Added some features to telnet server

3 files changed, 135 insertions, 7 deletions

diff --git a/server.c b/server.c
index 629d976..290739e 100644
--- a/server.c
+++ b/server.c
@@ -19,6 +19,7 @@
  */
 
 #include "joshua.h"
+#include "util.h"
 #include <errno.h>
 #include <netdb.h>
 #include <netinet/in.h>
@@ -29,10 +30,11 @@
 #include <sys/socket.h>
 #include <sys/types.h>
 #include <unistd.h>
-
+#define DEFAULT_PORT 23
 int server_socket;
 uint16_t port;
 int pipes[FD_SETSIZE][2];
+struct connection_data_t connection_data[FD_SETSIZE];
 int make_server_socket(uint16_t port)
 {
   int sock;
@@ -40,7 +42,7 @@ int make_server_socket(uint16_t port)
   sock=socket(AF_INET, SOCK_STREAM, 0);
   if(sock<0)
     {
-      printf("error creating socket.\n");
+      printf("error opening socket.\n");
       return -1;
     }
   name.sin_family=AF_INET;
@@ -56,7 +58,7 @@ int make_server_socket(uint16_t port)
 }
 int process_data(int fd)
 {
-  char buf[1024];
+  unsigned char buf[1024];
   memset(buf, 0, sizeof(buf));
   int ret=read(fd, buf, sizeof(buf));
   char ctrl_c[]={0xff, 0xf4, 0xff, 0xfd, 0x06, 0x00};
@@ -78,7 +80,91 @@ int process_data(int fd)
   else
     {
       printf("Client sends: %s\n", buf);
-      write(pipes[fd][1], buf, strlen(buf));
+      if(strlen(buf)>0)
+        {
+          if(buf[0]==0xff)
+            {
+              printf("String is command.\n");
+              printf("Hex dump: ");
+              for(int i=0;buf[i];++i)
+                {
+                  printf("%d ", buf[i]);
+                }
+              if(strlen(buf)<2)
+                {
+                  printf("Bad command (length<3).\n");
+                  return 0; /* not a fatal error */
+                }
+              unsigned char cmd=buf[1];
+#define WILL 251
+#define WONT 252
+#define DO 253
+#define DONT 254
+#define SB 250
+#define SE 240
+#define AYT 246
+#define NAWS 31
+              unsigned char opt=(strlen(buf)==2)?0:buf[2];
+              unsigned char nop[2]={0xff, 241};
+              switch(cmd)
+                {
+                case AYT:
+                  /* respond with IAC NOP */
+                  write(fd, nop, 2);
+                  break;
+                case WILL:
+                case DO:
+                  if(cmd==NAWS)
+                    {
+                      printf("Client offers NAWS\n");
+                    }
+                  else if(cmd==1)
+                    {
+                      printf("Client offers echo.\n");
+                    }
+                  break;
+                case WONT:
+                case DONT:
+                  if(cmd==NAWS)
+                    {
+                      printf("Client denies NAWS.\n");
+                    }
+                  else if(cmd==1)
+                    {
+                      printf("Client denies echo.\n");
+                    }
+                  break;
+                default:
+                  printf("Unknown command.\n");
+                  break;
+                }
+              if(cmd==SB)
+                {
+                  if(opt==NAWS)
+                    {
+                      if(strlen(buf)>=9)
+                        {
+                          uint16_t width, height;
+                          uint8_t width_hi, width_lo, height_hi, height_lo;
+                          width_hi=buf[3];
+                          width_lo=buf[4];
+                          height_hi=buf[5];
+                          height_lo=buf[6];
+                          width=(width_hi<<8)|width_lo;
+                          height=(height_hi<<8)|height_lo;
+                          connection_data[fd].know_termsize=(width==0 || height==0)?0:1; /* if any dimension is zero, unknown */
+                          connection_data[fd].term_height=height;
+                          connection_data[fd].term_width=width;
+                          printf("Client window is %dx%d\n", width, height);
+                        }
+                    }
+                }
+            }
+          else
+            {
+              write(pipes[fd][1], buf, strlen(buf));
+            }
+        }
       return 0;
     }
 }
@@ -88,14 +174,29 @@ void serv_cleanup()
   fflush(stdout);
   shutdown(server_socket, SHUT_RDWR);
 }
+void setup_new_connection(int fd)
+{
+  unsigned char will_naws[]={0xff, 251, 31};
+  write(fd, will_naws, sizeof(will_naws));
+  memset(&connection_data[fd], 0, sizeof(struct connection_data_t));
+}
 int main(int argc, char* argv[])
 {
   if(argc!=2)
     {
-      printf("Usage: %s PORT\n", argv[0]);
-      return 2;
+      printf("Listening on default port: %d\n", DEFAULT_PORT);
+      port=DEFAULT_PORT;
+    }
+  else
+    {
+      int port2=atoi(argv[1]);
+      if(port2<0 || port2>65535)
+        {
+          printf("Port out of range.\n");
+          return 2;
+        }
+      port=atoi(argv[1]);
     }
-  port=atoi(argv[1]);
   printf("Initializing server on port %u...\n", port);
   signal(SIGINT, &serv_cleanup);
   int sock=make_server_socket(port);
@@ -144,6 +245,8 @@ int main(int argc, char* argv[])
                   pid_t pid=fork();
                   if(pid==0) /* child */
                     {
+                      /* set up the connection */
+                      setup_new_connection(new);
                       be_joshua(new);
                       printf("Client exits\n");
                       shutdown(new, SHUT_RDWR);
diff --git a/util.c b/util.c
index 9539b46..c27981a 100644
--- a/util.c
+++ b/util.c
@@ -69,6 +69,7 @@ void refresh(void)
 }
 int getnstr(char* buf, int max)
 {
+  echo_on();
   memset(buf, 0, max);
   int ret=read(pipes[out_fd][0], buf, max);
   if(ret!=0)
@@ -81,4 +82,17 @@ int getnstr(char* buf, int max)
   if(ret<0)
     return ERR;
   return OK;
+  echo_off();
+}
+void echo_off(void)
+{
+  unsigned char echo_off[]={0xff, 254, 1};
+  write(out_fd, echo_off, 3);
+  fsync(out_fd);
+}
+void echo_on(void)
+{
+  unsigned char echo_on[]={0xff, 253, 1};
+  write(out_fd, echo_on, 3);
+  fsync(out_fd);
 }
diff --git a/util.h b/util.h
index 5f7e170..6b824fd 100644
--- a/util.h
+++ b/util.h
@@ -19,12 +19,23 @@
  */
 
 #define SLEEP_TIME 5000
+#include <stdint.h>
+#include <stdlib.h>
+struct connection_data_t {
+  int naws_enable:1;
+  int know_termsize:1;
+  uint16_t term_height;
+  uint16_t term_width;
+};
+extern struct connection_data_t connection_data[FD_SETSIZE];
 void allLower(char*);
 void print_string(const char*);
 void remove_punct(char*);
 void refresh(void);
 void clear(void);
 int getnstr(char*, int);
+void echo_off(void);
+void echo_on(void);
 #define ERR 1
 #define OK 0
 extern int out_fd;