proj/exam-2020W-2A: Add Musterlösung

proj/exam-2020W-2A/src/server.c

@@ -64,10 +64,32 @@ void error_exit(const char *msg) {
  * Hints: getaddrinfo(3), socket(2), listen(2)
  ************************************************************************/
 int setup_connection(const char *port_str) {
-    // put your code here
+    struct addrinfo hints, *ai;
+    memset(&hints, 0, sizeof hints);
+    hints.ai_family = AF_INET;
+    hints.ai_socktype = SOCK_STREAM;
+    hints.ai_flags = AI_PASSIVE;
 
-    // Replace with a meaningful return value
-    return -1;
+    int res = getaddrinfo(NULL, port_str, &hints, &ai);
+    if (res != 0)
+        error_exit("getaddrinfo() failed");
+
+    int sockfd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
+    if (sockfd < 0)
+        error_exit("socket() failed");
+
+    int reuse = 1;
+    if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse)) < 0)
+        error_exit("setsockopt() failed");
+
+    if (bind(sockfd, ai->ai_addr, ai->ai_addrlen) < 0)
+        error_exit("bind() failed");
+
+    freeaddrinfo(ai);
+
+    if (listen(sockfd, 1) < 0)
+        error_exit("listen() failed");
+    return sockfd;
 }
 
 /*******************************************************************************
@@ -91,7 +113,29 @@ int setup_connection(const char *port_str) {
  * Hints: accept(2), fdopen(3), fgets(3), fprintf(3), fclose(3)
  ******************************************************************************/
 void server_request_handler(int sockfd, const char *command) {
-    // put your code here
+    int connfd = accept(sockfd, NULL, NULL);
+    if (connfd < 0)
+        error_exit("accept() failed");
+
+
+    FILE *fps = fdopen(connfd, "w+");
+
+    char argument[MAX_ARGUMENT_LEN + 1] = {0};
+    fgets(argument, sizeof(argument), fps);
+
+    FILE *fpc = NULL;
+    fpc = execute_command(command, argument);
+
+    if (fpc) {
+        int c;
+        while ((c = fgetc(fpc)) != EOF)
+            fputc(c, fps);
+        fclose(fpc);
+    } else {
+        fputs("COMMAND_FAILED", fps);
+    }
+    fflush(fps);
+    fclose(fps);
 }
 
 /*******************************************************************************
@@ -120,10 +164,50 @@ void server_request_handler(int sockfd, const char *command) {
  * Hints: pipe(2), dup2(2), fork(2), exec(3), fdopen(3), wait(3)
  ******************************************************************************/
 FILE *execute_command(const char *command, const char *argument) {
-    // put your code here
+    // file stream to read the output of the process
+    FILE *proc_output = NULL;
 
-    // Replace with a meaningful return value
-    return NULL;
+    // file descriptors for the pipe for parent-child process communication
+    int c2p[2];
+
+    // create the pipes
+    if (pipe(c2p) == -1)
+        error_exit("cannot create pipe");
+
+    pid_t pid = fork();
+    switch (pid) {
+        case 0:
+            // duplicate write end to stdout
+            if (dup2(c2p[1], STDOUT_FILENO) == -1) {
+                error_exit("dup2() failed");
+            }
+            close(c2p[0]);
+            close(STDIN_FILENO);
+
+            // exec the command
+            if (execlp(command, command, argument, NULL) == -1) {
+                error_exit("exec() failed");
+            }
+        case -1:
+            error_exit("fork() failed");
+
+        default:
+            // parent process
+            proc_output = fdopen(c2p[0], "r");
+            if (proc_output == NULL) {
+                error_exit("fdopen() failed");
+            }
+            close(c2p[1]);
+
+            int stat = 0;
+            wait(&stat);
+
+            if (WIFEXITED(stat) && WEXITSTATUS(stat) == 0) {
+            } else {
+                proc_output = NULL;
+            }
+    }
+    return proc_output;
 }
 
 /*