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contact-form
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Initial version

tags/v1.0.0
Chris Smith 5 years ago
commit
a0186456a6
9 changed files with 387 additions and 0 deletions
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  1. 15
    0
      Dockerfile
  2. 21
    0
      LICENCE.adoc
  3. 53
    0
      README.adoc
  4. 34
    0
      failure.html
  5. 78
    0
      form.html
  6. 8
    0
      go.mod
  7. 9
    0
      go.sum
  8. 136
    0
      main.go
  9. 33
    0
      success.html

+ 15
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Dockerfile View File 

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+FROM golang:1.12 AS build
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+
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+WORKDIR /go/src/app
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+
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+COPY . .
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+RUN CGO_ENABLED=0 GO111MODULE=on go install .
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+
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+FROM scratch
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+COPY --from=build /go/bin/contact-form /contact-form
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+COPY --from=build /go/src/app/*.html /templates/
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+COPY --from=build /etc/ssl/certs/ca-certificates.crt /etc/ssl/certs/ca-certificates.crt
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+
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+WORKDIR /templates
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+ENTRYPOINT ["/contact-form"]
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+EXPOSE 8080

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LICENCE.adoc View File 

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+= MIT License
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+
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+Copyright © 2019 Chris Smith
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+
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+Permission is hereby granted, free of charge, to any person obtaining a copy
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+of this software and associated documentation files (the "Software"), to deal
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+in the Software without restriction, including without limitation the rights
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+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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+copies of the Software, and to permit persons to whom the Software is
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+furnished to do so, subject to the following conditions:
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+
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+The above copyright notice and this permission notice shall be included in all
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+copies or substantial portions of the Software.
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+
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+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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+SOFTWARE.

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README.adoc View File 

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+= Go contact form
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+
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+== About
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+
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+Provides a simple, tiny webservice that serves a contact form and sends responses
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+via e-mail.
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+
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+== Usage
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+
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+The simplest way to use this is via docker:
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+
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+    docker run -d csmith/contact-form -from form@server.com -to me@email.com .....
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+
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+You should place this service behind an TLS-terminating proxy, and ensure it
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+is requested over a secure connection.
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+
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+== Command line flags
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+
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+----
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+  -crsf-key string
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+        CRSF key to use
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+  -from string
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+        address to send e-mail from
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+  -port int
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+        port to listen on for connections (default 8080)
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+  -smtp-host string
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+        SMTP server to connect to
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+  -smtp-pass string
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+        password to supply to the SMTP server
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+  -smtp-port int
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+        port to use when connecting to the SMTP server (default 25)
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+  -smtp-user string
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+        username to supply to the SMTP server
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+  -subject string
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+        e-mail subject (default "Contact form submission")
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+  -to string
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+        address to send e-mail to
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+----
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+
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+_from_, _to_, _smtp-host_, _smtp-user_, and _smtp-pass_ are required; other options have vaguely sensible fallbacks.
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+
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+== Templates
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+
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+The form itself is loaded from `form.html` in the working directory; success and failure pages from `success.html`
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+and `failure.html` respectively. Each is loaded as a https://golang.org/pkg/html/template/[go html.template] and
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+can use the templating syntax described there.
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+
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+The form must contain the `{{ .csrfField }}` template field, which will automatically insert the CSRF token for
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+the request.
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+
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+== Licence
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+
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+This software is licensed under the MIT licence. See the LICENCE.adoc file for the full text.

