sendmail: really svn add it

1 files changed, 313 insertions, 0 deletions

diff --git a/networking/sendmail.c b/networking/sendmail.c
new file mode 100644
index 0000000..2ea10b1
--- /dev/null
+++ b/networking/sendmail.c
@@ -0,0 +1,313 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * bare bones sendmail
+ *
+ * Copyright (C) 2008 by Vladimir Dronnikov <dronnikov@gmail.com>
+ *
+ * Licensed under GPLv2, see file LICENSE in this tarball for details.
+ */
+#include "libbb.h"
+
+/*
+   Extracted from BB uuencode.c
+ */
+enum {
+	SRC_BUF_SIZE = 45,  /* This *MUST* be a multiple of 3 */
+	DST_BUF_SIZE = 4 * ((SRC_BUF_SIZE + 2) / 3),
+};
+
+static void uuencode(const char *fname)
+{
+	int fd;
+	char src_buf[SRC_BUF_SIZE];
+	char dst_buf[1 + DST_BUF_SIZE + 1];
+
+	fd = xopen(fname, O_RDONLY);
+	fflush(stdout);
+	dst_buf[0] = '\n';
+	while (1) {
+		size_t size = full_read(fd, src_buf, SRC_BUF_SIZE);
+		if (!size)
+			break;
+		if ((ssize_t)size < 0)
+			bb_perror_msg_and_die(bb_msg_read_error);
+		/* Encode the buffer we just read in */
+		bb_uuencode(dst_buf + 1, src_buf, size, bb_uuenc_tbl_base64);
+		xwrite(STDOUT_FILENO, dst_buf, 1 + 4 * ((size + 2) / 3));
+	}
+	close(fd);
+}
+
+// "inline" version
+// encodes content of given buffer instead of fd
+// used to encode subject and authentication terms
+static void uuencode_inline(const char *src_buf)
+{
+	size_t len;
+	char dst_buf[DST_BUF_SIZE + 1];
+
+	len = strlen(src_buf);
+	fflush(stdout);
+	while (len > 0) {
+		size_t chunk = (len <= SRC_BUF_SIZE) ? len : SRC_BUF_SIZE;
+		bb_uuencode(dst_buf, src_buf, chunk, bb_uuenc_tbl_base64);
+		xwrite(STDOUT_FILENO, dst_buf, 4 * ((chunk + 2) / 3));
+		src_buf += chunk;
+		len -= chunk;
+	}
+}
+
+#if ENABLE_FEATURE_SENDMAIL_NETWORK
+// generic signal handler
+static void signal_handler(int signo)
+{
+	int err;
+
+	if (SIGALRM == signo)
+		bb_error_msg_and_die("timed out");
+
+	// SIGCHLD. reap zombies
+	if (wait_any_nohang(&err) > 0)
+		if (WIFEXITED(err) && WEXITSTATUS(err))
+			bb_error_msg_and_die("child exited (%d)", WEXITSTATUS(err));
+}
+
+static pid_t helper_pid = -1;
+
+// read stdin, parses first bytes to a number, i.e. server response
+// if code = -1 then just return this number
+// if code != -1 then checks whether the number equals the code
+// if not equal -> die saying errmsg
+static int check(int code, const char *errmsg)
+{
+	char *answer;
+
+	// read a string and match it against the set of available answers
+	fflush(stdout);
+	answer = xmalloc_getline(stdin);
+	if (answer) {
+		int n = atoi(answer);
+		if (-1 == code || n == code) {
+			free(answer);
+			return n;
+		}
+	}
+	// TODO!!!: is there more elegant way to terminate child on program failure?
