From c7da9212cd18c06313fbf087205a93c06d8cacee Mon Sep 17 00:00:00 2001
From: Sean DuBois <sean@siobud.com>
Date: Tue, 10 Jul 2018 00:45:11 -0700
Subject: [PATCH] Add comments to SCTP + start InitAck

---
 internal/network/port-receive.go |  3 +--
 internal/sctp/association.go     |  9 ++++++++
 internal/sctp/chunk_init.go      | 17 +--------------
 internal/sctp/chunk_init_ack.go  | 36 +++++++++++++++++++++++---------
 4 files changed, 37 insertions(+), 28 deletions(-)

diff --git a/internal/network/port-receive.go b/internal/network/port-receive.go
index 08c1d0b6..242eb7ae 100644
--- a/internal/network/port-receive.go
+++ b/internal/network/port-receive.go
@@ -213,9 +213,8 @@ func (p *Port) networkLoop(remoteKey []byte, tlscfg *dtls.TLSCfg, b BufferTransp
 				p.sctpAssocations[in.srcAddr.String()] = sctp.NewAssocation(func(pkt *sctp.Packet) {
 					fmt.Printf("Handle packet %v \n", pkt)
 				}, func(data []byte) {
-
+					fmt.Printf("Handle data %v \n", data)
 				})
-
 			}
 		}
 	}
diff --git a/internal/sctp/association.go b/internal/sctp/association.go
index e459277f..d5330cf5 100644
--- a/internal/sctp/association.go
+++ b/internal/sctp/association.go
@@ -25,6 +25,8 @@ const (
 
 func (a AssociationState) String() string {
 	switch a {
+	case Open:
+		return "Open"
 	case CookieEchoed:
 		return "CookieEchoed"
 	case CookieWait:
@@ -70,6 +72,8 @@ type Association struct {
 	myMaxNumInboundStreams  uint16
 	myMaxNumOutboundStreams uint16
 
+	// TODO are these better as channels
+	// Put a blocking goroutine in port-recieve (vs callbacks)
 	outboundHandler func(*Packet)
 	dataHandler     func([]byte)
 }
@@ -143,6 +147,11 @@ func (a *Association) handleChunk(c Chunk) error {
 			a.myMaxNumInboundStreams = min(ct.numInboundStreams, a.myMaxNumInboundStreams)
 			a.myMaxNumOutboundStreams = min(ct.numOutboundStreams, a.myMaxNumOutboundStreams)
 			a.State = CookieEchoed
+
+			// TODO send packet attributes + append InitAck
+			// We should also cache the InitAck to handle CookieEchoed when we get Init
+			outbound := &Packet{}
+			a.outboundHandler(outbound)
 		case CookieEchoed:
 			// https://tools.ietf.org/html/rfc4960#section-5.2.1
 			// Upon receipt of an INIT in the COOKIE-ECHOED state, an endpoint MUST
diff --git a/internal/sctp/chunk_init.go b/internal/sctp/chunk_init.go
index b68235da..db50450c 100644
--- a/internal/sctp/chunk_init.go
+++ b/internal/sctp/chunk_init.go
@@ -128,22 +128,6 @@ func (i *Init) Unmarshal(raw []byte) error {
 			break
 		}
 	}
-
-	// TODO Sean-Der
-	// offset := initChunkMinLength
-	// for {
-	// 	remaining := len(i.Value) - offset
-	// 	if remaining == 0 {
-	// 		break
-	// 	} else if remaining < initOptionalVarHeaderLength {
-	// 		return errors.Errorf("%d bytes remain in init chunk value, not enough to build optional var header", remaining)
-	// 	}
-
-	// 	attributeType := binary.BigEndian.Uint16(i.Value[offset:])
-	// 	attributeLength := int(binary.BigEndian.Uint16(i.Value[offset+2:]))
-
-	// 	offset += attributeLength
-	// }
 	return nil
 }
 
@@ -152,6 +136,7 @@ func (i *Init) Marshal() ([]byte, error) {
 	return nil, errors.Errorf("Unimplemented")
 }
 
+// Check asserts the validity of this structs values
 func (i *Init) Check() error {
 	// Defines the maximum number of streams the sender of this INIT
 	// chunk allows the peer end to create in this association.  The
diff --git a/internal/sctp/chunk_init_ack.go b/internal/sctp/chunk_init_ack.go
index e9ee74d7..1104b064 100644
--- a/internal/sctp/chunk_init_ack.go
+++ b/internal/sctp/chunk_init_ack.go
@@ -1,6 +1,10 @@
 package sctp
 
-import "github.com/pkg/errors"
+import (
+	"encoding/binary"
+
+	"github.com/pkg/errors"
+)
 
 /*
 InitAck represents an SCTP Chunk of type INIT ACK
@@ -47,17 +51,16 @@ Host Name Address (Note 3)          Optional    11<Paste>
 */
 type InitAck struct {
 	ChunkHeader
-	// initiateTag                    uint32
-	// advertisedReceiverWindowCredit uint32
-	// numOutboundStreams             uint16
-	// numInboundStreams              uint16
-	// initialTSN                     uint32
-	// optionalParams                 []byte
+	initiateTag                    uint32
+	advertisedReceiverWindowCredit uint32
+	numOutboundStreams             uint16
+	numInboundStreams              uint16
+	initialTSN                     uint32
+	params                         []Param
 }
 
 const (
-// initAckChunkMinLength          = 16
-// initAckOptionalVarHeaderLength = 4
+	initAckChunkMinLength = 16
 )
 
 // Unmarshal populates a InitAck Chunk from a byte slice
@@ -67,5 +70,18 @@ func (i *InitAck) Unmarshal(raw []byte) error {
 
 // Marshal serializes a InitAck to bytes
 func (i *InitAck) Marshal() ([]byte, error) {
-	return nil, errors.Errorf("Unimplemented")
+	out := make([]byte, initAckChunkMinLength)
+	binary.BigEndian.PutUint32(out[0:], i.initiateTag)
+	binary.BigEndian.PutUint32(out[4:], i.advertisedReceiverWindowCredit)
+	binary.BigEndian.PutUint16(out[8:], i.numOutboundStreams)
+	binary.BigEndian.PutUint16(out[10:], i.numInboundStreams)
+	binary.BigEndian.PutUint32(out[12:], i.initialTSN)
+
+	// TODO fill in params
+	return out, nil
+}
+
+// Check asserts the validity of this structs values
+func (i *InitAck) Check() error {
+	return nil
 }