2 files changed, 93 insertions, 79 deletions

diff --git a/src/mime.c b/src/mime.c
index e6284d2..8e97f8b 100644
--- a/src/mime.c
+++ b/src/mime.c
@@ -35,17 +35,20 @@ static int mime_global_unqp(lua_State *L);
 static int mime_global_qpfmt(lua_State *L);
 static int mime_global_eol(lua_State *L);
 
-static void b64fill(UC *b64unbase);
+static void b64setup(UC *b64unbase);
 static size_t b64encode(UC c, UC *input, size_t size, luaL_Buffer *buffer);
 static size_t b64pad(const UC *input, size_t size, luaL_Buffer *buffer);
 static size_t b64decode(UC c, UC *input, size_t size, luaL_Buffer *buffer);
 
-static void qpfill(UC *qpclass, UC *qpunbase);
+static void qpsetup(UC *qpclass, UC *qpunbase);
 static void qpquote(UC c, luaL_Buffer *buffer);
 static size_t qpdecode(UC c, UC *input, size_t size, luaL_Buffer *buffer);
 static size_t qpencode(UC c, UC *input, size_t size, 
         const char *marker, luaL_Buffer *buffer);
 
+static const char *checklstring(lua_State *L, int n, size_t *l);
+static const char *optlstring(lua_State *L, int n, const char *v, size_t *l);
+
 /* code support functions */
 static luaL_reg func[] = {
     { "eol", mime_global_eol },
@@ -96,8 +99,27 @@ void mime_open(lua_State *L)
     lua_settable(L, -3);
     lua_pop(L, 1);
     /* initialize lookup tables */
-    qpfill(qpclass, qpunbase);
-    b64fill(b64unbase);
+    qpsetup(qpclass, qpunbase);
+    b64setup(b64unbase);
+}
+
+/*-------------------------------------------------------------------------*\
+* Check if a string was provided. We accept false also. 
+\*-------------------------------------------------------------------------*/
+static const char *checklstring(lua_State *L, int n, size_t *l)
+{
+    if (lua_isnil(L, n) || (lua_isboolean(L, n) && !lua_toboolean(L, n))) {
+        *l = 0;
+        return NULL;
+    } else return luaL_checklstring(L, n, l);
+}
+
+static const char *optlstring(lua_State *L, int n, const char *v, size_t *l)
+{
+    if (lua_isnil(L, n) || (lua_isboolean(L, n) && !lua_toboolean(L, n))) {
+        *l = 0;
+        return NULL;
+    } else return luaL_optlstring(L, n, v, l);
 }
 
 /*=========================================================================*\
@@ -105,19 +127,19 @@ void mime_open(lua_State *L)
 \*=========================================================================*/
 /*-------------------------------------------------------------------------*\
 * Incrementaly breaks a string into lines
-* A, n = fmt(B, length, left)
+* A, n = fmt(l, B, length, marker)
 * A is a copy of B, broken into lines of at most 'length' bytes. 
-* Left is how many bytes are left in the first line of B. 'n' is the number 
-* of bytes left in the last line of A. 
+* 'l' is how many bytes are left for the first line of B. 
+* 'n' is the number of bytes left in the last line of A. 
+* Marker is the end-of-line marker.
 \*-------------------------------------------------------------------------*/
 static int mime_global_fmt(lua_State *L)
 {
     size_t size = 0;
-    const UC *input = (UC *) (lua_isnil(L, 1)? NULL: 
-            luaL_checklstring(L, 1, &size));
+    int left = (int) luaL_checknumber(L, 1);
+    const UC *input = (UC *) checklstring(L, 2, &size);
     const UC *last = input + size;
-    int length = (int) luaL_checknumber(L, 2);
-    int left = (int) luaL_optnumber(L, 3, length);
+    int length = (int) luaL_optnumber(L, 3, 76);
     const char *marker = luaL_optstring(L, 4, CRLF);
     luaL_Buffer buffer;
     luaL_buffinit(L, &buffer);
@@ -140,7 +162,7 @@ static int mime_global_fmt(lua_State *L)
 /*-------------------------------------------------------------------------*\
 * Fill base64 decode map. 
 \*-------------------------------------------------------------------------*/
-static void b64fill(UC *b64unbase) 
+static void b64setup(UC *b64unbase) 
 {
     int i;
     for (i = 0; i < 255; i++) b64unbase[i] = 255;
@@ -255,7 +277,7 @@ static int mime_global_b64(lua_State *L)
     luaL_buffinit(L, &buffer);
     while (input < last) 
         asize = b64encode(*input++, atom, asize, &buffer);
-    input = (UC *) luaL_optlstring(L, 2, NULL, &isize);
+    input = (UC *) optlstring(L, 2, NULL, &isize);
     if (input) {
         last = input + isize;
         while (input < last) 
@@ -283,7 +305,7 @@ static int mime_global_unb64(lua_State *L)
     luaL_buffinit(L, &buffer);
     while (input < last) 
         asize = b64decode(*input++, atom, asize, &buffer);
-    input = (UC *) luaL_optlstring(L, 2, NULL, &isize);
+    input = (UC *) optlstring(L, 2, NULL, &isize);
     if (input) {
         last = input + isize;
         while (input < last) 
@@ -311,7 +333,7 @@ static int mime_global_unb64(lua_State *L)
 * Split quoted-printable characters into classes
 * Precompute reverse map for encoding
 \*-------------------------------------------------------------------------*/
-static void qpfill(UC *qpclass, UC *qpunbase)
+static void qpsetup(UC *qpclass, UC *qpunbase)
 {
     int i;
     for (i = 0; i < 256; i++) qpclass[i] = QP_QUOTED;
@@ -417,15 +439,14 @@ static int mime_global_qp(lua_State *L)
 