+	if (helper_pid > 0)
+		kill(helper_pid, SIGTERM);
+	if (!answer)
+		answer = (char*)"EOF";
+	else
+		*strchrnul(answer, '\r') = '\0';
+	bb_error_msg_and_die("error at %s: got '%s' instead", errmsg, answer);
+}
+
+static int puts_and_check(const char *msg, int code, const char *errmsg)
+{
+	puts(msg);
+	return check(code, errmsg);
+}
+#endif
+
+int sendmail_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
+int sendmail_main(int argc, char **argv)
+{
+	llist_t *recipients = NULL;
+	llist_t *bodies = NULL;
+	llist_t *attachments = NULL;
+	const char *from;
+	const char *notify;
+	const char *subject;
+	const char *charset = "utf-8";
+#if ENABLE_FEATURE_SENDMAIL_NETWORK
+	const char *wsecs = "10";
+	const char *server = "127.0.0.1";
+	const char *port = NULL;
+	const char *opt_user;
+	const char *opt_pass;
+	unsigned timeout;
+#endif
+	char *boundary;
+	unsigned opts;
+	enum {
+		OPT_f = 1 << 0,         // sender
+		OPT_n = 1 << 2,         // notification
+		OPT_s = 1 << 3,         // subject given
+		OPT_d = 1 << 7,         // dry run - no networking
+		OPT_w = 1 << 8,         // network timeout
+		OPT_h = 1 << 9,         // server
+		OPT_p = 1 << 10,        // port
+		OPT_U = 1 << 11,        // user specified
+		OPT_P = 1 << 12,        // password specified
+	};
+
+	// -f must be specified
+	// -t, -b, -a may be multiple
+	opt_complementary = "f:t::b::a::";
+	opts = getopt32(argv,
+		"f:t:n::s:b:a:c:" USE_FEATURE_SENDMAIL_NETWORK("dw:h:p:U:P:"),
+		&from, &recipients, &notify, &subject, &bodies, &attachments, &charset
+		USE_FEATURE_SENDMAIL_NETWORK(, &wsecs, &server, &port, &opt_user, &opt_pass)
+	);
+	//argc -= optind;
+	argv += optind;
+
+//printf("OPTS[%4x]\n", opts);
+
+	// TODO!!!: strip recipients and sender from <>
+
+	// establish connection
+#if ENABLE_FEATURE_SENDMAIL_NETWORK
+	timeout = xatou(wsecs);
+	if (!(opts & OPT_d)) {
+		// ask password if we need to and while we're still have terminal
+		// TODO: get password directly from /dev/tty? or from a secret file?
+		if ((opts & (OPT_U+OPT_P)) == OPT_U) {
+			if (!isatty(STDIN_FILENO) || !(opt_pass = bb_askpass(0, "Password: "))) {
+				bb_error_msg_and_die("no password");
+			}
+		}
+//printf("OPTS[%4x][%s][%s]\n", opts, opt_user, opt_pass);
+//exit(0);
+		// set chat timeout
+		alarm(timeout);
+		// connect to server
+		if (argv[0]) {
+			// if connection helper given
+			// setup vanilla unidirectional pipes interchange
+			int pipes[4];
+			xpipe(pipes);
+			xpipe(pipes+2);
+			helper_pid = vfork();
+			if (helper_pid < 0)
+				bb_perror_msg_and_die("vfork");
+			xdup2(pipes[(helper_pid)?0:2], STDIN_FILENO);
+			xdup2(pipes[(helper_pid)?3:1], STDOUT_FILENO);
+			if (ENABLE_FEATURE_CLEAN_UP)
+				for (int i = 4; --i >= 0; )
+					if (pipes[i] > STDOUT_FILENO)
+						close(pipes[i]);
+			// replace child with connection helper
+			if (!helper_pid) {
+				// child - try to execute connection helper
+				BB_EXECVP(argv[0], argv);
+				_exit(127);
+			}
+			// parent - check whether child is alive
+			sig_catch(SIGCHLD, signal_handler);
+			sig_catch(SIGALRM, signal_handler);
+			signal_handler(SIGCHLD);
+			// child seems OK -> parent goes on SMTP chat
+		} else {
+			// no connection helper provided -> make plain connect
+			int fd = create_and_connect_stream_or_die(
+				server,
+				bb_lookup_port(port, "tcp", 25)
+			);
+			xmove_fd(fd, STDIN_FILENO);
+			xdup2(STDIN_FILENO, STDOUT_FILENO);
+			// wait for OK
+			check(220, "INIT");
+		}
+		// mail user specified? try modern AUTHentication
+		if (opt_user && (334 == puts_and_check("auth login", -1, "auth login"))) {
+			uuencode_inline(opt_user);
+			puts_and_check("", 334, "AUTH");
+			uuencode_inline(opt_pass);
+			puts_and_check("", 235, "AUTH");
+		// no mail user specified or modern AUTHentication is not supported?
