tcpdrop: allow TCP connections to be filtered by cc-algo

In addition to filtering by stack and state, allow filtering
by the congestion control module used.  Choose the command line
options to be consistent with the ones of sockstat.

MFC after:	1 week
Sponsored by:	Netflix, Inc.

usr.sbin/tcpdrop/tcpdrop.8

@@ -34,13 +34,18 @@
 .Fl a
 .Nm tcpdrop
 .Op Fl l
-.Fl S Ar stack
+.Fl C Ar cc-algo
+.Op Fl S Ar stack
+.Op Fl s Ar state
 .Nm tcpdrop
 .Op Fl l
-.Fl s Ar state
+.Op Fl C Ar cc-algo
+.Fl S Ar stack
+.Op Fl s Ar state
 .Nm tcpdrop
 .Op Fl l
-.Fl S Ar stack
+.Op Fl C Ar cc-algo
+.Op Fl S Ar stack
 .Fl s Ar state
 .Sh DESCRIPTION
 The
@@ -54,6 +59,13 @@ is specified then
 will attempt to drop all TCP connections.
 .Pp
 If
+.Fl C Ar cc-algo
+is specified then
+.Nm
+will attempt to drop all connections using the TCP congestion control algorithm
+.Ar cc-algo .
+.Pp
+If
 .Fl S Ar stack
 is specified then
 .Nm
@@ -78,16 +90,20 @@ is one of
 .Dv FIN_WAIT_2 , or
 .Dv TIME_WAIT .
 .Pp
-If
+If multiple of
-.Fl S Ar stack
+.Fl C Ar cc-algo ,
+.Fl S Ar stack ,
 and
 .Fl s Ar state
 are specified,
 .Nm
-will attempt to drop all TCP connections being in the state
+will attempt to drop all TCP connections using the congestion control algorithm
-.Ar state
+.Ar cc-algo ,
+being in the state
+.Ar state ,
 and using the TCP stack
-.Ar stack .
+.Ar stack ,
+if specified.
 Since TCP connections in the
 .Dv TIME_WAIT
 state are not tied to any TCP stack, using the option
@@ -102,6 +118,7 @@ The
 .Fl l
 flag may be given in addition to the
 .Fl a ,
+.Fl C ,
 .Fl S ,
 or
 .Fl s
@@ -110,6 +127,7 @@ connections one at a time.
 .Pp
 If none of the
 .Fl a ,
+.Fl C ,
 .Fl S ,
 or
 .Fl s
@@ -154,6 +172,11 @@ port 22, the port used by
 # tcpdrop -l -a | grep -vw 22 | sh
 .Ed
 .Pp
+To drop all TCP connections using the new-reno congestion control algorithm use:
+.Bd -literal -offset indent
+# tcpdrop -C new-reno
+.Ed
+.Pp
 The following command will drop all connections using the TCP stack
 rack:
 .Bd -literal -offset indent
@@ -165,10 +188,10 @@ To drop all TCP connections in the LAST_ACK state use:
 # tcpdrop -s LAST_ACK
 .Ed
 .Pp
-To drop all TCP connections using the TCP stack rack and being in the
+To drop all TCP connections using the congestion control algorithm new-reno and
-LAST_ACK state use:
+the TCP stack rack and being in the LAST_ACK state use:
 .Bd -literal -offset indent
-# tcpdrop -S rack -s LAST_ACK
+# tcpdrop -C new-reno -S rack -s LAST_ACK
 .Ed
 .Sh SEE ALSO
 .Xr netstat 1 ,

usr.sbin/tcpdrop/tcpdrop.c

@@ -54,7 +54,7 @@ static char *findport(const char *);
 static struct xinpgen *getxpcblist(const char *);
 static void sockinfo(const struct sockaddr *, struct host_service *);
 static bool tcpdrop(const struct sockaddr *, const struct sockaddr *);
-static bool tcpdropall(const char *, int);
+static bool tcpdropall(const char *, const char *, int);
 static bool tcpdropbyname(const char *, const char *, const char *,
     const char *);
 static bool tcpdropconn(const struct in_conninfo *);
@@ -67,20 +67,26 @@ int
 main(int argc, char *argv[])
 {
 	char stack[TCP_FUNCTION_NAME_LEN_MAX];
+	char ca_name[TCP_CA_NAME_MAX];
 	char *lport, *fport;
 	bool dropall, dropspecific;
 	int ch, state;
 
 	dropall = false;
 	dropspecific = false;
+	ca_name[0] = '\0';
 	stack[0] = '\0';
 	state = -1;
 
-	while ((ch = getopt(argc, argv, "alS:s:")) != -1) {
+	while ((ch = getopt(argc, argv, "aC:lS:s:")) != -1) {
 		switch (ch) {
 		case 'a':
 			dropall = true;
 			break;
+		case 'C':
+			dropspecific = true;
+			strlcpy(ca_name, optarg, sizeof(ca_name));
+			break;
 		case 'l':
 			tcpdrop_list_commands = true;
 			break;
@@ -111,7 +117,7 @@ main(int argc, char *argv[])
 	if (dropall || dropspecific) {
 		if (argc != 0)
 			usage();
-		if (!tcpdropall(stack, state))
+		if (!tcpdropall(ca_name, stack, state))
 			exit(1);
 		exit(0);
 	}
@@ -223,7 +229,7 @@ tcpdrop(const struct sockaddr *lsa, const struct sockaddr *fsa)
 }
 
 static bool
-tcpdropall(const char *stack, int state)
+tcpdropall(const char *ca_name, const char *stack, int state)
 {
 	struct xinpgen *head, *xinp;
 	struct xtcpcb *xtp;
@@ -259,6 +265,14 @@ tcpdropall(const char *stack, int state)
 		if ((state != -1) && (xtp->t_state != state))
 			continue;
 
+		/*
+		 * If requested, skip sockets not having the requested
+		 * congestion control algorithm.
+		 */
+		if (ca_name[0] != '\0' &&
+		    strncmp(xtp->xt_cc, ca_name, TCP_CA_NAME_MAX))
+			continue;
+
 		/* If requested, skip sockets not having the requested stack. */
 		if (stack[0] != '\0' &&
 		    strncmp(xtp->xt_stack, stack, TCP_FUNCTION_NAME_LEN_MAX))
@@ -379,8 +393,8 @@ usage(void)
 "       tcpdrop local-address:local-port foreign-address:foreign-port\n"
 "       tcpdrop local-address.local-port foreign-address.foreign-port\n"
 "       tcpdrop [-l] -a\n"
-"       tcpdrop [-l] -S stack\n"
+"       tcpdrop [-l] -C cc-algo [-S stack] [-s state]\n"
-"       tcpdrop [-l] -s state\n"
+"       tcpdrop [-l] [-C cc-algo] -S stack [-s state]\n"
-"       tcpdrop [-l] -S stack -s state\n");
+"       tcpdrop [-l] [-C cc-algo] [-S stack] -s state\n");
 	exit(1);
 }