;
     fd_close(notif) ;
   }
-  stls_run(ctx, fds, tto, options, verbosity) ;
+  (void)tto ;
+  stls_run(ctx, fds, options, verbosity) ;
 }
 
 #else