Initial commit of twind - a small and simple gemini daemon

1 files changed, 191 insertions, 0 deletions

diff --git a/gemini.c b/gemini.c
new file mode 100644
index 0000000..ea78c82
--- /dev/null
+++ b/gemini.c
@@ -0,0 +1,191 @@
+/*
+ * Copyright (c) 2021 Matthias Schmidt <xhr@giessen.ccc.de>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <sys/socket.h>
+#include <sys/stat.h>
+
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "log.h"
+#include "twind.h"
+
+static void
+generate_meta(int status_code, char *meta_response_string, const char *mime)
+{
+	switch(status_code) {
+		case STATUS_INPUT:
+			snprintf(meta_response_string, 1024, "%d Present input\r\n", status_code);
+			break;
+		case STATUS_SENSITIVE_INPUT:
+			snprintf(meta_response_string, 1024, "%d Present sensitive input\r\n",
+				status_code);
+			break;
+		case STATUS_SUCCESS:
+			if (mime == NULL)
+				/* Could not deducte mime type, so send text/gemini as default */
+				snprintf(meta_response_string, 1024, "%d text/gemini\r\n", status_code);
+			else
+				snprintf(meta_response_string, 1024, "%d %s\r\n", status_code, mime);
+			break;
+		case STATUS_REDIRECT_TEMP:
+			snprintf(meta_response_string, 1024, "%d Temporary redirect\r\n",
+				status_code);
+			break;
+		case STATUS_REDIRECT_PERM:
+			snprintf(meta_response_string, 1024, "%d Permanent redirect\r\n",
+				status_code);
+			break;
+		case STATUS_TEMP_UNAVAILABLE:
+			snprintf(meta_response_string, 1024, "%d Temporary failure\r\n",
+				status_code);
+			break;
+		case STATUS_SERVER_UNAVAILABLE:
+			snprintf(meta_response_string, 1024, "%d Server unavailable\r\n",
+				status_code);
+			break;
+		case STATUS_CGI_ERROR:
+			snprintf(meta_response_string, 1024, "%d CGI Error\r\n", status_code);
+			break;
+		case STATUS_PROXY_ERROR:
+			snprintf(meta_response_string, 1024, "%d Proxy error\r\n", status_code);
+			break;
+		case STATUS_SLOW_DOWN:
+			snprintf(meta_response_string, 1024, "%d Slow down\r\n", status_code);
+			break;
+		case STATUS_PERM_FAILURE:
+			snprintf(meta_response_string, 1024, "%d Permanent failure\r\n", status_code);
+			break;
+		case STATUS_NOT_FOUND:
+			snprintf(meta_response_string, 1024, "%d Resource not found\r\n",
+				status_code);
+			break;
+		case STATUS_GONE:
+			snprintf(meta_response_string, 1024, "%d Resource is gone\r\n", status_code);
+			break;
+		case STATUS_PROXY_REQUEST_REFUSED:
+			snprintf(meta_response_string, 1024, "%d Proxy request refused\r\n",
+				status_code);
+			break;
+		case STATUS_BAD_REQUEST:
+			snprintf(meta_response_string, 1024, "%d Bad Request\r\n", status_code);
+			break;
+		case STATUS_CLIENT_CERT_REQUIRED:
+			snprintf(meta_response_string, 1024, "%d Client Certificate Required\r\n",
+				status_code);
+			break;
+		case STATUS_CERT_NOT_AUTHORIZED:
+			snprintf(meta_response_string, 1024, "%d Certificate not authorized\r\n",
+				status_code);
+			break;
+		case STATUS_CERT_NOT_VALID:
+			snprintf(meta_response_string, 1024, "%d Certificate not valid\r\n",
+				status_code);
+			break;
+		default:
+			snprintf(meta_response_string, 1024, "%d Unkown status code\r\n",
+				status_code);
+			break;
+	}
+}
+
+int
+send_non_success_response(SSL *ssl_peer, int status_code)
+{
+	char meta[1024];
+
+	memset(meta, 0, sizeof(meta));
+
+	generate_meta(status_code, meta, NULL);
+
+	log_debug("Send non success response to client: %d", status_code);
+
+	if (SSL_write(ssl_peer, meta, strlen(meta)) <= 0) {
+		log_warn("Could not send response to client");
+		return -1;
+	}
+
+	return 0;
+}
+
+int
+send_response(SSL *ssl_peer, int status_code, const char *gemini_file_path,
+	const char *mime)
+{
+	char meta[1024];
+	char buffer[1024];
+	int fd = -1, len;
+
+	// <STATUS><SPACE><META><CR><LF>
+
+	memset(meta, 0, sizeof(meta));
+	memset(buffer, 0, sizeof(buffer));
+
+	generate_meta(status_code, meta, mime);
+
+	if (SSL_write(ssl_peer, meta, strlen(meta)) <= 0) {
+		log_warn("Could not send response to client");
+		return -1;
+	}
+
+	/* Close connection and do not send a response if status code is not
+	 * a SUCCESS code
+	 */
+	if (status_code < 30 && status_code >= 20) {
+		fd = open(gemini_file_path, O_RDONLY);
+		if (fd == -1) {
+			log_warn("Cannot open requested file");
+			goto out;
+		}
+
+		while ((len = read(fd, buffer, sizeof(buffer)-1)) > 0) {
+			if (SSL_write(ssl_peer, buffer, len) <= 0) {
+				log_warn("Could not send response to client");
+				return -1;
+			}
+		}
+	}
+
+out:
+	close(fd);
+
+	return 0;
+}
+
+int
+check_gemini_file(const char *gemini_file_path)
+{
+	struct stat sb;
+
+	if (stat(gemini_file_path, &sb) == -1) {
+		log_warn("Cannot open requested file");
+		return -1;
+	}
+
+	if ((sb.st_mode & (S_IRUSR | S_IRGRP | S_IROTH)) == 0) {
+		log_warn("Cannot read requested file");
+		return -1;
+	}
+
+	if ((sb.st_mode & S_IFMT) == S_IFDIR)
+		return 1;
+
+	return 0;
+}