1 files changed, 283 insertions, 0 deletions
diff --git a/src/lib-mail/message-date.c b/src/lib-mail/message-date.c
new file mode 100644
index 0000000..7a7529a
--- /dev/null
+++ b/src/lib-mail/message-date.c
@@ -0,0 +1,283 @@
+/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */
+
+#include "lib.h"
+#include "str.h"
+#include "utc-offset.h"
+#include "utc-mktime.h"
+#include "rfc822-parser.h"
+#include "message-date.h"
+
+#include <ctype.h>
+
+/* RFC specifies ':' as the only allowed separator,
+   but be forgiving also for some broken ones */
+#define IS_TIME_SEP(c) \
+	((c) == ':' || (c) == '.')
+
+struct message_date_parser_context {
+	struct rfc822_parser_context parser;
+	string_t *str;
+};
+
+static const char *month_names[] = {
+	"Jan", "Feb", "Mar", "Apr", "May", "Jun",
+	"Jul", "Aug", "Sep", "Oct", "Nov", "Dec"
+};
+
+static const char *weekday_names[] = {
+	"Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"
+};
+
+static int parse_timezone(const unsigned char *str, size_t len)
+{
+	int offset;
+	char chr;
+
+	if (len == 5 && (*str == '+' || *str == '-')) {
+		/* numeric offset */
+		if (!i_isdigit(str[1]) || !i_isdigit(str[2]) ||
+		    !i_isdigit(str[3]) || !i_isdigit(str[4]))
+			return 0;
+
+		offset = ((str[1]-'0') * 10 + (str[2]-'0')) * 60  +
+			(str[3]-'0') * 10 + (str[4]-'0');
+		return *str == '+' ? offset : -offset;
+	}
+
+	if (len == 1) {
+		/* military zone - handle them the correct way, not as
+		   RFC822 says. RFC2822 though suggests that they'd be
+		   considered as unspecified.. */
+		chr = i_toupper(*str);
+		if (chr < 'J')
+			return (*str-'A'+1) * 60;
+		if (chr == 'J')
+			return 0;
+		if (chr <= 'M')
+			return (*str-'A') * 60;
+		if (chr < 'Z')
+			return ('M'-*str) * 60;
+		return 0;
+	}
+
+	if (len == 2 && i_toupper(str[0]) == 'U' && i_toupper(str[1]) == 'T') {
+		/* UT - Universal Time */
+		return 0;
+	}
+
+	if (len == 3) {
+		/* GMT | [ECMP][DS]T */
+		if (str[2] != 'T')
+			return 0;
+
+		switch (i_toupper(*str)) {
+		case 'E':
+			offset = -5 * 60;
+			break;
+		case 'C':
+			offset = -6 * 60;
+			break;
+		case 'M':
+			offset = -7 * 60;
+			break;
+		case 'P':
+			offset = -8 * 60;
+			break;
+		default:
+			/* GMT and others */
+			return 0;
+		}
+
+		if (i_toupper(str[1]) == 'D')
+			return offset + 60;
+		if (i_toupper(str[1]) == 'S')
+			return offset;
+	}
+
+	return 0;
+}
+
+static int next_token(struct message_date_parser_context *ctx,
+		      const unsigned char **value, size_t *value_len)
+{
+	int ret;
+
+	str_truncate(ctx->str, 0);
+	ret = ctx->parser.data >= ctx->parser.end ? 0 :
+		rfc822_parse_atom(&ctx->parser, ctx->str);
+
+	*value = str_data(ctx->str);
+	*value_len = str_len(ctx->str);
+	return ret < 0 ? -1 : *value_len > 0;
+}
+
+static bool
+message_date_parser_tokens(struct message_date_parser_context *ctx,
+			   time_t *timestamp_r, int *timezone_offset_r)
+{
+	struct tm tm;
+	const unsigned char *value;
+	size_t i, len;
+	int ret;
+
+	/* [weekday_name "," ] dd month_name [yy]yy hh:mi[:ss] timezone */
+	i_zero(&tm);
+
+        rfc822_skip_lwsp(&ctx->parser);
+
+	/* skip the optional weekday */
+	if (next_token(ctx, &value, &len) <= 0)
+		return FALSE;
+	if (len == 3) {
+		if (*ctx->parser.data != ',')
+			return FALSE;
+		ctx->parser.data++;
+		rfc822_skip_lwsp(&ctx->parser);
+
+		if (next_token(ctx, &value, &len) <= 0)
+			return FALSE;
+	}
+
+	/* dd */
+	if (len < 1 || len > 2 || !i_isdigit(value[0]))
+		return FALSE;
+
