[LARTC] Patch for arping

[sabat <sabat@eloan.com>]

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This is probably the wrong forum for this, a small patch for arping. 
However:

- the guy who wrote arping, part of iputils, also wrote iproute2
- that guy is pretty much unreachable -- or I have to presume so, 
because his ftp site, the main site for his work, has been broken for 
months now
- I don't know where else to send it
- it might be useful to someone else

It's just a fix for an annoyance -- you should be able to arping from a 
source address you don't actually have. Don't ask me why one would want 
to do this; it solves a detailed problem I have, and I can't be the only 
one.

Btw, if you're interested enough to have read this far, this patches 
cleanly over the RedHat 8.0-patched version of arping. It adds one 
option, -B, which means, "don't bother trying to bind, just do your 
business."

-Steve


--- arping.c	2003-02-13 00:45:26.000000000 -0800
+++ arping.c.new	2003-02-13 00:44:45.000000000 -0800
@@ -38,6 +38,7 @@
 char *device="eth0";
 int ifindex;
 char *source;
+int nobind=0;
 struct in_addr src, dst;
 char *target;
 int dad, unsolicited, advert;
@@ -62,7 +63,7 @@
 void usage(void)
 {
 	fprintf(stderr,
- 		"Usage: arping [-fqbDUAV] [-c count] [-w timeout] [-I device] [-s source] destination\n"
+ 		"Usage: arping [-fqbDUAVB] [-c count] [-w timeout] [-I device] [-s source] destination\n"
  		"  -f : quit on first reply\n"
 		"  -q : be quiet\n"
  		"  -b : keep broadcasting, don't go unicast\n"
@@ -70,6 +71,7 @@
 		"  -U : Unsolicited ARP mode, update your neighbours\n"
 		"  -A : ARP answer mode, update your neighbours\n"
 		"  -V : print version and exit\n"
+		"  -B : do not try to bind to source address\n"
 		"  -c count : how many packets to send\n"
 		"  -w timeout : how long to wait for a reply\n"
 		"  -I device : which ethernet device to use (eth0)\n"
@@ -306,7 +308,7 @@
 
 	setuid(uid);
 
-	while ((ch = getopt(argc, argv, "h?bfDUAqc:w:s:I:V")) != EOF) {
+	while ((ch = getopt(argc, argv, "h?bfDUAqc:w:s:I:VB")) != EOF) {
 		switch(ch) {
 		case 'b':
 			broadcast_only=1;
@@ -340,6 +342,9 @@
 		case 's':
 			source = optarg;
 			break;
+		case 'B':
+			nobind = 1;
+			break;
 		case 'V':
 			printf("arping utility, iputils-ss%s\n", SNAPSHOT);
 			exit(0);
@@ -428,7 +433,7 @@
 		saddr.sin_family = AF_INET;
 		if (src.s_addr) {
 			saddr.sin_addr = src;
-			if (bind(probe_fd, (struct sockaddr*)&saddr, sizeof(saddr)) == -1) {
+			if (!nobind && bind(probe_fd, (struct sockaddr*)&saddr, sizeof(saddr)) == -1) {
 				perror("bind");
 				exit(2);
 			}



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