ip: route: add congestion control metric

This patch adds configuration and dumping of congestion control metric
for ip route, for example:

  ip route add <dst> dev foo congctl [lock] dctcp

Reference: http://thread.gmane.org/gmane.linux.network/344733
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>

diff --git a/ip/iproute.c b/ip/iproute.c
index 5a496a91216fb908a7c3f68e870ea7579ffa7a8a..76d8e36ccc2b05df239e4ed7356b3fb3baf004c0 100644 (file)
--- a/ip/iproute.c
+++ b/ip/iproute.c
@@ -53,6 +53,7 @@ static const char *mx_names[RTAX_MAX+1] = {
        [RTAX_RTO_MIN]  = "rto_min",
        [RTAX_INITRWND] = "initrwnd",
        [RTAX_QUICKACK] = "quickack",
+       [RTAX_CC_ALGO]  = "congctl",
 };
 static void usage(void) __attribute__((noreturn));
 
@@ -80,8 +81,7 @@ static void usage(void)
        fprintf(stderr, "           [ window NUMBER] [ cwnd NUMBER ] [ initcwnd NUMBER ]\n");
        fprintf(stderr, "           [ ssthresh NUMBER ] [ realms REALM ] [ src ADDRESS ]\n");
        fprintf(stderr, "           [ rto_min TIME ] [ hoplimit NUMBER ] [ initrwnd NUMBER ]\n");
-       fprintf(stderr, "           [ features FEATURES ]\n");
-       fprintf(stderr, "           [ quickack BOOL ]\n");
+       fprintf(stderr, "           [ features FEATURES ] [ quickack BOOL ] [ congctl NAME ]\n");
        fprintf(stderr, "TYPE := [ unicast | local | broadcast | multicast | throw |\n");
        fprintf(stderr, "          unreachable | prohibit | blackhole | nat ]\n");
        fprintf(stderr, "TABLE_ID := [ local | main | default | all | NUMBER ]\n");
@@ -536,7 +536,7 @@ int print_route(const struct sockaddr_nl *who, struct nlmsghdr *n, void *arg)
                        mxlock = *(unsigned*)RTA_DATA(mxrta[RTAX_LOCK]);
 
                for (i=2; i<= RTAX_MAX; i++) {
-                       unsigned val;
+                       __u32 val;
 
                        if (mxrta[i] == NULL)
                                continue;
@@ -545,10 +545,12 @@ int print_route(const struct sockaddr_nl *who, struct nlmsghdr *n, void *arg)
                                fprintf(fp, " %s", mx_names[i]);
                        else
                                fprintf(fp, " metric %d", i);
+
                        if (mxlock & (1<<i))
                                fprintf(fp, " lock");
+                       if (i != RTAX_CC_ALGO)
+                               val = rta_getattr_u32(mxrta[i]);
 
-                       val = *(unsigned*)RTA_DATA(mxrta[i]);
                        switch (i) {
                        case RTAX_FEATURES:
                                print_rtax_features(fp, val);
@@ -573,6 +575,10 @@ int print_route(const struct sockaddr_nl *who, struct nlmsghdr *n, void *arg)
                                        fprintf(fp, " %gs", val/1e3);
                                else
                                        fprintf(fp, " %ums", val);
+                               break;
+                       case RTAX_CC_ALGO:
+                               fprintf(fp, " %s", rta_getattr_str(mxrta[i]));
+                               break;
                        }
                }
        }
@@ -925,6 +931,14 @@ static int iproute_modify(int cmd, unsigned flags, int argc, char **argv)
                        if (quickack != 1 && quickack != 0)
                                invarg("\"quickack\" value should be 0 or 1\n", *argv);
                        rta_addattr32(mxrta, sizeof(mxbuf), RTAX_QUICKACK, quickack);
+               } else if (matches(*argv, "congctl") == 0) {
+                       NEXT_ARG();
+                       if (strcmp(*argv, "lock") == 0) {
+                               mxlock |= 1 << RTAX_CC_ALGO;
+                               NEXT_ARG();
+                       }
+                       rta_addattr_l(mxrta, sizeof(mxbuf), RTAX_CC_ALGO, *argv,
+                                     strlen(*argv));
                } else if (matches(*argv, "rttvar") == 0) {
                        unsigned win;
                        NEXT_ARG();

diff --git a/man/man8/ip-route.8.in b/man/man8/ip-route.8.in
index 89960c1462d8a4b82533635a45a2ad2a1a6cbaa2..2b1583d5a30c50fa576cfa1326f55baf8452a449 100644 (file)
--- a/man/man8/ip-route.8.in
+++ b/man/man8/ip-route.8.in
@@ -116,7 +116,9 @@ replace " } "
 .B  features
 .IR FEATURES " ] [ "
 .B  quickack
-.IR BOOL " ]"
+.IR BOOL " ] [ "
+.B  congctl
+.IR NAME " ]"
 
 .ti -8
 .IR TYPE " := [ "
@@ -432,6 +434,21 @@ sysctl is set to 0.
 .BI quickack " BOOL " "(3.11+ only)"
 Enable or disable quick ack for connections to this destination.
 
+.TP
+.BI congctl " NAME " "(3.20+ only)"
+.TP
+.BI "congctl lock" " NAME " "(3.20+ only)"
+Sets a specific TCP congestion control algorithm only for a given destination.
+If not specified, Linux keeps the current global default TCP congestion control
+algorithm, or the one set from the application. If the modifier
+.B lock
+is not used, an application may nevertheless overwrite the suggested congestion
+control algorithm for that destination. If the modifier
+.B lock
+is used, then an application is not allowed to overwrite the specified congestion
+control algorithm for that destination, thus it will be enforced/guaranteed to
+use the proposed algorithm.
+
 .TP
 .BI advmss " NUMBER " "(2.3.15+ only)"
 the MSS ('Maximal Segment Size') to advertise to these