     size_t asize = 0, isize = 0;
     UC atom[3];
-    const UC *input = (UC *) (lua_isnil(L, 1) ? NULL: 
-            luaL_checklstring(L, 1, &isize));
+    const UC *input = (UC *) checklstring(L, 1, &isize);
     const UC *last = input + isize;
     const char *marker = luaL_optstring(L, 3, CRLF);
     luaL_Buffer buffer;
     luaL_buffinit(L, &buffer);
     while (input < last)
         asize = qpencode(*input++, atom, asize, marker, &buffer);
-    input = (UC *) luaL_optlstring(L, 2, NULL, &isize);
+    input = (UC *) optlstring(L, 2, NULL, &isize);
     if (input) {
         last = input + isize;
         while (input < last)
@@ -486,14 +507,13 @@ static int mime_global_unqp(lua_State *L)
 
     size_t asize = 0, isize = 0;
     UC atom[3];
-    const UC *input = (UC *) (lua_isnil(L, 1) ? NULL: 
-            luaL_checklstring(L, 1, &isize));
+    const UC *input = (UC *) checklstring(L, 1, &isize);
     const UC *last = input + isize;
     luaL_Buffer buffer;
     luaL_buffinit(L, &buffer);
     while (input < last)
         asize = qpdecode(*input++, atom, asize, &buffer);
-    input = (UC *) luaL_optlstring(L, 2, NULL, &isize);
+    input = (UC *) optlstring(L, 2, NULL, &isize);
     if (input) {
         last = input + isize;
         while (input < last)
@@ -506,21 +526,20 @@ static int mime_global_unqp(lua_State *L)
 
