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, 6 insertions, 2 deletions

diff --git a/src/ipcpd/unicast/CMakeLists.txt b/src/ipcpd/unicast/CMakeLists.txt
index f4887160..e1fe1074 100644
--- a/src/ipcpd/unicast/CMakeLists.txt
+++ b/src/ipcpd/unicast/CMakeLists.txt
@@ -13,6 +13,8 @@ include_directories(${CMAKE_SOURCE_DIR}/include)
 include_directories(${CMAKE_BINARY_DIR}/include)
 
 set(IPCP_UNICAST_TARGET ipcpd-unicast CACHE INTERNAL "")
+set(IPCP_UNICAST_MPL 60 CACHE STRING
+    "Default maximum packet lifetime for the unicast IPCP, in seconds")
 
 protobuf_generate_c(KAD_PROTO_SRCS KAD_PROTO_HDRS dir/kademlia.proto)
 
diff --git a/src/ipcpd/unicast/fa.c b/src/ipcpd/unicast/fa.c
index d59b9760..eb467a90 100644
--- a/src/ipcpd/unicast/fa.c
+++ b/src/ipcpd/unicast/fa.c
@@ -477,6 +477,7 @@ static int fa_wait_irmd_alloc(uint8_t *    dst,
         struct timespec ts  = {0, TIMEOUT * 1000};
         struct timespec abstime;
         int             fd;
+        time_t          mpl = IPCP_UNICAST_MPL;
 
         clock_gettime(PTHREAD_COND_CLOCK, &abstime);
 
@@ -497,7 +498,7 @@ static int fa_wait_irmd_alloc(uint8_t *    dst,
 
         assert(ipcpi.alloc_id == -1);
 
-        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_dbg("Failed to get fd for flow.");
@@ -598,6 +599,7 @@ static int fa_handle_flow_reply(struct fa_msg * msg,
         struct fa_flow * flow;
         uint8_t *        data;  /* Piggbacked data on flow alloc request. */
         size_t           dlen;  /* Length of piggybacked data.            */
+        time_t           mpl = IPCP_UNICAST_MPL;
 
         assert(len >= sizeof(*msg));
 
@@ -623,7 +625,7 @@ static int fa_handle_flow_reply(struct fa_msg * msg,
 
         pthread_rwlock_unlock(&fa.flows_lock);
 
-        if (ipcp_flow_alloc_reply(fd, msg->response, data, dlen))
+        if (ipcp_flow_alloc_reply(fd, msg->response, mpl, data, dlen))
                 return -EIRMD;
 
         return 0;