1IPSEC_INITSUBNET(3)        Library Functions Manual        IPSEC_INITSUBNET(3)
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NAME

6       ipsec initsubnet - initialize an ip_subnet
7       ipsec addrtosubnet - initialize a singleton ip_subnet
8       ipsec subnettypeof - get address type of an ip_subnet
9       ipsec masktocount - convert subnet mask to bit count
10       ipsec networkof - get base address of an ip_subnet
11       ipsec maskof - get subnet mask of an ip_subnet
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SYNOPSIS

14       #include <freeswan.h>
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16       const char *initsubnet(const ip_address *addr,
17           int maskbits, int clash, ip_subnet *dst);
18       const char *addrtosubnet(const ip_address *addr,
19           ip_subnet *dst);
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21       int subnettypeof(const ip_subnet *src);
22       int masktocount(const ip_address *src);
23       void networkof(const ip_subnet *src, ip_address *dst);
24       void maskof(const ip_subnet *src, ip_address *dst);
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DESCRIPTION

27       The  <freeswan.h>  library uses an internal type ip_subnet to contain a
28       description of an IP subnet (base address plus mask).  These  functions
29       provide basic tools for creating and examining this type.
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31       Initsubnet  initializes  a  variable *dst of type ip_subnet from a base
32       address and a count of mask bits.  The clash parameter  specifies  what
33       to  do if the base address includes 1 bits outside the prefix specified
34       by the mask (that is, in the ``host number'' part of the address):
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36              '0'  zero out host-number bits
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38              'x'  non-zero host-number bits are an error
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40       Initsubnet returns NULL for success and a pointer to  a  string-literal
41       error message for failure; see DIAGNOSTICS.
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43       Addrtosubnet  initializes  an  ip_subnet variable *dst to a ``singleton
44       subnet'' containing the single address *addr.  It returns NULL for suc‐
45       cess and a pointer to a string-literal error message for failure.
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47       Subnettypeof  returns the address type of a subnet, normally AF_INET or
48       AF_INET6.  (The <freeswan.h> header file arranges to include the neces‐
49       sary headers for these names to be known.)
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51       Masktocount  converts  a subnet mask, expressed as an address, to a bit
52       count suitable for use with initsubnet.  It returns -1 for  error;  see
53       DIAGNOSTICS.
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55       Networkof fills in *dst with the base address of subnet src.
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57       Maskof  fills  in *dst with the subnet mask of subnet src, expressed as
58       an address.
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SEE ALSO

61       inet(3), ipsec_ttosubnet(3), ipsec_rangetosubnet(3)
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DIAGNOSTICS

64       Fatal errors in initsubnet are: unknown address family;  unknown  clash
65       value;  impossible  mask bit count; non-zero host-number bits and clash
66       is 'x'.  Fatal errors in  addrtosubnet  are:  unknown  address  family.
67       Fatal  errors in masktocount are: unknown address family; mask bits not
68       contiguous.
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HISTORY

71       Written for the FreeS/WAN project by Henry Spencer.
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75                                 12 March 2002             IPSEC_INITSUBNET(3)
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