Ensure that mail headers are 7-bit clean, even when UTF-8 characters are used

in headers like 'Subject' and 'To'.
Closes AST-107.


git-svn-id: http://svn.digium.com/svn/asterisk/branches/1.4@148916 f38db490-d61c-443f-a65b-d21fe96a405b

1 files changed, 136 insertions, 24 deletions

diff --git a/apps/app_voicemail.c b/apps/app_voicemail.c
index f6401b2b5..f104d6ee8 100644
--- a/apps/app_voicemail.c
+++ b/apps/app_voicemail.c
@@ -2979,6 +2979,70 @@ static const struct tm *vmu_tm(const struct ast_vm_user *vmu, struct tm *tm)
 	return tm;
 }
 
+/*!\brief Check if the string would need encoding within the MIME standard, to
+ * avoid confusing certain mail software that expects messages to be 7-bit
+ * clean.
+ */
+static int check_mime(const char *str)
+{
+	for (; *str; str++) {
+		if (*str > 126 || *str < 32 || strchr("()<>@,:;/\"[]?.=", *str)) {
+			return 1;
+		}
+	}
+	return 0;
+}
+
+/*!\brief Encode a string according to the MIME rules for encoding strings
+ * that are not 7-bit clean or contain control characters.
+ *
+ * Additionally, if the encoded string would exceed the MIME limit of 76
+ * characters per line, then the encoding will be broken up into multiple
+ * sections, separated by a space character, in order to facilitate
+ * breaking up the associated header across multiple lines.
+ *
+ * \param start A string to be encoded
+ * \param end An expandable buffer for holding the result
+ * \param preamble The length of the first line already used for this string,
+ * to ensure that each line maintains a maximum length of 76 chars.
+ * \param postamble the length of any additional characters appended to the
+ * line, used to ensure proper field wrapping.
+ * \retval The encoded string.
+ */
+static char *encode_mime_str(const char *start, char *end, size_t endsize, size_t preamble, size_t postamble)
+{
+	char tmp[80];
+	int first_section = 1;
+	size_t endlen = 0, tmplen = 0;
+	*end = '\0';
+
+	tmplen = snprintf(tmp, sizeof(tmp), "=?%s?Q?", charset);
+	for (; *start; start++) {
+		int need_encoding = 0;
+		if (*start < 33 || *start > 126 || strchr("()<>@,:;/\"[]?.=_", *start)) {
+			need_encoding = 1;
+		}
+		if ((first_section && need_encoding && preamble + tmplen > 70) ||
+			(first_section && !need_encoding && preamble + tmplen > 72) ||
+			(!first_section && need_encoding && tmplen > 70) ||
+			(!first_section && !need_encoding && tmplen > 72)) {
+			/* Start new line */
+			endlen += snprintf(end + endlen, endsize - endlen, "%s%s?=", first_section ? "" : " ", tmp);
+			tmplen = snprintf(tmp, sizeof(tmp), "=?%s?Q?", charset);
+			first_section = 0;
+		}
+		if (need_encoding && *start == ' ') {
+			tmplen += snprintf(tmp + tmplen, sizeof(tmp) - tmplen, "_");
+		} else if (need_encoding) {
+			tmplen += snprintf(tmp + tmplen, sizeof(tmp) - tmplen, "=%hhX", *start);
+		} else {
+			tmplen += snprintf(tmp + tmplen, sizeof(tmp) - tmplen, "%c", *start);
+		}
+	}
+	snprintf(end + endlen, endsize - endlen, "%s%s?=%s", first_section ? "" : " ", tmp, endlen + postamble > 74 ? " " : "");
+	return end;
+}
+
 static void make_email_file(FILE *p, char *srcemail, struct ast_vm_user *vmu, int msgnum, char *context, char *mailbox, char *cidnum, char *cidname, char *attach, char *format, int duration, int attach_user_voicemail, struct ast_channel *chan, const char *category, int imap)
 {
 	char date[256];
@@ -2990,14 +3054,28 @@ static void make_email_file(FILE *p, char *srcemail, struct ast_vm_user *vmu, in
 	char tmpcmd[256];
 	char enc_cidnum[256] = "", enc_cidname[256] = "";
 	struct tm tm;
-	char *passdata2;
-	size_t len_passdata;
+	char *passdata = NULL, *passdata2;
+	size_t len_passdata, len_passdata2, tmplen;
 #ifdef IMAP_STORAGE
 #define ENDL "\r\n"
 #else
 #define ENDL "\n"
 #endif
 
