HTTP权威指南

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超文本传输协议（Hypertext Transfer Protocol，HTTP）是在万维网上进行通信时所使用的协议方案。HTTP有很多应用，但最著名的是用于web浏览器和web服务器之间的双工通信。 HTTP起初是一个简单的协议，因此你可能会认为关于这个协议没有太多好说的。但现在，你手上拿着的是却一本两磅重 的书。如果你对我们怎么会写出一本650页 的关于HTTP的书感到奇怪的话，可以去看一下目录。本书不仅仅是一本HTTP首部的参考手册；它是一本名副其实的web结构圣经。 本书中，我们尝试着将HTTP中一些互相关联且常被误解的规则梳理清楚，并编写了一系列基于各种主题的章节，对HTTP各方面的特性进行了介绍。纵观全书，我们对HTTP“为什么”这样做进行了详细的解释，而不仅仅停留在它是“怎么做”的。而且，为了节省大家寻找参考文献的时间，我们还对很多HTTP应用程序正常工作所必须的、重要的非HTTP技术进行了介绍。在组织得便于使用的附录中，可以找到按照字母排序的首部参考（这些首部构成了最常见的HTTP文本的基础）。我们希望这种概念性的设计有助于读者对HTTP的使用。 本书是为所有希望理解HTTP以及Web底层结构的人编写的。软硬件工程师也可以将本书作为HTTP及相关web技术的条理清楚的参考书使用。系统架构师和网络管理员可以通过本书更好地了解如何设计、实现并管理复杂的网络架构。性能工程师和分析人员可以从高速缓存和性能优化的相关章节中获益。市场营销和咨询专家可以通过概念的介绍更好地理解web技术的前景。 本书对一些常见的误解进行了说明，推荐了“各种使用诀窍”，提供了便捷的参考资料，并且对枯燥且令人费解的标准规范进行了可读性很强的介绍。在这本书里，我们对Web正常工作所必须且互相关联的技术进行了详细的介绍。 本书是很多对因特网技术充满热情的人经过大量工作写成的。希望对你有所帮助。

第一部分　HTTP：Web 的基础
第1 章　HTTP 概述 ............................................................................................................................3
1.1　HTTP——因特网的多媒体信使 ...............................................................................................4
1.2　Web 客户端和服务器 .................................................................................................................4
1.3　资源 ............................................................................................................................................5
1.3.1　媒体类型 ........................................................................................................................6
1.3.2　URI.................................................................................................................................7
1.3.3　URL ...............................................................................................................................7
1.3.4　URN ...............................................................................................................................8
1.4　事务 ............................................................................................................................................9
1.4.1　方法 ...............................................................................................................................9
1.4.2　状态码 ..........................................................................................................................10
1.4.3　Web 页面中可以包含多个对象 ..................................................................................10
1.5　报文 ..........................................................................................................................................11
1.6　连接 ..........................................................................................................................................13
1.6.1　TCP/IP ..........................................................................................................................13
1.6.2　连接、IP 地址及端口号 ..............................................................................................14
1.6.3　使用Telnet 实例 ..........................................................................................................16
1.7　协议版本 ..................................................................................................................................18
1.8　Web 的结构组件 .......................................................................................................................19
1.8.1　代理 ..............................................................................................................................19
1.8.2　缓存 ..............................................................................................................................20
1.8.3　网关 ..............................................................................................................................20
1.8.4　隧道 ..............................................................................................................................21
1.8.5　Agent 代理 ....................................................................................................................21
1.9　起始部分的结束语 ...................................................................................................................22
1.10　更多信息 ................................................................................................................................22
1.10.1　HTTP 协议信息 ........................................................................................................22
1.10.2　历史透视 ...................................................................................................................23
1.10.3　其他万维网信息 .......................................................................................................23
第2 章　URL 与资源 ........................................................................................................................25
2.1　浏览因特网资源 .......................................................................................................................26
2.2　URL 的语法 ..............................................................................................................................28
2.2.1　方案——使用什么协议 ..............................................................................................29
2.2.2　主机与端口 ..................................................................................................................30
2.2.3　用户名和密码 ..............................................................................................................30
2.2.4　路径 ..............................................................................................................................31
2.2.5　参数 ..............................................................................................................................31
2.2.6　查询字符串 ..................................................................................................................32
2.2.7　片段 ..............................................................................................................................33
2.3　URL 快捷方式 ..........................................................................................................................34
2.3.1　相对URL .....................................................................................................................34
2.3.2　自动扩展URL .............................................................................................................37
2.4　各种令人头疼的字符 ...............................................................................................................38
2.4.1　URL 字符集 .................................................................................................................38
2.4.2　编码机制 ......................................................................................................................38
2.4.3　字符限制 ......................................................................................................................39
2.4.4　另外一点说明 ..............................................................................................................40
2.5　方案的世界 ...............................................................................................................................40
2.6　未来展望 ..................................................................................................................................42
2.7　更多信息 ..................................................................................................................................44
第3 章　HTTP 报文 ..........................................................................................................................45
3.1　报文流 ......................................................................................................................................46
