.TH rewritehost 3
.SH NAME
rewritehost \- make syntactic changes to host names
.SH SYNTAX
.B #include <rewritehost.h>

int \fBrewritehost\fP(&\fIout\fR,\fIbuf\fR,\fIlen\fR,&\fIrules\fR);
.br
int \fBrewritehost_addr\fP(&\fIout\fR,\fIbuf\fR,\fIlen\fR,&\fIrules\fR);
.br
int \fBrewritehost_list\fP(&\fIout\fR,\fIbuf\fR,\fIlen\fR,&\fIrules\fR);

stralloc \fIrules\fR;
.br
stralloc \fIout\fR;
.br
char *\fIbuf\fR;
.br
unsigned int \fIlen\fR;
.SH DESCRIPTION
.B rewritehost
reads a host name from
.I buf
of length
.IR len ,
rewrites it according to instructions in
.IR rules ,
and puts the rewritten host name into
.IR out .
.I rules
is a series of \e0-terminated instructions;
see
.BR rewriting (5)
for the instruction format.

.B rewritehost_addr
reads an address in the form
.I user\fB@\fIhost
from
.I buf
of length
.IR len .
It rewrites
.I host
according to instructions in
.IR rules ,
unless both
.I user
and
.I host
are empty,
in which case it rewrites the address as the empty string.
It puts the rewritten address into
.IR out .
.B rewritehost_addr
accepts
.I user
as a synonym for
.I user\fB@
with an empty host name.

.B rewritehost_list
reads an address list from
.I buf
of length
.IR len ,
rewrites each address in the list
according to instructions in
.IR rules ,
and puts the rewritten address list into
.IR out .
The address list consists of \e0-terminated chunks;
a chunk is either an address preceded by a plus sign,
or a comment preceded by a left parenthesis.
.B rewritehost_list
copies comments without change.

Each function returns 1 if it succeeds,
0 if it runs out of memory.
.SH "SEE ALSO"
stralloc(3),
rewriting(5)