34-Openwrt uhttpd與rpcd

uhttpd作為一個簡單的web服務器,其代碼量并不多,而且組織結構比較清楚。和其它網絡服務器差不多,其main函數進行一些初始化(首先parse config-file,然后parse argv),然后進入一個循環,不斷地監聽,每當有一個客戶請求到達時,則對它進行處理。

1、uhttpd uci配置參數說明

/etc/init.d/uhttpd腳本會使用procd的方式啟動uhttpd進程,該工具后面可以帶很多參數,如下:

root@zihome:~# uhttpd -h
uhttpd: option requires an argument -- h
Usage: uhttpd -p [addr:]port -h docroot
        -f              Do not fork to background
        -c file         Configuration file, default is '/etc/httpd.conf'
        -p [addr:]port  Bind to specified address and port, multiple allowed
        -s [addr:]port  Like -p but provide HTTPS on this port
        -C file         ASN.1 server certificate file
        -K file         ASN.1 server private key file
        -h directory    Specify the document root, default is '.'
        -E string       Use given virtual URL as 404 error handler
        -I string       Use given filename as index for directories, multiple allowed
        -S              Do not follow symbolic links outside of the docroot
        -D              Do not allow directory listings, send 403 instead
        -R              Enable RFC1918 filter
        -n count        Maximum allowed number of concurrent script requests
        -N count        Maximum allowed number of concurrent connections
        -l string       URL prefix for Lua handler, default is '/lua'
        -L file         Lua handler script, omit to disable Lua
        -u string       URL prefix for UBUS via JSON-RPC handler
        -U file         Override ubus socket path
        -a              Do not authenticate JSON-RPC requests against UBUS session api
        -X              Enable CORS HTTP headers on JSON-RPC api
        -x string       URL prefix for CGI handler, default is '/cgi-bin'
        -i .ext=path    Use interpreter at path for files with the given extension
        -t seconds      CGI, Lua and UBUS script timeout in seconds, default is 60
        -T seconds      Network timeout in seconds, default is 30
        -k seconds      HTTP keepalive timeout
        -d string       URL decode given string
        -r string       Specify basic auth realm
        -m string       MD5 crypt given string

openwrt上面還是通過uci來配置uhttpd,配置文件如下:

config uhttpd 'main'
        list listen_http '0.0.0.0:80'
        list listen_http '[::]:80'
        list listen_https '0.0.0.0:443'
        list listen_https '[::]:443'
        option home '/www'
        option rfc1918_filter '1'
        option max_requests '3'
        option max_connections '10'
        option cert '/etc/uhttpd.crt'
        option key '/etc/uhttpd.key'
        option cgi_prefix '/cgi-bin'
        option script_timeout '120'
        option network_timeout '60'
        option http_keepalive '60'
        option tcp_keepalive '5'
        option no_ubusauth '0'
        option ubus_prefix '/ubus'

uHTTPd 配置項含義:

名 稱 類 型 含 義
listen_http 字符串 定義服務器的 IP 和端口。指所監聽的非加密的地址和端口。如果僅給出端口號,將同時服務于IPv4和IPv6請求。使用0.0.0.0:80僅綁定在 IPv4 接口,使用[::]:80 僅綁定 IPv6
home 目錄路徑 定義服務器的文檔根目錄
max_requests 整型數字 最大的并行請求數,如果大于這個值,后續的請求將進入排隊隊列中
cert 文件路徑 用于 HTTPS 連接的 ASN.1/DER 證書。在提供 HTTS 連接時必須提供
key 文件路徑 用于 HTTPS 連接的 ASN.1/DER 私鑰。在提供 HTTPS 連接時必須提供
cgi_prefix 字符串 定義 CGI 腳本的相對于根目錄的前綴。如果沒有該選項,CGI功能將不支持
script_timeout 整型數字 Lua 或CGI請求的最大等待時間秒值。如果沒有輸出產生,則超時后執行就結束了
network_timeout 整型數字 網絡活動的最大等待時間,如果指定的秒數內沒有網絡活動發生,則程序終止,連接關閉
tcp_keepalive 整型數字 tcp 心跳檢測時間間隔,發現對端已不存在時則關閉連接。設置為 0 則關閉 tcp 心跳檢測
realm 字符串 基本認證的域值,默認為主機名,是當客戶端進行基本認證的提示內容
config 文件路徑 用于基本認證的配置文件
no_dirlists 是否顯示文件列表 正常情況可以直接通過瀏覽器查看文件,不安全可以使用該字段屏蔽瀏覽器查看
max_requests 最大請求數 同時處理的請求的最大數量。當這個數量被超過時,額外的請求將被放入隊列中等待
max_connections 最大連接數 同時處理的最大TCP連接數量。當這個數量被超過時,額外的TCP連接嘗試將被放入隊列中等待
ubus_prefix ubus前綴 使用JSON-RPC訪問,如http://192.168.18.1/ubus.
ubus_noauth session認證 關閉后可以不用認證,直接訪問http接口