3.1.1　报文流入源端服务器 ..................................................................................................46
3.1.2　报文向下游流动 ..........................................................................................................47
3.2　报文的组成部分 .......................................................................................................................47
3.2.1　报文的语法 ..................................................................................................................48
3.2.2　起始行 ..........................................................................................................................50
3.2.3　首部 ..............................................................................................................................53
3.2.4　实体的主体部分 ..........................................................................................................55
3.2.5　版本0.9 的报文 ...........................................................................................................55
3.3　方法 ..........................................................................................................................................56
3.3.1　安全方法 ......................................................................................................................56
3.3.2　GET ...............................................................................................................................56
3.3.3　HEAD ...........................................................................................................................57
3.3.4　PUT ...............................................................................................................................57
3.3.5　POST .............................................................................................................................58
3.3.6　TRACE .........................................................................................................................58
3.3.7　OPTIONS......................................................................................................................60
3.3.8　DELETE .......................................................................................................................60
3.3.9　扩展方法 ......................................................................................................................61
3.4　状态码 ......................................................................................................................................62
3.4.1　100 ～ 199——信息性状态码 ....................................................................................62
3.4.2　200 ～ 299——成功状态码 ........................................................................................63
3.4.3　300 ～ 399——重定向状态码 ....................................................................................64
3.4.4　400 ～ 499——客户端错误状态码 ............................................................................68
3.4.5　500 ～ 599——服务器错误状态码 ............................................................................69
3.5　首部 ..........................................................................................................................................70
3.5.1　通用首部 ......................................................................................................................71
3.5.2　请求首部 ......................................................................................................................72
3.5.3　响应首部 ......................................................................................................................74
3.5.4　实体首部 ......................................................................................................................75
3.6　更多信息 ..................................................................................................................................77
第4 章　连接管理 ..............................................................................................................................79
4.1　TCP 连接..................................................................................................................................80
4.1.1　TCP 的可靠数据管道 ..................................................................................................80
4.1.2　TCP 流是分段的、由IP 分组传送.............................................................................81
4.1.3　保持TCP 连接的正确运行 .........................................................................................82
4.1.4　用TCP 套接字编程 .....................................................................................................84
4.2　对TCP 性能的考虑..................................................................................................................85
4.2.1　HTTP 事务的时延 .......................................................................................................86
4.2.2　性能聚焦区域 ..............................................................................................................87
4.2.3　TCP 连接的握手时延 ..................................................................................................87
4.2.4　延迟确认 ......................................................................................................................88
4.2.5　TCP 慢启动 ..................................................................................................................89
4.2.6　Nagle 算法与TCP_NODELAY ...................................................................................89
4.2.7　TIME_WAIT 累积与端口耗尽 ....................................................................................90
4.3　HTTP 连接的处理 ....................................................................................................................91
4.3.1　常被误解的Connection 首部 .................................................................................91
4.3.2　串行事务处理时延 ......................................................................................................92
4.4　并行连接 ..................................................................................................................................94
4.4.1　并行连接可能会提高页面的加载速度 ......................................................................94
4.4.2　并行连接不一定更快 ..................................................................................................95
4.4.3　并行连接可能让人“感觉”更快一些 ......................................................................95
4.5　持久连接 ..................................................................................................................................96
4.5.1　持久以及并行连接 ......................................................................................................96
4.5.2　HTTP/1.0+ Keep-Alive 连接 .......................................................................................97
4.5.3　keep-Alive 操作 ............................................................................................................98
4.5.4　keep-Alive 选项 ............................................................................................................98
4.5.5　keep-Alive 连接的限制和规则 ....................................................................................99
4.5.6　keep-Alive 和哑代理 ..................................................................................................100
4.5.7　插入Proxy-Connection ......................................................................................102
4.5.8　HTTP/1.1 持久连接 ...................................................................................................104
4.5.9　持久连接的限制和规则 ............................................................................................104
4.6　管道化连接 .............................................................................................................................105
