Function tok822_externalize

lib_acl_cpp/src/mime/internal/tok822_parse.cpp:274–395

/* tok822_externalize - token tree to string, external form */

ACL_VSTRING *tok822_externalize(ACL_VSTRING *vp, TOK822 *tree, int flags)
{
	ACL_VSTRING *tmp;
	TOK822 *tp;
	ssize_t start = 0;
	TOK822 *addr = 0;
	ssize_t addr_len = 0;

	/*
	 * Guard against a Sendmail buffer overflow (CERT advisory CA-2003-07).
	 * The problem was that Sendmail could store too much non-address text
	 * (comments, phrases, etc.) into a static 256-byte buffer.
	 * 
	 * When the buffer fills up, fixed Sendmail versions remove comments etc.
	 * and reduce the information to just <$g>, which expands to <address>.
	 * No change is made when an address expression (text separated by
	 * commas) contains no address. This fix reportedly also protects
	 * Sendmail systems that are still vulnerable to this problem.
	 * 
	 * Postfix takes the same approach, grudgingly. To avoid unnecessary damage,
	 * Postfix removes comments etc. only when the amount of non-address text
	 * in an address expression (text separated by commas) exceeds 250 bytes.
	 * 
	 * With Sendmail, the address part of an address expression is the
	 * right-most <> instance in that expression. If an address expression
	 * contains no <>, then Postfix guarantees that it contains at most one
	 * non-comment string; that string is the address part of the address
	 * expression, so there is no ambiguity.
	 * 
	 * Finally, we note that stress testing shows that other code in Sendmail
	 * 8.12.8 bluntly truncates ``text <address>'' to 256 bytes even when
	 * this means chopping the <address> somewhere in the middle. This is a
	 * loss of control that we're not entirely comfortable with. However,
	 * unbalanced quotes and dangling backslash do not seem to influence the
	 * way that Sendmail parses headers, so this is not an urgent problem.
	 */
#define MAX_NONADDR_LENGTH 250

#define RESET_NONADDR_LENGTH { \
	start = (ssize_t) ACL_VSTRING_LEN(vp); \
	addr = 0; \
	addr_len = 0; \
}

#define ENFORCE_NONADDR_LENGTH do { \
	if (addr && (ssize_t) ACL_VSTRING_LEN(vp) - addr_len > start + MAX_NONADDR_LENGTH) \
		strip_address(vp, start, addr->head); \
} while(0)

	if (flags & TOK822_STR_WIPE)
		ACL_VSTRING_RESET(vp);

	if (flags & TOK822_STR_TRNC)
		RESET_NONADDR_LENGTH;

	for (tp = tree; tp; tp = tp->next) {
		switch (tp->type) {
		case ',':