1 4b33cdd0 2015-11-30 stephen.d package p9p
3 4b33cdd0 2015-11-30 stephen.d import (
9 4b33cdd0 2015-11-30 stephen.d "golang.org/x/net/context"
12 4b33cdd0 2015-11-30 stephen.d // TODO(stevvooe): Add net/http.Server-like type here to manage connections.
13 4b33cdd0 2015-11-30 stephen.d // Coupled with Handler mux, we can get a very http-like experience for 9p
14 4b33cdd0 2015-11-30 stephen.d // servers.
16 4b33cdd0 2015-11-30 stephen.d // ServeConn the 9p handler over the provided network connection.
17 4b33cdd0 2015-11-30 stephen.d func ServeConn(ctx context.Context, cn net.Conn, handler Handler) error {
19 4b33cdd0 2015-11-30 stephen.d // TODO(stevvooe): It would be nice if the handler could declare the
20 4b33cdd0 2015-11-30 stephen.d // supported version. Before we had handler, we used the session to get
21 4b33cdd0 2015-11-30 stephen.d // the version (msize, version := session.Version()). We must decided if
22 4b33cdd0 2015-11-30 stephen.d // we want to proxy version and message size decisions all the back to the
23 4b33cdd0 2015-11-30 stephen.d // origin server or make those decisions at each link of a proxy chain.
25 4b33cdd0 2015-11-30 stephen.d ch := newChannel(cn, codec9p{}, DefaultMSize)
26 4b33cdd0 2015-11-30 stephen.d negctx, cancel := context.WithTimeout(ctx, 1*time.Second)
27 4b33cdd0 2015-11-30 stephen.d defer cancel()
29 4b33cdd0 2015-11-30 stephen.d // TODO(stevvooe): For now, we negotiate here. It probably makes sense to
30 4b33cdd0 2015-11-30 stephen.d // do this outside of this function and then pass in a ready made channel.
31 4b33cdd0 2015-11-30 stephen.d // We are not really ready to export the channel type yet.
33 4b33cdd0 2015-11-30 stephen.d if err := servernegotiate(negctx, ch, DefaultVersion); err != nil {
34 4b33cdd0 2015-11-30 stephen.d // TODO(stevvooe): Need better error handling and retry support here.
35 4b33cdd0 2015-11-30 stephen.d return fmt.Errorf("error negotiating version:", err)
38 4b33cdd0 2015-11-30 stephen.d ctx = withVersion(ctx, DefaultVersion)
40 4b33cdd0 2015-11-30 stephen.d c := &conn{
41 4b33cdd0 2015-11-30 stephen.d ctx: ctx,
42 4b33cdd0 2015-11-30 stephen.d ch: ch,
43 4b33cdd0 2015-11-30 stephen.d handler: handler,
44 4b33cdd0 2015-11-30 stephen.d closed: make(chan struct{}),
47 4b33cdd0 2015-11-30 stephen.d return c.serve()
50 4b33cdd0 2015-11-30 stephen.d // conn plays role of session dispatch for handler in a server.
51 4b33cdd0 2015-11-30 stephen.d type conn struct {
52 4b33cdd0 2015-11-30 stephen.d ctx context.Context
53 4b33cdd0 2015-11-30 stephen.d session Session
54 4b33cdd0 2015-11-30 stephen.d ch Channel
55 4b33cdd0 2015-11-30 stephen.d handler Handler
56 4b33cdd0 2015-11-30 stephen.d closed chan struct{}
57 4b33cdd0 2015-11-30 stephen.d err error // terminal error for the conn
60 4b33cdd0 2015-11-30 stephen.d // activeRequest includes information about the active request.
61 4b33cdd0 2015-11-30 stephen.d type activeRequest struct {
62 4b33cdd0 2015-11-30 stephen.d ctx context.Context
63 4b33cdd0 2015-11-30 stephen.d request *Fcall
64 4b33cdd0 2015-11-30 stephen.d cancel context.CancelFunc
67 4b33cdd0 2015-11-30 stephen.d // serve messages on the connection until an error is encountered.
68 4b33cdd0 2015-11-30 stephen.d func (c *conn) serve() error {
69 4b33cdd0 2015-11-30 stephen.d tags := map[Tag]*activeRequest{} // active requests
71 4b33cdd0 2015-11-30 stephen.d requests := make(chan *Fcall) // sync, read-limited
72 4b33cdd0 2015-11-30 stephen.d responses := make(chan *Fcall)
73 4b33cdd0 2015-11-30 stephen.d completed := make(chan *Fcall, 1)
75 4b33cdd0 2015-11-30 stephen.d // read loop
76 4b33cdd0 2015-11-30 stephen.d go c.read(requests)
77 4b33cdd0 2015-11-30 stephen.d go c.write(responses)
79 4b33cdd0 2015-11-30 stephen.d log.Println("server.run()")
81 4b33cdd0 2015-11-30 stephen.d select {
82 4b33cdd0 2015-11-30 stephen.d case req := <-requests:
83 4b33cdd0 2015-11-30 stephen.d if _, ok := tags[req.Tag]; ok {
84 4b33cdd0 2015-11-30 stephen.d select {
85 4b33cdd0 2015-11-30 stephen.d case responses <- newErrorFcall(req.Tag, ErrDuptag):
86 4b33cdd0 2015-11-30 stephen.d // Send to responses, bypass tag management.
