* Add new version of exim's local scan rspamd scanner

1 files changed, 377 insertions, 0 deletions

diff --git a/contrib/exim/local_scan.c.in b/contrib/exim/local_scan.c.in
new file mode 100644
index 000000000..68eec62cd
--- /dev/null
+++ b/contrib/exim/local_scan.c.in
@@ -0,0 +1,377 @@
+/*
+ * This program is RSPAMD agent for use with
+ * exim (http://www.exim.org) MTA by its local_scan feature.
+ *
+ * To enable exim local scan please copy this file to exim source tree
+ * Local/local_scan.c, edit Local/Makefile to add
+ *
+ * LOCAL_SCAN_SOURCE=Local/local_scan.c
+ * LOCAL_SCAN_HAS_OPTIONS=yes
+ *
+ * and compile exim.
+ *
+ * For exim compilation with local scan feature details please visit
+ * http://www.exim.org/exim-html-current/doc/html/spec_html/ch42.html
+ *
+ * For RSPAMD details please visit
+ * https://bitbucket.org/vstakhov/rspamd/
+ *
+ * Example configuration:
+ * **********************
+ *
+ * local_scan_timeout = 50s
+ *
+ * begin local_scan
+ *       rspam_ip = 127.0.0.1
+ *       rspam_port = 11333
+ *       rspam_skip_sasl_authenticated = true
+ *       # don't reject message if on of recipients from this list
+ *       rspam_skip_rcpt = postmaster@example.com : some_user@example.com
+ *       rspam_message = "Spam rejected; If this is not spam, please contact <postmaster@example.com>"
+ *
+ *
+ * $Id: local_scan.c 646 2010-08-11 11:49:36Z ayuzhaninov $
+ */
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/uio.h>
+
+#include <netinet/in.h>
+#include <arpa/inet.h>
+
+#include <errno.h>
+#include <math.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "local_scan.h"
+
+#define REQUEST_LINES	64
+#define REPLY_BUF_SIZE	16384
+#define HEADER_STATUS	"X-Rspam-Status"
+#define HEADER_METRIC	"X-Rspam-Metric"
+#define HEADER_SCORE	"X-Rspam-Score"
+
+/* configuration options */
+static uschar *daemon_ip = US"127.0.0.1";
+static int max_scan_size = 4 * 1024 * 1024;
+static uschar *reject_message = US"Spam message rejected";
+static int daemon_port = 11333;
+static BOOL skip_authenticated = TRUE;
+static uschar *want_spam_rcpt_list = US"";
+
+/* the entries must appear in alphabetical order */
+optionlist local_scan_options[] = {
+	{ "rspam_ip", opt_stringptr, &daemon_ip },
+	{ "rspam_max_scan_size", opt_mkint, &max_scan_size },
+	{ "rspam_message", opt_stringptr, &reject_message },
+	{ "rspam_port", opt_int, &daemon_port },
+	{ "rspam_skip_rcpt", opt_stringptr, &want_spam_rcpt_list },
+	{ "rspam_skip_sasl_authenticated", opt_bool, &skip_authenticated },
+};
+
+int local_scan_options_count = sizeof(local_scan_options) / sizeof(optionlist);
+
+/* push formatted line into vector */
+int push_line(struct iovec *iov, int i, const char *fmt, ...);
+
+int
+local_scan(int fd, uschar **return_text)
+{
+	struct stat sb;
+	struct sockaddr_in server_in;
+	int s, i, r, request_p = 0, headers_count = 0, is_spam = 0, is_reject = 0;
+	off_t message_size;
+	struct iovec request_v[REQUEST_LINES], *headers_v;
+#if "@CMAKE_SYSTEM_NAME@" == "FreeBSD"
+	struct sf_hdtr headers_sf;
+#endif
+	uschar *helo, *log_buf;
+	header_line *header_p;
