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 send(mosq->sock, buf, count, MSG_NOSIGNAL);
-	return write(mosq->sock, buf, count);
-#else
-	return send(mosq->sock, buf, count, 0);
-#endif
 
 #ifdef WITH_TLS
 	}

lib/net_mosq.h

@@ -19,6 +19,7 @@ Contributors:
 #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)