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failure.html View File 

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+<!DOCTYPE html>
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+<html lang="en">
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+<head>
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+    <meta http-equiv="Content-Type" content="text/html" charset="UTF-8"/>
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+    <title>Contact me</title>
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+    <style type="text/css">
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+        .page {
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+            width: 480px;
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+            padding: 8% 0 0;
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+            margin: auto;
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+        }
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+
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+        .form {
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+            position: relative;
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+            z-index: 1;
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+            background: #FFFFFF;
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+            max-width: 360px;
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+            margin: 0 auto 100px;
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+            padding: 45px;
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+            text-align: center;
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+            box-shadow: 0 0 20px 0 rgba(0, 0, 0, 0.2), 0 5px 5px 0 rgba(0, 0, 0, 0.24);
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+            font-family: sans-serif;
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+        }
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+    </style>
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+</head>
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+<body>
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+<div class="page">
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+    <div class="form">
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+        Your message could not be sent at this time.
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+        Please go back and try again.
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+    </div>
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+</div>
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+</body>
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+</html>

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form.html View File 

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+<!DOCTYPE html>
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+<html lang="en">
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+<head>
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+    <meta http-equiv="Content-Type" content="text/html" charset="UTF-8"/>
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+    <title>Contact me</title>
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+    <style type="text/css">
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+        .page {
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+            width: 640px;
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+            padding: 8% 0 0;
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+            margin: auto;
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+        }
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+
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+        .form {
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+            position: relative;
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+            z-index: 1;
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+            background: #FFFFFF;
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+            max-width: 640px;
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+            margin: 0 auto 100px;
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+            padding: 25px 45px 35px 45px;
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+            text-align: center;
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+            box-shadow: 0 0 20px 0 rgba(0, 0, 0, 0.2), 0 5px 5px 0 rgba(0, 0, 0, 0.24);
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+        }
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+
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+        .form input, .form textarea {
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+            outline: 0;
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+            background: #f2f2f2;
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+            width: 100%;
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+            border: 0;
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+            margin: 0 0 15px;
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+            padding: 15px;
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+            box-sizing: border-box;
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+            font-size: 14px;
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+        }
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+
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+        .form textarea {
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+            resize: vertical;
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+        }
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+
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+        .form button {
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+            text-transform: uppercase;
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+            outline: 0;
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+            background: #4CAF50;
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+            width: 100%;
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+            border: 0;
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+            padding: 15px;
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+            color: #FFFFFF;
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+            font-size: 14px;
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+            transition: all 0.3 ease;
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+            cursor: pointer;
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+        }
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+
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+        .form button:hover, .form button:active, .form button:focus {
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+            background: #43A047;
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+        }
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+
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+        h1 {
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+            font-family: sans-serif;
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+            font-variant: all-small-caps;
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+            font-size: 1.4em;
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+            margin: 0 0 0.9em 0;
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+        }
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+    </style>
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+</head>
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+<body>
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+<div class="page">
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+    <div class="form">
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+        <form action="submit" method="post">
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+            <h1>Contact me</h1>
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+            {{ .csrfField }}
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+            <input type="text" name="name" placeholder="Your name">
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+            <input type="email" name="from" placeholder="Your e-mail address">
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+            <textarea name="message" placeholder="Your message"></textarea>
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+            <button>SEND</button>
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+        </form>
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+    </div>
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+</div>
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+</body>
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+</html>

+ 8
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go.mod View File 

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+module contact-form
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+
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+go 1.12
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+
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+require (
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+	github.com/gorilla/csrf v1.5.1 // indirect
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+	github.com/gorilla/mux v1.7.1 // indirect
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+)

+ 9
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go.sum View File 

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+github.com/gorilla/context v1.1.1/go.mod h1:kBGZzfjB9CEq2AlWe17Uuf7NDRt0dE0s8S51q0aT7Yg=
2 
+github.com/gorilla/csrf v1.5.1 h1:UASc2+EB0T51tvl6/2ls2ciA8/qC7KdTO7DsOEKbttQ=
3 
+github.com/gorilla/csrf v1.5.1/go.mod h1:HTDW7xFOO1aHddQUmghe9/2zTvg7AYCnRCs7MxTGu/0=
4 
+github.com/gorilla/mux v1.7.1 h1:Dw4jY2nghMMRsh1ol8dv1axHkDwMQK2DHerMNJsIpJU=
5 
+github.com/gorilla/mux v1.7.1/go.mod h1:1lud6UwP+6orDFRuTfBEV8e9/aOM/c4fVVCaMa2zaAs=
6 
+github.com/gorilla/securecookie v1.1.1 h1:miw7JPhV+b/lAHSXz4qd/nN9jRiAFV5FwjeKyCS8BvQ=
7 
+github.com/gorilla/securecookie v1.1.1/go.mod h1:ra0sb63/xPlUeL+yeDciTfxMRAA+MP+HVt/4epWDjd4=
8 
+github.com/pkg/errors v0.8.0 h1:WdK/asTD0HN+q6hsWO3/vpuAkAr+tw6aNJNDFFf0+qw=
9 
+github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=

