Error handling taken care

Author: avinashjoshi

Makefile

@@ -1,4 +1,4 @@
-# Use this Makefile to compile the code
+# Use this Makefile to compile tutor program
 # Collaborators: Avinash Joshi <[email protected]>
 #                Sandeep Shenoy <[email protected]>
 

README

@@ -9,11 +9,11 @@ Collaborators: Avinash Joshi <[email protected]>, Sandeep Shenoy <sxs115220
 -----------------------
 
 0) Compiling the code
-	make all
+	`make all`
 1) Removing object files
-	make clean
+	`make clean`
 2) Removing all compiled files
-	make cleanall
+	`make cleanall`
 
 Note: You may want to have a look at the file Makefile
 
@@ -73,7 +73,7 @@ Joining the tree (join):
 
 	If No, then ROOT sends a list of its child nodes. The requesting node now sends a UDP Join Request to each of this nodes. This will continue until the requesting node joins the tree.
 
-	Once the requesting node is accept as a child by one of the node, a UDP Socket and TCP Socket will be created on this child's port. A persistance TCP Connection will also be established with the node that accepted the request which becomes the parent node.
+	Once the requesting node is accepted as a child by one of the node, a UDP Socket and TCP Socket will be created on this child's port. A persistance TCP Connection will also be established with the node that accepted the request which becomes the parent node.
 
 
 Computing the path till the ROOT (computepath):
@@ -82,12 +82,12 @@ Computing the path till the ROOT (computepath):
 	Any node in the tree, to compute its path to ROOT, will send a TCP request to its parent node asking for the path from itself to ROOT. This request would flow from requesting node to ROOT node and then back to requesting node. Finally, we will be having the path from the requesting node to ROOT node.
 
 
- File in the application
-------------------------------
+Source File in the application
+-------------------------------
 
 0) tutor.c
 1) udp.c
 2) tcp.c
 3) join.c
 4) services.c
-
+5) myHeader.h

join.c

@@ -10,6 +10,19 @@
  */
 
 #include "myheader.h"
+#include <signal.h>
+#include <setjmp.h>
+
+#define RECV_TIMEOUT 5	/* timeout in seconds */
+
+static sigjmp_buf recv_timed_out;
+
+/* timeout handler */
+void
+timeout_handler (int signum) {
+	signal(SIGALRM, SIG_DFL);
+	siglongjmp(recv_timed_out, 1);
+}
 
 struct list_details {
 	char node_name[50];
@@ -23,7 +36,7 @@ struct list_details {
  * with the node that accepted the request
  *
  */
-void
+int
 join_tree(int uport,int tport,int r_uport,int r_tport,char* host) {
 
 	char *udp_buffer;
@@ -35,14 +48,14 @@ join_tree(int uport,int tport,int r_uport,int r_tport,char* host) {
 	char **list, *t_list[5], *temp_str;
 
 	if ((temp_udp_sockfd = socket (AF_INET,SOCK_DGRAM,0)) < 0) {
-		fprintf (stderr,"udp: Socket couldn't be opened\n");
-		exit (EXIT_FAILURE);
+		perror ("socket() failed");
+		return -1;
 	}
 
 	/* create hostent structure from  user entered host name*/
 	if ((he = gethostbyname(host)) == NULL) {
-		printf("\n%s: error in gethostbyname()", "tutor");
-		exit(0);
+		fprintf(stdout, "Unable to resolve host %s", host);
+		return -1;
 	}
 
 	while (1) {
@@ -70,11 +83,27 @@ join_tree(int uport,int tport,int r_uport,int r_tport,char* host) {
 		strcat (sendbuff, port_ch);
 
 		if ((bytes_sent = sendto (temp_udp_sockfd, sendbuff, strlen(sendbuff), 0, (struct sockaddr *) &server_addr, server_addr_size)) < 0) {
-			exit (EXIT_FAILURE);
+			perror ("sendto() error");
+			return -1;
 		}
 
-		if ((bytes_received = recvfrom (temp_udp_sockfd, udp_buffer, STRLEN, 0, (struct sockaddr *) &server_addr, (socklen_t *) &server_addr_size)) < 0) {
-			exit (EXIT_FAILURE);
+		if (sigsetjmp(recv_timed_out, 1)) {
+			printf("recvfrom() timed out\n\n");
+			return -1;
+		}
+
+		/* set timer and handler */
+		signal(SIGALRM, timeout_handler);
+		alarm(RECV_TIMEOUT);
+
+		bytes_received = recvfrom (temp_udp_sockfd, udp_buffer, STRLEN, 0, (struct sockaddr *) &server_addr, (socklen_t *) &server_addr_size);
+
+		alarm(0);
+		signal(SIGALRM, SIG_DFL);
+
+		if (bytes_received < 0) {
+			perror ("recvfrom() error");
+			return -1;
 		}
 
 		if (udp_buffer[0] == 'a') {
@@ -128,4 +157,5 @@ join_tree(int uport,int tport,int r_uport,int r_tport,char* host) {
 		udp_buffer = NULL;
 	}
 	close(temp_udp_sockfd);
+	return 1;
 }

myheader.h

@@ -48,7 +48,7 @@ create_tcp(size_t,int);
 void
 make_persistance(char*,int);
 
