strbuf_addch(out, '"');
}
-static int is_rfc2047_special(char ch)
+enum rfc2047_type {
+ RFC2047_SUBJECT,
+ RFC2047_ADDRESS,
+};
+
+static int is_rfc2047_special(char ch, enum rfc2047_type type)
{
- if (ch == ' ' || ch == '\n')
+ /*
+ * rfc2047, section 4.2:
+ *
+ * 8-bit values which correspond to printable ASCII characters other
+ * than "=", "?", and "_" (underscore), MAY be represented as those
+ * characters. (But see section 5 for restrictions.) In
+ * particular, SPACE and TAB MUST NOT be represented as themselves
+ * within encoded words.
+ */
+
+ /*
+ * rule out non-ASCII characters and non-printable characters (the
+ * non-ASCII check should be redundant as isprint() is not localized
+ * and only knows about ASCII, but be defensive about that)
+ */
+ if (non_ascii(ch) || !isprint(ch))
+ return 1;
+
+ /*
+ * rule out special printable characters (' ' should be the only
+ * whitespace character considered printable, but be defensive and use
+ * isspace())
+ */
+ if (isspace(ch) || ch == '=' || ch == '?' || ch == '_')
return 1;
- return (non_ascii(ch) || (ch == '=') || (ch == '?') || (ch == '_'));
+ /*
+ * rfc2047, section 5.3:
+ *
+ * As a replacement for a 'word' entity within a 'phrase', for example,
+ * one that precedes an address in a From, To, or Cc header. The ABNF
+ * definition for 'phrase' from RFC 822 thus becomes:
+ *
+ * phrase = 1*( encoded-word / word )
+ *
+ * In this case the set of characters that may be used in a "Q"-encoded
+ * 'encoded-word' is restricted to: <upper and lower case ASCII
+ * letters, decimal digits, "!", "*", "+", "-", "/", "=", and "_"
+ * (underscore, ASCII 95.)>. An 'encoded-word' that appears within a
+ * 'phrase' MUST be separated from any adjacent 'word', 'text' or
+ * 'special' by 'linear-white-space'.
+ */
+
+ if (type != RFC2047_ADDRESS)
+ return 0;
+
+ /* '=' and '_' are special cases and have been checked above */
+ return !(isalnum(ch) || ch == '!' || ch == '*' || ch == '+' || ch == '-' || ch == '/');
}
static void add_rfc2047(struct strbuf *sb, const char *line, int len,
- const char *encoding)
+ const char *encoding, enum rfc2047_type type)
{
static const int max_length = 78; /* per rfc2822 */
static const int max_encoded_length = 76; /* per rfc2047 */
line_len += strlen(encoding) + 5; /* 5 for =??q? */
for (i = 0; i < len; i++) {
unsigned ch = line[i] & 0xFF;
- int is_special = is_rfc2047_special(ch);
+ int is_special = is_rfc2047_special(ch, type);
/*
* According to RFC 2047, we could encode the special character
display_name_length = name_tail - line;
strbuf_addstr(sb, "From: ");
if (!has_rfc822_specials(line, display_name_length)) {
- add_rfc2047(sb, line, display_name_length, encoding);
+ add_rfc2047(sb, line, display_name_length,
+ encoding, RFC2047_ADDRESS);
} else {
struct strbuf quoted = STRBUF_INIT;
add_rfc822_quoted("ed, line, display_name_length);
- add_rfc2047(sb, quoted.buf, quoted.len, encoding);
+ add_rfc2047(sb, quoted.buf, quoted.len,
+ encoding, RFC2047_ADDRESS);
strbuf_release("ed);
}
if (namelen - display_name_length + last_line_length(sb) > 78) {
strbuf_grow(sb, title.len + 1024);
if (pp->subject) {
strbuf_addstr(sb, pp->subject);
- add_rfc2047(sb, title.buf, title.len, encoding);
+ add_rfc2047(sb, title.buf, title.len, encoding, RFC2047_SUBJECT);
} else {
strbuf_addbuf(sb, &title);
}