+	char reply_buf[REPLY_BUF_SIZE], io_buf[BUFSIZ];
+	ssize_t size;
+	char *tok_ptr, *str;
+	char mteric[128], result[8];
+	float score, required_score;
+
+	*return_text = reject_message;
+
+	/*
+	 * one msaage can be send via exim+rspamd twice
+	 * remove header from previous pass
+	 */
+	header_remove(0, US HEADER_STATUS);
+	header_remove(0, US HEADER_METRIC);
+
+	/* check message size */
+	fstat(fd,&sb); /* XXX shuld check error */
+	message_size = sb.st_size - SPOOL_DATA_START_OFFSET;
+	if (message_size > max_scan_size) {
+		header_add(' ', HEADER_STATUS ": skip_big\n");
+		log_write (0, LOG_MAIN, "rspam: message larger than rspam_max_scan_size, accept");
+		return LOCAL_SCAN_ACCEPT;
+	}
+
+	/* don't scan mail from authenticated hosts */
+	if (skip_authenticated && sender_host_authenticated != NULL) {
+		header_add(' ', HEADER_STATUS ": skip_authenticated\n");
+		log_write(0, LOG_MAIN, "rspam: from=<%s> ip=%s authenticated (%s), skip check\n",
+				sender_address,
+				sender_host_address == NULL ? US"localhost" : sender_host_address,
+				sender_host_authenticated);
+		return LOCAL_SCAN_ACCEPT;
+	}
+
+	/*
+	 * add status header, which mean, that message was not scanned
+	 * if message will be scanned, this header will be replaced
+	 */
+	header_add(' ', HEADER_STATUS ": check_error\n");
+
+	/* create socket */
+	memset(&server_in, 0, sizeof(server_in));
+	server_in.sin_family = AF_INET;
+	server_in.sin_port = htons(daemon_port);
+	server_in.sin_addr.s_addr = inet_addr(daemon_ip);
+	if ((s = socket(PF_INET, SOCK_STREAM, 0)) < 0) {
+		log_write(0, LOG_MAIN, "rspam: socket (%d: %s)", errno, strerror(errno));
+		return LOCAL_SCAN_ACCEPT;
+	}
+	if (connect(s, (struct sockaddr *) &server_in, sizeof(server_in)) < 0) {
+		close(s);
+		log_write(0, LOG_MAIN, "rspam: can't connect to %s:%d (%d: %s)", daemon_ip, daemon_port, errno, strerror(errno));
+		return LOCAL_SCAN_ACCEPT;
+	}
+
+	/* count message headers */
+	for (header_p = header_list; header_p != NULL; header_p = header_p->next) {
+		/* header type '*' is used for replaced or deleted header */
+		if (header_p->type == '*')
+			continue;
+		headers_count++;
+	}
+
+	/* write message headers to vector */
+#if "@CMAKE_SYSTEM_NAME@" == "FreeBSD"
+	memset(&headers_sf, 0, sizeof(headers_sf));
+	if (headers_count > 0) {
+		headers_v = store_get((headers_count + 1)* sizeof(*headers_v));
+		i = 0;
+		for (header_p = header_list; header_p != NULL; header_p = header_p->next) {
+			if (header_p->type == '*')
+				continue;
+			headers_v[i].iov_base = header_p->text;
+			headers_v[i].iov_len = header_p->slen;
+			i++;
+			message_size += header_p->slen;
+		}
+		headers_v[i].iov_base = "\n";
+		headers_v[i].iov_len = strlen("\n");
+		message_size += strlen("\n");
+
+		headers_sf.headers = headers_v;
+		headers_sf.hdr_cnt = headers_count + 1;
+	}
+#else
+	if (headers_count > 0) {
+		headers_v = store_get((headers_count + 1)* sizeof(*headers_v));
+		i = 0;
+		for (header_p = header_list; header_p != NULL; header_p = header_p->next) {
+			if (header_p->type == '*')
+				continue;
