lib-smtp: Implemented parsing and encoding for common SMTP syntax ele…

…ments.

src/lib-smtp/Makefile.am

@@ -13,13 +13,15 @@ AM_CPPFLAGS = \
 libsmtp_la_SOURCES = \
 	smtp-parser.c \
 	smtp-address.c \
+	smtp-syntax.c \
 	lmtp-client.c \
 	smtp-submit-settings.c \
 	smtp-submit.c
 
 headers = \
 	smtp-parser.h \
 	smtp-address.h \
+	smtp-syntax.h \
 	lmtp-client.h \
 	smtp-submit-settings.h \
 	smtp-submit.h

src/lib-smtp/smtp-syntax.c

@@ -0,0 +1,258 @@
+/* Copyright (c) 2013-2017 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "str.h"
+#include "array.h"
+#include "smtp-parser.h"
+
+#include "smtp-syntax.h"
+
+#include <ctype.h>
+
+/*
+ * String
+ */
+
+int smtp_string_parse(const char *string,
+	const char **value_r, const char **error_r)
+{
+	struct smtp_parser parser;
+	int ret;
+
+	if (string == NULL || *string == '\0') {
+		*value_r = "";
+		return 1;
+	}
+
+	smtp_parser_init(&parser, pool_datastack_create(), string);
+
+	if ((ret=smtp_parser_parse_string(&parser, value_r)) < 0) {
+		if (error_r != NULL)
+			*error_r = parser.error;
+		return -1;
+	}
+	if (parser.cur < parser.end) {
+		*error_r = "Invalid character in string";
+		return -1;
+	}
+	return 1;
+}
+
+void smtp_string_write(string_t *out, const char *value)
+{
+	bool quoted = FALSE;
+	const unsigned char *p, *pend, *pblock;
+	size_t begin = str_len(out);
+
+	if (value == NULL)
+		return;
+	p = (const unsigned char *)value;
+	pend = p + strlen(value);
+	while (p < pend) {
+		pblock = p;
+		while (p < pend && smtp_char_is_atext(*p))
+			p++;
+
+		if (!quoted && p < pend) {
+			quoted = TRUE;
+			str_insert(out, begin, "\"");
+		}
+
+		str_append_n(out, pblock, p-pblock);
+		if (p >= pend)
+			break;
+
+		i_assert(quoted);
+		i_assert(smtp_char_is_qpair(*p));
+
+		if (!smtp_char_is_qtext(*p))
+			str_append_c(out, '\\');
+		str_append_c(out, *p);
+
+		p++;
+	}
+
+	if (quoted)
+		str_append_c(out, '\"');
+}
+
+/*
+ * Xtext encoding
+ */
+
+int smtp_xtext_parse(const char *xtext,
+	const char **value_r, const char **error_r)
+{
+	struct smtp_parser parser;
+	string_t *value = NULL;
+	int ret;
+
+	if (xtext == NULL || *xtext == '\0') {
+		*value_r = "";
+		return 1;
+	}
+
+	if (value_r != NULL)
+		value = t_str_new(256);
+	smtp_parser_init(&parser, pool_datastack_create(), xtext);
+
+	if ((ret=smtp_parser_parse_xtext(&parser, value)) < 0) {
+		if (error_r != NULL)
+			*error_r = parser.error;
+		return -1;
+	}
+	if (parser.cur < parser.end) {
+		*error_r = "Invalid character in xtext";
+		return -1;
+	}
+
+	if (value_r != NULL) {
+		*value_r = str_c(value);
+		if (strlen(*value_r) != str_len(value)) {
+			if (*error_r != NULL)
+				*error_r = "Encountered NUL character in xtext";
+			return -1;
+		}
+	}
+	return 1;
+}
+
+void smtp_xtext_encode(string_t *out, const unsigned char *data,
+	size_t size)
+{
+	const unsigned char *p, *pbegin, *pend;
+
+	p = data;
+	pend = p + size;
+	while (p < pend) {
+		pbegin = p;
+		while (p < pend && smtp_char_is_xtext(*p))
+			p++;
+
+		str_append_n(out, pbegin, p-pbegin);
+		if (p >= pend)
+			break;
+
+		str_printfa(out, "+%02X", (unsigned int)*p);
+		p++;
+	}
+}
+
+/*
+ * HELO domain
+ */
+
+int smtp_helo_domain_parse(const char *helo,
+	bool allow_literal, const char **domain_r)
+{
+	struct smtp_parser parser;
+	int ret;
+
+	smtp_parser_init(&parser, pool_datastack_create(), helo);
+
+	if ((ret=smtp_parser_parse_domain(&parser, domain_r)) == 0) {
+		if (allow_literal)
+			ret = smtp_parser_parse_address_literal(&parser, domain_r, NULL);
+	}
+
+	if (ret <= 0 || (parser.cur < parser.end && *parser.cur != ' '))
