Golang使用HTTP代理连接失败问题求助

golang.org/x/net/proxy 包默认只支持 SOCKS5 代理，不支持 HTTP/HTTPS 代理。你需要使用 net/http 包中的 Transport 来配置 HTTP 代理。以下是修改后的代码：

package main

import (
    "fmt"
    "net/http"
    "net/url"
    "os"
)

var host = "https://google.com"

func main() {
    fmt.Println("Inside main...")

    // 设置代理环境变量
    if os.Getenv("http_proxy") == "" {
        os.Setenv("http_proxy", "http://192.130.0.10:3200")
    }

    proxyURL, err := url.Parse(os.Getenv("http_proxy"))
    if err != nil {
        fmt.Println("Failed to parse proxy URL:", err)
        return
    }

    fmt.Println("System proxy is:", proxyURL)

    // 创建 HTTP 客户端并配置代理
    transport := &http.Transport{
        Proxy: http.ProxyURL(proxyURL),
    }

    client := &http.Client{
        Transport: transport,
        Timeout:   30 * time.Second,
    }

    fmt.Println("Connecting to...", host)

    resp, err := client.Get(host)
    if err != nil {
        fmt.Println("Request failed:", err)
        return
    }
    defer resp.Body.Close()

    fmt.Printf("Connected! Status: %s\n", resp.Status)
}

如果你需要通用的 TCP 连接（不仅仅是 HTTP），可以使用以下方法：

package main

import (
    "fmt"
    "net"
    "net/url"
    "os"
    "time"
)

var host = "google.com:80"

func main() {
    fmt.Println("Inside main...")

    if os.Getenv("http_proxy") == "" {
        os.Setenv("http_proxy", "http://192.130.0.10:3200")
    }

    proxyURL, err := url.Parse(os.Getenv("http_proxy"))
    if err != nil {
        fmt.Println("Failed to parse proxy URL:", err)
        return
    }

    fmt.Println("System proxy is:", proxyURL)

    // 通过 HTTP 代理建立 TCP 连接
    conn, err := net.DialTimeout("tcp", proxyURL.Host, 10*time.Second)
    if err != nil {
        fmt.Println("Failed to connect to proxy:", err)
        return
    }
    defer conn.Close()

    // 发送 CONNECT 请求到代理服务器
    connectReq := fmt.Sprintf("CONNECT %s HTTP/1.1\r\nHost: %s\r\n\r\n", host, host)
    _, err = conn.Write([]byte(connectReq))
    if err != nil {
        fmt.Println("Failed to send CONNECT request:", err)
        return
    }

    // 读取代理响应
    buffer := make([]byte, 4096)
    n, err := conn.Read(buffer)
    if err != nil {
        fmt.Println("Failed to read proxy response:", err)
        return
    }

    response := string(buffer[:n])
    fmt.Println("Proxy response:", response)

    // 检查响应是否包含 "200 Connection established"
    if !contains(response, "200") {
        fmt.Println("Proxy connection failed")
        return
    }

    fmt.Println("Successfully connected through HTTP proxy")
    // 现在可以通过 conn 进行数据传输
}

func contains(s, substr string) bool {
    return len(s) >= len(substr) && (s == substr || len(s) > len(substr) && (s[:len(substr)] == substr || contains(s[1:], substr)))
}

对于需要同时支持 HTTP 和 SOCKS 代理的情况：

package main

import (
    "fmt"
    "net/http"
    "net/url"
    "os"
    "time"
    "golang.org/x/net/proxy"
)

func createHTTPClient() *http.Client {
    httpProxy := os.Getenv("http_proxy")
    if httpProxy == "" {
        return &http.Client{Timeout: 30 * time.Second}
    }

    proxyURL, err := url.Parse(httpProxy)
    if err != nil {
        fmt.Println("Warning: Invalid proxy URL, using direct connection")
        return &http.Client{Timeout: 30 * time.Second}
    }

    // 检查是否是 SOCKS 代理
    if proxyURL.Scheme == "socks5" {
        dialer, err := proxy.FromURL(proxyURL, proxy.Direct)
        if err != nil {
            fmt.Println("Warning: Failed to create SOCKS dialer, using direct connection")
            return &http.Client{Timeout: 30 * time.Second}
        }

        transport := &http.Transport{
            Dial: dialer.Dial,
        }
        return &http.Client{
            Transport: transport,
            Timeout:   30 * time.Second,
        }
    }

    // HTTP/HTTPS 代理
    transport := &http.Transport{
        Proxy: http.ProxyURL(proxyURL),
    }
    return &http.Client{
        Transport: transport,
        Timeout:   30 * time.Second,
    }
}

func main() {
    client := createHTTPClient()
    resp, err := client.Get("https://google.com")
    if err != nil {
        fmt.Println("Request failed:", err)
        return
    }
    defer resp.Body.Close()
    fmt.Printf("Success! Status: %s\n", resp.Status)
}