+		} else {
+			// fallback to simple HELO authentication
+			// fetch domain name (defaults to local)
+			const char *domain = strchr(from, '@');
+			if (domain)
+				domain++;
+			else
+				domain = "local";
+			printf("helo %s\n", domain);
+			check(250, "HELO");
+		}
+
+		// set addresses
+		printf("mail from:<%s>\n", from);
+		check(250, "MAIL FROM");
+		for (llist_t *to = recipients; to; to = to->link) {
+			printf("rcpt to:<%s>\n", to->data);
+			check(250, "RCPT TO");
+		}
+		puts_and_check("data", 354, "DATA");
+		// no timeout while sending message
+		alarm(0);
+	}
+#endif
+
+	// now put message
+	// put address headers
+	printf("From: %s\n", from);
+	for (llist_t *to = recipients; to; to = to->link) {
+		printf("To: %s\n", to->data);
+	}
+	// put encoded subject
+	if (opts & OPT_s) {
+		printf("Subject: =?%s?B?", charset);
+		uuencode_inline(subject);
+		puts("?=");
+	}
+	// put notification
+	if (opts & OPT_n) {
+		const char *s = notify;
+		if (!s[0])
+			s = from; // notify sender by default
+		printf("Disposition-Notification-To: %s\n", s);
+	}
+	// put common headers and body start
+	//srand(?);
+	boundary = xasprintf("%d-%d-%d", rand(), rand(), rand());
+	printf(
+		"X-Mailer: busybox " BB_VER " sendmail\n"
+		"X-Priority: 3\n"
+		"Message-ID: <%s>\n"
+		"Mime-Version: 1.0\n"
+		"Content-Type: multipart/mixed; boundary=\"%s\"\n"
+		"\n"
+		"--%s\n"
+		"Content-Type: text/plain; charset=%s\n"
+		"%s\n%s"
+		, boundary, boundary, boundary, charset
+		, "Content-Disposition: inline"
+		, "Content-Transfer-Encoding: base64\n"
+	);
+	// put body(ies)
+	for (llist_t *f = bodies; f; f = f->link) {
+		uuencode(f->data);
+	}
+	// put attachment(s)
+	for (llist_t *f = attachments; f; f = f->link) {
+		printf(
+			"\n--%s\n"
+			"Content-Type: application/octet-stream\n"
+			"%s; filename=\"%s\"\n"
+			"%s"
+			, boundary
+			, "Content-Disposition: inline"
+			, bb_get_last_path_component_strip(f->data)
+			, "Content-Transfer-Encoding: base64\n"
+		);
+		uuencode(f->data);
+	}
+	// put terminator
+	printf("\n--%s--\n\n", boundary);
+	if (ENABLE_FEATURE_CLEAN_UP)
+		free(boundary);
+
+#if ENABLE_FEATURE_SENDMAIL_NETWORK
+	// end message and say goodbye
+	if (!(opts & OPT_d)) {
+		alarm(timeout);
+		puts_and_check(".", 250, "BODY");
+		puts_and_check("quit", 221, "QUIT");
+	}
+#endif
+
+	return 0;
+}