+#ifdef FEATURE_EXTERNAL_FILTERS
+/*********************************************************************
+ *
+ * Function : get_external_filter
+ *
+ * Description : Lookup the code to execute for an external filter.
+ * Masks the misuse of the re_filterfile_spec.
+ *
+ * Parameters :
+ * 1 : csp = Current client state (buffers, headers, etc...)
+ * 2 : name = Name of the content filter to get
+ *
+ * Returns : A pointer to the requested code
+ * or NULL if the filter wasn't found
+ *
+ *********************************************************************/
+static const char *get_external_filter(const struct client_state *csp,
+ const char *name)
+{
+ struct re_filterfile_spec *external_filter;
+
+ external_filter = get_filter(csp, name, FT_EXTERNAL_CONTENT_FILTER);
+ if (external_filter == NULL)
+ {
+ log_error(LOG_LEVEL_FATAL,
+ "Didn't find stuff to execute for external filter: %s",
+ name);
+ }
+
+ return external_filter->patterns->first->str;
+
+}
+
+
+/*********************************************************************
+ *
+ * Function : set_privoxy_variables
+ *
+ * Description : Sets a couple of privoxy-specific environment variables
+ *
+ * Parameters :
+ * 1 : csp = Current client state (buffers, headers, etc...)
+ *
+ * Returns : N/A
+ *
+ *********************************************************************/
+static void set_privoxy_variables(const struct client_state *csp)
+{
+ int i;
+ struct {
+ const char *name;
+ const char *value;
+ } env[] = {
+ { "PRIVOXY_URL", csp->http->url },
+ { "PRIVOXY_PATH", csp->http->path },
+ { "PRIVOXY_HOST", csp->http->host },
+ { "PRIVOXY_ORIGIN", csp->ip_addr_str },
+ };
+
+ for (i = 0; i < SZ(env); i++)
+ {
+ if (setenv(env[i].name, env[i].value, 1))
+ {
+ log_error(LOG_LEVEL_ERROR, "Failed to set %s=%s: %E",
+ env[i].name, env[i].value);
+ }
+ }
+}
+
+
+/*********************************************************************
+ *
+ * Function : execute_external_filter
+ *
+ * Description : Pipe content into external filter and return the output
+ *
+ * Parameters :
+ * 1 : csp = Current client state (buffers, headers, etc...)
+ * 2 : name = Name of the external filter to execute
+ * 3 : content = The original content to filter
+ * 4 : size = The size of the content buffer
+ *
+ * Returns : a pointer to the (newly allocated) modified buffer.
+ * or NULL if there were no hits or something went wrong
+ *
+ *********************************************************************/
+static char *execute_external_filter(const struct client_state *csp,
+ const char *name, char *content, size_t *size)
+{
+ char cmd[200];
+ char file_name[FILENAME_MAX];
+ FILE *fp;
+ char *filter_output;
+ int fd;
+ int ret;
+ size_t new_size;
+ const char *external_filter;
+
+ if (csp->config->temporary_directory == NULL)
+ {
+ log_error(LOG_LEVEL_ERROR,
+ "No temporary-directory configured. Can't execute filter: %s",
+ name);
+ return NULL;
+ }
+
+ external_filter = get_external_filter(csp, name);
+
+ if (sizeof(file_name) < snprintf(file_name, sizeof(file_name),
+ "%s/privoxy-XXXXXXXX", csp->config->temporary_directory))
+ {
+ log_error(LOG_LEVEL_ERROR, "temporary-directory path too long");
+ return NULL;
+ }
+
+ fd = mkstemp(file_name);
+ if (fd == -1)
+ {
+ log_error(LOG_LEVEL_ERROR, "mkstemp() failed to create %s: %E", file_name);
+ return NULL;
+ }
+
+ fp = fdopen(fd, "w");
+ if (fp == NULL)
+ {
+ log_error(LOG_LEVEL_ERROR, "fdopen() failed: %E");
+ unlink(file_name);
+ return NULL;
+ }
+
+ /*
+ * The size may be zero if a previous filter discarded everything.
+ *
+ * This isn't necessary unintentional, so we just don't try
+ * to fwrite() nothing and let the user deal with the rest.
+ */
+ if ((*size != 0) && fwrite(content, *size, 1, fp) != 1)
+ {
+ log_error(LOG_LEVEL_ERROR, "fwrite(..., %d, 1, ..) failed: %E", *size);
+ unlink(file_name);
+ fclose(fp);
+ return NULL;
+ }
+ fclose(fp);
+
+ if (sizeof(cmd) < snprintf(cmd, sizeof(cmd), "%s < %s", external_filter, file_name))
+ {
+ log_error(LOG_LEVEL_ERROR,
+ "temporary-directory or external filter path too long");
+ unlink(file_name);
+ return NULL;
+ }
+
+ log_error(LOG_LEVEL_RE_FILTER, "Executing '%s': %s", name, cmd);
+
+ /*
+ * The locking is necessary to prevent other threads
+ * from overwriting the environment variables before
+ * the popen fork. Afterwards this no longer matters.
+ */
+ privoxy_mutex_lock(&external_filter_mutex);
+ set_privoxy_variables(csp);
+ fp = popen(cmd, "r");
+ privoxy_mutex_unlock(&external_filter_mutex);
+ if (fp == NULL)
+ {
+ log_error(LOG_LEVEL_ERROR, "popen(\"%s\", \"r\") failed: %E", cmd);
+ unlink(file_name);
+ return NULL;
+ }
+
+ filter_output = malloc_or_die(*size);
+
+ new_size = 0;
+ while (!feof(fp) && !ferror(fp))
+ {
+ size_t len;
+ /* Could be bigger ... */
+ enum { READ_LENGTH = 2048 };
+
+ if (new_size + READ_LENGTH >= *size)
+ {
+ char *p;
+
+ /* Could be considered wasteful if the content is 'large'. */
+ *size = (*size != 0) ? *size * 2 : READ_LENGTH;
+
+ p = realloc(filter_output, *size);
+ if (p == NULL)
+ {
+ log_error(LOG_LEVEL_ERROR, "Out of memory while reading "
+ "external filter output. Using what we got so far.");
+ break;
+ }
+ filter_output = p;
+ }
+ len = fread(&filter_output[new_size], 1, READ_LENGTH, fp);
+ if (len > 0)
+ {
+ new_size += len;
+ }
+ }
+
+ ret = pclose(fp);
+ if (ret == -1)
+ {
+ log_error(LOG_LEVEL_ERROR, "Executing %s failed: %E", cmd);
+ }
+ else
+ {
+ log_error(LOG_LEVEL_RE_FILTER,
+ "Executing '%s' resulted in return value %d. "
+ "Read %d of up to %d bytes.", name, (ret >> 8), new_size, *size);
+ }
+
+ unlink(file_name);
+ *size = new_size;
+
+ return filter_output;
+
+}
+#endif /* def FEATURE_EXTERNAL_FILTERS */
+
+