Don't set SIGPIPE to ignore, use MSG_NOSIGNAL instead.

Closes #2564. Thanks to nmeum.

ChangeLog.txt

@@ -21,6 +21,7 @@ Client library:
  cmake version to 3.1, which is still ancient.
 - Fix use of `MOSQ_OPT_TLS_ENGINE` being unable to be used due to the openssl
  ctx not being initialised until starting to connect. Closes #2537.
+- Don't set SIGPIPE to ignore, use MSG_NOSIGNAL instead. Closes #2564.
 
 Clients:
 - Fix mosquitto_pub incorrectly reusing topic aliases when reconnecting.

lib/mosquitto.c

@@ -109,10 +109,6 @@ struct mosquitto *mosquitto_new(const char *id, bool clean_start, void *userdata
  return NULL;
  }
 
-#ifndef WIN32
- signal(SIGPIPE, SIG_IGN);
-#endif
-
  mosq = (struct mosquitto *)mosquitto__calloc(1, sizeof(struct mosquitto));
  if(mosq){
  mosq->sock = INVALID_SOCKET;

lib/net_mosq.c

@@ -1041,11 +1041,7 @@ ssize_t net__write(struct mosquitto *mosq, const void *buf, size_t count)
  /* Call normal write/send */
 #endif
 
-#ifndef WIN32
- return write(mosq->sock, buf, count);
-#else
- return send(mosq->sock, buf, count, 0);
-#endif
+ return send(mosq->sock, buf, count, MSG_NOSIGNAL);
 
 #ifdef WITH_TLS
  }

lib/net_mosq.h

@@ -19,6 +19,7 @@ SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
 #define NET_MOSQ_H
 
 #ifndef WIN32
+# include <sys/socket.h>
 # include <unistd.h>
 #else
 # include <winsock2.h>
@@ -51,6 +52,10 @@ typedef SSIZE_T ssize_t;
 #define INVALID_SOCKET -1
 #endif
 
+#ifndef MSG_NOSIGNAL
+# define MSG_NOSIGNAL 0
+#endif
+
 /* Macros for accessing the MSB and LSB of a uint16_t */
 #define MOSQ_MSB(A) (uint8_t)((A & 0xFF00) >> 8)
 #define MOSQ_LSB(A) (uint8_t)(A & 0x00FF)