/etc/init.d/uhttpd腳本在啟動的時候會去獲取/etc/config/uhttpd配置里面的信息然后進行啟動,我們現在用到的參數如下:

root@zihome:/# ps | grep uhttp
 1395 root      1556 S    /usr/sbin/uhttpd -f -h /www -r openwrt -x /cgi-bin -t 120 -T 60 -k 60 -A 5 -n 3 -N 10 -R -p 0.0.0.0:80 -p [::]:80
31572 root      1520 S    grep uhttp

https://openwrt.org/docs/guide-user/services/webserver/uhttpd

2、uhttpd的登錄認證超時機制

登錄做為web登錄最基礎的功能,其背后是由rpcd提供的session模式實現的。

session模式實現了創建、更新、退出、添加acl權限等功能。

具體使用可以查看rpcd的介紹:

'session' @3602a25d
        "create":{"timeout":"Integer"}
        "list":{"ubus_rpc_session":"String"}
        "grant":{"ubus_rpc_session":"String","scope":"String","objects":"Array"}
        "revoke":{"ubus_rpc_session":"String","scope":"String","objects":"Array"}
        "access":{"ubus_rpc_session":"String","scope":"String","object":"String","function":"String"}
        "set":{"ubus_rpc_session":"String","values":"Table"}
        "get":{"ubus_rpc_session":"String","keys":"Array"}
        "unset":{"ubus_rpc_session":"String","keys":"Array"}
        "destroy":{"ubus_rpc_session":"String"}
        "login":{"username":"String","password":"String","timeout":"Integer"

3、ubus over http功能

在openwrt默認的web應用中,很主要的一共功能點,就是展示和設置信息。因為ubus -v list里面覆蓋了大部分我們需要的信息,所以如果可以通過一種簡單的rpc方案,通過http直接訪問ubus的內容那就方便了。

這就是ubus over http功能,web發送一個http請求,這個請求的結構根據ubus命令封裝之后,直接從ubus接口里面獲取內容返回給web頁面。

因為ubus接口里面包含了太多的信息,我們不想把所有信息都暴露給web,所以有了rpcd里面的acls權限管理。權限管理里面說明了只能執行那些命令。

使用該功能需要在uci里面把配置打開

option ubus_prefix  /ubus

之后可以用postman發送post請求

登錄:

{
    "jsonrpc":"2.0",
    "id":1,
    "method":"call",
    "params":[
        "00000000000000000000000000000000",
        "session",
        "login",
        {
            "username":"root",
            "password":"admin"
        }
    ]
}

此時會返回該賬號的session,還有權限之類的

{
    "jsonrpc": "2.0",
    "id": 1,
    "result": [
        0,
        {
            "ubus_rpc_session": "e5333f3fe2ed4601be3b0a8da0a6998e",
            "timeout": 300,
            "expires": 300,
            "acls": {
                "access-group": {
                    "luci-access": [
                        "read",
                        "write"
                    ],
                    "luci-app-firewall": [
                        "read",
                        "write"
                    ],
                    ...
                    "uci-access": [
                        "read",
                        "write"
                    ],
                    "unauthenticated": [
                        "read"
                    ]
                },
                "cgi-io": {
                    "backup": [
                        "read"
                    ],
                    "download": [
                        "read"
                    ],
                    "exec": [
                        "read"
                    ],
                    "upload": [
                        "write"
                    ]
                },
                "file": {
                    "/": [
                        "list"
                    ],
                    "/*": [
                        "list"
                    ],
                    "/bin/dmesg -r": [
                        "exec"
                    ],
                   ...
                    "/usr/sbin/logread -e ^": [
                        "exec"
                    ]
                },
                "ubus": {
                    "file": [
                        "list",
                        "read",
                        "stat",
                        "write",
                        "remove",
                        "exec"
                    ],
                    "hostapd.*": [
                        "del_client"
                    ],
                    "iwinfo": [
                        "assoclist",
                        "freqlist",
                        "txpowerlist",
                        "countrylist",
                        "scan"
                    ],
                    "luci": [
                        "getFeatures",
                        "getConntrackList",
                        "getInitList",
                        "getLocaltime",
                        "getProcessList",
                        "getRealtimeStats",
                        "getTimezones",
                        "getLEDs",
                        "getUSBDevices",
                        "getSwconfigFeatures",
                        "getSwconfigPortState",
                        "getBlockDevices",
                        "getMountPoints",
                        "setInitAction",
                        "setLocaltime",
                        "setPassword",
                        "setBlockDetect",
                        "getConntrackHelpers"
                    ],
                    "luci-rpc": [
                        "getBoardJSON",
                        "getDHCPLeases",
                        "getDSLStatus",
                        "getDUIDHints",
                        "getHostHints",
                        "getNetworkDevices",
                        "getWirelessDevices"
                    ],
                    "network": [
                        "get_proto_handlers"
                    ],
                    "network.interface": [
                        "dump"
                    ],
                    "network.rrdns": [
                        "lookup"
                    ],
                    "session": [
                        "access",
                        "login"
                    ],
                    "system": [
                        "board",
                        "info",
                        "validate_firmware_image"
                    ],
                    "uci": [
                        "changes",
                        "get",
                        "add",
                        "apply",
                        "confirm",
                        "delete",
                        "order",
                        "set",
                        "rename"
                    ]
                },
                "uci": {
                    "*": [
                        "read",
                        "write"
                    ],
                    ...
                    "uhttpd": [
                        "read",
                        "write"
                    ]
                }
            },
            "data": {
                "username": "root"
            }
        }
    ]
}