87 4b33cdd0 2015-11-30 stephen.d case <-c.ctx.Done():
88 4b33cdd0 2015-11-30 stephen.d return c.ctx.Err()
89 4b33cdd0 2015-11-30 stephen.d case <-c.closed:
90 4b33cdd0 2015-11-30 stephen.d return c.err
92 4b33cdd0 2015-11-30 stephen.d continue
95 4b33cdd0 2015-11-30 stephen.d switch msg := req.Message.(type) {
96 4b33cdd0 2015-11-30 stephen.d case MessageTflush:
97 4b33cdd0 2015-11-30 stephen.d log.Println("server: flushing message", msg.Oldtag)
99 4b33cdd0 2015-11-30 stephen.d var resp *Fcall
100 4b33cdd0 2015-11-30 stephen.d // check if we have actually know about the requested flush
101 4b33cdd0 2015-11-30 stephen.d active, ok := tags[msg.Oldtag]
102 4b33cdd0 2015-11-30 stephen.d if ok {
103 4b33cdd0 2015-11-30 stephen.d active.cancel() // cancel the context of oldtag
104 4b33cdd0 2015-11-30 stephen.d resp = newFcall(req.Tag, MessageRflush{})
105 4b33cdd0 2015-11-30 stephen.d } else {
106 4b33cdd0 2015-11-30 stephen.d resp = newErrorFcall(req.Tag, ErrUnknownTag)
109 4b33cdd0 2015-11-30 stephen.d select {
110 4b33cdd0 2015-11-30 stephen.d case responses <- resp:
111 4b33cdd0 2015-11-30 stephen.d // bypass tag management in completed.
112 4b33cdd0 2015-11-30 stephen.d case <-c.ctx.Done():
113 4b33cdd0 2015-11-30 stephen.d return c.ctx.Err()
114 4b33cdd0 2015-11-30 stephen.d case <-c.closed:
115 4b33cdd0 2015-11-30 stephen.d return c.err
117 4b33cdd0 2015-11-30 stephen.d default:
118 4b33cdd0 2015-11-30 stephen.d // Allows us to session handlers to cancel processing of the fcall
119 4b33cdd0 2015-11-30 stephen.d // through context.
120 4b33cdd0 2015-11-30 stephen.d ctx, cancel := context.WithCancel(c.ctx)
122 4b33cdd0 2015-11-30 stephen.d // The contents of these instances are only writable in the main
123 4b33cdd0 2015-11-30 stephen.d // server loop. The value of tag will not change.
124 4b33cdd0 2015-11-30 stephen.d tags[req.Tag] = &activeRequest{
125 4b33cdd0 2015-11-30 stephen.d ctx: ctx,
126 4b33cdd0 2015-11-30 stephen.d request: req,
127 4b33cdd0 2015-11-30 stephen.d cancel: cancel,
130 4b33cdd0 2015-11-30 stephen.d go func(ctx context.Context, req *Fcall) {
131 4b33cdd0 2015-11-30 stephen.d var resp *Fcall
132 4b33cdd0 2015-11-30 stephen.d msg, err := c.handler.Handle(ctx, req.Message)
133 4b33cdd0 2015-11-30 stephen.d if err != nil {
134 4b33cdd0 2015-11-30 stephen.d // all handler errors are forwarded as protocol errors.
135 4b33cdd0 2015-11-30 stephen.d resp = newErrorFcall(req.Tag, err)
136 4b33cdd0 2015-11-30 stephen.d } else {
137 4b33cdd0 2015-11-30 stephen.d resp = newFcall(req.Tag, msg)
140 4b33cdd0 2015-11-30 stephen.d select {
141 4b33cdd0 2015-11-30 stephen.d case completed <- resp:
142 4b33cdd0 2015-11-30 stephen.d case <-ctx.Done():
143 4b33cdd0 2015-11-30 stephen.d return
144 4b33cdd0 2015-11-30 stephen.d case <-c.closed:
145 4b33cdd0 2015-11-30 stephen.d return
147 4b33cdd0 2015-11-30 stephen.d }(ctx, req)
149 4b33cdd0 2015-11-30 stephen.d case resp := <-completed:
150 4b33cdd0 2015-11-30 stephen.d // only responses that flip the tag state traverse this section.
151 4b33cdd0 2015-11-30 stephen.d active, ok := tags[resp.Tag]
152 4b33cdd0 2015-11-30 stephen.d if !ok {
153 4b33cdd0 2015-11-30 stephen.d panic("BUG: unbalanced tag")
156 4b33cdd0 2015-11-30 stephen.d select {
157 4b33cdd0 2015-11-30 stephen.d case responses <- resp:
158 4b33cdd0 2015-11-30 stephen.d case <-active.ctx.Done():
159 4b33cdd0 2015-11-30 stephen.d // the context was canceled for some reason, perhaps timeout or
160 4b33cdd0 2015-11-30 stephen.d // due to a flush call. We treat this as a condition where a
161 4b33cdd0 2015-11-30 stephen.d // response should not be sent.
