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, 7 insertions, 2 deletions

diff --git a/src/ipcpd/local/CMakeLists.txt b/src/ipcpd/local/CMakeLists.txt
index a84f4f1b..10fd0120 100644
--- a/src/ipcpd/local/CMakeLists.txt
+++ b/src/ipcpd/local/CMakeLists.txt
@@ -13,6 +13,8 @@ include_directories(${CMAKE_SOURCE_DIR}/include)
 include_directories(${CMAKE_BINARY_DIR}/include)
 
 set(IPCP_LOCAL_TARGET ipcpd-local CACHE INTERNAL "")
+set(IPCP_LOCAL_MPL 2 CACHE STRING
+    "Default maximum packet lifetime for the Ethernet IPCPs, in seconds")
 
 set(LOCAL_SOURCES
   # Add source files here
diff --git a/src/ipcpd/local/main.c b/src/ipcpd/local/main.c
index c0e0b702..20f06ef8 100644
--- a/src/ipcpd/local/main.c
+++ b/src/ipcpd/local/main.c
@@ -204,6 +204,7 @@ static int ipcp_local_flow_alloc(int             fd,
         struct timespec ts     = {0, ALLOC_TIMEOUT * MILLION};
         struct timespec abstime;
         int             out_fd = -1;
+        time_t          mpl    = IPCP_LOCAL_MPL;
 
         log_dbg("Allocating flow to " HASH_FMT " on fd %d.", HASH_VAL(dst), fd);
         assert(dst);
@@ -227,7 +228,8 @@ static int ipcp_local_flow_alloc(int             fd,
 
         assert(ipcpi.alloc_id == -1);
 
-        out_fd = ipcp_flow_req_arr(dst, ipcp_dir_hash_len(), qs, data, len);
+        out_fd = ipcp_flow_req_arr(dst, ipcp_dir_hash_len(), qs, mpl,
+                                   data, len);
         if (out_fd < 0) {
                 pthread_mutex_unlock(&ipcpi.alloc_lock);
                 log_dbg("Flow allocation failed: %d", out_fd);
@@ -261,6 +263,7 @@ static int ipcp_local_flow_alloc_resp(int          fd,
         struct timespec ts     = {0, ALLOC_TIMEOUT * MILLION};
         struct timespec abstime;
         int             out_fd = -1;
+        time_t          mpl    = IPCP_LOCAL_MPL;
 
         clock_gettime(PTHREAD_COND_CLOCK, &abstime);
 
@@ -303,7 +306,7 @@ static int ipcp_local_flow_alloc_resp(int          fd,
 
         fset_add(local_data.flows, fd);
 
-        if (ipcp_flow_alloc_reply(out_fd, response, data, len) < 0)
+        if (ipcp_flow_alloc_reply(out_fd, response, mpl, data, len) < 0)
                 return -1;
 
         log_info("Flow allocation completed, fds (%d, %d).", out_fd, fd);