+			headers_v[i].iov_base = header_p->text;
+			headers_v[i].iov_len = header_p->slen;
+			i++;
+			message_size += header_p->slen;
+		}
+		headers_v[i].iov_base = "\n";
+		headers_v[i].iov_len = strlen("\n");
+		message_size += strlen("\n");
+#endif
+
+	/* write request to vector */
+	r = 0;
+	r += push_line(request_v, request_p++, "SYMBOLS RSPAMC/1.1\r\n");
+	r += push_line(request_v, request_p++, "Content-length: " OFF_T_FMT "\r\n", message_size);
+	r += push_line(request_v, request_p++, "Queue-Id: %s\r\n", message_id);
+	r += push_line(request_v, request_p++, "From: %s\r\n", sender_address);
+	r += push_line(request_v, request_p++, "Recipient-Number: %d\r\n", recipients_count);
+	for (i = 0; i < recipients_count; i ++)
+		r += push_line(request_v, request_p++, "Rcpt: %s\r\n", recipients_list[i].address);
+	if ((helo = expand_string(US"$sender_helo_name")) != NULL && *helo != '\0')
+		r += push_line(request_v, request_p++, "Helo: %s\r\n", helo);
+	if (sender_host_address != NULL)
+		r += push_line(request_v, request_p++, "IP: %s\r\n", sender_host_address);
+	r += push_line(request_v, request_p++, "\r\n");
+
+	if (r < 0) {
+		close(s);
+		return LOCAL_SCAN_ACCEPT;
+	}
+
+	/* send request */
+	if (writev(s, request_v, request_p) < 0) {
+		close(s);
+		log_write(0, LOG_MAIN, "rspam: can't send request to %s:%d (%d: %s)", daemon_ip, daemon_port, errno, strerror(errno));
+		return LOCAL_SCAN_ACCEPT;
+	}
+
+#if "@CMAKE_SYSTEM_NAME@" == "FreeBSD"
+	/* send headers (from iovec) and message body (from file) */
+	if (sendfile(fd, s, SPOOL_DATA_START_OFFSET, 0, &headers_sf, NULL, 0) < 0) {
+		close(s);
+		log_write(0, LOG_MAIN, "rspam: can't send message to %s:%d (%d: %s)", daemon_ip, daemon_port, errno, strerror(errno));
+		return LOCAL_SCAN_ACCEPT;
+	}
+#else
+	/* send headers */
+	if (writev(s, headers_v, headers_count) < 0) {
+		close(s);
+		log_write(0, LOG_MAIN, "rspam: can't send headers to %s:%d (%d: %s)", daemon_ip, daemon_port, errno, strerror(errno));
+		return LOCAL_SCAN_ACCEPT;
+	}
+
+	/* Send message */
+	while ((r = read (fd, io_buf, sizeof (io_buf))) > 0) {
+		if (write (s, io_buf, r) < 0) {
+			close(s);
+			log_write(0, LOG_MAIN, "rspam: can't send message to %s:%d (%d: %s)", daemon_ip, daemon_port, errno, strerror(errno));
+			return LOCAL_SCAN_ACCEPT;
+		}	
+	}
+#endif
+
+	/* read reply from rspamd */
+	reply_buf[0] = '\0';
+	size = 0;
+	while ((r = read(s, reply_buf + size, sizeof(reply_buf) - size - 1)) > 0 && size < sizeof(reply_buf) - 1) {
+		size += r;
+	}
+
+	if (r < 0) {
+		close(s);
+		log_write(0, LOG_MAIN, "rspam: can't read from %s:%d (%d: %s)", daemon_ip, daemon_port, errno, strerror(errno));
+		return LOCAL_SCAN_ACCEPT;
+	}
+	reply_buf[size] = '\0';
+	close(s);
+
+	if (size >= REPLY_BUF_SIZE - 1) {
+		log_write(0, LOG_MAIN, "rspam: buffer is full, reply may be truncated");
+	}
+
+	/* parse reply */
+	tok_ptr = reply_buf;
+
+	/*
+	 * rspamd can use several metrics, logic implimented here:
+	 * if any metric more than reject_score - will reject
+	 * if any metric true - message will be marked as spam
+	 */
+
