Each line lists one ipsec I/F. A table entry consists of:
Ttosubnet ANDs the mask with the address before returning, so that any non-network bits in the address are turned off (e.g., 10.1.2.3/24 is synonymous with 10.1.2.0/24). Subnettot always generates the decimal-integer-bit-count form of the mask, with no leading zeros.
The srclen parameter of ttoaddr and ttosubnet specifies the length of the text 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 af parameter of ttoaddr and ttosubnet specifies the address family of interest. It should be either AF_INET or AF_INET6.
The dstlen parameter of addrtot and subnettot 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 constants, ADDRTOT_BUF and SUBNETTOT_BUF, which are the sizes of buffers just large enough for worst-case results.
The format parameter of addrtot and subnettot specifies what format is to be used for the conversion. The value 0 (not the character '0', but a zero value) specifies a reasonable default, and is in fact the only format currently available in subnettot. Addrtot also accepts format values 'r' (signifying a text form suitable for DNS reverse lookups, e.g. 4.3.2.1.IN-ADDR.ARPA. for IPv4 and RFC 2874 format for IPv6), and 'R' (signifying an alternate reverse-lookup form, an error for IPv4 and RFC 1886 format for IPv6). Reverse-lookup names always end with a ``.''.
The text-to-binary functions return NULL for success and a pointer to a string-literal error message for failure; see DIAGNOSTICS. The binary-to-text functions return 0 for a failure, and otherwise always return 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 buf