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Diffstat (limited to 'libmailutils/dot.c')
-rw-r--r-- | libmailutils/dot.c | 268 |
1 files changed, 268 insertions, 0 deletions
diff --git a/libmailutils/dot.c b/libmailutils/dot.c new file mode 100644 index 000000000..a0d43fad7 --- /dev/null +++ b/libmailutils/dot.c @@ -0,0 +1,268 @@ +/* GNU Mailutils -- a suite of utilities for electronic mail + Copyright (C) 2003, 2007, 2010 Free Software Foundation, Inc. + + This library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 3 of the License, or (at your option) any later version. + + This library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General + Public License along with this library; if not, write to the + Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, + Boston, MA 02110-1301 USA */ + +/* This file implements a DOT filter, useful for data I/O in + such protocols as POP3 and SMTP. When encoding, this filter + "byte-stuffs" the input by outputting an additional '.' in front + of any '.' appearing at the beginning of a line. Upon closing the + filter in this mode, it outputs additional ".\n". + + When decoding, the reverse is performed: any '.' appearing at the + beginning of a line is removed. A single dot on a line by itself + marks end of the stream. + + MU also provides a hairy version of this filter, called CRLFDOT. + In addition to byte-stuffing, CRLFDOT also performs CRLF/LF translation. + */ + +#ifdef HAVE_CONFIG_H +# include <config.h> +#endif + +#include <stdlib.h> +#include <string.h> +#include <mailutils/errno.h> +#include <mailutils/filter.h> +#include <mailutils/stream.h> + +enum dot_decode_state + { + dot_decode_init, /* initial state */ + dot_decode_char, /* Any character excepting [\r\n.] */ + dot_decode_lf, /* prev. char was \n */ + dot_decode_dot, /* 2 prev. chars were \n. */ + dot_decode_end /* final state, a \n.\n seen. */ + }; + +static enum dot_decode_state +new_decode_state (enum dot_decode_state state, int c) +{ + switch (state) + { + case dot_decode_init: + switch (c) + { + case '.': + return dot_decode_dot; + } + break; + + case dot_decode_char: + switch (c) + { + case '\n': + return dot_decode_lf; + } + break; + + case dot_decode_lf: + switch (c) + { + case '.': + return dot_decode_dot; + } + + case dot_decode_dot: + switch (c) + { + case '\n': + return dot_decode_end; + } + break; + + case dot_decode_end: + return dot_decode_end; + } + return dot_decode_char; +} + +/* Move min(isize,osize) bytes from iptr to optr, replacing each \r\n + with \n. */ +static enum mu_filter_result +_dot_decoder (void *xd, + enum mu_filter_command cmd, + struct mu_filter_io *iobuf) +{ + int *pstate = xd; + size_t i, j; + const unsigned char *iptr; + size_t isize; + char *optr; + size_t osize; + + switch (cmd) + { + case mu_filter_init: + *pstate = dot_decode_init; + return mu_filter_ok; + + case mu_filter_done: + return mu_filter_ok; + + default: + break; + } + + iptr = (const unsigned char *) iobuf->input; + isize = iobuf->isize; + optr = iobuf->output; + osize = iobuf->osize; + + for (i = j = 0; *pstate != dot_decode_end && i < isize && j < osize; i++) + { + unsigned char c = *iptr++; + int curstate = *pstate; + + *pstate = new_decode_state (curstate, c); + if (!(c == '.' && (curstate == dot_decode_init || + curstate == dot_decode_lf))) + optr[j++] = c; + } + + if (*pstate == dot_decode_end) + iobuf->eof = 1; + + iobuf->isize = i; + iobuf->osize = j; + return mu_filter_ok; +} + +enum dot_encode_state + { + dot_encode_init, /* initial state */ + dot_encode_char, /* Any character excepting \n */ + dot_encode_lf, /* prev. char was \n */ + }; + +static enum dot_encode_state +new_encode_state (int c) +{ + switch (c) + { + case '\n': + return dot_encode_lf; + } + return dot_encode_char; +} + +/* Move min(isize,osize) bytes from iptr to optr, replacing each \n + with \r\n. Any input \r\n sequences remain untouched. */ +static enum mu_filter_result +_dot_encoder (void *xd, + enum mu_filter_command cmd, + struct mu_filter_io *iobuf) +{ + enum mu_filter_result result; + size_t i, j; + const unsigned char *iptr; + size_t isize; + char *optr; + size_t osize; + int *state = xd; + + switch (cmd) + { + case mu_filter_init: + *state = dot_encode_init; + return mu_filter_ok; + + case mu_filter_done: + return mu_filter_ok; + + default: + break; + } + + iptr = (const unsigned char *) iobuf->input; + isize = iobuf->isize; + optr = iobuf->output; + osize = iobuf->osize; + + for (i = j = 0; i < isize && j < osize; i++, iptr++) + { + unsigned char c = *iptr; + int curstate = *state; + + if (c == '.' && (curstate == dot_encode_init || + curstate == dot_encode_lf)) + { + if (j + 2 > osize) + { + if (i == 0) + { + iobuf->osize = 2; + return mu_filter_moreoutput; + } + break; + } + optr[j++] = '.'; + optr[j++] = '.'; + } + else + optr[j++] = c; + + *state = new_encode_state (c); + } + + result = mu_filter_ok; + if (cmd == mu_filter_lastbuf) + { + switch (*state) + { + case dot_encode_lf: + if (j + 2 > osize) + result = mu_filter_again; + break; + + default: + if (j + 3 > osize) + result = mu_filter_again; + else + optr[j++] = '\n'; + } + + if (result == mu_filter_ok) + { + optr[j++] = '.'; + optr[j++] = '\n'; + } + } + + iobuf->isize = i; + iobuf->osize = j; + return result; +} + +static int +alloc_state (void **pret, int mode MU_ARG_UNUSED, void *data MU_ARG_UNUSED) +{ + *pret = malloc (sizeof (int)); + if (!*pret) + return ENOMEM; + return 0; +} + +static struct _mu_filter_record _dot_filter = { + "DOT", + 0, + alloc_state, + _dot_encoder, + _dot_decoder +}; + +mu_filter_record_t mu_dot_filter = &_dot_filter; |