39 lines
1.1 KiB
Go
39 lines
1.1 KiB
Go
package smtp
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import (
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"net"
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"regexp"
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"github.com/zmap/zgrab2"
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)
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// This is the regex used in zgrab.
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// Corner cases like "200 OK\r\nthis is not valid at all\x00\x01\x02\x03\r\n" will be matched.
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var smtpEndRegex = regexp.MustCompile(`(?:^\d\d\d\s.*\r\n$)|(?:^\d\d\d-[\s\S]*\r\n\d\d\d\s.*\r\n$)`)
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const readBufferSize int = 0x10000
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// Connection wraps the state and access to the SMTP connection.
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type Connection struct {
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Conn net.Conn
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}
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// ReadResponse reads from the connection until it matches the smtpEndRegex. Copied from the original zgrab.
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// TODO: Catch corner cases, parse out response code.
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func (conn *Connection) ReadResponse() (string, error) {
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ret := make([]byte, readBufferSize)
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n, err := zgrab2.ReadUntilRegex(conn.Conn, ret, smtpEndRegex)
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if err != nil {
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return "", nil
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}
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return string(ret[0:n]), nil
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}
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// SendCommand sends a command, followed by a CRLF, then wait for / read the server's response.
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func (conn *Connection) SendCommand(cmd string) (string, error) {
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if _, err := conn.Conn.Write([]byte(cmd + "\r\n")); err != nil {
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return "", err
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}
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return conn.ReadResponse()
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}
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