4.7　关闭连接的奥秘 .....................................................................................................................106
4.7.1　“任意”解除连接 ......................................................................................................106
4.7.2　Content-Length 及截尾操作 ...............................................................................107
4.7.3　连接关闭容限、重试以及幂等性 ............................................................................107
4.7.4　正常关闭连接 ............................................................................................................108
4.8　更多信息 ................................................................................................................................110
4.8.1　HTTP 连接 .................................................................................................................110
4.8.2　HTTP 性能问题 .........................................................................................................110
4.8.3　TCP/IP ........................................................................................................................ 111
第二部分　HTTP 结构
第5 章　Web 服务器 ......................................................................................................................115
5.1　各种形状和尺寸的Web 服务器 ............................................................................................116
5.1.1　Web 服务器的实现 ....................................................................................................116
5.1.2　通用软件Web 服务器 ...............................................................................................117
5.1.3　Web 服务器设备 ........................................................................................................117
5.1.4　嵌入式Web 服务器 ...................................................................................................118
5.2　最小的Perl Web 服务器 ........................................................................................................118
5.3　实际的Web 服务器会做些什么 ............................................................................................120
5.4　第一步——接受客户端连接 .................................................................................................121
5.4.1　处理新连接 ................................................................................................................121
5.4.2　客户端主机名识别 ....................................................................................................122
5.4.3　通过ident 确定客户端用户 ......................................................................................122
5.5　第二步——接收请求报文 .....................................................................................................123
5.5.1　报文的内部表示法 ....................................................................................................124
5.5.2　连接的输入/ 输出处理结构 .....................................................................................125
5.6　第三步——处理请求 .............................................................................................................126
5.7　第四步——对资源的映射及访问 .........................................................................................126
5.7.1　docroot ........................................................................................................................127
5.7.2　目录列表 ....................................................................................................................129
5.7.3　动态内容资源的映射 ................................................................................................130
5.7.4　服务器端包含项（SSI） .............................................................................................131
5.7.5　访问控制 ....................................................................................................................131
5.8　第五步——构建响应 .............................................................................................................131
5.8.1　响应实体 ....................................................................................................................131
5.8.2　MIME 类型.................................................................................................................132
5.8.3　重定向 ........................................................................................................................133
5.9　第六步——发送响应 .............................................................................................................134
5.10　第七步——记录日志 ...........................................................................................................134
5.11　更多信息 ...............................................................................................................................134
第6 章　代理 ....................................................................................................................................135
6.1　Web 的中间实体 .....................................................................................................................136
6.1.1　私有和共享代理 ........................................................................................................136
6.1.2　代理与网关的对比 ....................................................................................................137
6.2　为什么使用代理 .....................................................................................................................138
6.3　代理会去往何处 .....................................................................................................................143
6.3.1　代理服务器的部署 ....................................................................................................144
6.3.2　代理的层次结构 ........................................................................................................144
6.3.3　代理是如何获取流量的 ............................................................................................147
6.4　客户端的代理设置 .................................................................................................................148
6.4.1　客户端的代理配置：手工 ........................................................................................149
6.4.2　客户端代理配置：PAC 文件 ....................................................................................149
6.4.3　客户端代理配置：WPAD .........................................................................................150
6.5　与代理请求有关的棘手问题 .................................................................................................151
6.5.1　代理URI 与服务器URI 的不同 ...............................................................................151
6.5.2　与虚拟主机一样的问题 ............................................................................................152
6.5.3　拦截代理会收到部分URI.........................................................................................153
6.5.4　代理既可以处理代理请求，也可以处理服务器请求 ............................................154
6.5.5　转发过程中对URI 的修改........................................................................................154
6.5.6　URI 的客户端自动扩展和主机名解析.....................................................................155
6.5.7　没有代理时URI 的解析............................................................................................155
6.5.8　有显式代理时URI 的解析........................................................................................156
6.5.9　有拦截代理时解析URI.............................................................................................156
6.6　追踪报文 ................................................................................................................................157
6.6.1　Via 首部.....................................................................................................................158
6.6.2　TRACE 方法 ..............................................................................................................162
6.7　代理认证 ................................................................................................................................164
