Initial revision

src/libraries/libisc-new/demo/mux.c

+/*
+** libmux.c                A set of functions to implement a multiplexing
+**                         protocol above the ISC library
+**
+** Copyright (c) 1992 Peter Eriksson and Per Cederqvist of the
+**                    Lysator Academic Computer Association.
+**
+** history:
+** 920210 pen      initial coding
+*/
+
+#include <stdio.h>
+#include <isc.h>
+#include "mux.h"
+
+
+#define MAXSESSIONS 20
+
+
+typedef struct mux_session
+{
+  IscSession *scb;
+  int id;
+} MuxSession;
+
+
+typedef struct mux_control
+{
+  IscSession *scb[MAXSESSIONS];
+} MuxControl;
+
+
+
+
+static int
+mux_session_write_fn(IscHandlerList *hl,
+		     IscSession *scb,
+		     IscMessage *msg)
+{
+  /* Here, SCB is a pointer to a MUX simulated session */
+  MuxSession *msp = scb->udg;
+  
+  isc_printf(msp->scb, "MSG #%d %d:", msp->id, msg->length);
+  isc_write(msp->scb, msg->buffer, msg->length);
+  isc_flush(msp->scb);
+  
+  return msg->length;
+}
+
+
+static int
+mux_session_close_fn(IscHandlerList *hl,
+		     IscSession *scb)
+{
+  return 0;
+}
+
+
+static void
+mux_session_destroy_fn(IscHandlerList *hl,
+		       IscSession *scb)
+{
+  MuxSession *msp;
+  MuxControl *mcp;
+
+
+  msp = scb->udg;
+
+  /* Remove this MUX session from the MUX controller */
+  mcp = msp->scb->udg;
+  mcp->scb[msp->id] = NULL;
+  
+  free(msp);
+}
+
+
+
+static IscSessionFuns isc_session_funs =
+{
+  NULL,
+  &mux_session_write_fn,
+  &mux_session_close_fn,
+  NULL,
+  NULL,
+  &mux_session_destroy_fn,
+  NULL
+};
+
+
+
+
+/*
+** Allocate storage for a MUX control structure
+*/
+MuxControl *
+mux_newcontrol(void)
+{
+  MuxControl *mcp;
+  int i;
+  
+
+  mcp = malloc(sizeof(MuxControl));
+  if (!mcp)
+    return NULL;
+
+  for (i = 0; i < MAXSESSIONS; i++)
+    mcp->scb[i] = NULL;
+
+  return mcp;
+}
+
+
+
+
+/*
+** Create a new MUX session on a MUX control session
+*/
+IscSession *
+mux_newsession(IscSession *scb)
+{
+  MuxSession *msp;
+  MuxControl *mcp;
+  int i;
+
+
+  mcp = scb->udg;
+  
+  for (i = 0; i < MAXSESSIONS; i++)
+    if (mcp->scb[i] == NULL)
+    {
+      msp = malloc(sizeof(MuxSession));
+      if (!msp)
+	return NULL;
+
+      mcp->scb[i] = isc_create(scb->cfg, &mux_session_funs);
+      
+      msp->id  = i;
+      msp->scb = scb;
+      mcp->scb[i]->udg = msp;
+      
+      return scb;
+    }
+
+  return NULL;
+}
+
+
+
+
+int
+mux_control_close_fn(IscHandlerList *hl,
+		     IscSession *scb)
+{
+  MuxControl *mcp;
+  int i;
+
+  mcp = scb->udg;
+  for (i = 0; i < MAXSESSIONS; i++)
+    if (mcp->scb[i])
+    {
+      isc_close(mcp->scb[i]);
+      mcp->scb[i] = NULL;
+    }
+
+  if (!hl)
+    return 0;
+  else
+    return (*hl->hcb->close)(hl->old.close, scb);
+}
+
+
+
+void
+mux_control_destroy_fn(IscSession *scb)
+{
+  mux_control_close_fn(scb);
+
+  free(mcp);
+}
+
+
+IscEvent *
+mux_control_parse_fn(IscSession *scb,
+		     IscMesssage *msg)
+{
+  MuxControl *mcp;
+  IscEvent *ep;
+  IscMessage *nmsg;
+  int id;
+
+  
+/* Here we handle the MUX-to-MUX protocol */
+
+  mcp = scb->udg;
+  ep = isc_newevent();
+  
+  while (parse_msg(msg, &ep->event, &id, &nmsg))
+    switch (ep->event)
+    {
+      case ISC_EVENT_LOGIN:
+        ep->session = mux_newsession(scb);
+        return ep;
+      
+      case ISC_EVENT_LOGOUT:
+	isc_close(mcp->scb[id]);
+	mcp->scb[id] = NULL;
+	break;
+      
+      case ISC_EVENT_MESSAGE:
+	isc_pushqueue(mcp->scb[id]->rd_msg_q, nmsg);
+	break;
+
+      default:
+	/* Do something, perhaps */
+    }
+  
+  return NULL;
+}
+
+
+/*
+** Callback function to accept new sessions
+*/
+IscSession *
+mux_control_accept_fn(IscSession *scb,
+		      IscMessage *msg)
+{
+  IscSession *nscb;
+  
+  nscb = isc_tcp_accept_fn(scb, msg);
+  
+  nscb->fun->close   = &mux_control_close_fn;
+  nscb->fun->destroy = &mux_control_destroy_fn;
+  nscb->fun->parse   = &mux_control_parse_fn;
+
+  nscb->udg = mux_newcontrol();
+  
+  return nscb;
+}
+
+
+
+/*
+** Establish a TCP/IP port to listen at for new MUX connections
+*/
+IscSession *
+mux_listentcp(IscMaster *mcb,
+			  const char *address,
+			  const char *service)
+{
+  IscSession *scb;
+
+
+  scb = isc_listentcp(mcb, address, service);
+  if (!scb)
+    return NULL
+      
+  scb->fun->accept = &mux_control_accept_fn;
+
+  return scb;
+}