basic message parsing

src/hdbd.c

@@ -1,5 +1,8 @@
+#define _POSIX_C_SOURCE 200809L /* needed for strndup */
+
 #include <strops.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <sys/types.h>
 #include <unistd.h>
 #include <string.h>
@@ -12,6 +15,68 @@ int server_sock;
 struct sockaddr_un server;
 int sockaddr_len;
 
+/*
+    Message format: (Basically like a command line)
+    operation operand1 operand2 operand3
+    Supports up to 3 operands
+*/
+void parse_message(char *buffer, char *operation, char *operand1, char *operand2, char *operand3) {
+    int len_to_ws = 0;
+    int offset = 0;
+    char log_line[1000] = {0};
+    
+    sprintf(log_line, "Beginning of parsing message: '%s'", buffer);
+    syslog(LOG_DEBUG, log_line);
+
+    len_to_ws = strcspn(buffer, " ");
+    strncpy(operation, buffer, len_to_ws);
+    offset = len_to_ws + 1;
+
+    sprintf(log_line, "operation = '%s'", operation);
+    syslog(LOG_DEBUG, log_line);
+
+    if (strlen(buffer) == offset - 1) {
+        syslog(LOG_DEBUG, "Finished parsing message.");
+        return;
+    }
+    
+    len_to_ws = strcspn(buffer + offset, " ");
+    strncpy(operand1, buffer + offset, len_to_ws);
+    offset += len_to_ws + 1;
+
+    sprintf(log_line, "operand1 = '%s'", operand1);
+    syslog(LOG_DEBUG, log_line);
+
+    if (strlen(buffer) == offset -1) {
+        syslog(LOG_DEBUG, "Finished parsing message.");
+        return;
+    }
+
+    len_to_ws = strcspn(buffer + offset, " ");
+    strncpy(operand2, buffer + offset, len_to_ws);
+    offset += len_to_ws + 1;
+
+    sprintf(log_line, "operand2 = '%s'", operand2);
+    syslog(LOG_DEBUG, log_line);
+
+    if (strlen(buffer) == offset -1) {
+        syslog(LOG_DEBUG, "Finished parsing message.");
+        return;
+    }
+    
+    len_to_ws = strcspn(buffer + offset, " ");
+    strncpy(operand3, buffer + offset, len_to_ws);
+    offset += len_to_ws + 1;
+
+    sprintf(log_line, "operand3 = '%s'", operand3);
+    syslog(LOG_DEBUG, log_line);
+
+    if (strlen(buffer) == offset -1) {
+        syslog(LOG_DEBUG, "Finished parsing message.");
+        return;
+    }
+}
+
 int main() {
     /* 
      Setup daemon
@@ -40,7 +105,7 @@ int main() {
     close(STDERR_FILENO);
 
     openlog("hdbd", LOG_CONS|LOG_PID, LOG_USER);
-    syslog(LOG_INFO, "Hello from hdbd");
+    syslog(LOG_NOTICE, "Daemon setup done.");
 
     /* Setup Unix Socket */
     server_sock = socket(AF_UNIX, SOCK_STREAM, 0);
@@ -61,48 +126,52 @@ int main() {
         return 1;
     }
 
+    syslog(LOG_NOTICE, "Unix Socket up and running.");
+
     /* Actual program */
     int client_sock;
     int data_length = 0;
-    char receive_buf[1000];
-    char send_buf[1000];
-    char log_line[10000]; 
-    memset(receive_buf, 0, sizeof receive_buf);
-    memset(send_buf, 0, sizeof send_buf);
-    memset(log_line, 0, sizeof log_line);
-
-
-    syslog(LOG_INFO, "Listening for connections...");
+    char receive_buf[1000] = {0};
+    char send_buf[1000] = {0};
+    char log_line[10000] = {0};
+    char operation[1000] = {0};
+    char operand1[1000] = {0};
+    char operand2[1000] = {0};
+    char operand3[1000] = {0};
 
     while(1) {
         client_sock = accept(server_sock, NULL, NULL);
         if (client_sock == -1) {
             return 1;
         }
-        syslog(LOG_INFO, "Accepted a connection");
-        data_length = recv(client_sock, receive_buf, sizeof receive_buf, 0);
+        syslog(LOG_INFO, "Accepted a connection.");
+        data_length = read(client_sock, receive_buf, sizeof receive_buf);
         if (data_length <= 0) {
-            syslog(LOG_WARNING, "Received no data from client");
+            syslog(LOG_WARNING, "Received no data from client!");
             strcpy(send_buf, "Failed to receive any data.");
             send(client_sock, send_buf, strlen(send_buf), 0);
             close(client_sock);
             continue;
         }
         
-        sprintf(log_line, "Received from Client: %s", receive_buf);
+        sprintf(log_line, "Received from Client: '%s'", receive_buf);
         syslog(LOG_DEBUG, log_line);
 
-        if (strstr(receive_buf, "shutdown") != NULL) {
-            syslog(LOG_NOTICE, "Shutting down");
-            strcpy(send_buf, "Shutting down.");
+        parse_message(receive_buf, operation, operand1, operand2, operand3);
+
+        if (strcmp(operation, "shutdown") == 0) {
+            syslog(LOG_NOTICE, "Starting shutdown.");
+            strcpy(send_buf, "Shutting down daemon.");
             send(client_sock, send_buf, strlen(send_buf), 0);
             close(client_sock);
             break;
         }
         
+        syslog(LOG_INFO, "Closing connection.");
         close(client_sock);
     }
     
     close(server_sock);
+    syslog(LOG_NOTICE, "Bye Bye.");
     return 0;
 }