-void 
+int 
 join_tree (int,int,int,int,char*);
 
 void

tcp.c

@@ -157,8 +157,8 @@ handle_persistance (void *p) {
 	int cstatus = connect(clientSockid,(struct sockaddr *)&servaddr,sizeof(servaddr));
 
 	if (cstatus < 0) {
-		perror ("connect() error");
-		return NULL;
+		perror ("connect() to parent error");
+		exit (EXIT_FAILURE);
 	}
 
 	DBG (("Persistant connection with %s:%d", t_det.thost, t_det.tport));
@@ -181,6 +181,7 @@ handle_tcp (void* tport) {
 	sock = socket(AF_INET,SOCK_STREAM,0);
 	if (sock < 0) {
 		perror ("socket() error");
+		exit (EXIT_FAILURE);
 	}
 
 	/* So that we can re-bind to it without TIME_WAIT problems */
@@ -201,14 +202,14 @@ handle_tcp (void* tport) {
 	int bstatus = bind(sock, (struct sockaddr *)&servaddr,sizeof(servaddr));
 	if (bstatus < 0) {
 		perror ("bind() error");
-		return NULL;
+		exit (EXIT_FAILURE);
 	}
 
 	//Convert the socket to listening socket
 	int lstatus = listen(sock,5);
 	if (lstatus < 0) {
 		perror ("listen() error");
-		return NULL;
+		exit (EXIT_FAILURE);
 	}
 	else {
 		DBG (("Listening..."));

tutor.c

@@ -122,7 +122,7 @@ main (int argc, char **argv) {
 	char *tport_arg, *uport_arg;
 	char *in_line = (char *) malloc (sizeof (char) * 100);
 	char *command, *com_arg, *host;
-	int join_uport;
+	int join_uport, join_status;
 	// Flags for the commands
 	int makeserver_f = 0, join_f = 0, computepath_f = 0;
 
@@ -254,8 +254,11 @@ main (int argc, char **argv) {
 			if ((join_uport = check_value (com_arg, "port")) == -1)
 				continue;
 
+			join_status = join_tree (uport, tport, join_uport, 1234, host);
+			sleep (2);
+			if (join_status == -1)
+				continue;
 			join_f = 1;
-			join_tree (uport, tport, join_uport, 1234, host);
 			fprintf (stdout, "You are now a tutor with ID:%d. Reach your instructor @ %s:%s", node_number, parent.ip, parent.tport);
 			continue;
 		}

udp.c

@@ -8,6 +8,7 @@
  *
  * Contributors: Avinash Joshi <[email protected]>, Sandeep Shenoy <[email protected]>
  */
+
 #include "myheader.h"
 
 int child_count=0;
@@ -62,8 +63,8 @@ handle_udp (void* uport) {
 
 	//Creates a UDP socket
 	if ((udp_sockfd = socket (AF_INET,SOCK_DGRAM,0)) < 0) {
-		fprintf (stderr,"udp: Socket couldn't be opened\n");
-		exit (EXIT_FAILURE);
+		perror ("socket() failed");
+		return NULL;
 	}
 
 	//Creates a local server structure
@@ -77,15 +78,15 @@ handle_udp (void* uport) {
 	gethostname (server_host, 49);
 	if ((he = gethostbyname(server_host)) == NULL) {
 		herror(server_host);
-		puts("error resolving hostname..");
-		return NULL;
+		fprintf (stdout, "Unable to resolve host %s", server_host);
+		exit (EXIT_FAILURE);
 	}
 	struct in_addr **tmp = (struct in_addr **) he->h_addr_list;
 	DBG (("Hostname:IP = %s:%s", server_host, inet_ntoa(*tmp[0])));
 
 	/*Binds the socket*/
 	if (bind (udp_sockfd, (struct sockaddr *) &server_addr, sizeof(server_addr)) < 0) {
-		fprintf (stderr,"udp: Socket couldn't be bind\n");
+		perror ("bind() failed");
 		exit (EXIT_FAILURE);
 	}
 	int next_node = (node_number * k_child) + 1;
@@ -99,7 +100,8 @@ handle_udp (void* uport) {
 		bzero (&udp_buffer,sizeof(udp_buffer));
 		char temp[STRLEN];
 		if ((bytes_received = recvfrom(udp_sockfd, udp_buffer, STRLEN, 0, (struct sockaddr *) &client_addr, (socklen_t *) &client_addr_size)) < 0) {
-			exit(EXIT_FAILURE);
+			perror ("recvfrom() failed");
+			exit (EXIT_FAILURE);
 		}
 
 		char temp_buff[50], *temp_port, *temp_command;
@@ -132,7 +134,8 @@ handle_udp (void* uport) {
 				next_node++;
 				DBG (("Sending %s", temp));
 				if ((bytes_sent = sendto(udp_sockfd,temp,strlen(temp),0,(struct sockaddr *)&client_addr,client_addr_size)) < 0) {
-					exit(EXIT_FAILURE);
+					perror ("sendto() failed");
+					exit (EXIT_FAILURE);
 				}
 				child_count++;
 			}
@@ -155,12 +158,12 @@ handle_udp (void* uport) {
 				}
 				DBG (("Sending %s",temp));
 				if ((bytes_sent = sendto(udp_sockfd,temp,strlen(temp),0,(struct sockaddr *)&client_addr,client_addr_size)) < 0) {
-					exit(EXIT_FAILURE);
+					perror ("sendto() failed");
+					exit (EXIT_FAILURE);
 				}
 			}
 		}
 
 	}
-
 	return NULL;
 }