本文介绍 SDK 通过代理访问 TOS 的过程。

当客户端位于火山网络外，且大部分客户端无法访问外网，如客户端位于客户本地机房且无外网访问权限时，可以通过搭建代理服务器，将SDK的请求通过代理发送到TOS服务端。

TOS SDK 支持设置 HTTP 协议代理服务发送请求（目前只支持 HTTP 协议代理）。

本实验使用Go SDK跟squid代理服务实现代理转发SDK请求。

• 预计部署时间：30分钟
• 级别：初级
• 相关产品：TOS
• 受众： 通用

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一、安装squid

您可以使用如下命令安装squid并启动服务。

yum install squid -y
systemctl start squid
systemctl status squid

安装成功后，进程状态如下：

[root@xxxxxx ~]# systemctl status squid
● squid.service - Squid caching proxy
   Loaded: loaded (/usr/lib/systemd/system/squid.service; disabled; vendor preset: disabled)
   Active: active (running) since 四 2023-10-19 21:22:18 CST; 5 days ago
  Process: 12335 ExecStart=/usr/sbin/squid $SQUID_OPTS -f $SQUID_CONF (code=exited, status=0/SUCCESS)
  Process: 12329 ExecStartPre=/usr/libexec/squid/cache_swap.sh (code=exited, status=0/SUCCESS)
 Main PID: 12338 (squid)
    Tasks: 3
   Memory: 14.0M
   CGroup: /system.slice/squid.service
           ├─12338 /usr/sbin/squid -f /etc/squid/squid.conf
           ├─12340 (squid-1) -f /etc/squid/squid.conf
           └─12341 (logfile-daemon) /var/log/squid/access.log

配置文件如下：

[root@xxxx ~]# cat /etc/squid/squid.conf
#
# Recommended minimum configuration:
#

# Example rule allowing access from your local networks.
# Adapt to list your (internal) IP networks from where browsing
# should be allowed
acl localnet src 10.0.0.0/8	# RFC1918 possible internal network
acl localnet src 172.16.0.0/12	# RFC1918 possible internal network
acl localnet src 192.168.0.0/16	# RFC1918 possible internal network
acl localnet src fc00::/7       # RFC 4193 local private network range
acl localnet src fe80::/10      # RFC 4291 link-local (directly plugged) machines

acl SSL_ports port 443
acl Safe_ports port 80		# http
acl Safe_ports port 21		# ftp
acl Safe_ports port 443		# https
acl Safe_ports port 70		# gopher
acl Safe_ports port 210		# wais
acl Safe_ports port 1025-65535	# unregistered ports
acl Safe_ports port 280		# http-mgmt
acl Safe_ports port 488		# gss-http
acl Safe_ports port 591		# filemaker
acl Safe_ports port 777		# multiling http
acl CONNECT method CONNECT

#
# Recommended minimum Access Permission configuration:
#
# Deny requests to certain unsafe ports
#http_access deny !Safe_ports

# Deny CONNECT to other than secure SSL ports
#http_access deny CONNECT !SSL_ports
http_access allow localnet
# Only allow cachemgr access from localhost
http_access allow localhost manager
http_access deny manager

# We strongly recommend the following be uncommented to protect innocent
# web applications running on the proxy server who think the only
# one who can access services on "localhost" is a local user
#http_access deny to_localhost

#
# INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
#
# Example rule allowing access from your local networks.
# Adapt localnet in the ACL section to list your (internal) IP networks
# from where browsing should be allowed
http_access allow localnet
http_access allow localhost
# And finally deny all other access to this proxy
#http_access deny all
http_access allow all
# Squid normally listens to port 3128
http_port 3128

# Uncomment and adjust the following to add a disk cache directory.
#cache_dir ufs /var/spool/squid 100 16 256

# Leave coredumps in the first cache dir
coredump_dir /var/spool/squid

#
# Add any of your own refresh_pattern entries above these.
#
refresh_pattern ^ftp:		1440	20%	10080
refresh_pattern ^gopher:	1440	0%	1440
refresh_pattern -i (/cgi-bin/|\?) 0	0%	0
refresh_pattern .		0	20%	4320

本配置文件只做示例演示，您可以根据实际环境调整配置文件。

二、代码实现

本示例代码使用TOS Go SDK完成，示例为上传对象至TOS。

示例代码如下：

package main

import (
	"fmt"
	"github.com/volcengine/ve-tos-golang-sdk/v2/tos"
	"golang.org/x/net/context"
	"os"
)

func checkErr(err error) {
	if err != nil {
		if serverErr, ok := err.(*tos.TosServerError); ok {
			fmt.Println("Error:", serverErr.Error())
			fmt.Println("Request ID:", serverErr.RequestID)
			fmt.Println("Response Status Code:", serverErr.StatusCode)
			fmt.Println("Response Header:", serverErr.Header)
			fmt.Println("Response Err Code:", serverErr.Code)
			fmt.Println("Response Err Msg:", serverErr.Message)
		} else if clientErr, ok := err.(*tos.TosClientError); ok {
			fmt.Println("Error:", clientErr.Error())
			fmt.Println("Client Cause Err:", clientErr.Cause.Error())
		} else {
			fmt.Println("Error:", err)
		}
		panic(err)
	}
}

func main() {
	var (
		ak       = "xxx"
		sk       = "xxx"
		endpoint = "http://tos-cn-beijing.volces.com"
		region   = "cn-beijing"

		proxyHost = "http://代理服务器地址"
		proxyPort = 3128 //代理服务器端口
	)
	proxy, err := tos.NewProxy(proxyHost, proxyPort)
	checkErr(err)
	credential := tos.NewStaticCredentials(ak, sk)
	// 可以通过 tos.WithProxy 的方式添加请求代理
	client, err := tos.NewClientV2(endpoint, tos.WithCredentials(credential), tos.WithRegion(region), tos.WithProxy(proxy))
	checkErr(err)
	fmt.Println(client.Client)
	fmt.Println("start")


	file, _ := os.Open("/Users/xxxxx")

	inputStruct := tos.PutObjectBasicInput{
		Bucket: "xxxx",
		Key:    "xxxx",
	}

	putResult, err1 := client.PutObjectV2(context.Background(), &tos.PutObjectV2Input{
		inputStruct,
		file,
	})

	checkErr(err1)

	fmt.Println(putResult)

	client.Close()
}

程序执行后，您可以看到proxy返回的响应，然后可以通过控制台检查上传对象是否成功。

参考文档：
[1] TOS Go SDK