From: Colin Patrick McCabe <cmccabe@alumni.cmu.edu>
Date: Wed, 11 Aug 2010 19:00:57 +0000 (-0700)
Subject: Add show_default_sockopts program to do just that.
X-Git-Url: http://club.cc.cmu.edu/~cmccabe/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f5b653d2b0cc30f2bbdeb73ef3e0ffb9b39bd7b5;p=cmccabe-bin

Add show_default_sockopts program to do just that.

Also update Makefile.
---

diff --git a/Makefile b/Makefile
index 22ef97c..20927e9 100644
--- a/Makefile
+++ b/Makefile
@@ -4,9 +4,11 @@ all:		errno_speak simple_time
 
 errno_speak:	errno_speak.o
 
+show_default_sockopts:	show_default_sockopts.o
+
 simple_time:	simple_time.o
 
 vimstart:	vimstart.o
 
 clean:
-	rm -rf errno_speak simple_time *.o
+	rm -rf errno_speak show_default_sockopts simple_time vimstart *.o
diff --git a/show_default_sockopts.c b/show_default_sockopts.c
new file mode 100644
index 0000000..cc5f0d4
--- /dev/null
+++ b/show_default_sockopts.c
@@ -0,0 +1,108 @@
+#include <netinet/in.h>
+#include <netinet/tcp.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+/*
+ * show_default_sockopts
+ *
+ * Show the default socket options 
+ *
+ * Colin McCabe
+ */
+
+struct option_t {
+	int opt;
+	const char *descr;
+};
+
+void option_query(int s, int type, struct option_t *p)
+{
+	int value, vlen = 4;
+
+	for (; p->descr != NULL; ++p) {
+		if (getsockopt(s, type, p->opt, (void *)&value, &vlen) == -1) {
+			fprintf(stderr,"getsocketopts: could not test %s\n",
+				p->descr);
+		}
+		else {
+			printf("Default %s = %d\n", p->descr, value);
+		}
+	}
+}
+
+struct option_t so_option[] = {
+#ifdef SO_ACCEPTCONN
+	{ SO_ACCEPTCONN, "SO_ACCEPTCON: accepting connections" },
+#endif
+#ifdef SO_BROADCAST
+	{ SO_BROADCAST, "SO_BROADCAST, broadcast allowed" },
+#endif
+#ifdef SO_REUSEADDR
+	{ SO_REUSEADDR, "SO_REUSEADDR, address recycling" },
+#endif
+#ifdef SO_KEEPALIVE
+	{ SO_KEEPALIVE, "SO_KEEPALIVE, send keepalive packets" },
+#endif
+	/* { SO_LINGER, "SO_LINGER, lingers on close"}, */
+#ifdef SO_OOBINLINE
+	{ SO_OOBINLINE, "SO_OOBINLINE, oob data folded inline"},
+#endif
+#ifdef SO_SNDBUF
+	{ SO_SNDBUF, "SO_SNDBUF, send buffer size" },
+#endif
+#ifdef SO_RCVLOWAT
+	{ SO_RCVLOWAT, "SO_RCVLOWAT, receive low-water mark"},
+#endif
+#ifdef SO_SNDLOWAT
+	{ SO_SNDLOWAT, "SO_SNDLOWAT, send low-water mark"},
+#endif
+#ifdef SO_RCVTIMEO
+	{ SO_RCVTIMEO, "SO_RCVTIMEO, receive timeout"},
+#endif
+#ifdef SO_SNDTIMEO
+	{ SO_SNDTIMEO, "SO_SNDTIMEO, send timeout"},
+#endif
+#ifdef SO_RCVBUF
+	{ SO_RCVBUF, "SO_RCVBUF, receive buffer size"},
+#endif
+#ifdef SO_ERROR
+	{ SO_ERROR, "SO_ERROR, error status"},
+#endif
+#ifdef SO_TYPE
+	{ SO_TYPE, "SO_TYPE, socket type"},
+#endif
+	{ 0, NULL }
+};
+
+struct option_t tcp_option[] = {
+#ifdef TCP_MAXSEG
+	  { TCP_MAXSEG, "TCP_MAXSEG, maximum segment size (mss)"},
+#endif
+#ifdef TCP_NODELAY
+	  { TCP_NODELAY, "TCP_NODELAY, send even tiny packets"},
+#endif
+	  { 0, NULL}
+};
+
+int main(int argc, char **argv)
+{
+	int s;
+	if ((getuid()) != 0) {
+		fprintf(stderr,"%s: you must be root to run this program.\n", argv[0]);
+		return 1;
+	}
+
+	if ((s = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0) {
+		perror("failed to create a socket to test.");
+		return 1;
+	}
+	option_query(s, SOL_SOCKET, so_option);
+	option_query(s, IPPROTO_TCP, tcp_option);
+
+	(void) close(s);
+	return 0;
+}