6.8　代理的互操作性 .....................................................................................................................165
6.8.1　处理代理不支持的首部和方法 ................................................................................165
6.8.2　OPTIONS：发现可选特性的支持............................................................................166
6.8.3　Allow 首部 ................................................................................................................167
6.9　更多信息 ................................................................................................................................167
第7 章　缓存 ....................................................................................................................................169
7.1　冗余的数据传输 .....................................................................................................................170
7.2　带宽瓶颈 ................................................................................................................................170
7.3　瞬间拥塞 ................................................................................................................................171
7.4　距离时延 ................................................................................................................................172
7.5　命中和未命中的 .....................................................................................................................173
7.5.1　再验证 ........................................................................................................................173
7.5.2　命中率 ........................................................................................................................175
7.5.3　字节命中率 ................................................................................................................176
7.5.4　区分命中和未命中的情况 ........................................................................................176
7.6　缓存的拓扑结构 .....................................................................................................................177
7.6.1　私有缓存 ....................................................................................................................177
7.6.2　公有代理缓存 ............................................................................................................177
7.6.3　代理缓存的层次结构 ................................................................................................179
7.6.4　网状缓存、内容路由以及对等缓存 ........................................................................180
7.7　缓存的处理步骤 .....................................................................................................................181
7.7.1　第一步——接收 ........................................................................................................181
7.7.2　第二步——解析 ........................................................................................................182
7.7.3　第三步——查找 ........................................................................................................182
7.7.4　第四步——新鲜度检测 ............................................................................................182
7.7.5　第五步——创建响应 ................................................................................................182
7.7.6　第六步——发送 ........................................................................................................183
7.7.7　第七步——日志 ........................................................................................................183
7.7.8　缓存处理流程图 ........................................................................................................183
7.8　保持副本的新鲜 .....................................................................................................................183
7.8.1　文档过期 ....................................................................................................................184
7.8.2　过期日期和年龄 ........................................................................................................185
7.8.3　服务器再验证 ............................................................................................................185
7.8.4　用条件方法进行再验证 ............................................................................................186
7.8.5　If-Modified-Since:Date 再验证 .......................................................................187
7.8.6　If-None-Match􀀀实体标签再验证 .......................................................................189
7.8.7　强弱验证器 ................................................................................................................190
7.8.8　什么时候应该使用实体标签和最近修改日期 ........................................................190
7.9　对缓存能力的控制 .................................................................................................................191
7.9.1　no-Store 与no-Cache 响应首部 .........................................................................191
7.9.2　Max-Age 响应首部 ...................................................................................................192
7.9.3　Expires 响应首部 ...................................................................................................192
7.9.4　Must-Revalidate 响应首部 .................................................................................192
7.9.5　试探性过期 ................................................................................................................193
7.9.6　客户端的新鲜度限制 ................................................................................................194
7.9.7　注意事项 ....................................................................................................................194
7.10　设置缓存控制 .......................................................................................................................195
7.10.1　控制Apache 的HTTP 首部 ....................................................................................195
7.10.2　通过HTTP-EQUIV 控制HTML 缓存 ...................................................................196
7.11　详细算法 ...............................................................................................................................197
7.11.1　年龄和新鲜生存期 ...................................................................................................198
7.11.2　使用期的计算 ...........................................................................................................198
7.11.3　完整的使用期计算算法 ...........................................................................................201
7.11.4　新鲜生存期计算 .......................................................................................................202
7.11.5　完整的服务器—新鲜度算法 ...................................................................................202
7.12　缓存和广告 ...........................................................................................................................204
7.12.1　发布广告者的两难处境 ..........................................................................................204
7.12.2　发布者的响应 ..........................................................................................................204
7.12.3　日志迁移 ..................................................................................................................205
7.12.4　命中计数和使用限制 ..............................................................................................205
7.13　更多信息 ...............................................................................................................................205
第8 章　集成点：网关隧道及中继 .............................................................................................207
8.1　网关 ........................................................................................................................................208
8.2　协议网关 ................................................................................................................................210
