First experimental implementation of ESMTP, HELO fallback and various improvements

conf.c

@@ -38,6 +38,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <ctype.h>
 #include <syslog.h>
 #include <stdarg.h>
 
@@ -74,12 +75,34 @@ trim_line(char *line)
 static void
 chomp(char *str)
 {
+	char *p;
+	size_t i;
 	size_t len = strlen(str);
 
+	/* remove trailing spaces */
+	for (i = 0; i < len; i++) {
+		if (!isspace(str[i]))
+		    break;
+	}
+
+	memmove(str, str + i, len + 1 - i);
+	len -= i;
 	if (len == 0)
 		return;
-	if (str[len - 1] == '\n')
-		str[len - 1] = 0;
+
+	/* remove ending spaces (also handles ending '\n', if any) */
+	while (len-- > 0) {
+		if (!isspace(str[len]))
+			break;
+	}
+
+	str[len + 1] = 0;
+
+	/* remove comments */
+	p = strchr(str, '#');
+	if (p) {
+		*p = 0;
+	}
 }
 
 /*
@@ -88,7 +111,7 @@ chomp(char *str)
  * file format is:
  * user|host:password
  *
- * A line starting with # is treated as comment and ignored.
+ * Anything following a # is treated as comment and ignored.
  */
 void
 parse_authfile(const char *path)
@@ -97,6 +120,7 @@ parse_authfile(const char *path)
 	struct authuser *au;
 	FILE *a;
 	char *data;
+	int error;
 	int lineno = 0;
 
 	a = fopen(path, "r");
@@ -105,16 +129,11 @@ parse_authfile(const char *path)
 		/* NOTREACHED */
 	}
 
-	while (!feof(a)) {
-		if (fgets(line, sizeof(line), a) == NULL)
-			break;
+	while (fgets(line, sizeof(line), a)) {
 		lineno++;
 
 		chomp(line);
 
-		/* We hit a comment */
-		if (*line == '#')
-			continue;
 		/* Ignore empty lines */
 		if (*line == 0)
 			continue;
@@ -138,8 +157,14 @@ parse_authfile(const char *path)
 
 		SLIST_INSERT_HEAD(&authusers, au, next);
 	}
-
+
+	error = ferror(a);
 	fclose(a);
+
+	if (error) {
+		errlog(1, "I/O error while reading file `%s'", path);
+		/* NOTREACHED */
+	}
 }
 
 /*
@@ -153,6 +178,7 @@ parse_conf(const char *config_path)
 	char *data;
 	FILE *conf;
 	char line[2048];
+	int error;
 	int lineno = 0;
 
 	conf = fopen(config_path, "r");
@@ -164,17 +190,11 @@ parse_conf(const char *config_path)
 		/* NOTREACHED */
 	}
 
-	while (!feof(conf)) {
-		if (fgets(line, sizeof(line), conf) == NULL)
-			break;
+	while (fgets(line, sizeof(line), conf)) {
 		lineno++;
 
 		chomp(line);
 
-		/* We hit a comment */
-		if (strchr(line, '#'))
-			*strchr(line, '#') = 0;
-
 		data = line;
 		word = strsep(&data, EQS);
 
@@ -186,12 +206,20 @@ parse_conf(const char *config_path)
 			data = strdup(data);
 		else
 			data = NULL;
-
+		
 		if (strcmp(word, "SMARTHOST") == 0 && data != NULL)
 			config.smarthost = data;
-		else if (strcmp(word, "PORT") == 0 && data != NULL)
-			config.port = atoi(data);
-		else if (strcmp(word, "ALIASES") == 0 && data != NULL)
+		else if (strcmp(word, "PORT") == 0 && data != NULL) {
+			char*check;
+			long port = strtol(data, &check, 10);
+
+			if (*check != '\0' || port < 0 || port > 0xffff) {
+				errlogx(1, "invalid value for PORT in %s:%d", config_path, lineno);
+				/* NOTREACHED */
+			}
+
+			config.port = (unsigned int)port;
+		} else if (strcmp(word, "ALIASES") == 0 && data != NULL)
 			config.aliases = data;
 		else if (strcmp(word, "SPOOLDIR") == 0 && data != NULL)
 			config.spooldir = data;
@@ -217,8 +245,12 @@ parse_conf(const char *config_path)
                                 user = NULL;
 			config.masquerade_host = host;
 			config.masquerade_user = user;
-		} else if (strcmp(word, "STARTTLS") == 0 && data == NULL)
+		} else if (strcmp(word, "VERBOSE") == 0 && data == NULL)
+			config.features |= VERBOSE;
+		else if (strcmp(word, "STARTTLS") == 0 && data == NULL)
 			config.features |= STARTTLS;
+		else if (strcmp(word, "NOHELO") == 0 && data == NULL)
+			config.features |= NOHELO;
 		else if (strcmp(word, "OPPORTUNISTIC_TLS") == 0 && data == NULL)
 			config.features |= TLS_OPP;
 		else if (strcmp(word, "SECURETRANSFER") == 0 && data == NULL)
@@ -235,5 +267,19 @@ parse_conf(const char *config_path)
 		}
 	}
 
