Apply FD_CLOEXEC on sockets (#1301)

Add an option to set `SOCK_CLOEXEC` when connecting to the server.

* Apply FD_CLOEXEC on sockets
* Added an options flag, switched to SOCK_CLOEXEC to set the option atomically in socket()
* More elegant flow
* Remove endif comment

Co-authored-by: Michael Grunder <[email protected]>

* Remove another endif comment

Co-authored-by: Michael Grunder <[email protected]>

---------

Co-authored-by: Lenny Lyytinen <[email protected]>
Co-authored-by: Michael Grunder <[email protected]>

Author: 3 people

hiredis.c

@@ -835,6 +835,9 @@ redisContext *redisConnectWithOptions(const redisOptions *options) {
     if (options->options & REDIS_OPT_PREFER_IPV6) {
         c->flags |= REDIS_PREFER_IPV6;
     }
+    if (options->options & REDIS_OPT_SET_SOCK_CLOEXEC) {
+        c->flags |= REDIS_OPT_SET_SOCK_CLOEXEC;
+    }
 
     /* Set any user supplied RESP3 PUSH handler or use freeReplyObject
      * as a default unless specifically flagged that we don't want one. */

hiredis.h

@@ -165,6 +165,7 @@ struct redisSsl;
 #define REDIS_OPT_PREFER_IPV4 0x20       /* Prefer IPv4 in DNS lookups. */
 #define REDIS_OPT_PREFER_IPV6 0x40       /* Prefer IPv6 in DNS lookups. */
 #define REDIS_OPT_PREFER_IP_UNSPEC (REDIS_OPT_PREFER_IPV4 | REDIS_OPT_PREFER_IPV6)
+#define REDIS_OPT_SET_SOCK_CLOEXEC 0x80  /* Set SOCK_CLOEXEC on socket file descriptor. */
 
 /* In Unix systems a file descriptor is a regular signed int, with -1
  * representing an invalid descriptor. In Windows it is a SOCKET

net.c

@@ -122,11 +122,20 @@ static int redisSetReuseAddr(redisContext *c) {
 
 static int redisCreateSocket(redisContext *c, int type) {
     redisFD s;
-    if ((s = socket(type, SOCK_STREAM, 0)) == REDIS_INVALID_FD) {
-        __redisSetErrorFromErrno(c,REDIS_ERR_IO,NULL);
+    int flags = SOCK_STREAM;
+
+#ifdef SOCK_CLOEXEC
+    if (c->flags & REDIS_OPT_SET_SOCK_CLOEXEC) {
+        flags |= SOCK_CLOEXEC;
+    }
+#endif
+
+    if ((s = socket(type, flags, 0)) == REDIS_INVALID_FD) {
+        __redisSetErrorFromErrno(c, REDIS_ERR_IO, NULL);
         return REDIS_ERR;
     }
     c->fd = s;
+
     if (type == AF_INET) {
         if (redisSetReuseAddr(c) == REDIS_ERR) {
             return REDIS_ERR;
@@ -512,11 +521,21 @@ static int _redisContextConnectTcp(redisContext *c, const char *addr, int port,
         return REDIS_ERR;
     }
     for (p = servinfo; p != NULL; p = p->ai_next) {
-addrretry:
-        if ((s = socket(p->ai_family,p->ai_socktype,p->ai_protocol)) == REDIS_INVALID_FD)
+addrretry: {
+        int sock_type = p->ai_socktype;
+
+#ifdef SOCK_CLOEXEC
+        if (c->flags & REDIS_OPT_SET_SOCK_CLOEXEC) {
+            sock_type |= SOCK_CLOEXEC;
+        }
+#endif
+
+        if ((s = socket(p->ai_family, sock_type, p->ai_protocol)) == REDIS_INVALID_FD)
             continue;
+}
 
         c->fd = s;
+
         if (redisSetBlocking(c,0) != REDIS_OK)
             goto error;
         if (c->tcp.source_addr) {