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  75. <article>
  76. <h1>HTTPS Client</h1>
  77. <p>前章でOpenSSLのセットアップが済んだので、さっそくHTTPSクライアントを使ってみましょう。2章で使った <code>httplib::Client</code> がそのまま使えます。コンストラクタに <code>https://</code> 付きのURLを渡すだけです。</p>
  78. <h2>GETリクエスト</h2>
  79. <p>実在するHTTPSサイトにアクセスしてみましょう。</p>
  80. <div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2d2d2d;">
  81. <span style="color:#cc99cc;">#define </span><span style="color:#d3d0c8;">CPPHTTPLIB_OPENSSL_SUPPORT
  82. </span><span style="color:#cc99cc;">#include </span><span style="color:#d3d0c8;">&quot;</span><span style="color:#99cc99;">httplib.h</span><span style="color:#d3d0c8;">&quot;
  83. </span><span style="color:#cc99cc;">#include </span><span style="color:#d3d0c8;">&lt;</span><span style="color:#99cc99;">iostream</span><span style="color:#d3d0c8;">&gt;
  84. </span><span style="color:#d3d0c8;">
  85. </span><span style="color:#cc99cc;">int </span><span style="color:#6699cc;">main</span><span style="color:#d3d0c8;">() {
  86. </span><span style="color:#d3d0c8;"> httplib::Client </span><span style="color:#6699cc;">cli</span><span style="color:#d3d0c8;">(&quot;</span><span style="color:#99cc99;">https://nghttp2.org</span><span style="color:#d3d0c8;">&quot;);
  87. </span><span style="color:#d3d0c8;">
  88. </span><span style="color:#d3d0c8;"> </span><span style="color:#cc99cc;">auto</span><span style="color:#d3d0c8;"> res = cli.</span><span style="color:#6699cc;">Get</span><span style="color:#d3d0c8;">(&quot;</span><span style="color:#99cc99;">/</span><span style="color:#d3d0c8;">&quot;);
  89. </span><span style="color:#d3d0c8;"> </span><span style="color:#cc99cc;">if </span><span style="color:#d3d0c8;">(res) {
  90. </span><span style="color:#d3d0c8;"> std::cout &lt;&lt; res-&gt;</span><span style="color:#f2777a;">status </span><span style="color:#d3d0c8;">&lt;&lt; std::endl; </span><span style="color:#747369;">// 200
  91. </span><span style="color:#d3d0c8;"> std::cout &lt;&lt; res-&gt;</span><span style="color:#f2777a;">body</span><span style="color:#d3d0c8;">.</span><span style="color:#6699cc;">substr</span><span style="color:#d3d0c8;">(</span><span style="color:#f99157;">0</span><span style="color:#d3d0c8;">, </span><span style="color:#f99157;">100</span><span style="color:#d3d0c8;">) &lt;&lt; std::endl; </span><span style="color:#747369;">// HTMLの先頭部分
  92. </span><span style="color:#d3d0c8;"> } </span><span style="color:#cc99cc;">else </span><span style="color:#d3d0c8;">{
  93. </span><span style="color:#d3d0c8;"> std::cout &lt;&lt; &quot;</span><span style="color:#99cc99;">Error: </span><span style="color:#d3d0c8;">&quot; &lt;&lt; </span><span style="color:#6699cc;">httplib::to_string</span><span style="color:#d3d0c8;">(res.</span><span style="color:#6699cc;">error</span><span style="color:#d3d0c8;">()) &lt;&lt; std::endl;
  94. </span><span style="color:#d3d0c8;"> }
  95. </span><span style="color:#d3d0c8;">}
  96. </span></pre>
  97. </div><div data-code-theme="light"><pre style="background-color:#ffffff;">
  98. <span style="font-weight:bold;color:#a71d5d;">#define </span><span style="color:#323232;">CPPHTTPLIB_OPENSSL_SUPPORT
  99. </span><span style="font-weight:bold;color:#a71d5d;">#include </span><span style="color:#183691;">&quot;httplib.h&quot;
  100. </span><span style="font-weight:bold;color:#a71d5d;">#include </span><span style="color:#183691;">&lt;iostream&gt;
  101. </span><span style="color:#323232;">
  102. </span><span style="font-weight:bold;color:#a71d5d;">int </span><span style="font-weight:bold;color:#795da3;">main</span><span style="color:#323232;">() {
  103. </span><span style="color:#323232;"> httplib::Client cli(</span><span style="color:#183691;">&quot;https://nghttp2.org&quot;</span><span style="color:#323232;">);
  104. </span><span style="color:#323232;">
  105. </span><span style="color:#323232;"> </span><span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> res </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> cli.Get(</span><span style="color:#183691;">&quot;/&quot;</span><span style="color:#323232;">);
  106. </span><span style="color:#323232;"> </span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(res) {
  107. </span><span style="color:#323232;"> std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;status </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl; </span><span style="font-style:italic;color:#969896;">// 200
