const char *atoasr(const char *src, size_t srclen,
char *type, struct in_addr *addrs);
size_t rangetoa(struct in_addr *addrs, int format,
char *dst, size_t dstlen);
A single address can be any form acceptable to ipsec_atoaddr(3): dotted decimal, DNS name, or hexadecimal number. A subnet specification uses the form network/mask interpreted by ipsec_atosubnet(3).
An address range is two ipsec_atoaddr(3) addresses separated by a ... delimiter. If there are four dots rather than three, the first is taken as part of the begin address, e.g. for a complete DNS name which ends with . to suppress completion attempts. The begin address of a range must be less than or equal to the end address.
The srclen parameter of atoasr specifies the length of the ASCII string pointed to by src; it is an error for there to be anything else (e.g., a terminating NUL) within that length. As a convenience for cases where an entire NUL-terminated string is to be converted, a srclen value of 0 is taken to mean strlen(src).
The type parameter of atoasr must point to a char variable used to record which form was found. The addrs parameter must point to a two-element array of struct in_addr which receives the results. The values stored into *type, and the corresponding values in the array, are:
*typeaddrs[0]addrs[1]
address'a'address-
subnet 's'networkmask
range 'r'beginend
The dstlen parameter of rangetoa specifies the size of the dst parameter; under no circumstances are more than dstlen bytes written to dst. A result which will not fit is truncated. Dstlen can be zero, in which case dst need not be valid and no result is written, but the return value is unaffected; in all other cases, the (possibly truncated) result is NUL-terminated. The freeswan.h header file defines a constant, RANGETOA_BUF, which is the size of a buffer just large enough for worst-case results.
The format parameter of rangetoa specifies what format is to be used for the conversion. The value 0 (not the ASCII character '0', but a zero value) specifies a reasonable default, and is in fact the only format currently available. This parameter is a hedge against future needs.
Atoasr returns NULL for success and a pointer to a string-literal error message for failure; see DIAGNOSTICS. Rangetoa returns 0 for a failure, and otherwise always returns the size of buffer which would be needed to accommodate the full conversion result, including terminating NUL; it is the caller's responsibility to check this against the size of the provided buffer to determine whether truncation has occurred.
Fatal errors in rangetoa are: unknown format.
The error-reporting convention lends itself to slightly obscure code, because many readers will not think of NULL as signifying success. A good way to make it clearer is to write something like:
const char *error;
error = atoasr( /* ... */ );
if (error != NULL) {
/* something went wrong */