+		return -1;
+
+	return 0;
+}
+
+/*
+ * EHLO reply
+ */
+
+static int smtp_parse_ehlo_line(struct smtp_parser *parser,
+	const char **key_r, const char *const **params_r)
+{
+	const unsigned char *pbegin = parser->cur;
+	ARRAY_TYPE(const_string) params = ARRAY_INIT;
+	const char *param;
+
+	/*
+	   ehlo-line      = ehlo-keyword *( SP ehlo-param )
+	   ehlo-keyword   = (ALPHA / DIGIT) *(ALPHA / DIGIT / "-")
+	                    ; additional syntax of ehlo-params depends on
+	                    ; ehlo-keyword
+	   ehlo-param     = 1*(%d33-126)
+	                    ; any CHAR excluding <SP> and all
+	                    ; control characters (US-ASCII 0-31 and 127
+	                    ; inclusive)
+	 */
+
+	if (parser->cur >= parser->end || !i_isalnum(*parser->cur)) {
+		parser->error = "Unexpected character in EHLO keyword";
+		return -1;
+	}
+	parser->cur++;
+
+	while (parser->cur < parser->end &&
+		(i_isalnum(*parser->cur) || *parser->cur == '-'))
+		parser->cur++;
+
+	if (key_r != NULL)
+		*key_r = p_strdup_until(parser->pool, pbegin, parser->cur);
+
+	if (parser->cur >= parser->end) {
+		if (params_r != NULL)
+			*params_r = p_new(parser->pool, const char *, 1);
+		return 1;
+	}
+	if (*parser->cur != ' ') {
+		parser->error = "Unexpected character in EHLO keyword";
+		return -1;
+	}
+	parser->cur++;
+
+	pbegin = parser->cur;
+	if (params_r != NULL)
+		p_array_init(&params, parser->pool, 32);
+	while (parser->cur < parser->end) {
+		if (*parser->cur == ' ') {
+			if (parser->cur+1 >= parser->end || *(parser->cur+1) == ' ') {
+				parser->error = "Missing EHLO parameter after ' '";
+				return -1;
+			}
+			if (params_r != NULL) {
+				param = p_strdup_until(parser->pool, pbegin, parser->cur);
+				array_append(&params, &param, 1);
+			}
+			pbegin = parser->cur + 1;
+		} else if (!smtp_char_is_ehlo_param(*parser->cur)) {
+			parser->error = "Unexpected character in EHLO parameter";
+			return -1;
+		}
+		parser->cur++;
+	}
+
+	if (params_r != NULL) {
+		array_append_zero(&params);
+		*params_r = array_idx(&params, 0);
+	}
+	return 1;
+}
+
+int smtp_ehlo_line_parse(const char *ehlo_line, const char **key_r,
+	const char *const **params_r, const char **error_r)
+{
+	struct smtp_parser parser;
+	int ret;
+
+	if (ehlo_line == NULL || *ehlo_line == '\0') {
+		if (error_r != NULL)
+			*error_r = "Parameter is empty";
+		return -1;
+	}
+
+	smtp_parser_init(&parser, pool_datastack_create(), ehlo_line);
+
+	if ((ret=smtp_parse_ehlo_line(&parser, key_r, params_r)) <= 0) {
+		if (error_r != NULL)
+			*error_r = parser.error;
+		return -1;
+	}
+	return 1;
+}

src/lib-smtp/smtp-syntax.h

@@ -0,0 +1,45 @@
+#ifndef SMTP_SYNTAX_H
+#define SMTP_SYNTAX_H
+
+struct smtp_parser;
+
+/*
+ * String
+ */
+
+int smtp_string_parse(const char *string,
+	const char **value_r, const char **error_r);
+void smtp_string_write(string_t *out, const char *value);
+
+/*
+ * Xtext encoding
+ */
+
+int smtp_xtext_parse(const char *xtext,
+	const char **value_r, const char **error_r);
+
+void smtp_xtext_encode(string_t *out,
+	const unsigned char *data, size_t size);
+static inline void
+smtp_xtext_encode_cstr(string_t *out, const char *data)
+{
+	smtp_xtext_encode(out,
+		(const unsigned char *)data, strlen(data));
+}
+
+/*
+ * HELO domain
+ */
+
+int smtp_helo_domain_parse(const char *helo,
+	bool allow_literal, const char **domain_r);
+
+/*
+ * EHLO reply
+ */
+
+int smtp_ehlo_line_parse(const char *ehlo_line,
+	const char **key_r, const char *const **params_r,
+	const char **error_r);
+
+#endif