  108. </span><span style="color:#323232;"> std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;body.substr(</span><span style="color:#0086b3;">0</span><span style="color:#323232;">, </span><span style="color:#0086b3;">100</span><span style="color:#323232;">) </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl; </span><span style="font-style:italic;color:#969896;">// HTMLの先頭部分
  109. </span><span style="color:#323232;"> } </span><span style="font-weight:bold;color:#a71d5d;">else </span><span style="color:#323232;">{
  110. </span><span style="color:#323232;"> std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt; </span><span style="color:#183691;">&quot;Error: &quot; </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt; </span><span style="color:#323232;">httplib::to_string(res.error()) </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;
  111. </span><span style="color:#323232;"> }
  112. </span><span style="color:#323232;">}
  113. </span></pre>
  114. </div></div>
  115. <p>2章では <code>httplib::Client cli("http://localhost:8080")</code> と書きましたよね。スキームを <code>https://</code> に変えるだけです。<code>Get()</code> や <code>Post()</code> など、2章で学んだAPIはすべてそのまま使えます。</p>
  116. <div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2d2d2d;">
  117. <span style="color:#6699cc;">curl</span><span style="color:#d3d0c8;"> https://nghttp2.org/
  118. </span></pre>
  119. </div><div data-code-theme="light"><pre style="background-color:#ffffff;">
  120. <span style="color:#323232;">curl https://nghttp2.org/
  121. </span></pre>
  122. </div></div>
  123. <h2>ポートの指定</h2>
  124. <p>HTTPSのデフォルトポートは443です。別のポートを使いたい場合は、URLにポートを含めます。</p>
  125. <div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2d2d2d;">
  126. <span style="color:#d3d0c8;">httplib::Client </span><span style="color:#6699cc;">cli</span><span style="color:#d3d0c8;">(&quot;</span><span style="color:#99cc99;">https://localhost:8443</span><span style="color:#d3d0c8;">&quot;);
  127. </span></pre>
  128. </div><div data-code-theme="light"><pre style="background-color:#ffffff;">
  129. <span style="color:#323232;">httplib::Client </span><span style="font-weight:bold;color:#795da3;">cli</span><span style="color:#323232;">(</span><span style="color:#183691;">&quot;https://localhost:8443&quot;</span><span style="color:#323232;">);
  130. </span></pre>
  131. </div></div>
  132. <h2>CA証明書の検証</h2>
  133. <p><code>httplib::Client</code> はHTTPS接続時、デフォルトでサーバー証明書を検証します。信頼できるCA(認証局)が発行した証明書を持つサーバーにしか接続しません。</p>
  134. <p>CA証明書は、macOSならKeychain、LinuxならシステムのCA証明書ストア、WindowsならWindowsの証明書ストアから自動で読み込みます。ほとんどの場合、追加の設定は要りません。</p>
  135. <h3>CA証明書ファイルの指定</h3>
  136. <p>環境によってはシステムのCA証明書が見つからないこともあります。そのときは <code>set_ca_cert_path()</code> でパスを直接指定してください。</p>
  137. <div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2d2d2d;">
  138. <span style="color:#d3d0c8;">httplib::Client </span><span style="color:#6699cc;">cli</span><span style="color:#d3d0c8;">(&quot;</span><span style="color:#99cc99;">https://nghttp2.org</span><span style="color:#d3d0c8;">&quot;);
  139. </span><span style="color:#d3d0c8;">cli.</span><span style="color:#6699cc;">set_ca_cert_path</span><span style="color:#d3d0c8;">(&quot;</span><span style="color:#99cc99;">/etc/ssl/certs/ca-certificates.crt</span><span style="color:#d3d0c8;">&quot;);
  140. </span><span style="color:#d3d0c8;">
  141. </span><span style="color:#cc99cc;">auto</span><span style="color:#d3d0c8;"> res = cli.</span><span style="color:#6699cc;">Get</span><span style="color:#d3d0c8;">(&quot;</span><span style="color:#99cc99;">/</span><span style="color:#d3d0c8;">&quot;);
  142. </span></pre>
  143. </div><div data-code-theme="light"><pre style="background-color:#ffffff;">
  144. <span style="color:#323232;">httplib::Client </span><span style="font-weight:bold;color:#795da3;">cli</span><span style="color:#323232;">(</span><span style="color:#183691;">&quot;https://nghttp2.org&quot;</span><span style="color:#323232;">);
  145. </span><span style="color:#323232;">cli.set_ca_cert_path(</span><span style="color:#183691;">&quot;/etc/ssl/certs/ca-certificates.crt&quot;</span><span style="color:#323232;">);
  146. </span><span style="color:#323232;">
  147. </span><span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> res </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> cli.Get(</span><span style="color:#183691;">&quot;/&quot;</span><span style="color:#323232;">);
  148. </span></pre>
  149. </div></div><div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2d2d2d;">
