feature: implement base85 like Go's encoding/ascii85

Author: spacewander

.gitignore

@@ -1,3 +1,5 @@
 t/servroot
 *.o
 librestybaseencoding.so
+modp_b85_gen
+bm.lua

Makefile

@@ -12,8 +12,10 @@ ${OBJ} : %.o : %.c
 ${LIB} : ${OBJ}
 	$(CC) $^ $(LDFLAGS) -o $@
 
+modp_b85_gen: modp_b85_gen.o arraytoc.o
+
 clean:
-	rm -f $(LIB) *.o
+	rm -f $(LIB) modp_b85_gen *.o
 
 test: $(LIB)
 	prove -r t/

README.md

@@ -29,6 +29,8 @@ Table of Contents
     * [decode_base64](#decode_base64)
     * [encode_base64url](#encode_base64url)
     * [decode_base64url](#decode_base64url)
+    * [encode_base85](#encode_base85)
+    * [encode_base85](#encode_base85)
 
 ## MUST READ
 
@@ -147,3 +149,20 @@ Read the 'Must Read' section for more info.
 
 [Back to TOC](#table-of-contents)
 
+### encode_base85
+`syntax: encoded = encode_base85(raw)`
+
+Encode given string into base85 format with/without padding '='.
+Note that there is not a standard but too many variants of so-called base85.
+This module's implementation should be compatiable with Go's encoding/ascii85
+module (not in the level of API argument, but in the level of encode/decode rules).
+
+[Back to TOC](#table-of-contents)
+
+### encode_base85
+`syntax: raw, err = decode_base85(encoded)`
+
+Decode base85 format string into its raw value. If the given string is not valid base85 encoded, the `raw` will be `nil` and `err` will be `"invalid input"`.
+
+[Back to TOC](#table-of-contents)
+

arraytoc.c

@@ -0,0 +1,85 @@
+#include "arraytoc.h"
+#include <stdio.h>
+
+/* dump uint32_t as hex digits */
+void uint32_array_to_c_hex(const uint32_t* ary, size_t sz, const char* name)
+{
+    size_t i = 0;
+
+    printf("static const uint32_t %s[%d] = {\n    ", name, (int)sz);
+    for (;;) {
+        printf("0x%08x", ary[i]);
+        ++i;
+        if (i == sz)
+            break;
+        if (i % 6 == 0) {
+            printf(",\n    ");
+        } else {
+            printf(", ");
+        }
+    }
+    printf("\n};\n");
+}
+
+/**
+ * prints char array as a c program snippet
+ */
+void char_array_to_c(const char* ary, size_t sz, const char* name)
+{
+    uint8_t tmp;
+    size_t i = 0;
+
+    printf("static const uint8_t %s[%d] = {\n    ", name, (int)sz);
+
+    for (;;) {
+        if (ary[i] == 0) {
+            printf("'\\0'");
+        } else if (ary[i] == '\n') {
+            printf("'\\n'");
+        } else if (ary[i] == '\t') {
+            printf("'\\t'");
+        } else if (ary[i] == '\r') {
+            printf("'\\r'");
+        } else if (ary[i] == '\'') {
+            printf("'\\''");
+        } else if (ary[i] == '\\') {
+            printf("'\\\\'");
+        } else if (ary[i] < 32 || ary[i] > 126) {
+            tmp = (uint8_t)ary[i];
+            printf("0x%02x", tmp);
+        } else {
+            printf("'%c'", (char)ary[i]);
+        }
+        ++i;
+        if (i == sz)
+            break;
+        if (i % 10 == 0) {
+            printf(",\n    ");
+        } else {
+            printf(", ");
+        }
+    }
+    printf("\n};\n");
+}
+
+/**
+ * prints an uint array as a c program snippet
+ */
+void uint32_array_to_c(const uint32_t* ary, size_t sz, const char* name)
+{
+    size_t i = 0;
+
+    printf("static const uint32_t %s[%d] = {\n    ", name, (int)sz);
+    for (;;) {
+        printf("%u", ary[i]);
+        ++i;
+        if (i == sz)
+            break;
+        if (i % 12 == 0) {
+            printf(",\n    ");
+        } else {
+            printf(", ");
+        }
+    }
+    printf("\n};\n");
+}

arraytoc.h

@@ -0,0 +1,43 @@
+#ifndef COM_MODP_STRINGENCODERS_ARRAYTOC
+#define COM_MODP_STRINGENCODERS_ARRAYTOC
+
+#include "modp_stdint.h"
+
+#ifdef __cplusplus
+#define BEGIN_C extern "C" {
+#define END_C }
+#else
+#define BEGIN_C
+#define END_C
+#endif
+
+BEGIN_C
+
+/** \brief output a uint32_t array into source code
+ *
+ *
+ * \param[in] ary the input array
+ * \param[in] size number of elements in array
+ * \param[in] name the name of the struct for the source code
+ *
+ */
+void uint32_array_to_c(const uint32_t* ary, size_t size, const char* name);
+
+/** \brief output an uint32_t array into source code as hex values
+ *
+ * \param[in] ary the input array
+ * \param[in] size number of elements in array
+ * \param[in] name the name of the struct for source code
+ *
+ */
+void uint32_array_to_c_hex(const uint32_t* ary, size_t size, const char* name);
+
+/** \brief output a char array into source code
+ *
+ * \param[in] ary the input array
+ * \param[in] size number of elements in array
+ * \param[in] name the name of the struct for source code
+ */
+void char_array_to_c(const char* ary, size_t size, const char* name);
+
+#endif

lib/resty/base_encoding.lua

@@ -1,7 +1,9 @@
 local error = error
 local tostring = tostring
 local type = type
+local ceil = math.ceil
 local floor = math.floor
+local str_rep = string.rep
 local base = require "resty.core.base"
 local get_string_buf = base.get_string_buf
 local ffi = require "ffi"
@@ -48,6 +50,8 @@ size_t modp_b16_encode(char* dest, const char* str, size_t len,
 size_t modp_b16_decode(char* dest, const char* src, size_t len);
 size_t modp_b2_encode(char* dest, const char* str, size_t len);
 size_t modp_b2_decode(char* dest, const char* str, size_t len);
+size_t modp_b85_encode(char* dest, const char* str, size_t len);
+size_t modp_b85_decode(char* dest, const char* str, size_t len);
 ]])
 
 
@@ -291,4 +295,47 @@ function _M.decode_base2(s)
 end
 
 
+local function base85_encoded_length(len)
+    return len / 4 * 5
+end
+
+
+function _M.encode_base85(s)
+    s = check_encode_str(s)
+
+    local slen = #s
+    if slen == 0 then
+        return ""
+    end
+
+    local dlen = base85_encoded_length(slen)
+    local dst = get_string_buf(dlen)
+    local r_dlen = encoding.modp_b85_encode(dst, s, slen)
+    return ffi_string(dst, r_dlen)
+end
+
+
+local function base85_decoded_length(len)
+    return ceil(len / 5) * 4
+end
+
+
+function _M.decode_base85(s)
+    check_decode_str(s, 1)
+
+    local slen = #s
+    if slen == 0 then
+        return ""
+    end
+
+    local dlen = base85_decoded_length(slen)
+    local dst = get_string_buf(dlen)
+    local r_dlen = encoding.modp_b85_decode(dst, s, slen)
+    if r_dlen == -1 then
+        return nil, "invalid input"
+    end
+    return ffi_string(dst, r_dlen)
+end
+
+
 return _M