8.2.1　HTTP/*：服务器端Web 网关 ..................................................................................211
8.2.2　HTTP/HTTPS：服务器端安全网关 .........................................................................212
8.2.3　HTTPS/HTTP 客户端安全加速器网关 ....................................................................212
8.3　资源网关 ................................................................................................................................213
8.3.1　通用网关接口（CGI） ................................................................................................215
8.3.2　服务器扩展API .........................................................................................................215
8.4　应用程序接口和Web 服务 ....................................................................................................216
8.5　隧道 ........................................................................................................................................217
8.5.1　用CONNECT 建立HTTP 隧道................................................................................217
8.5.2　数据隧道、定时及连接管理 ....................................................................................219
8.5.3　SSL 隧道.....................................................................................................................219
8.5.4　SSL 隧道与HTTP/HTTPS 网关的对比 ...................................................................220
8.5.5　隧道认证 ....................................................................................................................221
8.5.6　隧道的安全性考虑 ....................................................................................................221
8.6　中继 ........................................................................................................................................222
8.7　更多信息 ................................................................................................................................224
第9 章　Web 机器人 ......................................................................................................................225
9.1　爬虫及爬行方式 .....................................................................................................................226
9.1.1　从哪儿开始：根集 ....................................................................................................226
9.1.2　链接的提取以及相对链接的标准化 ........................................................................227
9.1.3　避免环路的出现 ........................................................................................................228
9.1.4　循环与复制 ................................................................................................................228
9.1.5　面包屑留下的痕迹 ....................................................................................................229
9.1.6　别名与机器人环路 ....................................................................................................230
9.1.7　规范化URL ...............................................................................................................230
9.1.8　文件系统连接环路 ....................................................................................................231
9.1.9　动态虚拟Web 空间 ...................................................................................................232
9.1.10　避免循环和重复 ......................................................................................................233
9.2　机器人的HTTP ......................................................................................................................236
9.2.1　识别请求首部 ............................................................................................................236
9.2.2　虚拟主机 ....................................................................................................................236
9.2.3　条件请求 ....................................................................................................................237
9.2.4　对响应的处理 ............................................................................................................238
9.2.5　User-Agent 目标 ....................................................................................................239
9.3　行为不当的机器人 .................................................................................................................239
9.4　拒绝机器人访问 .....................................................................................................................240
9.4.1　拒绝机器人访问标准 ................................................................................................241
9.4.2　Web 站点和robots.txt 文件 .......................................................................................242
9.4.3　robots.txt 文件的格式 ................................................................................................243
9.4.4　其他有关robots.txt 的知识 .......................................................................................246
9.4.5　缓存和robots.txt 的过期 ...........................................................................................246
9.4.6　拒绝机器人访问的Perl 代码 ....................................................................................247
9.4.7　HTML 的robot-control 元标签 ........................................................................249
9.5　机器人的规范 .........................................................................................................................251
9.6　搜索引擎 ................................................................................................................................254
9.6.1　大格局 ........................................................................................................................255
9.6.2　现代搜索引擎结构 ....................................................................................................255
9.6.3　全文索引 ....................................................................................................................255
9.6.4　发布查询请求 ............................................................................................................257
9.6.5　对结果进行排序，并提供查询结果 ........................................................................258
9.6.6　欺诈 ............................................................................................................................258
9.7　更多信息 ................................................................................................................................258
第10 章　HTTP-NG .......................................................................................................................261
10.1　HTTP 发展中存在的问题 ....................................................................................................262
10.2　HTTP-NG 的活动 .................................................................................................................263
10.3　模块化及功能增强 ...............................................................................................................263
10.4　分布式对象 ...........................................................................................................................264
10.5　第一层——报文传输 ...........................................................................................................264
10.6　第二层——远程调用 ...........................................................................................................265
10.7　第三层——Web 应用 ...........................................................................................................265
10.8　WebMUX ..............................................................................................................................265
10.9　二进制连接协议 ...................................................................................................................266
10.10　当前的状态 .........................................................................................................................267
