pythonclient

README.md

@@ -3,10 +3,32 @@
 
 ## Team Members
 - team member 1
+Charlie Welland
 - team member 2
+Charlotte Kroll
 
 ## Lab Question Answers
 
-Answer for Question 1: 
+Question 1: How did the reliability of UDP change when you added 50% loss to 
+your local environment? Why did this occur?
 
-...
+The realiability of the UDP changed when I added the %50 loss to the
+local environment. It seemed like half of the packages failed to come through.
+
+Question 2: How did the reliability of TCP change? Why did this occur?
+
+While we told the reliability of TCP to change by %50 for the worse, the packages
+still seemed to come through. This is do to the TCP system checking to see if
+packages were delivered. If they are not, it will send them again. This is
+different than UDP because if a package is not delivered in UDP, it's tough 
+luck. Due to this TCP protocol, the packages will still get delivered even 
+after calling 
+sudo tc qdisc add dev lo parent root netem loss 50%
+
+Question 3: How did the speed of the TCP response change? Why might this happen?
+
+The speed of the TCP response slowed significantly. This was due to the TCP
+process putting the server in time out while it still made sure all 
+previous packages were received. If the packages were not being received on
+first attempt, the system would wait till the package was eventually recieved.
+This caused the system to slow substantially.

tcp_client.py

@@ -8,11 +8,19 @@
 import socket
 
 def main():
-    # TODO: Create a socket and connect it to the server at the designated IP and port
+	HOST = "localhost"
+	PORT = 19000
+	with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
+		s.connect((HOST,PORT))
+		message = str(input("Enter a message: "))
+		s.sendall(message.encode("utf-8"))
+		data = s.recv(1024)
+		s.close()
+		decoded = data.decode("utf-8")
+	print(f"Received {decoded!r}")   
+
+# TODO: Create a socket and connect it to the server at the designated IP and port
     # TODO: Get user input and send it to the server using your TCP socket
     # TODO: Receive a response from the server and close the TCP connection
-    pass
-
-
 if __name__ == '__main__':
-    main()
+    main()

tcp_server.c

@@ -18,17 +18,25 @@ void error(const char *msg)
 int main(int argc, char *argv[])
 {
     /* 1. What is argc and *argv[]?
-     *
+     argc and argv[] are ways for the main() function to interact and get commands from
+     the command line. argc contains the amount of arguments are being passes while
+     *argv[] is an array of pointers to the arguments being passed.
      */
     int sockfd, newsockfd, portno;
     /* 2. What is a UNIX file descriptor and file descriptor table?
-     *
+     A file descriptor is a single integer that contains information to identify an
+     open file. A file descriptor table is just a collection of these file descriptor
+     so that the operating system can access this information.
      */
     socklen_t clilen;
 
     struct sockaddr_in serv_addr, cli_addr;
     /* 3. What is a struct? What's the structure of sockaddr_in?
-     *
+     A stuct is a data type that is a collection of other data types. Its essentially
+     a big block of smaller nuggest of information. A struct commonly has data types such as
+     strings or ints but it can also be a collection of other structs or classes. Here, 
+     serv_addr and cli_addr are just instances of the struct sockaddr_in. Together the 
+     struct stores internet addresses.
      */
 
     int n;
@@ -39,7 +47,10 @@ int main(int argc, char *argv[])
 
     sockfd = socket(AF_INET, SOCK_STREAM, 0);
     /* 4. What are the input parameters and return value of socket()
-     *
+     AF_INET tells the socket what address family to talk to. Here, AF_INET tells the socket to use IPv4.
+     sock stream tells the function the socket type being used. Here, it is telling the function that the
+     TCP protocol is being used. Finally, 0 tells the socket function to use the default protocol for 
+     SOCK_STREAM. The return value of socket() is just a file descriptor.
      */
 
     if (sockfd < 0) 
@@ -54,23 +65,36 @@ int main(int argc, char *argv[])
              sizeof(serv_addr)) < 0) 
              error("ERROR on binding");
     /* 5. What are the input parameters of bind() and listen()?
-     *
+     The first input parameter of bind() is sockfd. It is a socket descriptor which tells the function the socket’s endpoint.
+     Next is (struct sockaddr *) &serv_addr, it is a pointer that has the server's address information. Last is sizeof(serv_addr) 
+     it represents the size of sockaddr. listen() has two input parameters. The first is sockfd, a socket descriptor that tells
+     the function that this is a passive socket so it receives connection requests. Lastly, we have backlog. It contains the 
+     largest number of connections that can possibly be waiting for the socket.
      */
 
     listen(sockfd,5);
     clilen = sizeof(cli_addr);
 
     while(1) {
         /* 6.  Why use while(1)? Based on the code below, what problems might occur if there are multiple simultaneous connections to handle?
-        *
+        The while loop to make sure the program always iterates through the while loop to make sure it it always ready to
+	recieve new addresses. The issue is with this is if it is running through the while loop accepting one new address,
+	an even newer address could be missed. 
         */
 
 	char buffer[256];
         newsockfd = accept(sockfd, 
                     (struct sockaddr *) &cli_addr, 
                     &clilen);
 	/* 7. Research how the command fork() works. How can it be applied here to better handle multiple connections?
-         * 
+         The fork() command is a way to create a new process in Unix-like operating systems by copying the current one.
+         The new process is called a "child process" and it's a complete copy of the "parent process," including its program,
+         memory, and information about what it's doing. The child process runs on its own and can do different things from the
+         parent process. The fork() command returns a special number to let the parent and child know who's who. The child
+         process can then change what it's running using the exec() command. It can be used to handle multiple client connections
+         in a TCP client-server system simultaneously. The server creates a child process for each incoming connection, allowing
+         the parent process to keep listening for new connections. This way, multiple clients can be served efficiently without
+         blocking other clients. 
          */
 
 	if (newsockfd < 0) 
@@ -80,7 +104,7 @@ int main(int argc, char *argv[])
 	n = read(newsockfd,buffer,255);
         if (n < 0) 
             error("ERROR reading from socket");
-        //printf("Here is the message: %s\n",buffer);
+        printf("Here is the message: %s\n",buffer);
         n = write(newsockfd,"I got your message",18);
         if (n < 0) 
             error("ERROR writing to socket");
@@ -91,5 +115,6 @@ int main(int argc, char *argv[])
 }
 
 /* This program makes several system calls such as 'bind', and 'listen.' What exactly is a system call?
- *
- */
+    A system call is just a way for the user to request some sort of service that is ran by the operating system.
+    These inlcude read(), write(), fork(), etc.
+ */