如何解压http

我试图读取包含http压缩消息的tcp数据包，但它失败了'在zlib解压缩期间异常:(-3)不正确的头检查'。我的代码出了什么问题，或者有一个库可以为我做这些?

std::string decompress_string(const std::string& str) {
    z_stream zs;                        // z_stream is zlib's control structure
    memset(&zs, 0, sizeof(zs));
    if (inflateInit(&zs) != Z_OK)
        throw(std::runtime_error("inflateInit failed while decompressing."));
    zs.next_in = (Bytef*)str.data();
    zs.avail_in = str.size();
    int ret;
    char outbuffer[32768];
    std::string outstring;
    // get the decompressed bytes blockwise using repeated calls to inflate
    do {
        zs.next_out = reinterpret_cast<Bytef*>(outbuffer);
        zs.avail_out = sizeof(outbuffer);
        ret = inflate(&zs, 0);
        if (outstring.size() < zs.total_out) {
            outstring.append(outbuffer,
                             zs.total_out - outstring.size());
        }
    } while (ret == Z_OK);
    inflateEnd(&zs);
    if (ret != Z_STREAM_END) {          // an error occurred that was not EOF
        qDebug()  << "Exception during zlib decompression: (" << ret << ") " << zs.msg;
        return "";
    }
    return outstring;
}
std::string parseHttp(std::string payload) {
    size_t index = payload.find("rnrn");
    if (index == std::string::npos) {
        qDebug() << "http body not found, dropped.";
        return "";
    }
    std::string body = payload.substr(index + 4);
    if (payload.find("Content-Encoding: gzip") == std::string::npos){
        return body;
    } else {
        return decompress_string(body);
    }
}