+	tm.tm_mday = value[0]-'0';
+	if (len == 2) {
+		if (!i_isdigit(value[1]))
+			return FALSE;
+		tm.tm_mday = (tm.tm_mday * 10) + (value[1]-'0');
+	}
+
+	/* month name */
+	if (next_token(ctx, &value, &len) <= 0 || len < 3)
+		return FALSE;
+
+	for (i = 0; i < 12; i++) {
+		if (i_memcasecmp(month_names[i], value, 3) == 0) {
+			tm.tm_mon = i;
+			break;
+		}
+	}
+	if (i == 12)
+		return FALSE;
+
+	/* [yy]yy */
+	if (next_token(ctx, &value, &len) <= 0 || (len != 2 && len != 4))
+		return FALSE;
+
+	for (i = 0; i < len; i++) {
+		if (!i_isdigit(value[i]))
+			return FALSE;
+		tm.tm_year = tm.tm_year * 10 + (value[i]-'0');
+	}
+
+	if (len == 2) {
+		/* two digit year, assume 1970+ */
+		if (tm.tm_year < 70)
+			tm.tm_year += 100;
+	} else {
+		if (tm.tm_year < 1900)
+			return FALSE;
+		tm.tm_year -= 1900;
+	}
+
+	/* hh, allow also single digit */
+	if (next_token(ctx, &value, &len) <= 0 ||
+	    len < 1 || len > 2 || !i_isdigit(value[0]))
+		return FALSE;
+	tm.tm_hour = value[0]-'0';
+	if (len == 2) {
+		if (!i_isdigit(value[1]))
+			return FALSE;
+		tm.tm_hour = tm.tm_hour * 10 + (value[1]-'0');
+	}
+
+	/* :mm (may be the last token) */
+	if (!IS_TIME_SEP(*ctx->parser.data))
+		return FALSE;
+	ctx->parser.data++;
+	rfc822_skip_lwsp(&ctx->parser);
+
+	if (next_token(ctx, &value, &len) < 0 || len != 2 ||
+	    !i_isdigit(value[0]) || !i_isdigit(value[1]))
+		return FALSE;
+	tm.tm_min = (value[0]-'0') * 10 + (value[1]-'0');
+
+	/* [:ss] */
+	if (ctx->parser.data < ctx->parser.end &&
+	    IS_TIME_SEP(*ctx->parser.data)) {
+		ctx->parser.data++;
+		rfc822_skip_lwsp(&ctx->parser);
+
+		if (next_token(ctx, &value, &len) <= 0 || len != 2 ||
+		    !i_isdigit(value[0]) || !i_isdigit(value[1]))
+			return FALSE;
+		tm.tm_sec = (value[0]-'0') * 10 + (value[1]-'0');
+	}
+
+	if ((ret = next_token(ctx, &value, &len)) < 0)
+		return FALSE;
+	if (ret == 0) {
+		/* missing timezone */
+		*timezone_offset_r = 0;
+	} else {
+		/* timezone. invalid timezones are treated as GMT, because
+		   we may not know all the possible timezones that are used
+		   and it's better to give at least a mostly correct reply.
+		   FIXME: perhaps some different strict version of this
+		   function would be useful? */
+		*timezone_offset_r = parse_timezone(value, len);
+	}
+
+	tm.tm_isdst = -1;
+	*timestamp_r = utc_mktime(&tm);
+	if (*timestamp_r == (time_t)-1)
+		return FALSE;
+
+	*timestamp_r -= *timezone_offset_r * 60;
+
+	return TRUE;
+}
+
+bool message_date_parse(const unsigned char *data, size_t size,
+			time_t *timestamp_r, int *timezone_offset_r)
+{
+	bool success;
+
+	T_BEGIN {
+		struct message_date_parser_context ctx;
+
+		rfc822_parser_init(&ctx.parser, data, size, NULL);
+		ctx.str = t_str_new(128);
+		success = message_date_parser_tokens(&ctx, timestamp_r,
+						     timezone_offset_r);
+		rfc822_parser_deinit(&ctx.parser);
+	} T_END;
+
+	return success;
+}
+
+const char *message_date_create(time_t timestamp)
+{
+	struct tm *tm;
+	int offset;
+	bool negative;
+
+	tm = localtime(&timestamp);
+	offset = utc_offset(tm, timestamp);
+	if (offset >= 0)
+		negative = FALSE;
+	else {
+		negative = TRUE;
+		offset = -offset;
+	}
+
+	return t_strdup_printf("%s, %02d %s %04d %02d:%02d:%02d %c%02d%02d",
+			       weekday_names[tm->tm_wday],
+			       tm->tm_mday,
+			       month_names[tm->tm_mon],
+			       tm->tm_year+1900,
+			       tm->tm_hour, tm->tm_min, tm->tm_sec,
+			       negative ? '-' : '+', offset / 60, offset % 60);
+}