+ 136
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main.go View File 

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+package main
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+
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+import (
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+	"flag"
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+	"fmt"
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+	"github.com/gorilla/csrf"
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+	"github.com/gorilla/mux"
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+	"html/template"
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+	"log"
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+	"math/rand"
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+	"net/http"
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+	"net/smtp"
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+	"os"
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+	"strings"
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+)
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+
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+const (
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+	csrfFieldName = "csrf.Token"
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+)
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+
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+var (
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+	fromAddress, toAddress, subject, smtpServer, smtpUsername, smtpPassword, csrfKey *string
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+	smtpPort, port                                                                   *int
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+	formTemplate, successTemplate, failureTemplate                                   *template.Template
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+)
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+
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+func sendMail(replyTo, message string) bool {
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+	auth := smtp.PlainAuth("", *smtpUsername, *smtpPassword, *smtpServer)
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+	body := fmt.Sprintf("To: %s\r\nSubject: %s\r\nReply-to: %s\r\nFrom: Online contact form <%s>\r\n\r\n%s\r\n", *toAddress, *subject, replyTo, *fromAddress, message)
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+	err := smtp.SendMail(fmt.Sprintf("%s:%d", *smtpServer, *smtpPort), auth, *fromAddress, []string{*toAddress}, []byte(body))
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+	if err != nil {
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+		log.Printf("Unable to send mail: %s", err)
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+		return false
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+	}
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+	return true
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+}
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+
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+func handleForm(rw http.ResponseWriter, req *http.Request) {
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+	body := ""
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+	for k, v := range req.Form {
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+		if k != csrfFieldName {
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+			body += fmt.Sprintf("%s:\r\n%s\r\n\r\n", strings.ToUpper(k), v[0])
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+		}
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+	}
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+	if sendMail(req.Form.Get("from"), body) {
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+		rw.Header().Add("Location", "success")
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+	} else {
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+		rw.Header().Add("Location", "failure")
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+	}
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+	rw.WriteHeader(http.StatusTemporaryRedirect)
51 
+}
52 
+
53 
+func showForm(rw http.ResponseWriter, req *http.Request) {
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+	_ = formTemplate.ExecuteTemplate(rw, "form.html", map[string]interface{}{
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+		csrf.TemplateTag: csrf.TemplateField(req),
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+	})
57 
+}
58 
+
59 
+func showSuccess(rw http.ResponseWriter, req *http.Request) {
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+	_ = successTemplate.ExecuteTemplate(rw, "success.html", map[string]interface{}{
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+		csrf.TemplateTag: csrf.TemplateField(req),
62 
+	})
63 
+}
64 
+
65 
+func showFailure(rw http.ResponseWriter, req *http.Request) {
