From ac868fa87da18cdebb86103b35ce250bd171f700 Mon Sep 17 00:00:00 2001
From: ian <ian>
Date: Sun, 11 Apr 1999 21:01:49 +0000
Subject: [PATCH] SIGPIPE protection available.

---
 src/adns.h     |  1 +
 src/event.c    |  2 ++
 src/general.c  | 29 +++++++++++++++++++++++++++++
 src/internal.h | 13 ++++++++++++-
 src/transmit.c |  2 ++
 5 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/src/adns.h b/src/adns.h
index 32addba..5726e25 100644
--- a/src/adns.h
+++ b/src/adns.h
@@ -42,6 +42,7 @@ typedef enum {
   adns_if_debug=        0x0008, /* enable all output to stderr plus debug msgs */
   adns_if_noautosys=    0x0010, /* do not make syscalls at every opportunity */
   adns_if_eintr=        0x0020, /* allow _wait and _synchronous to return EINTR */
+  adns_if_nosigpipe=    0x0040, /* applic has SIGPIPE set to SIG_IGN, do not protect */
 } adns_initflags;
 
 typedef enum {
diff --git a/src/event.c b/src/event.c
index 5041f8c..db3dad6 100644
--- a/src/event.c
+++ b/src/event.c
@@ -284,7 +284,9 @@ static int internal_callback(adns_state ads, int maxfd,
     } else if (callb_checkfd(maxfd,exceptfds,ads->tcpsocket)) {
       adns__tcp_broken(ads,"select","exceptional condition detected");
     } else if (ads->tcpsend.used && callb_checkfd(maxfd,writefds,ads->tcpsocket)) {
+      adns__sigpipe_protect(ads);
       r= write(ads->tcpsocket,ads->tcpsend.buf,ads->tcpsend.used);
+      adns__sigpipe_unprotect(ads);
       if (r<0) {
 	if (errno!=EAGAIN && errno!=EWOULDBLOCK && errno!=ENOMEM && errno!=EINTR) {
 	  adns__tcp_broken(ads,"write",strerror(errno));
diff --git a/src/general.c b/src/general.c
index 33946ad..b701b9f 100644
--- a/src/general.c
+++ b/src/general.c
@@ -270,3 +270,32 @@ void adns__isort(void *array, int nobjs, int sz, void *tempbuf,
     }
   }
 }
+
+/* SIGPIPE protection. */
+
+void adns__sigpipe_protect(adns_state ads) {
+  sigset_t toblock;
+  struct sigaction sa;
+  int r;
+
+  if (ads->iflags & adns_if_nosigpipe) return;
+
+  sigfillset(&toblock);
+  sigdelset(&toblock,SIGPIPE);
+
+  sa.sa_handler= SIG_IGN;
+  sigfillset(&sa.sa_mask);
+  sa.sa_flags= 0;
+  
+  r= sigprocmask(SIG_SETMASK,&toblock,&ads->stdsigmask); assert(!r);
+  r= sigaction(SIGPIPE,&sa,&ads->stdsigpipe); assert(!r);
+}
+
+void adns__sigpipe_unprotect(adns_state ads) {
+  int r;
+
+  if (ads->iflags & adns_if_nosigpipe) return;
+
+  r= sigaction(SIGPIPE,&ads->stdsigpipe,0); assert(!r);
+  r= sigprocmask(SIG_SETMASK,&ads->stdsigmask,0); assert(!r);
+}
diff --git a/src/internal.h b/src/internal.h
index 5e42ade..9a5f23d 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -31,6 +31,7 @@ typedef unsigned char byte;
 #include <stdarg.h>
 #include <assert.h>
 #include <unistd.h>
+#include <signal.h>
 
 #include <sys/time.h>
 
@@ -249,6 +250,8 @@ struct adns__state {
   int nservers, nsortlist, tcpserver;
   enum adns__tcpstate { server_disconnected, server_connecting, server_ok } tcpstate;
   struct timeval tcptimeout;
+  struct sigaction stdsigpipe;
+  sigset_t stdsigmask;
   struct server {
     struct in_addr addr;
   } servers[MAXSERVERS];
@@ -302,7 +305,15 @@ void adns__isort(void *array, int nobjs, int sz, void *tempbuf,
  * sz bytes long.  needswap should return !0 if a>b (strictly, ie
  * wrong order) 0 if a<=b (ie, order is fine).
  */
-  
+
+void adns__sigpipe_protect(adns_state);
+void adns__sigpipe_unprotect(adns_state);
+/* If SIGPIPE protection is not disabled, will block all signals except
+ * SIGPIPE, and set SIGPIPE's disposition to SIG_IGN.  (And then restore.)
+ * Each call to _protect must be followed by a call to _unprotect before
+ * any significant amount of code gets to run.
+ */
+
 /* From transmit.c: */
 
 adns_status adns__mkquery(adns_state ads, vbuf *vb, int *id_r,
diff --git a/src/transmit.c b/src/transmit.c
index d3978c3..d0b9d95 100644
--- a/src/transmit.c
+++ b/src/transmit.c
@@ -179,7 +179,9 @@ void adns__query_tcp(adns_query qu, struct timeval now) {
     iov[0].iov_len= 2;
     iov[1].iov_base= qu->query_dgram;
     iov[1].iov_len= qu->query_dglen;
+    adns__sigpipe_protect(qu->ads);
     wr= writev(qu->ads->tcpsocket,iov,2);
+    adns__sigpipe_unprotect(qu->ads);
     if (wr < 0) {
       if (!(errno == EAGAIN || errno == EINTR || errno == ENOSPC ||
 	    errno == ENOBUFS || errno == ENOMEM)) {
-- 
2.30.2