162 4b33cdd0 2015-11-30 stephen.d log.Println("canceled", resp, active.ctx.Err())
164 4b33cdd0 2015-11-30 stephen.d delete(tags, resp.Tag)
165 4b33cdd0 2015-11-30 stephen.d case <-c.ctx.Done():
166 4b33cdd0 2015-11-30 stephen.d return c.ctx.Err()
167 4b33cdd0 2015-11-30 stephen.d case <-c.closed:
168 4b33cdd0 2015-11-30 stephen.d return c.err
173 4b33cdd0 2015-11-30 stephen.d // read takes requests off the channel and sends them on requests.
174 4b33cdd0 2015-11-30 stephen.d func (c *conn) read(requests chan *Fcall) {
176 4b33cdd0 2015-11-30 stephen.d req := new(Fcall)
177 4b33cdd0 2015-11-30 stephen.d if err := c.ch.ReadFcall(c.ctx, req); err != nil {
178 4b33cdd0 2015-11-30 stephen.d if err, ok := err.(net.Error); ok {
179 4b33cdd0 2015-11-30 stephen.d if err.Timeout() || err.Temporary() {
180 4b33cdd0 2015-11-30 stephen.d // TODO(stevvooe): A full idle timeout on the connection
181 4b33cdd0 2015-11-30 stephen.d // should be enforced here. No logging because it is quite
182 4b33cdd0 2015-11-30 stephen.d // chatty.
183 4b33cdd0 2015-11-30 stephen.d continue
187 4b33cdd0 2015-11-30 stephen.d c.CloseWithError(fmt.Errorf("error reading fcall: %v", err))
188 4b33cdd0 2015-11-30 stephen.d return
191 4b33cdd0 2015-11-30 stephen.d select {
192 4b33cdd0 2015-11-30 stephen.d case requests <- req:
193 4b33cdd0 2015-11-30 stephen.d case <-c.ctx.Done():
194 4b33cdd0 2015-11-30 stephen.d c.CloseWithError(c.ctx.Err())
195 4b33cdd0 2015-11-30 stephen.d return
196 4b33cdd0 2015-11-30 stephen.d case <-c.closed:
197 4b33cdd0 2015-11-30 stephen.d return
202 4b33cdd0 2015-11-30 stephen.d func (c *conn) write(responses chan *Fcall) {
204 4b33cdd0 2015-11-30 stephen.d select {
205 4b33cdd0 2015-11-30 stephen.d case resp := <-responses:
206 4b33cdd0 2015-11-30 stephen.d if err := c.ch.WriteFcall(c.ctx, resp); err != nil {
207 4b33cdd0 2015-11-30 stephen.d if err, ok := err.(net.Error); ok {
208 4b33cdd0 2015-11-30 stephen.d if err.Timeout() || err.Temporary() {
209 4b33cdd0 2015-11-30 stephen.d // TODO(stevvooe): A full idle timeout on the
210 4b33cdd0 2015-11-30 stephen.d // connection should be enforced here. We log here,
211 4b33cdd0 2015-11-30 stephen.d // since this is less common.
212 4b33cdd0 2015-11-30 stephen.d log.Println("9p server: temporary error writing fcall: %v", err)
213 4b33cdd0 2015-11-30 stephen.d continue
217 4b33cdd0 2015-11-30 stephen.d c.CloseWithError(fmt.Errorf("error writing fcall: %v", err))
218 4b33cdd0 2015-11-30 stephen.d return
220 4b33cdd0 2015-11-30 stephen.d case <-c.ctx.Done():
221 4b33cdd0 2015-11-30 stephen.d c.CloseWithError(c.ctx.Err())
222 4b33cdd0 2015-11-30 stephen.d return
223 4b33cdd0 2015-11-30 stephen.d case <-c.closed:
224 4b33cdd0 2015-11-30 stephen.d return
229 4b33cdd0 2015-11-30 stephen.d func (c *conn) Close() error {
230 4b33cdd0 2015-11-30 stephen.d return c.CloseWithError(nil)
233 4b33cdd0 2015-11-30 stephen.d func (c *conn) CloseWithError(err error) error {
234 4b33cdd0 2015-11-30 stephen.d select {
235 4b33cdd0 2015-11-30 stephen.d case <-c.closed:
236 4b33cdd0 2015-11-30 stephen.d return c.err
237 4b33cdd0 2015-11-30 stephen.d default:
238 4b33cdd0 2015-11-30 stephen.d close(c.closed)
239 4b33cdd0 2015-11-30 stephen.d if err == nil {
240 4b33cdd0 2015-11-30 stephen.d c.err = err
241 4b33cdd0 2015-11-30 stephen.d } else {
242 4b33cdd0 2015-11-30 stephen.d c.err = ErrClosed
245 4b33cdd0 2015-11-30 stephen.d return c.err