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+	_ = failureTemplate.ExecuteTemplate(rw, "failure.html", map[string]interface{}{
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+		csrf.TemplateTag: csrf.TemplateField(req),
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+	})
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+}
70 
+
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+func randomKey() string {
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+	var runes = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")
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+	b := make([]rune, 32)
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+	for i := range b {
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+		b[i] = runes[rand.Intn(len(runes))]
76 
+	}
77 
+	return string(b)
78 
+}
79 
+
80 
+func checkFlag(value string, name string) {
81 
+	if len(value) == 0 {
82 
+		_, _ = fmt.Fprintf(os.Stderr, "No %s specified\n", name)
83 
+		flag.Usage()
84 
+		os.Exit(1)
85 
+	}
86 
+}
87 
+
88 
+func loadTemplate(file string) (result *template.Template) {
89 
+	var err error
90 
+	result, err = template.ParseFiles(file)
91 
+	if err != nil {
92 
+		_, _ = fmt.Fprintf(os.Stderr, "Unable to load %s: %s\n", file, err.Error())
93 
+		os.Exit(1)
94 
+	}
95 
+	return
96 
+}
97 
+
98 
+func main() {
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+	fromAddress = flag.String("from", "", "address to send e-mail from")
100 
+	toAddress = flag.String("to", "", "address to send e-mail to")
101 
+	subject = flag.String("subject", "Contact form submission", "e-mail subject")
102 
+	smtpServer = flag.String("smtp-host", "", "SMTP server to connect to")
103 
+	smtpPort = flag.Int("smtp-port", 25, "port to use when connecting to the SMTP server")
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+	smtpUsername = flag.String("smtp-user", "", "username to supply to the SMTP server")
105 
+	smtpPassword = flag.String("smtp-pass", "", "password to supply to the SMTP server")
106 
+	csrfKey = flag.String("crsf-key", "", "CRSF key to use")
107 
+	port = flag.Int("port", 8080, "port to listen on for connections")
108 
+	flag.Parse()
109 
+
110 
+	checkFlag(*fromAddress, "from address")
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+	checkFlag(*toAddress, "to address")
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+	checkFlag(*smtpServer, "SMTP server")
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+	checkFlag(*smtpUsername, "SMTP username")
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+	checkFlag(*smtpPassword, "SMTP password")
115 
+
116 
+	if len(*csrfKey) != 32 {
117 
+		newKey := randomKey()
118 
+		csrfKey = &newKey
119 
+	}
120 
+
121 
+	formTemplate = loadTemplate("form.html")
122 
+	successTemplate = loadTemplate("success.html")
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+	failureTemplate = loadTemplate("failure.html")
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+
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+	r := mux.NewRouter()
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+	r.HandleFunc("/", showForm).Methods("GET")
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+	r.HandleFunc("/success", showSuccess).Methods("GET")
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+	r.HandleFunc("/failure", showFailure).Methods("GET")
129 
+	r.HandleFunc("/submit", handleForm).Methods("POST")
130 
+
131 
+	CSRF := csrf.Protect([]byte(*csrfKey), csrf.FieldName(csrfFieldName))
132 
+	err := http.ListenAndServe(fmt.Sprintf(":%d", *port), CSRF(r))
133 
+	if err != nil {
134 
+		_, _ = fmt.Fprintf(os.Stderr, "Unable to listen on port %d: %s\n", *port, err.Error())
135 
+	}
136 
+}

+ 33
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success.html View File 

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+<!DOCTYPE html>
2 
+<html lang="en">
3 
+<head>
4 
+    <meta http-equiv="Content-Type" content="text/html" charset="UTF-8"/>
5 
+    <title>Contact me</title>
6 
+    <style type="text/css">
7 
+        .page {
8 
+            width: 480px;
9 
+            padding: 8% 0 0;
10 
+            margin: auto;
11 
+        }
12 
+
13 
+        .form {
14 
+            position: relative;
15 
+            z-index: 1;
16 
+            background: #FFFFFF;
17 
+            max-width: 360px;
18 
+            margin: 0 auto 100px;
19 
+            padding: 45px;
20 
+            text-align: center;
21 
+            box-shadow: 0 0 20px 0 rgba(0, 0, 0, 0.2), 0 5px 5px 0 rgba(0, 0, 0, 0.24);
22 
+            font-family: sans-serif;
23 
+        }
24 
+    </style>
25 
+</head>
26 
+<body>
27 
+<div class="page">
28 
+    <div class="form">
29 
+        Your message has been sent. Thank you!
30 
+    </div>
31 
+</div>
32 
+</body>
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+</html>

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