daydaytalk-fwutils/target/tencent/board/generate_user_sig.lua

--[[
* Module:   GenerateUserSig (Lua version)
* Function: Generate UserSig for Tencent Cloud IM/Board SDK
* Reference: C++ implementation provided
* Note: This implementation uses Lua's standard libraries and assumes the presence of 'openssl' and 'zlib' Lua modules.
* Usage: require this module and call gen_user_sig(user_id, sdkappid, secretkey, expiretime)
--]]
require("app.app")
local zlib = require("zlib")
local base64 = require("app.module.base64")
local M = {}

-- Helper: base64 encode, then replace +, /, = as required by Tencent
local function base64_url_encode(data)
    local b64 = base64.encode(data)
    -- 按照C++代码的字符替换规则
    b64 = b64:gsub("+", "*"):gsub("/", "-"):gsub("=", "_")
    return b64
end
 
-- Helper: HMAC-SHA256
local function hmac_sha256(key, msg)
    -- 确保参数都是字符串类型
    return codec.hmac_sha256(tostring(key), tostring(msg))
end

-- Helper: hex string -> binary string
local function hex_to_bin(hex)
    return (hex:gsub("..", function(cc)
        return string.char(tonumber(cc, 16))
    end))
end

-- Helper: Generate the HMAC-SHA256 signature string
local function gen_hmac_sig(user_id, sdkappid, curr_time, expire_time, secret_key)
    local content = string.format(
        "TLS.identifier:%s\nTLS.sdkappid:%d\nTLS.time:%d\nTLS.expire:%d\n",
        user_id, sdkappid, curr_time, expire_time
    )
    -- 底层返回十六进制摘要，需转为二进制再做标准Base64
    local sig_hex = hmac_sha256(secret_key, content)
    local sig_bin = hex_to_bin(sig_hex)
    return base64.encode(sig_bin)
end

-- Main: Generate the UserSig JSON, compress, and base64 encode
local function gen_user_sig(user_id, sdkappid, secretkey, expiretime)
    assert(user_id and user_id ~= "", "user_id must not be empty")
    assert(tonumber(sdkappid) and tonumber(sdkappid) > 0, "sdkappid must be a positive integer")
    assert(tonumber(expiretime) and tonumber(expiretime) > 0, "expiretime must be a positive integer")
    assert(secretkey and secretkey ~= "", "secretkey must not be empty")

    local curr_time = os.time()
    -- 按官方JS示例：TLS.expire 使用持续时间（秒），不是绝对时间戳
    local expire_time = expiretime

    local sig = gen_hmac_sig(user_id, sdkappid, curr_time, expire_time, secretkey)

    -- Compose JSON string (严格按照C++代码的格式和顺序)
    local json = string.format(
        '{"TLS.ver":"2.0","TLS.identifier":"%s","TLS.sdkappid":%d,"TLS.expire":%d,"TLS.time":%d,"TLS.sig":"%s"}',
        user_id, sdkappid, expire_time, curr_time, sig
    )

    -- Compress with zlib (raw deflate) - 使用Z_BEST_SPEED压缩级别
    local deflater = zlib.deflate()
    local compressed, eof, bytes_in, bytes_out = deflater(json, "finish")

    -- Base64 encode and replace chars as required
    local user_sig = base64_url_encode(compressed)
    return user_sig
end

-- Public API
M.gen_user_sig = gen_user_sig

return M