+	/* One alloca for multiple fields */
+	len_passdata2 = strlen(vmu->fullname);
+	if (emailsubject && (tmplen = strlen(emailsubject)) > len_passdata2) {
+		len_passdata2 = tmplen;
+	}
+	if ((tmplen = strlen(emailtitle)) > len_passdata2) {
+		len_passdata2 = tmplen;
+	}
+	if ((tmplen = strlen(fromstring)) > len_passdata2) {
+		len_passdata2 = tmplen;
+	}
+	len_passdata2 = len_passdata2 * 3 + 200;
+	passdata2 = alloca(len_passdata2);
+
 	if (cidnum) {
 		strip_control(cidnum, enc_cidnum, sizeof(enc_cidnum));
 	}
@@ -3020,37 +3098,71 @@ static void make_email_file(FILE *p, char *srcemail, struct ast_vm_user *vmu, in
 	if (*fromstring) {
 		struct ast_channel *ast;
 		if ((ast = ast_channel_alloc(0, AST_STATE_DOWN, 0, 0, "", "", "", 0, 0))) {
-			char *passdata;
-			int vmlen = strlen(fromstring)*3 + 200;
-			if ((passdata = alloca(vmlen))) {
-				memset(passdata, 0, vmlen);
-				prep_email_sub_vars(ast, vmu, msgnum + 1, context, mailbox, enc_cidnum, enc_cidname, dur, date, passdata, vmlen, category);
-				pbx_substitute_variables_helper(ast, fromstring, passdata, vmlen);
-				len_passdata = strlen(passdata) * 2 + 3;
-				passdata2 = alloca(len_passdata);
-				fprintf(p, "From: %s <%s>" ENDL, quote(passdata, passdata2, len_passdata), who);
-			} else
-				ast_log(LOG_WARNING, "Cannot allocate workspace for variable substitution\n");
+			char *ptr;
+			memset(passdata2, 0, len_passdata2);
+			prep_email_sub_vars(ast, vmu, msgnum + 1, context, mailbox, enc_cidnum, enc_cidname, dur, date, passdata2, len_passdata2, category);
+			pbx_substitute_variables_helper(ast, fromstring, passdata2, len_passdata2);
+			len_passdata = strlen(passdata2) * 3 + 300;
+			passdata = alloca(len_passdata);
+			if (check_mime(passdata2)) {
+				int first_line = 1;
+				encode_mime_str(passdata2, passdata, len_passdata, strlen("From: "), strlen(who) + 3);
+				while ((ptr = strchr(passdata, ' '))) {
+					*ptr = '\0';
+					fprintf(p, "%s %s" ENDL, first_line ? "From:" : "", passdata);
+					first_line = 0;
+					passdata = ptr + 1;
+				}
+				fprintf(p, "%s %s <%s>" ENDL, first_line ? "From:" : "", passdata, who);
+			} else {
+				fprintf(p, "From: %s <%s>" ENDL, quote(passdata, passdata2, len_passdata2), who);
+			}
 			ast_channel_free(ast);
 		} else
 			ast_log(LOG_WARNING, "Cannot allocate the channel for variables substitution\n");
 	} else
 		fprintf(p, "From: Asterisk PBX <%s>" ENDL, who);
-	len_passdata = strlen(vmu->fullname) * 2 + 3;
-	passdata2 = alloca(len_passdata);
-	fprintf(p, "To: %s <%s>" ENDL, quote(vmu->fullname, passdata2, len_passdata), vmu->email);
+
+	if (check_mime(vmu->fullname)) {
+		int first_line = 1;
+		char *ptr;
+		encode_mime_str(vmu->fullname, passdata2, len_passdata2, strlen("To: "), strlen(vmu->email) + 3);
+		while ((ptr = strchr(passdata2, ' '))) {
+			*ptr = '\0';
+			fprintf(p, "%s %s" ENDL, first_line ? "To:" : "", passdata2);
+			first_line = 0;
+			passdata2 = ptr + 1;
+		}
+		fprintf(p, "%s %s <%s>" ENDL, first_line ? "To:" : "", passdata2, vmu->email);
+	} else {
+		fprintf(p, "To: %s <%s>" ENDL, quote(vmu->fullname, passdata2, len_passdata2), vmu->email);
+	}
 	if (emailsubject) {
 		struct ast_channel *ast;
 		if ((ast = ast_channel_alloc(0, AST_STATE_DOWN, 0, 0, "", "", "", 0, 0))) {
-			char *passdata;
-			int vmlen = strlen(emailsubject)*3 + 200;
-			if ((passdata = alloca(vmlen))) {
-				memset(passdata, 0, vmlen);
-				prep_email_sub_vars(ast, vmu, msgnum + 1, context, mailbox, cidnum, cidname, dur, date, passdata, vmlen, category);
-				pbx_substitute_variables_helper(ast, emailsubject, passdata, vmlen);
-				fprintf(p, "Subject: %s" ENDL, passdata);
+			int vmlen = strlen(emailsubject) * 3 + 200;
+			/* Only allocate more space if the previous was not large enough */
+			if (vmlen > len_passdata) {
+				passdata = alloca(vmlen);
+				len_passdata = vmlen;
+			}
+
+			memset(passdata, 0, len_passdata);
+			prep_email_sub_vars(ast, vmu, msgnum + 1, context, mailbox, cidnum, cidname, dur, date, passdata, len_passdata, category);
+			pbx_substitute_variables_helper(ast, emailsubject, passdata, len_passdata);
+			if (check_mime(passdata)) {
+				int first_line = 1;
+				char *ptr;
+				encode_mime_str(passdata, passdata2, len_passdata2, strlen("Subject: "), 0);
+				while ((ptr = strchr(passdata2, ' '))) {
+					*ptr = '\0';
+					fprintf(p, "%s %s" ENDL, first_line ? "Subject:" : "", passdata2);
+					first_line = 0;
+					passdata2 = ptr + 1;
+				}
+				fprintf(p, "%s %s" ENDL, first_line ? "Subject:" : "", passdata2);
 			} else {
-				ast_log(LOG_WARNING, "Cannot allocate workspace for variable substitution\n");
+				fprintf(p, "Subject: %s" ENDL, passdata);
 			}
 			ast_channel_free(ast);
 		} else {