Initial basic messaging server.

.gitignore

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+.cache
+CMakeCache.txt
+CMakeFiles
+cmake_install.cmake
+compile_commands.json
+.dir-locals.el
+Makefile
+Urchin-*

CMakeLists.txt

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+cmake_minimum_required(VERSION 3.16)
+project(Urchin
+    VERSION 0
+    DESCRIPTION "Simple Mud Experiment in C"
+    HOMEPAGE_URL "https://git.warwick-new.co.uk/"
+    LANGUAGES C)
+
+set(CMAKE_C_STANDARD 90)
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
+set(CMAKE_C_CLANG_TIDY)
+
+# Compile Server
+file(GLOB_RECURSE SERVER_SOURCE_FILES
+    ${CMAKE_SOURCE_DIR}/src/server/*.c)
+
+file(GLOB_RECURSE SERVER_HEADER_FILES
+    ${CMAKE_SOURCE_DIR}/src/server/*.h)
+
+add_executable(${PROJECT_NAME}-server ${SERVER_HEADER_FILES} ${SERVER_SOURCE_FILES})
+
+# Compile Client
+file(GLOB_RECURSE CLIENT_SOURCE_FILES
+    ${CMAKE_SOURCE_DIR}/src/client/*.c)
+
+file(GLOB_RECURSE CLIENT_HEADER_FILES
+    ${CMAKE_SOURCE_DIR}/src/client/*.h)
+
+add_executable(${PROJECT_NAME}-client ${CLIENT_HEADER_FILES} ${CLIENT_SOURCE_FILES})

src/client/main.c

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+// Sorry in advance for all the comments. This project is also a way for me to
+// learn C.
+
+#include <netdb.h>      // Contains host structure
+#include <netinet/in.h> //sockaddr_in
+#include <stdio.h>
+#include <stdlib.h> // Keeping for conversion functions
+#include <string.h>
+#include <strings.h>
+#include <sys/socket.h> // sockaddr
+#include <sys/types.h>
+
+void error_crash(const char *msg) {
+  fprintf(stderr, "error crash: %s\n", msg);
+  exit(EXIT_FAILURE);
+}
+
+void error_warn(const char *msg) { fprintf(stderr, "warning: %s\n", msg); }
+
+// TODO: Save the logs somewhere
+void error_log(const char *msg) { fprintf(stderr, "log: %s\n", msg); }
+
+int main(int argc, char *argv[]) {
+  // Set up containers for file descriptor id's
+  int sockfd, portno, errflag;
+  struct sockaddr_in serv_addr;
+  bzero((char *)&serv_addr, sizeof(serv_addr));
+  struct hostent *server;
+  char msgbuffer[255];
+
+  if (argc < 2) {
+    error_crash("Not enough server info has been provided");
+  }
+
+  if (argc > 2) {
+    portno = atoi(argv[2]);
+  } else {
+    portno = 3940;
+  }
+
+  // Create socket
+  sockfd = socket(AF_INET, SOCK_STREAM, 0);
+  if (sockfd < 0)
+    error_crash("Can't open socket.");
+
+  server = gethostbyname(argv[1]);
+  if (server == NULL)
+    error_crash("No such host exists :(");
+
+  serv_addr.sin_family = AF_INET;
+  bcopy((char *)server->h_addr, (char *)&serv_addr.sin_addr.s_addr,
+        server->h_length);
+  serv_addr.sin_port = htons(portno);
+  errflag = connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr));
+  if (errflag < 0)
+    error_crash("Failed to connect to host");
+
+  while (1) {
+    bzero(msgbuffer, sizeof msgbuffer);
+    fgets(msgbuffer, sizeof msgbuffer, stdin);
+    errflag = write(sockfd, msgbuffer, strlen(msgbuffer));
+    if (errflag < 0)
+      error_crash("Failed to write message");
+
+    bzero(msgbuffer, sizeof msgbuffer);
+    errflag = read(sockfd, msgbuffer, sizeof msgbuffer);
+    if (errflag < 0)
+      error_crash("Failed to read message");
+
+    printf("Server: %s", msgbuffer);
+
+    int cmp = strncmp("Bye", msgbuffer, 3);
+    if (cmp == 0)
+      break;
+  }
+
+  close(sockfd);
+  return EXIT_SUCCESS;
+}

src/server/main.c

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+// Sorry in advance for all the comments. This project is also a way for me to
+// learn C.
+
+#include <netinet/in.h> //sockaddr_in
+#include <stdio.h>
+#include <stdlib.h> // Keeping for conversion functions
+#include <string.h>
+#include <strings.h>
+#include <sys/socket.h> // sockaddr
+#include <sys/types.h>
+
+void error_crash(const char *msg) {
+  fprintf(stderr, "error crash: %s\n", msg);
+  exit(EXIT_FAILURE);
+}
+
+void error_warn(const char *msg) { fprintf(stderr, "warning: %s\n", msg); }
+
+// TODO: Save the logs somewhere
+void error_log(const char *msg) { fprintf(stderr, "log: %s\n", msg); }
+
+int main(int argc, char *argv[]) {
+  // Set up containers for file descriptor id's
+  int sockfd, clientsockfd, portno, errflag;
+  char msgbuffer[255];
+
+  // Set port number.
+  if (argc > 1) {
+    portno = atoi(argv[1]);
+  } else {
+    portno = 3940;
+  }
+
+  // Socket address info
+  struct sockaddr_in serv_addr, cli_addr;
+  socklen_t clilen = sizeof cli_addr; // We can do this here as cli_addr isn't
+                                      // touched until it's used
+
+  // Create socket
+  sockfd = socket(AF_INET, SOCK_STREAM, 0);
+  if (sockfd < 0) {
+    error_crash("Can't open socket.");
+  }
+
+  // Make sure there is no junk data in serve_addr
+  bzero((char *)&serv_addr, sizeof serv_addr);
+
+  // Tell the connection to use ipv4 and port number
+  serv_addr.sin_family = AF_INET;
+  serv_addr.sin_addr.s_addr = INADDR_ANY;
+  serv_addr.sin_port = htons(portno);
+
+  // Bind Socket
+  errflag = bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr));
+  if (errflag < 0) {
+    error_crash("Can't bind socket");
+  }
+
+  errflag = listen(sockfd, 5);
+  if (errflag < 0) {
+    error_crash("Can't listen for connections");
+  }
+
+  char portstr[5]; // Buffer to store string version of port
+  snprintf(portstr, sizeof portstr, "%d", portno);
+  printf("Server Listening on port: %s\n", portstr);
+
+  clientsockfd = accept(sockfd, (struct sockaddr *)&cli_addr, &clilen);
+  if (clientsockfd < 0) {
+    error_crash("Can't accept connection");
+  }
+
+  while (1) {
+    // Empty message buffer
+    bzero(msgbuffer, sizeof msgbuffer);
+
+    errflag = read(clientsockfd, msgbuffer, sizeof msgbuffer);
+    if (errflag < 0) {
+      error_crash("Didn't recieve message from connection");
+    }
+    printf("Client: %s\n", msgbuffer);
+
+    // clear buffer for writing
+    bzero(msgbuffer, sizeof msgbuffer);
+    fgets(msgbuffer, sizeof msgbuffer, stdin);
+
+    errflag = write(clientsockfd, msgbuffer, strlen(msgbuffer));
+    if (errflag < 0) {
+      error_crash("Couldn't write response message");
+    }
+
+    int cmp = strncmp("Bye", msgbuffer, 3);
+    if (cmp == 0)
+      break;
+  }
+
+  close(clientsockfd);
+  close(sockfd);
+
+  return EXIT_SUCCESS;
+}