Add MTU as socket property to be defined at creation.

examples/sender.py

@@ -5,7 +5,7 @@ host = sys.argv[1]
 port = int(sys.argv[2])
 localport = int(sys.argv[3])
 
-s = prrt.PrrtSocket(("127.0.1.1", localport))
+s = prrt.PrrtSocket(("127.0.1.1", localport), mtu=150)
 s.connect((host, port))
 
 for i in range(10):

prrt/cprrt.pxd

@@ -119,7 +119,7 @@ cdef extern from "proto/socket.h":
 
     ctypedef prrtSocket PrrtSocket
 
-    cdef PrrtSocket* PrrtSocket_create(const uint32_t target_delay)
+    cdef PrrtSocket* PrrtSocket_create(const uint32_t mtu, const uint32_t target_delay)
     bint PrrtSocket_bind(PrrtSocket *sock_ptr, const_char *ipAddress, const uint16_t port)
     int PrrtSocket_close(const PrrtSocket *sock_ptr)
     int PrrtSocket_connect(PrrtSocket *sock_ptr, const_char *host, const uint16_t port)

prrt/proto/socket.c

@@ -50,12 +50,12 @@ struct timespec abstime_from_now(prrtTimedelta_t wait_time) {
     return deadline;
 }
 
-PrrtSocket *PrrtSocket_create(prrtTimedelta_t target_delay_us) {
+PrrtSocket *PrrtSocket_create(prrtByteCount_t mtu, prrtTimedelta_t target_delay_us) {
     assert(sizeof(float) == 4);
     PrrtSocket *s = (PrrtSocket *) calloc(1, sizeof(PrrtSocket));
     check_mem(s);
 
-
+    s->mtu = mtu;
     s->isHardwareTimestamping = false;
     s->interfaceName = NULL;
 
@@ -219,6 +219,10 @@ int PrrtSocket_connect(PrrtSocket *s, const char *host, const uint16_t port) {
 }
 
 int PrrtSocket_send(PrrtSocket *s, const uint8_t *data, const size_t data_len) {
+    if (data_len > s->mtu) {
+        PERROR("Data to be sent (%d bytes) is too long, as MTU is %d.\n", data_len, s->mtu);
+        return -1;
+    }
     XlapTimestampPlaceholder tsph;
     XlapTimestampPlaceholderInitialize(&tsph);
     XlapTimeStampClock(&tsph, ts_any_packet, 0, PrrtSendStart);
@@ -425,8 +429,10 @@ int PrrtSocket_close(PrrtSocket *s) {
 uint32_t PrrtSocket_get_sock_opt(PrrtSocket *s, const char *name) {
     if (strcmp(name, "targetdelay") == 0) {
         return PrrtApplicationConstraints_get_target_delay(s->applicationConstraints);
+    } else if (strcmp(name, "mtu") == 0) {
+        return s->mtu;
     } else {
-        PERROR("Unknwon property %s", name);
+        PERROR("Unknown property %s\n", name);
         return 0;
     }
 }

prrt/proto/socket.h

@@ -78,10 +78,11 @@ typedef struct prrtSocket {
     char *interfaceName;
 
     atomic_bool isThreadPinning;
+    prrtByteCount_t mtu;
 } PrrtSocket;
 
 
-PrrtSocket *PrrtSocket_create(prrtTimedelta_t target_delay_us);
+PrrtSocket *PrrtSocket_create(prrtByteCount_t mtu, prrtTimedelta_t target_delay_us);
 
 bool PrrtSocket_enable_hardware_timestamping(PrrtSocket *s, const char * interface_name);
 

prrt/prrt.pyx

@@ -92,6 +92,9 @@ cdef extern from "util/mpsc_queue.c":
 cdef sockaddr_to_addr_and_port(sockaddr_in addr):
     return (cprrt.PrrtSocket_inet_ntoa(&addr.sin_addr).decode("utf8"), cprrt.PrrtSocket_ntohs(addr.sin_port))
 
+class PayloadTooBigException(Exception):
+    pass
+
 class PrrtCodingConfiguration:
     def __init__(self, n, k, n_cycle=None):
         if n < k:
@@ -118,10 +121,10 @@ class PrrtCodingConfiguration:
 cdef class PrrtSocket:
     cdef cprrt.PrrtSocket* _c_socket
 
-    def __cinit__(self, address, target_delay = 1, thread_pinning = False):
+    def __cinit__(self, address, mtu = 1500, target_delay = 1, thread_pinning = False):
         host, port = address
         target_delay_us = target_delay * 1000**2
-        self._c_socket = cprrt.PrrtSocket_create(target_delay_us)
+        self._c_socket = cprrt.PrrtSocket_create(mtu, target_delay_us)
         if thread_pinning:
             cprrt.PrrtSocket_enable_thread_pinning(self._c_socket)
         cprrt.PrrtSocket_bind(self._c_socket, host.encode("utf8"), port)
@@ -182,7 +185,12 @@ cdef class PrrtSocket:
         cprrt.PrrtSocket_connect(self._c_socket, encodedHost, port)
 
     def send(self, data):
-        cprrt.PrrtSocket_send(self._c_socket, data, len(data))
+        mtu = cprrt.PrrtSocket_get_sock_opt(self._c_socket, "mtu")
+        data_len = len(data)
+        if len(data) < mtu:
+            cprrt.PrrtSocket_send(self._c_socket, data, data_len)
+        else:
+            raise PayloadTooBigException("Sending packet of {} bytes on a socket with MTU of {} bytes failed.".format(data_len, mtu))
 
 
     # Receiving

prrt/receiver.c

@@ -97,7 +97,7 @@ int main(int argc, char **argv) {
     }
     #endif
 
-    s = PrrtSocket_create(HALF_TIMESTAMP-1);
+    s = PrrtSocket_create(1500, HALF_TIMESTAMP - 1);
     check(s != NULL, "Could not create socket.");
 
     if(strcmp(arguments.hardwarestamping_interface, "-") != 0) {

prrt/sender.c

@@ -101,7 +101,7 @@ int main(int argc, char **argv) {
     #endif
 
 
-    PrrtSocket *s = PrrtSocket_create(10 * 1000 * 1000);
+    PrrtSocket *s = PrrtSocket_create(1400, 10 * 1000 * 1000);
     check(s != NULL, "Socket create failed.");
 
     if(strcmp(arguments.hardwarestamping_interface, "-") != 0) {