+	/* First line is: <PROTOCOL>/<VERSION> <ERROR_CODE> <ERROR_REPLY> */
+	str = strsep(&tok_ptr, "\r\n");
+	if (str != NULL && sscanf(str, "%*s %d %*s", &i) == 1) {
+		if (i != 0) {
+			log_write(0, LOG_MAIN, "rspam: server error: %s", str);
+			return LOCAL_SCAN_ACCEPT;
+		}
+	} else {
+		log_write(0, LOG_MAIN, "rspam: bad reply from server: %s", str);
+		return LOCAL_SCAN_ACCEPT;
+	}
+
+	while ((str = strsep(&tok_ptr, "\r\n")) != NULL) {
+		/* skip empty tockens */
+		if (*str == '\0')
+			continue;
+		if (strncmp(str, "Metric:", strlen("Metric:")) == 0) {
+			/*
+			 * parse line like
+			 * Metric: default; False; 27.00 / 30.00
+			 */
+			if (sscanf(str, "Metric: %s %s %f / %f",
+				mteric, result, &score, &required_score) == 4) {
+				log_write(0, LOG_MAIN, "rspam: metric %s %s %.2f / %.2f",
+					mteric, result, score, required_score);
+				header_add(' ', HEADER_METRIC ": %s %s %.2f / %.2f\n",
+					mteric, result, score, required_score);
+				/* integers score for use in sieve ascii-numeric comparator */
+				if (strcmp(mteric, "default;") == 0)
+					 header_add(' ', HEADER_SCORE ": %d\n",
+						(int)round(score));
+			} else {
+				log_write(0, LOG_MAIN, "rspam: can't parse: %s", str);
+				return LOCAL_SCAN_ACCEPT;
+			}
+		} else if (strncmp(str, "Action:", strlen("Action:")) == 0) {
+			/* line like Action: add header */
+			str += strlen("Action: ");
+			if (strncmp(str, "reject", strlen("reject")) == 0) {
+				is_reject = 1;
+				is_spam = 1;
+			} else if (strncmp(str, "add header", strlen("add header")) == 0) {
+				is_spam = 1;
+			}
+		}
+	}
+
+	/* XXX many allocs by string_sprintf()
+	 * better to sprintf() to single buffer allocated by store_get()
+	 */
+	log_buf = string_sprintf("message to");
+	for (i = 0; i < recipients_count; i ++) {
+		log_buf = string_sprintf("%s %s", log_buf, recipients_list[i].address);
+		if (is_reject && lss_match_address(recipients_list[i].address, want_spam_rcpt_list, TRUE) == OK) {
+			is_reject = 0;
+			log_write(0, LOG_MAIN, "rspam: %s want spam, don't reject this message", recipients_list[i].address);
+		}
+	}
+
+	if (is_reject) {
+		log_write(0, LOG_MAIN, "rspam: reject %s", log_buf);
+		return LOCAL_SCAN_REJECT;
+	}
+
+	header_remove(0, US HEADER_STATUS);
+	if (is_spam) {
+		header_add(' ', HEADER_STATUS ": spam\n");
+		log_write(0, LOG_MAIN, "rspam: message marked as spam");
+	} else {
+		header_add(' ', HEADER_STATUS ": ham\n");
+		log_write(0, LOG_MAIN, "rspam: message marked as ham");
+	}
+
+	return LOCAL_SCAN_ACCEPT;
+}
+
+int
+push_line(struct iovec *iov, const int i, const char *fmt, ...)
+{
+	va_list ap;
+	size_t len;
+	char buf[512];
+
+	if (i >= REQUEST_LINES) {
+		log_write(0, LOG_MAIN, "rspam: %s: index out of bounds", __FUNCTION__);
+		return (-1);
+	}
+
+	va_start(ap, fmt);
+	len = vsnprintf(buf, sizeof(buf), fmt, ap);
+	va_end(ap);
+
+	iov[i].iov_base = string_copy(US buf);
+	iov[i].iov_len = len;
+
+	if (len >= sizeof(buf)) {
+		log_write(0, LOG_MAIN, "rspam: %s: error, string was longer than %d", __FUNCTION__, sizeof(buf));
+		return (-1);
+	}
+
+	return 0;
+}
+