envelope: impl
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184
src/envelope.cpp
184
src/envelope.cpp
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@ -18,6 +18,26 @@
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#include "envelope.h"
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/*
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* helpers
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*/
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inline static bool acceptable_char (char c)
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{
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return
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(c >= 'a' && c <= 'z') ||
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(c >= 'A' && c <= 'Z') ||
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(c >= '0' && c <= '9') ||
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c == '_' || c == '.';
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}
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static bool acceptable_id (const std::string&a)
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{
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for (size_t i = 0; i < a.length(); ++i)
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if (!acceptable_char (a[i]) ) return false;
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return true;
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}
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/*
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* how do the ascii envelopes look like?
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*
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@ -34,7 +54,7 @@
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* To distinguish ourselves from PGP, we use six dashes and prefixed CCR name.
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* No version information is supplied - versioning should be contained
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* preferably in typeident, e.g. like "message" "better_message" and
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* "bettermessage-version3".
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* "bettermessage_version3.5".
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*
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* Cleartext two-part messages and similar evil sorceries are generalized to
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* multipart messages using the "part cut".
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@ -42,33 +62,151 @@
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* Also, to prevent cleartext embedding conflicts, we add termident, which is
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* basically a random string of letters and numbers that serves as a mark that
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* must be the same on the begin and end.
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*
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* Also also, there's always newline before cut/end, even if there already is a
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* newline from previous cut. Therefore, size 0 section looks like it has an
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* empty line inside.
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*/
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size_t envelope_get (const std::string&data, size_t offset,
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std::string&out_type,
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std::vector<std::string>&out_parts)
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size_t envelope_read (const std::string&data, size_t offset,
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std::string&out_type,
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std::vector<std::string>&out_parts)
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{
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for (;;) {
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//try to find begin mark.
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std::string
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begin_prefix = "------ccr begin ",
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begin_suffix = "------\n";
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size_t begin = data.find (begin_prefix, offset);
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//nothing possible found, die.
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if (begin == data.npos) return 0;
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//verify it's on the beginning of the line
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if (begin > 0) if (data[begin - 1] != '\n') {
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offset += begin_prefix.length();
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continue;
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}
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//try to parse the typeident and termident
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std::string type, term;
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offset += begin_prefix.length();
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//find and verify possible positions of type and term strings
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size_t eoterm = data.find (begin_suffix, offset),
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eotype = data.find (' ', offset);
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if (eoterm == data.npos ||
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eotype == data.npos ||
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eotype > (eoterm - 1) )
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continue;
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type = data.substr (offset, eotype);
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term = data.substr (eotype + 1, eoterm);
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//verify that type&term are only of acceptable characters
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if (!acceptable_id (type) || !acceptable_id (term) )
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continue;
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offset = eoterm + begin_suffix.length();
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//read all sections
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std::string
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cut_sep = "\n------ccr cut " + type + " " + term + "------\n",
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end_sep = "\n------ccr end " + type + " " + term + "------\n";
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out_parts.clear();
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bool retry = false;
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for (;;) {
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//find closest cut or sep
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size_t cut_pos = data.find (cut_sep, offset),
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end_pos = data.find (end_sep, offset);
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if (end_pos == data.npos) {
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//can't even find end, don't care about cut_pos
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retry = true;
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break;
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}
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if ( cut_pos != data.npos && cut_pos < end_pos) {
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//there is cut
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out_parts.push_back (data.substr (offset,
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cut_pos) );
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} else {
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//no cut, it's till the end
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out_parts.push_back (data.substr (offset,
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end_pos) );
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}
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if (cut_pos == data.npos) {
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//it was end_pos, finished!
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offset = end_pos + end_sep.length();
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break;
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} else {
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//move offset for next search
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offset = cut_pos + cut_sep.length();
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}
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}
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if (retry) continue;
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//return the modified offset
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return offset;
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}
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}
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/*
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* The Much Simpler Envelope Formatter!
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*/
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static void gen_random_term (std::string&out, prng&rng, size_t length)
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{
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//this could be longer, but don't generate absolute mess.
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static const char letters[] = "abcdefghijklmnopqrstuvwxyz0123456789";
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out.resize (length);
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for (size_t i = 0; i < length; ++i) {
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out[i] = letters[rng.random (36)];
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}
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}
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std::string envelope_format (const std::string&type,
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const std::vector<std::string>& parts,
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prng&rng)
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{
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size_t begin;
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restart:
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//try to find begin mark.
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begin = data.find ("------ccr begin ", offset);
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//nothing possible found, die.
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if (begin == data.npos) return 0;
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//try to parse the begin mark
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std::string type, mark;
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//TODO parse it lol
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//TODO move offset
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//read all sections
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for (;;) {
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std::string term;
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gen_random_term (term, rng, 16);
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std::string
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cut_sep = "\n------ccr cut " + type + " " + term + "------\n",
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end_sep = "\n------ccr end " + type + " " + term + "------\n";
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//check whether there's no collision with boundary
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bool good = true;
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std::vector<std::string>::const_iterator i, e;
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for (i = parts.begin(), e = parts.end(); i != e; ++i) {
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if ( i->find (cut_sep) != i->npos ||
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i->find (end_sep) != i->npos) {
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good = false;
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break;
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}
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}
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if (!good) continue; //retry generating the termident mark
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//now construct the result
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std::string
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res = "------ccr begin " + type + " " + term + "------\n";
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if (parts.size() > 0) {
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res += parts[0];
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for (i = parts.begin() + 1, e = parts.end();
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i != e; ++i) {
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res += cut_sep;
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res += *i;
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}
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}
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res += end_sep;
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}
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//return the modified offset
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return offset;
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}
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@ -22,8 +22,10 @@
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#include <string>
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#include <vector>
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#include "prng.h"
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/*
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* Tools for finding envelopes in ascii/utf-8 text.
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* Tool for finding envelopes in ascii/utf-8 text.
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*
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* We simply don't care about wide chars in text, UTF-16+, nor conflicting
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* encodings, nor any similar abominations.
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@ -31,11 +33,19 @@
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* envelope_get tries to find an envelope in text data, starting from offset,
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* returning the offset of first possible following envelope or 0 if nothing
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* usuable was found.
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*
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* Finally, no one wants to see CRLF line endings here. Ever. ffs.
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*/
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size_t envelope_get (const std::string& data, size_t offset,
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std::string&out_type,
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std::vector<std::string>&out_parts);
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size_t envelope_read (const std::string& data, size_t offset,
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std::string&out_type,
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std::vector<std::string>&out_parts);
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/*
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* this simply formats a compatible envelope
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*/
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std::string envelope_format (const std::string&type,
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const std::vector<std::string>& parts,
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prng&rng);
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#endif
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