+	error = ferror(conf);
 	fclose(conf);
+
+	if (error) {
+		errlog(1, "I/O error while reading file `%s'", config_path);
+		/* NOTREACHED */
+	}
+
+	/* ensure a meaningful configuration */
+	if ((config.features & STARTTLS) != 0) {
+		if ((config.features & SECURETRANS) == 0) {
+			syslog(LOG_WARNING, "STARTTLS enabled in `%s', implicitly assuming SECURETRANSFER is enabled", config_path);
+			config.features |= SECURETRANS;
+		}
+	}
 }

crypto.c

@@ -40,6 +40,7 @@
 #include <openssl/pem.h>
 #include <openssl/rand.h>
 
+#include <string.h>
 #include <syslog.h>
 
 #include "dma.h"
@@ -77,7 +78,7 @@ init_cert_file(SSL_CTX *ctx, const char *path)
 }
 
 int
-smtp_init_crypto(int fd, int feature)
+smtp_init_crypto(struct connection *c)
 {
 	SSL_CTX *ctx = NULL;
 	const SSL_METHOD *meth = NULL;
@@ -107,64 +108,70 @@ smtp_init_crypto(int fd, int feature)
 	}
 
 	/*
-	 * If the user wants STARTTLS, we have to send EHLO here
+	 * If STARTTLS is required, issue it here
 	 */
-	if (((feature & SECURETRANS) != 0) &&
-	     (feature & STARTTLS) != 0) {
-		/* TLS init phase, disable SSL_write */
-		config.features |= NOSSL;
-
-		send_remote_command(fd, "EHLO %s", hostname());
-		if (read_remote(fd, 0, NULL) == 2) {
-			send_remote_command(fd, "STARTTLS");
-			if (read_remote(fd, 0, NULL) != 2) {
-				if ((feature & TLS_OPP) == 0) {
-					syslog(LOG_ERR, "remote delivery deferred: STARTTLS not available: %s", neterr);
-					return (1);
-				} else {
-					syslog(LOG_INFO, "in opportunistic TLS mode, STARTTLS not available: %s", neterr);
-					return (0);
-				}
+	if ((config.features & STARTTLS) != 0) {
+		/* TLS init phase */
+		if ((c->flags & HASSTARTTLS) != 0) {
+			send_remote_command(c, "STARTTLS");
+			if (read_remote(c, NULL, NULL) != 220) {
+				/* even in opportunistic TLS, if server marked it as available, an error
+				* is unexpected
+				*/
+				syslog(LOG_ERR, "remote delivery deferred: STARTTLS failed: %s", neterr);
+				return (1);
 			}
+
+			/* End of TLS init phase */	
+			c->flags |= USESTARTTLS;
+		} else {
+			if ((config.features & TLS_OPP) == 0) {
+				/* remote has no STARTTLS but user required it */
+				syslog(LOG_ERR, "remote delivery deferred: STARTTLS not available");
+				return (1);
+			}
+
+			/* disable STARTTLS, opportunistic mode */
+			syslog(LOG_INFO, "in opportunistic TLS mode, STARTTLS not available");
 		}
-		/* End of TLS init phase, enable SSL_write/read */
-		config.features &= ~NOSSL;
 	}
 
-	config.ssl = SSL_new(ctx);
-	if (config.ssl == NULL) {
+	c->ssl = SSL_new(ctx);
+	if (c->ssl == NULL) {
 		syslog(LOG_NOTICE, "remote delivery deferred: SSL struct creation failed: %s",
 		       ssl_errstr());
 		return (1);
 	}
 
 	/* Set ssl to work in client mode */
-	SSL_set_connect_state(config.ssl);
+	SSL_set_connect_state(c->ssl);
 
 	/* Set fd for SSL in/output */
-	error = SSL_set_fd(config.ssl, fd);
+	error = SSL_set_fd(c->ssl, c->fd);
 	if (error == 0) {
 		syslog(LOG_NOTICE, "remote delivery deferred: SSL set fd failed: %s",
 		       ssl_errstr());
 		return (1);
 	}
 
