Melora Hugues
3a1bb20a1f
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Ref #4 This commit adds an active monitoring of the current public IP. If a change is detected, then a message is sent to the given Telegram channel. Add a few tests for the main monitoring logic.
65 lines
1.5 KiB
Go
65 lines
1.5 KiB
Go
package ip
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import (
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"bytes"
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"context"
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"fmt"
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"io"
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"net"
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"net/http"
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"time"
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)
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const ifconfigURL = "https://ifconfig.me"
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const httpMaxRead = 100
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const httpTimeout = 10 * time.Second
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type IPGetter interface {
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GetCurrentPublicIP(ctx context.Context) (net.IP, error)
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}
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type concreteIPGetter struct {
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httpClt *http.Client
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remoteAddress string
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timeout time.Duration
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}
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func (c *concreteIPGetter) GetCurrentPublicIP(ctx context.Context) (net.IP, error) {
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reqCtx, cancel := context.WithTimeout(ctx, c.timeout)
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defer cancel()
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req, err := http.NewRequestWithContext(reqCtx, http.MethodGet, c.remoteAddress, nil)
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if err != nil {
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return nil, fmt.Errorf("failed to prepare public IP request: %w", err)
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}
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resp, err := c.httpClt.Do(req)
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if err != nil {
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return nil, fmt.Errorf("failed to get current IP from ifconfig: %w", err)
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}
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if resp.StatusCode != http.StatusOK {
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return nil, fmt.Errorf("invalid returncode %d", resp.StatusCode)
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}
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if resp.ContentLength > httpMaxRead {
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return nil, fmt.Errorf("response too big: %d/%d", resp.ContentLength, httpMaxRead)
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}
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buf := bytes.NewBuffer([]byte{})
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if _, err := io.CopyN(buf, resp.Body, resp.ContentLength); err != nil {
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return nil, fmt.Errorf("error parsing body: %w", err)
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}
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content := string(buf.Bytes())
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res := net.ParseIP(content)
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if res == nil {
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return nil, fmt.Errorf("got an invalid public IP %q", content)
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}
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return res, nil
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}
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func New() IPGetter {
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return &concreteIPGetter{
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httpClt: http.DefaultClient,
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remoteAddress: ifconfigURL,
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timeout: httpTimeout,
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}
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}
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