Introduced SCM_CREDENTIALS / SCM_CREDS in the socket control msgs.

src/nxt_socket_msg.c

@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) Igor Sysoev
+ * Copyright (C) NGINX, Inc.
+ */
+
+#include <nxt_main.h>
+#include <nxt_socket_msg.h>
+
+
+ssize_t
+nxt_sendmsg(nxt_socket_t s, nxt_iobuf_t *iob, nxt_uint_t niob,
+    const nxt_send_oob_t *oob)
+{
+    struct msghdr  msg;
+
+    msg.msg_name = NULL;
+    msg.msg_namelen = 0;
+    msg.msg_iov = iob;
+    msg.msg_iovlen = niob;
+    /* Flags are cleared just to suppress valgrind warning. */
+    msg.msg_flags = 0;
+
+    if (oob != NULL && oob->size != 0) {
+        msg.msg_control = (void *) oob->buf;
+        msg.msg_controllen = oob->size;
+
+    } else {
+        msg.msg_control = NULL;
+        msg.msg_controllen = 0;
+    }
+
+    return sendmsg(s, &msg, 0);
+}
+
+
+ssize_t
+nxt_recvmsg(nxt_socket_t s, nxt_iobuf_t *iob, nxt_uint_t niob,
+    nxt_recv_oob_t *oob)
+{
+    ssize_t        n;
+    struct msghdr  msg;
+
+    msg.msg_name = NULL;
+    msg.msg_namelen = 0;
+    msg.msg_iov = iob;
+    msg.msg_iovlen = niob;
+    msg.msg_control = oob->buf;
+    msg.msg_controllen = sizeof(oob->buf);
+
+    n = recvmsg(s, &msg, 0);
+
+    if (nxt_fast_path(n != -1)) {
+        oob->size = msg.msg_controllen;
+    }
+
+    return n;
+}