1 files changed, 51 insertions, 11 deletions

diff --git a/protocol.txt b/protocol.txt
index fd07ced..1ba36ce 100644
--- a/protocol.txt
+++ b/protocol.txt
@@ -8,31 +8,71 @@ field.
 Each message containing data has a sequence number. This sequence number is in
 the seqnum range [0, SEQ_SIZE = 256). Windowing ARQ is applied for efficiency,
 with a window size of WIN_SIZE = 16. Each party has an independent seqnum
-counter. Only messages in the current window range may be sent.
+counter and an independent window. Only messages in the current window range may
+be sent.
 
 The first message byte is the message type. The message types are described
 below. All structs are packed.
 
 
-struct prot_data {
+struct protm_estab {
   uint8_t type = 1;
+  uint8_t ack;
+}
+
+Requests that a new connection is to be established; this message should be sent
+by the client.
+If ack=0, then this is an establishment request: the receiving part is asked to
+respond with a protm_estab(ack=1) message to finish the connection
+establishment.
+If ack=1, then this is an establishment acknowledgement, which makes the
+connection ready to use for both parties.
+If an ack=0 message is received by a client, the message can be ignored.
+If an ack=0 message is received by a server that already has a connection with
+that client, the connection should be terminated and the request replied with a
+protm_term(ack=0).
+If an ack=1 message is received by a server, the message can be ignored.
+If an ack=1 message is received by a client while no unanswered ack=0 message
+had been sent to that server, the client should reply with a protm_term(ack=0)
+message.
+
+
+struct protm_term {
+  uint8_t type = 2;
+  uint8_t ack;
+}
+
+Communicates termination requests and acknowledgements.
+If ack=0, then this is a termination request: the receiving party is asked to
+respond with a protm_term(ack=1) message to acknowledge the termination.
+If ack=1, then this is a termination acknowledgement, which terminates the
+connection for both parties.
+If an ack=0 message is received while no connection is active, the program
+should respond with an ack=1 message (an earlier ack=1 message could have been
+lost).
+If an ack=1 message is received while no connection is active, the message can
+be ignored.
+
+
+struct protm_data {
+  uint8_t type = 3;
   uint8_t seqnum, rr;
   uint32_t size;
   uint8_t data[size];
 }
 
-Transmits application data, with piggy-back of a prot_rr message with nrej=0.
+Transmits application data, with piggy-back of a protm_rr message with nrej=0.
 
 - 'seqnum' is the sequence number of this message.
-- 'rr' is the expected next seqnum, as in the prot_rr message. This can shift
+- 'rr' is the expected next seqnum, as in the protm_rr message. This can shift
   the window.
 - 'size' is the number of bytes of data sent in this packet.
 - 'data' contains the next-protocol-level data sent in this message.
 
 
 
-struct prot_rr {
-  uint8_t type = 2;
+struct protm_rr {
+  uint8_t type = 4;
   uint8_t rr, nrej;
   uint8_t rej[nrej];
 }
@@ -49,10 +89,10 @@ recipient is asked to resend its messages with seqnums in 'rej'.
 
 
 
-struct prot_rr_poll {
-  uint8_t type = 3;
+struct protm_rr_poll {
+  uint8_t type = 5;
 }
 
-Asks for a prot_rr message, because the sender has new data to send but thinks
-the window is full. The receiver of a prot_rr_poll should send its current
-prot_rr message.
+Asks for a protm_rr message, because the sender has new data to send but thinks
+the window is full. The receiver of a protm_rr_poll should send its current
+protm_rr message.