 	/* Open SSL connection */
-	error = SSL_connect(config.ssl);
+	error = SSL_connect(c->ssl);
 	if (error < 0) {
 		syslog(LOG_ERR, "remote delivery deferred: SSL handshake failed fatally: %s",
 		       ssl_errstr());
 		return (1);
 	}
 
 	/* Get peer certificate */
-	cert = SSL_get_peer_certificate(config.ssl);
+	cert = SSL_get_peer_certificate(c->ssl);
 	if (cert == NULL) {
 		syslog(LOG_WARNING, "remote delivery deferred: Peer did not provide certificate: %s",
 		       ssl_errstr());
 	}
 	X509_free(cert);
-
+
+	/* At this point we can safely use SSL write/read*/
+	c->flags |= USESSL;
 	return (0);
 }
 
@@ -217,10 +224,10 @@ hmac_md5(unsigned char *text, int text_len, unsigned char *key, int key_len,
          */
 
         /* start out by storing key in pads */
-        bzero( k_ipad, sizeof k_ipad);
-        bzero( k_opad, sizeof k_opad);
-        bcopy( key, k_ipad, key_len);
-        bcopy( key, k_opad, key_len);
+        memset(k_ipad, 0, sizeof(k_ipad));
+        memset(k_opad, 0, sizeof(k_opad));
+        memcpy(k_ipad, key, key_len);
+        memcpy(k_opad, key, key_len);
 
         /* XOR key with ipad and opad values */
         for (i=0; i<64; i++) {
@@ -250,27 +257,40 @@ hmac_md5(unsigned char *text, int text_len, unsigned char *key, int key_len,
  * CRAM-MD5 authentication
  */
 int
-smtp_auth_md5(int fd, char *login, char *password)
+smtp_auth_md5(struct connection *c, char *login, char *password)
 {
 	unsigned char digest[BUF_SIZE];
 	char buffer[BUF_SIZE], ascii_digest[33];
 	char *temp;
 	int len, i;
+	size_t buffsize = sizeof(buffer);
 	static char hextab[] = "0123456789abcdef";
-
-	temp = calloc(BUF_SIZE, 1);
+
 	memset(buffer, 0, sizeof(buffer));
 	memset(digest, 0, sizeof(digest));
 	memset(ascii_digest, 0, sizeof(ascii_digest));
 
 	/* Send AUTH command according to RFC 2554 */
-	send_remote_command(fd, "AUTH CRAM-MD5");
-	if (read_remote(fd, sizeof(buffer), buffer) != 3) {
-		syslog(LOG_DEBUG, "smarthost authentication:"
-		       " AUTH cram-md5 not available: %s", neterr);
+	send_remote_command(c, "AUTH CRAM-MD5");
+	if (read_remote(c, &buffsize, buffer) != 334) {
 		/* if cram-md5 is not available */
-		free(temp);
-		return (-1);
+		syslog(LOG_DEBUG, "smarthost authentication:"
+		       " AUTH CRAM-MD5 failed: %s", neterr);
+		return (1);
+	}
+
+	if (buffsize > sizeof(buffer)) {
+		syslog(LOG_DEBUG, "smarthost authentication:"
+		       " oversized response to AUTH CRAM-MD5");
+		return (1);
+	}
+
+	/* allocate decoding buffer */
+	temp = calloc(BUF_SIZE, 1);
+	if (!temp) {
+	      syslog(LOG_WARNING, "remote delivery deferred:"
+	                          " memory allocation failed");
+	      return (1);
 	}
 
 	/* skip 3 char status + 1 char space */
@@ -291,17 +311,17 @@ smtp_auth_md5(int fd, char *login, char *password)
 	/* encode answer */
 	len = base64_encode(buffer, strlen(buffer), &temp);
 	if (len < 0) {
-		syslog(LOG_ERR, "can not encode auth reply: %m");
-		return (-1);
+		syslog(LOG_ERR, "cannot encode auth reply: %m");
+		return (1);
 	}
 
 	/* send answer */
-	send_remote_command(fd, "%s", temp);
+	send_remote_command(c, "%s", temp);
 	free(temp);
-	if (read_remote(fd, 0, NULL) != 2) {
+	if (read_remote(c, NULL, NULL) != 220) {
 		syslog(LOG_WARNING, "remote delivery deferred:"
-				" AUTH cram-md5 failed: %s", neterr);
-		return (-2);
+				" AUTH CRAM-MD5 failed: %s", neterr);
+		return (1);
 	}
 
 	return (0);