  150. <span style="color:#6699cc;">curl</span><span style="color:#f2777a;"> --cacert</span><span style="color:#d3d0c8;"> /etc/ssl/certs/ca-certificates.crt https://nghttp2.org/
  151. </span></pre>
  152. </div><div data-code-theme="light"><pre style="background-color:#ffffff;">
  153. <span style="color:#323232;">curl --cacert /etc/ssl/certs/ca-certificates.crt https://nghttp2.org/
  154. </span></pre>
  155. </div></div>
  156. <h3>証明書検証の無効化</h3>
  157. <p>開発中、自己署名証明書のサーバーに接続したいときは、検証を無効にできます。</p>
  158. <div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2d2d2d;">
  159. <span style="color:#d3d0c8;">httplib::Client </span><span style="color:#6699cc;">cli</span><span style="color:#d3d0c8;">(&quot;</span><span style="color:#99cc99;">https://localhost:8443</span><span style="color:#d3d0c8;">&quot;);
  160. </span><span style="color:#d3d0c8;">cli.</span><span style="color:#6699cc;">enable_server_certificate_verification</span><span style="color:#d3d0c8;">(</span><span style="color:#f99157;">false</span><span style="color:#d3d0c8;">);
  161. </span><span style="color:#d3d0c8;">
  162. </span><span style="color:#cc99cc;">auto</span><span style="color:#d3d0c8;"> res = cli.</span><span style="color:#6699cc;">Get</span><span style="color:#d3d0c8;">(&quot;</span><span style="color:#99cc99;">/</span><span style="color:#d3d0c8;">&quot;);
  163. </span></pre>
  164. </div><div data-code-theme="light"><pre style="background-color:#ffffff;">
  165. <span style="color:#323232;">httplib::Client </span><span style="font-weight:bold;color:#795da3;">cli</span><span style="color:#323232;">(</span><span style="color:#183691;">&quot;https://localhost:8443&quot;</span><span style="color:#323232;">);
  166. </span><span style="color:#323232;">cli.enable_server_certificate_verification(</span><span style="color:#0086b3;">false</span><span style="color:#323232;">);
  167. </span><span style="color:#323232;">
  168. </span><span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> res </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> cli.Get(</span><span style="color:#183691;">&quot;/&quot;</span><span style="color:#323232;">);
  169. </span></pre>
  170. </div></div><div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2d2d2d;">
  171. <span style="color:#6699cc;">curl</span><span style="color:#f2777a;"> -k</span><span style="color:#d3d0c8;"> https://localhost:8443/
  172. </span></pre>
  173. </div><div data-code-theme="light"><pre style="background-color:#ffffff;">
  174. <span style="color:#323232;">curl -k https://localhost:8443/
  175. </span></pre>
  176. </div></div>
  177. <p>本番では絶対に無効にしないでください。中間者攻撃のリスクがあります。</p>
  178. <h2>リダイレクトの追跡</h2>
  179. <p>HTTPSサイトへのアクセスでは、リダイレクトに遭遇することがよくあります。たとえば <code>http://</code> から <code>https://</code> へ、あるいは <code>www</code> なしから <code>www</code> ありへ転送されるケースです。</p>
  180. <p>デフォルトではリダイレクトを追跡しません。リダイレクト先は <code>Location</code> ヘッダーで確認できます。</p>
  181. <div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2d2d2d;">
  182. <span style="color:#d3d0c8;">httplib::Client </span><span style="color:#6699cc;">cli</span><span style="color:#d3d0c8;">(&quot;</span><span style="color:#99cc99;">https://nghttp2.org</span><span style="color:#d3d0c8;">&quot;);
  183. </span><span style="color:#d3d0c8;">
  184. </span><span style="color:#cc99cc;">auto</span><span style="color:#d3d0c8;"> res = cli.</span><span style="color:#6699cc;">Get</span><span style="color:#d3d0c8;">(&quot;</span><span style="color:#99cc99;">/httpbin/redirect/3</span><span style="color:#d3d0c8;">&quot;);
  185. </span><span style="color:#cc99cc;">if </span><span style="color:#d3d0c8;">(res) {
  186. </span><span style="color:#d3d0c8;"> std::cout &lt;&lt; res-&gt;</span><span style="color:#f2777a;">status </span><span style="color:#d3d0c8;">&lt;&lt; std::endl; </span><span style="color:#747369;">// 302
  187. </span><span style="color:#d3d0c8;"> std::cout &lt;&lt; res-&gt;</span><span style="color:#6699cc;">get_header_value</span><span style="color:#d3d0c8;">(&quot;</span><span style="color:#99cc99;">Location</span><span style="color:#d3d0c8;">&quot;) &lt;&lt; std::endl;
  188. </span><span style="color:#d3d0c8;">}
  189. </span></pre>
  190. </div><div data-code-theme="light"><pre style="background-color:#ffffff;">
  191. <span style="color:#323232;">httplib::Client </span><span style="font-weight:bold;color:#795da3;">cli</span><span style="color:#323232;">(</span><span style="color:#183691;">&quot;https://nghttp2.org&quot;</span><span style="color:#323232;">);