 /*-------------------------------------------------------------------------*\
 * Incrementally breaks a quoted-printed string into lines
-* A, n = qpfmt(B, length, left)
+* A, n = qpfmt(l, B, length)
 * A is a copy of B, broken into lines of at most 'length' bytes. 
-* Left is how many bytes are left in the first line of B. 'n' is the number 
-* of bytes left in the last line of A. 
+* 'l' is how many bytes are left for the first line of B. 
+* 'n' is the number of bytes left in the last line of A. 
 * There are two complications: lines can't be broken in the middle
 * of an encoded =XX, and there might be line breaks already
 \*-------------------------------------------------------------------------*/
 static int mime_global_qpfmt(lua_State *L)
 {
     size_t size = 0;
-    const UC *input = (UC *) (lua_isnil(L, 1)? NULL: 
-            luaL_checklstring(L, 1, &size));
+    int left = (int) luaL_checknumber(L, 1);
+    const UC *input = (UC *) checklstring(L, 2, &size);
     const UC *last = input + size;
-    int length = (int) luaL_checknumber(L, 2);
-    int left = (int) luaL_optnumber(L, 3, length);
+    int length = (int) luaL_optnumber(L, 3, 76);
     luaL_Buffer buffer;
     luaL_buffinit(L, &buffer);
     while (input < last) {
@@ -597,15 +616,14 @@ static int mime_global_eol(lua_State *L)
 {
     size_t asize = 0, isize = 0;
     UC atom[2];
-    const UC *input = (UC *) (lua_isnil(L, 1)? NULL: 
-            luaL_checklstring(L, 1, &isize));
+    const UC *input = (UC *) checklstring(L, 1, &isize);
     const UC *last = input + isize;
     const char *marker = luaL_optstring(L, 3, CRLF);
     luaL_Buffer buffer;
     luaL_buffinit(L, &buffer);
     while (input < last)
         asize = eolconvert(*input++, atom, asize, marker, &buffer);
-    input = (UC *) luaL_optlstring(L, 2, NULL, &isize);
+    input = (UC *) optlstring(L, 2, NULL, &isize);
     if (input) {
         last = input + isize;
         while (input < last)
diff --git a/src/mime.lua b/src/mime.lua
index 86b3af2..0251f6e 100644
--- a/src/mime.lua
+++ b/src/mime.lua
@@ -10,75 +10,71 @@ socket.mime = mime
 setmetatable(mime, { __index = _G })
 setfenv(1, mime)
 
-base64 = {}
-qprint = {}
+-- encode, decode and wrap algorithm tables
+local et = {}
+local dt = {}
+local wt = {}
 
-function base64.encode()
-    local unfinished = ""
-    return function(chunk)
-        local done
-        done, unfinished = b64(unfinished, chunk)
-        return done
+-- creates a function that chooses an algorithm from a given table 
+local function choose(table)
+    return function(method, ...)
+        local f = table[method or "nil"]
+        if not f then return nil, "unknown method (" .. tostring(method) .. ")"
+        else return f(unpack(arg)) end
     end
 end
 
-function base64.decode()
-    local unfinished = ""
+-- creates a function that cicles a filter with a given initial
+-- context and extra arguments
+local function cicle(f, ctx, ...)
     return function(chunk)
-        local done
-        done, unfinished = unb64(unfinished, chunk)
-        return done
+        local ret
+        ret, ctx = f(ctx, chunk, unpack(arg))
+        return ret
     end
 end
 
-function qprint.encode(mode)
-    mode = (mode == "binary") and "=0D=0A" or "\13\10" 
-    local unfinished = ""
-    return function(chunk)
-        local done
-        done, unfinished = qp(unfinished, chunk, mode)
-        return done
-    end
+-- function that choose the encoding, decoding or wrap algorithm
+encode = choose(et) 
+decode = choose(dt)
+wrap = choose(wt)
+
+-- define the encoding algorithms
+et['base64'] = function()
+    return cicle(b64, "")
 end
 
-function qprint.decode()
-    local unfinished = ""
-    return function(chunk)
-        local done
-        done, unfinished = unqp(unfinished, chunk)
-        return done
-    end
+et['quoted-printable'] = function(mode)
+    return cicle(qp, "", (mode == "binary") and "=0D=0A" or "\13\10")
+end
+
+-- define the decoding algorithms
+dt['base64'] = function()
+    return cicle(unb64, "")
 end
 
-function split(length, marker)
+dt['quoted-printable'] = function()
+    return cicle(unqp, "")
+end
+
+-- define the wrap algorithms
+wt['character'] = function(length)
     length = length or 76
-    local left = length
-    return function(chunk)
-        local done
-        done, left = fmt(chunk, length, left, marker)
-        return done
-    end
+    return cicle(fmt, length, length) 
 end
+wt['base64'] = wt['character']
 
-function qprint.split(length)
+wt['quoted-printable'] = function(length)
     length = length or 76
-    local left = length
-    return function(chunk)
-        local done
-        done, left = qpfmt(chunk, length, left)
-        return done
-    end
+    return cicle(qpfmt, length, length) 
 end
 
+-- define the end-of-line translation function
 function canonic(marker)
-    local unfinished = ""
-    return function(chunk)
-        local done
-        done, unfinished = eol(unfinished, chunk, marker)
-        return done
-    end
+    return cicle(eol, "", marker)
 end
 
+-- chains several filters together
 function chain(...)
     local layers = table.getn(arg)
     return function (chunk)