10.11　更多信息 .............................................................................................................................267
第三部分　识别、认证与安全
第11 章　客户端识别与cookie 机制 ........................................................................................271
11.1　个性化接触 ...........................................................................................................................272
11.2　HTTP 首部 ............................................................................................................................273
11.3　客户端IP 地址 .....................................................................................................................274
11.4　用户登录 ...............................................................................................................................275
11.5　胖URL .................................................................................................................................277
11.6　cookie ...................................................................................................................................278
11.6.1　cookie 的类型 .........................................................................................................278
11.6.2　cookie 是如何工作的 .............................................................................................279
11.6.3　cookie 罐：客户端的状态 .....................................................................................280
11.6.4　不同站点使用不同的cookie .................................................................................282
11.6.5　cookie 成分 .............................................................................................................283
11.6.6　cookies 版本0（Netscape） ....................................................................................284
11.6.7　cookies 版本1（RFC 2965） ..................................................................................285
11.6.8　cookie 与会话跟踪 .................................................................................................288
11.6.9　cookie 与缓存 .........................................................................................................290
11.6.10　cookie、安全性和隐私 ........................................................................................291
11.7　更多信息 ...............................................................................................................................292
第12 章　基本认证机制 ................................................................................................................293
12.1　认证 ......................................................................................................................................294
12.1.1　HTTP 的质询/ 响应认证框架 ...............................................................................294
12.1.2　认证协议与首部 .....................................................................................................295
12.1.3　安全域 .....................................................................................................................296
12.2　基本认证 ...............................................................................................................................297
12.2.1　基本认证实例 .........................................................................................................298
12.2.2　Base-64 用户名/ 密码编码 ....................................................................................298
12.2.3　代理认证 .................................................................................................................299
12.3　基本认证的安全缺陷 ...........................................................................................................300
12.4　更多信息 ...............................................................................................................................301
第13 章　摘要认证 .........................................................................................................................303
13.1　摘要认证的改进 ...................................................................................................................304
13.1.1　用摘要保护密码的 .................................................................................................304
13.1.2　单向摘要 .................................................................................................................306
13.1.3　用随机数防止重放攻击 .........................................................................................307
13.1.4　摘要认证的握手机制 .............................................................................................307
13.2　摘要的计算 ...........................................................................................................................308
13.2.1　摘要算法的输入数据 .............................................................................................308
13.2.2　算法H(d) 和KD(s,d) .............................................................................................310
13.2.3　与安全性相关的数据（A1） ..................................................................................310
13.2.4　与报文有关的数据（A2） ......................................................................................310
13.2.5　摘要算法总述 ....................................................................................................................311
13.2.6　摘要认证会话 .........................................................................................................312
13.2.7　预授权 .....................................................................................................................312
13.2.8　随机数的选择 .........................................................................................................315
13.2.9　对称认证 .................................................................................................................315
13.3　增强保护质量 .......................................................................................................................316
13.3.1　报文完整性保护 .....................................................................................................316
13.3.2　摘要认证首部 .........................................................................................................317
13.4　应该考虑的实际问题 ...........................................................................................................317
13.4.1　多重质询 .................................................................................................................318
13.4.2　差错处理 .................................................................................................................318
13.4.3　保护空间 .................................................................................................................318
13.4.4　重写URI .................................................................................................................319
13.4.5　缓存 .........................................................................................................................319
13.5　安全性考虑 ...........................................................................................................................320
13.5.1　首部篡改 .................................................................................................................320
13.5.2　重放攻击 .................................................................................................................320
13.5.3　多重认证机制 .........................................................................................................320
13.5.4　词典攻击 .................................................................................................................321
13.5.5　恶意代理攻击和中间人攻击 .................................................................................321
13.5.6　选择明文攻击 .........................................................................................................321
