ipdpd: Pass MPL to application at flow_allocation

The maximum packet lifetime (MPL) is a property of the flow that needs
to be passed to the reliable transmission protocol (FRCP) for its
correct operation. Previously, the value of MPL was set fixed as one
of the (fixed) Delta-t parameters. This patch makes the MPL a property
of the layer, and it can now be set per layer-type at build time.
This is a step towards a proper MPL estimator in the flow allocator.

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

2 files changed, 8 insertions, 4 deletions

diff --git a/src/ipcpd/eth/CMakeLists.txt b/src/ipcpd/eth/CMakeLists.txt
index d7105b4f..d57e1848 100644
--- a/src/ipcpd/eth/CMakeLists.txt
+++ b/src/ipcpd/eth/CMakeLists.txt
@@ -85,6 +85,8 @@ if (HAVE_ETH)
     "Bypass the Qdisc in the kernel when using raw sockets")
   set(IPCP_ETH_LO_MTU 1500 CACHE STRING
     "Restrict Ethernet MTU over loopback interfaces")
+  set(IPCP_ETH_MPL 5 CACHE STRING
+    "Default maximum packet lifetime for the Ethernet IPCPs, in seconds")
 
   set(ETH_LLC_SOURCES
     # Add source files here
diff --git a/src/ipcpd/eth/eth.c b/src/ipcpd/eth/eth.c
index 8b34d303..f62bd0a7 100644
--- a/src/ipcpd/eth/eth.c
+++ b/src/ipcpd/eth/eth.c
@@ -575,6 +575,7 @@ static int eth_ipcp_req(uint8_t *       r_addr,
         struct timespec ts = {0, ALLOC_TIMEO * MILLION};
         struct timespec abstime;
         int             fd;
+        time_t          mpl = IPCP_ETH_MPL;
 
         clock_gettime(PTHREAD_COND_CLOCK, &abstime);
 
@@ -594,7 +595,7 @@ static int eth_ipcp_req(uint8_t *       r_addr,
         }
 
         /* reply to IRM, called under lock to prevent race */
-        fd = ipcp_flow_req_arr(dst, ipcp_dir_hash_len(), qs, data, len);
+        fd = ipcp_flow_req_arr(dst, ipcp_dir_hash_len(), qs, mpl, data, len);
         if (fd < 0) {
                 pthread_mutex_unlock(&ipcpi.alloc_lock);
                 log_err("Could not get new flow from IRMd.");
@@ -636,8 +637,9 @@ static int eth_ipcp_alloc_reply(uint8_t *    r_addr,
                                 const void * data,
                                 size_t       len)
 {
-        int ret = 0;
-        int fd = -1;
+        int    ret = 0;
+        int    fd  = -1;
+        time_t mpl = IPCP_ETH_MPL;
 
         pthread_rwlock_wrlock(&eth_data.flows_lock);
 
@@ -672,7 +674,7 @@ static int eth_ipcp_alloc_reply(uint8_t *    r_addr,
 #elif defined(BUILD_ETH_LLC)
         log_dbg("Flow reply, fd %d, SSAP %d, DSAP %d.", fd, ssap, dsap);
 #endif
-        if ((ret = ipcp_flow_alloc_reply(fd, response, data, len)) < 0)
+        if ((ret = ipcp_flow_alloc_reply(fd, response, mpl, data, len)) < 0)
                 return -1;
 
         return ret;