Packetdrill does multiple calls to the random number generator

[cpaasch]

I experience that packetdrill does multiple calls to the random number generator to generate keys or nonces (for the MP_JOIN).

It looks to me that it always calls new_subflow_inbound, even if we are retransmitting SYN+MP_JOIN's, like:

0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+0  setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+0  bind(3, {sa_family = AF_INET, sin_port = htons(13000), sin_addr = inet_addr("192.168.0.1")}, ...) = 0
+0  listen(3, 1) = 0

+0  socket(..., SOCK_STREAM, IPPROTO_TCP) = 5
+0  setsockopt(5, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+0  bind(5, {sa_family = AF_INET, sin_port = htons(13001), sin_addr = inet_addr("192.168.0.1")}, ...) = 0
+0  listen(5,1) = 0

+0  < S 0:0(0) win 32792 <mss 1460,sackOK,nop,nop,nop,wscale 7,mp_capable key_a> sock(3)
+0  > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 7,mp_capable key_b> sock(3)
+0  < . 1:1(0) ack 1 win 257 <mp_capable key_a key_b> sock(3)
+0  accept(3, ..., ...) = 4

//First subflow
+0  < S 0:0(0) win 32792 <mss 1460,sackOK,nop,nop,nop,wscale 7,mp_join_syn address_id=0 token=sha1_32(key_b)> sock(5)
+0  > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 7, mp_join_syn_ack backup=0 address_id=0 sender_hmac=trunc_l64_hmac(key_b key_a) > sock(5)
+0.1  < S 0:0(0) win 32792 <mss 1460,sackOK,nop,nop,nop,wscale 7,mp_join_syn address_id=0 token=sha1_32(key_b)> sock(5)
+0  > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 7, mp_join_syn_ack backup=0 address_id=0 sender_hmac=trunc_l64_hmac(key_b key_a) > sock(5)
+0  < . 1:1(0) ack 1 win 32792 <mp_join_ack sender_hmac=full_160_hmac(key_a key_b)> sock(5)
+0 mp_join_accept(5) = 6

+0 > . 1:1(0) ack 1 <...> sock(6) // reliably mp_join_ack

I think it is ok that packetdrill uses static values for the random nonce or keys. If somebody wants to use different values he can still set them manually in the packetdrill-script.