13.5.7　存储密码 .................................................................................................................322
13.6　更多信息 ...............................................................................................................................322
第14 章　安全HTTP .....................................................................................................................323
14.1　保护HTTP 的安全 ...............................................................................................................324
14.2　数字加密 ...............................................................................................................................326
14.2.1　密码编制的机制与技巧 .........................................................................................326
14.2.2　密码 .........................................................................................................................327
14.2.3　密码机 .....................................................................................................................328
14.2.4　使用了密钥的密码 .................................................................................................328
14.2.5　数字密码 .................................................................................................................328
14.3　对称密钥加密技术 ...............................................................................................................330
14.3.1　密钥长度与枚举攻击 .............................................................................................330
14.3.2　建立共享密钥 .........................................................................................................332
14.4　公开密钥加密技术 ...............................................................................................................332
14.4.1　RSA .........................................................................................................................333
14.4.2　混合加密系统和会话密钥 .....................................................................................334
14.5　数字签名 ...............................................................................................................................334
14.6　数字证书 ...............................................................................................................................336
14.6.1　证书的主要内容 .....................................................................................................336
14.6.2　X.509 v3 证书 .........................................................................................................337
14.6.3　用证书对服务器进行认证 .....................................................................................338
14.7　HTTPS——细节介绍 ...........................................................................................................339
14.7.1　HTTPS 概述 ............................................................................................................339
14.7.2　HTTPS 方案 ............................................................................................................340
14.7.3　建立安全传输 .........................................................................................................341
14.7.4　SSL 握手 .................................................................................................................341
14.7.5　服务器证书 .............................................................................................................343
14.7.6　站点证书的有效性 .................................................................................................344
14.7.7　虚拟主机与证书 .....................................................................................................345
14.8　HTTPS 客户端实例 ..............................................................................................................345
14.8.1　OpenSSL .................................................................................................................346
14.8.2　简单的HTTPS 客户端 ...........................................................................................347
14.8.3　执行OpenSSL 客户端 ...........................................................................................350
14.9　通过代理以隧道形式传输安全流量 ...................................................................................351
14.10　更多信息 .............................................................................................................................353
14.10.1　HTTP 安全性 ........................................................................................................353
14.10.2　SSL 与TLS ...........................................................................................................353
14.10.3　公开密钥基础设施 ...............................................................................................354
14.10.4　数字密码 ...............................................................................................................354
第四部分　实体、编码和国际化
第15 章　实体和编码 .....................................................................................................................357
15.1　报文是箱子，实体是货物 ...................................................................................................359
15.1.1　实体主体 .................................................................................................................360
15.2　Content-Length: 实体的大小 ......................................................................................361
15.2.1　检测截尾 .................................................................................................................361
15.2.2　错误的Content-Length ....................................................................................362
15.2.3　Content-Length 与持久连接 ............................................................................362
15.2.4　内容编码 .................................................................................................................362
15.2.5　确定实体主体长度的规则 .....................................................................................362
15.3　实体摘要 ...............................................................................................................................364
15.4　媒体类型和字符集 ...............................................................................................................364
15.4.1　文本的字符编码 .....................................................................................................365
15.4.2　多部分媒体类型 .....................................................................................................365
15.4.3　多部分表格提交 .....................................................................................................366
15.4.4　多部分范围响应 .....................................................................................................367
15.5　内容编码 ...............................................................................................................................368
15.5.1　内容编码过程 .........................................................................................................368
15.5.2　内容编码类型 .........................................................................................................369
15.5.3　Accept-Encoding 首部 .....................................................................................369
15.6　传输编码和分块编码 ...........................................................................................................371
15.6.1　可靠传输 .................................................................................................................371
15.6.2　Transfer-Encoding 首部 .................................................................................372
15.6.3　分块编码 .................................................................................................................373
15.6.4　内容编码与传输编码的结合 .................................................................................375
