steamdlfilter.c

#include <sys/socket.h>
#include <sys/types.h>
#include <libconfig.h>
#include <string.h>
#include <stdlib.h>
#include <dlfcn.h>
#include <stdio.h>

ssize_t send(int sockfd, const void *buf, size_t len, int flags) {

  const char * cbuf = (const char *) buf; 

  ssize_t (*original_send) (int, const void*, size_t, int) = dlsym(RTLD_NEXT, "send");

  config_t config;
  config_init(&config);
  const char * chome = getenv("HOME");
  char prelog[100];
  char precfg[100];
  char * log = strcpy(prelog, chome);
  char * cfg = strcpy(precfg, chome);
  const char * configpath = strcat(cfg,"/.config/steamdlfilter/config");
  const char * logpath = strcat(log, "/.steamdlfilter.log");


  config_read_file(&config, configpath);

  int filterenabled;
  const char * enablepath = "filterenabled";

  config_lookup_bool(&config, enablepath, &filterenabled);


  if (strstr(cbuf, "/depot/") && filterenabled == 1) {

	  FILE *logfp;
	  char *logmode = "a+";

	  int logging;
	  const char * logconfigpath = "logging";

	  config_lookup_bool(&config, logconfigpath, &logging);

	  const char * unmeteredserver;
	  const char * serverpath = "unmeteredservers";

      const int nServers = config_setting_length( config_lookup(&config, serverpath) );

      /* Loop over all servers in config and check for any matches */
      int allowedserver = 0;
      int i;
      for(i=0; i < nServers; i++) {
          /* Lookup path is serverpath.[i] */
          int indexlength = 0;
          if (i!=0) indexlength = floor( log10( abs(i))) + 1;
          char * servername = malloc(strlen(serverpath) + indexlength + 3 + 1); /* 3 for ".[]" and 1 for null termination */
          strcpy(servername, serverpath);
          char * indexstr = malloc(indexlength + 3 + 1);
          char * tempformat = ".[%d]";
          sprintf(indexstr, tempformat, i);
          servername = strcat(servername, indexstr);
          config_lookup_string(&config, servername, &unmeteredserver); 
          if(strstr(cbuf, unmeteredserver)) {
              allowedserver = 1;
              break;
          }
      }

	  if (allowedserver) {	  
		  if (logging == 1) {
		  	logfp = fopen(logpath, logmode);
                  	fprintf(logfp, "=======ALLOWED=======\n%s\n", cbuf);
                  	fclose(logfp);
		  }
                  return original_send(sockfd, buf, len, flags);
    }
	  else {
                  if (logging == 1) {
			logfp = fopen(logpath, logmode);
			fprintf(logfp, "=======BLOCKED=======\n%s\n", cbuf);
			fclose(logfp);
		  }
                  return -1;
    }
	  

  }
  else 
      return original_send(sockfd, buf, len, flags);
  config_destroy(&config);

}