Created the second homework, aka "echoserver."

echoserver/Makefile

@@ -0,0 +1,20 @@
+CC = gcc -Wall -std=c11 -pedantic
+SOURCES = echoserver.c 
+OBJECTS = echoserver.o 
+
+all: echoserver
+
+echoserver: $(OBJECTS)
+	$(CC) $(OBJECTS) -o echoserver
+
+echoserver.o: echoserver.c
+	$(CC) -c echoserver.c -o echoserver.o
+
+clean:
+	rm -f $(OBJECTS) echoserver echoserver.out
+
+clean_objects:
+	rm -f $(OBJECTS)
+
+run:
+	./echoserver

echoserver/README.md

@@ -0,0 +1,10 @@
+# Running the echoserver
+Use `make` to compile the echoserver.
+Use `make run` to run the echoserver. This will run on an infinite loop.
+Use `Ctrl+C` to stop the echoserver.
+
+## echoserver communication
+Communicating with the server can happen using telnet in TCP mode.
+
+## echoserver information
+The echoserver runs on TCP port 8888.

echoserver/echoserver.c

@@ -0,0 +1,115 @@
+// header files
+#include "echoserver.h"
+
+// constants
+// echoserver port is 8888
+#define ECHOPORT 8888
+#define BUFFER_SIZE 1024
+#define MAX_CONNECT_QUEUE 10
+
+// prototypes
+
+// main function
+int main(int argc, char **argv)
+{
+    // initialize program (variables and structs)
+    bool quitFlag = true;
+    int socketEchoFD;
+    int clientEchoFD;
+    char message[BUFFER_SIZE];
+    struct sockaddr_in serverAddr;
+    struct sockaddr_storage clientAddr;
+    socklen_t clientSize;
+    memset(&serverAddr, 0, sizeof(serverAddr));
+    memset(&clientAddr, 0, sizeof(clientAddr));
+    // define a TCP socket
+    socketEchoFD = socket(AF_INET, SOCK_STREAM, 0);
+    if(socketEchoFD < 0)
+    {
+        printf("Unable to create the socket.\n");
+        return -1;
+    }
+    // use the setsockopt function to make the socket accept different configurations
+    // CODE HERE
+    // bind the TCP socket to port 8888 / ECHOPORT
+    serverAddr.sin_family = AF_INET;
+    serverAddr.sin_addr.s_addr = INADDR_ANY;
+    serverAddr.sin_port = htons(ECHOPORT);
+    int bindCheck = bind(socketEchoFD, &serverAddr, sizeof(serverAddr));
+    if(bindCheck < 0)
+    {
+        printf("Unable to bind the socket to the port or address.\n Is either in use?");
+        return -1;
+    }
+    // the server will now accept client connections by listening.
+    listen(socketEchoFD, MAX_CONNECT_QUEUE);
+    // while loop that will continue to listen for messages from clients.
+    printf("Echoserver listening on port: %d\n", ECHOPORT);
+    // while(quitFlag)
+    // {
+    //     int clientAddrLen;
+    //     int receivedDataLen;
+    //     // grab the data from the client
+    //     receivedDataLen = recvfrom(socketEchoFD, message, BUFFER_SIZE, MSG_WAITALL, &clientAddr, &clientAddrLen);
+    //     message[receivedDataLen] = '\0';
+    //     // if "01189998811991197253\r\n" is received, then close the server.
+    //     if(strcmp(message, "01189998811991197253\n") == 0 || strcmp(message, "01189998811991197253\r\n") == 0)
+    //     {
+    //         // if the server recv'd the close command, then close the server.
+    //         printf("\nServer received close.\n");
+    //         quitFlag = false;
+    //     }
+    //     // otherwise, repeat/echo back the message to the client.
+    //     // setup the reply message
+    //     char reply[BUFFER_SIZE];
+    //     // add the current time to the reply
+    //     sprintf(reply, "%d", time(NULL));
+    //     // send the reply to the requestee
+    //     sendto(socketEchoFD, (const char *)reply, strlen(reply), 0, (const struct sockaddr *)&clientAddr, clientAddrLen);
+    //     // log the time command recv'd
+    //     printf("\nServer received time. Replied with: %d\n", time(NULL));
+    // }
+    while (quitFlag)
+    {
+        // grab the size of the listened clients
+        clientSize = sizeof(clientAddr);
+        // grab the client's socket information
+        clientEchoFD = accept(socketEchoFD, &clientAddr, &clientSize);
+        // check to see if the client socket is actually connected
+        if(clientEchoFD == -1)
+        {
+            printf("Unable to accept from the client.\n");
+            return -1;
+        }
+        // grab the data from the client, save to message.
+        // NEW CODE HERE
+        // if "01189998811991197253\r\n" is received, then close the server.
+        if (strcmp(message, "01189998811991197253\n") == 0 || strcmp(message, "01189998811991197253\r\n") == 0)
+        {
+            // if the server recv'd the close command, then close the server.
+            printf("\nServer received close.\n");
+            quitFlag = false;
+        }
+        // otherwise, repeat/echo back the message to the client.
+        // NEW CODE HERE
+        // close the accepted listening socket since it is no longer needed.
+        close(clientEchoFD);
+    }
+    // close the socket
+    close(socketEchoFD);
+    // profit???
+    return 0;
+}
+
+// function definitions
+
+/*
+Name: ???
+Process: ???
+Function Input/Parameters: ???
+Function Output/Parameters: ???
+Function Output/Returned: ???
+Device Input/Device: ???
+Device Output/Device: ???
+Dependencies: ???
+*/

echoserver/echoserver.h

@@ -0,0 +1,23 @@
+#ifndef ECHOSERVER
+#define ECHOSERVER
+
+// included libraries
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <math.h>
+#include <stdbool.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+#include <time.h>
+#include <unistd.h>
+#include <errno.h>
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+// data structures
+
+// function prototypes
+
+#endif // ECHOSERVER