之后我們就可以使用這個session進行發送ubus請求,比如系統信息

{
    "jsonrpc":"2.0",
    "id":1,
    "method":"call",
    "params":[
        "2cd182b0120310db8869b43d4340a307",
        "system",
        "board",
        {
           
        }
    ]
}

返回內容:

{
    "jsonrpc": "2.0",
    "id": 1,
    "result": [
        0,
        {
            "kernel": "4.14.275",
            "hostname": "OpenWrt",
            "system": "Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz",
            "model": "VMware, Inc. VMware Virtual Platform",
            "board_name": "vmware-inc-vmware-virtual-platform",
            "release": {
                "distribution": "OpenWrt",
                "version": "19.07-SNAPSHOT",
                "revision": "r11430-ecbbb37",
                "target": "x86/64",
                "description": "OpenWrt 19.07-SNAPSHOT r11430-ecbbb37"
            }
        }
    ]
}

可以看到返回的內容跟直接輸入ubus call一致

root@OpenWrt:~# ubus call system board
{
    "kernel": "4.14.275",
    "hostname": "OpenWrt",
    "system": "Intel(R) Core(TM) i7-6700 CPU @ 3.40GHz",
    "model": "VMware, Inc. VMware Virtual Platform",
    "board_name": "vmware-inc-vmware-virtual-platform",
    "release": {
        "distribution": "OpenWrt",
        "version": "19.07-SNAPSHOT",
        "revision": "r11430-ecbbb37",
        "target": "x86/64",
        "description": "OpenWrt 19.07-SNAPSHOT r11430-ecbbb37"
    }
}

當然如果不屬于上面權限的ubus消息是無法發送的,比如

{
    "jsonrpc":"2.0",
    "id":1,
    "method":"call",
    "params":[
        "2cd182b0120310db8869b43d4340a307",
        "network.interface.lan",
        "status",
        {
           
        }
    ]
}

返回沒有權限

{
    "jsonrpc": "2.0",
    "id": 1,
    "error": {
        "code": -32002,
        "message": "Access denied"
    }
}

這些權限的配置都位于/usr/share/rpcd/acl.d/目錄下面配置,我們可以自己按照規則增刪。

上面json請求的結構體描述如下:

{ "jsonrpc": "2.0",
  "id": <unique-id-to-identify-request>, 
  "method": "call",
  "params": [
             <ubus_rpc_session>, <ubus_object>, <ubus_method>, 
             { <ubus_arguments> }
            ]
}
{ "jsonrpc": "2.0", "id": 1, "method": "call", "params": [ "c1ed6c7b025d0caca723a816fa61b668", "file", "read", { "path": "/etc/board.json" } ] }

how to use ubus over http in openwrt 12.09
https://www.cnblogs.com/nicephil/p/6768381.html#e4bdbfe794a8e696b9e6b395_2

openwrt-rpcd服務ACL配置錯誤風險分析:https://www.cnblogs.com/hac425/p/9416854.html

https://openwrt.org/docs/techref/ubus#access_to_ubus_over_http

4、cgi框架

要運行cgi程序,首先意味著需fork出一個子進程,并通過execl函數替換進程空間為cgi程序;其次,數據傳遞,子進程替換了進程空間后,怎么獲得原信息,有怎么把回饋數據傳輸給父進程(即uhttpd),父進程又怎么接收這些數據。

https://www.cnblogs.com/zmkeil/archive/2013/05/14/3078766.html

?著作權歸作者所有,轉載或內容合作請聯系作者
平臺聲明:文章內容(如有圖片或視頻亦包括在內)由作者上傳并發布,文章內容僅代表作者本人觀點,簡書系信息發布平臺,僅提供信息存儲服務。

推薦閱讀更多精彩內容