  192. </span><span style="color:#323232;">
  193. </span><span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> res </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> cli.Get(</span><span style="color:#183691;">&quot;/httpbin/redirect/3&quot;</span><span style="color:#323232;">);
  194. </span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(res) {
  195. </span><span style="color:#323232;"> std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;status </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl; </span><span style="font-style:italic;color:#969896;">// 302
  196. </span><span style="color:#323232;"> std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;get_header_value(</span><span style="color:#183691;">&quot;Location&quot;</span><span style="color:#323232;">) </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;
  197. </span><span style="color:#323232;">}
  198. </span></pre>
  199. </div></div><div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2d2d2d;">
  200. <span style="color:#6699cc;">curl</span><span style="color:#d3d0c8;"> https://nghttp2.org/httpbin/redirect/3
  201. </span></pre>
  202. </div><div data-code-theme="light"><pre style="background-color:#ffffff;">
  203. <span style="color:#323232;">curl https://nghttp2.org/httpbin/redirect/3
  204. </span></pre>
  205. </div></div>
  206. <p><code>set_follow_location(true)</code> を設定すると、リダイレクトを自動で追跡して、最終的なレスポンスを返してくれます。</p>
  207. <div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2d2d2d;">
  208. <span style="color:#d3d0c8;">httplib::Client </span><span style="color:#6699cc;">cli</span><span style="color:#d3d0c8;">(&quot;</span><span style="color:#99cc99;">https://nghttp2.org</span><span style="color:#d3d0c8;">&quot;);
  209. </span><span style="color:#d3d0c8;">cli.</span><span style="color:#6699cc;">set_follow_location</span><span style="color:#d3d0c8;">(</span><span style="color:#f99157;">true</span><span style="color:#d3d0c8;">);
  210. </span><span style="color:#d3d0c8;">
  211. </span><span style="color:#cc99cc;">auto</span><span style="color:#d3d0c8;"> res = cli.</span><span style="color:#6699cc;">Get</span><span style="color:#d3d0c8;">(&quot;</span><span style="color:#99cc99;">/httpbin/redirect/3</span><span style="color:#d3d0c8;">&quot;);
  212. </span><span style="color:#cc99cc;">if </span><span style="color:#d3d0c8;">(res) {
  213. </span><span style="color:#d3d0c8;"> std::cout &lt;&lt; res-&gt;</span><span style="color:#f2777a;">status </span><span style="color:#d3d0c8;">&lt;&lt; std::endl; </span><span style="color:#747369;">// 200(最終的なレスポンス)
  214. </span><span style="color:#d3d0c8;">}
  215. </span></pre>
  216. </div><div data-code-theme="light"><pre style="background-color:#ffffff;">
  217. <span style="color:#323232;">httplib::Client </span><span style="font-weight:bold;color:#795da3;">cli</span><span style="color:#323232;">(</span><span style="color:#183691;">&quot;https://nghttp2.org&quot;</span><span style="color:#323232;">);
  218. </span><span style="color:#323232;">cli.set_follow_location(</span><span style="color:#0086b3;">true</span><span style="color:#323232;">);
  219. </span><span style="color:#323232;">
  220. </span><span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> res </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> cli.Get(</span><span style="color:#183691;">&quot;/httpbin/redirect/3&quot;</span><span style="color:#323232;">);
  221. </span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(res) {
  222. </span><span style="color:#323232;"> std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;status </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl; </span><span style="font-style:italic;color:#969896;">// 200(最終的なレスポンス)
  223. </span><span style="color:#323232;">}
  224. </span></pre>
  225. </div></div><div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2d2d2d;">
  226. <span style="color:#6699cc;">curl</span><span style="color:#f2777a;"> -L</span><span style="color:#d3d0c8;"> https://nghttp2.org/httpbin/redirect/3
  227. </span></pre>
  228. </div><div data-code-theme="light"><pre style="background-color:#ffffff;">
  229. <span style="color:#323232;">curl -L https://nghttp2.org/httpbin/redirect/3
  230. </span></pre>
  231. </div></div>
  232. <h2>次のステップ</h2>
  233. <p>HTTPSクライアントの使い方がわかりましたね。次は自分でHTTPSサーバーを立ててみましょう。自己署名証明書の作り方から始めます。</p>
  234. <p><strong>次:</strong> <a href="../07-https-server">HTTPS Server</a></p>
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