15.6.5　传输编码的规则 .....................................................................................................375
15.7　随时间变化的实例 ...............................................................................................................375
15.8　验证码和新鲜度 ...................................................................................................................376
15.8.1　新鲜度 .....................................................................................................................377
15.8.2　有条件的请求与验证码 .........................................................................................378
15.9　范围请求 ...............................................................................................................................380
15.10　差异编码 .............................................................................................................................382
15.11　更多信息 .............................................................................................................................385
第16 章　国际化 ..............................................................................................................................387
16.1　HTTP 对国际性内容的支持 ................................................................................................388
16.2　字符集与HTTP ....................................................................................................................389
16.2.1　字符集是把字符转换为二进制码的编码 .............................................................389
16.2.2　字符集和编码如何工作 .........................................................................................390
16.2.3　字符集不对，字符就不对 .....................................................................................391
16.2.4　标准化的MIME charset 值 ....................................................................................391
16.2.5　Content-Type 首部和Charset 首部以及META 标志 .................................393
16.2.6　Accept-Charset 首部 ........................................................................................393
16.3　多语言字符编码入门 ...........................................................................................................394
16.3.1　字符集术语 .............................................................................................................394
16.3.2　字符集的命名很糟糕 .............................................................................................395
16.3.3　字符 .........................................................................................................................396
16.3.4　字形、连笔以及表示形式 .....................................................................................396
16.3.5　编码后的字符集 .....................................................................................................397
16.3.6　字符编码方案 .........................................................................................................399
16.4　语言标记与HTTP ................................................................................................................402
16.4.1　Content-Language 首部 ...................................................................................402
16.4.2　Accept-Language 首部 .....................................................................................403
16.4.3　语言标记的类型 .....................................................................................................404
16.4.4　子标记 .....................................................................................................................404
16.4.5　大小写 .....................................................................................................................405
16.4.6　IANA 语言标记注册 ..............................................................................................405
16.4.7　第一个子标记——名字空间 .................................................................................405
16.4.8　第二个子标记——名字空间 .................................................................................406
16.4.9　其余子标记——名字空间 .....................................................................................407
16.4.10　配置和语言有关的首选项 ...................................................................................407
16.4.11　语言标记参考表 ...................................................................................................407
16.5　国际化的URI .......................................................................................................................408
16.5.1　全球性的可转抄能力与有意义的字符的较量 .....................................................408
16.5.2　URI 字符集合 .........................................................................................................408
16.5.3　转义和反转义 .........................................................................................................409
16.5.4　转义国际化字符 .....................................................................................................409
16.5.5　URI 中的模态切换 .................................................................................................410
16.6　其他需要考虑的地方 ...........................................................................................................410
16.6.1　首部和不合规范的数据 .........................................................................................410
16.6.2　日期 .........................................................................................................................411
16.6.3　域名 .........................................................................................................................411
16.7　更多信息 ...............................................................................................................................411
16.7.1　附录 .........................................................................................................................411
16.7.2　互联网的国际化 .....................................................................................................411
16.7.3　国际标准 .................................................................................................................412
第17 章　内容协商与转码 ............................................................................................................413
17.1　内容协商技术 .......................................................................................................................414
17.2　客户端驱动的协商 ...............................................................................................................415
17.3　服务器驱动的协商 ...............................................................................................................415
17.3.1　内容协商首部集 .....................................................................................................416
17.3.2　内容协商首部中的质量值 .....................................................................................417
17.3.3　随其他首部集而变化 .............................................................................................417
17.3.4　Apache 中的内容协商 ............................................................................................417
17.3.5　服务器端扩展 .........................................................................................................418
17.4　透明协商 ...............................................................................................................................419
17.4.1　进行缓存与备用候选 .............................................................................................419
17.4.2　Vary 首部 ...............................................................................................................420
17.5　转码 ......................................................................................................................................422
17.5.1　格式转换 .................................................................................................................422
17.5.2　信息综合 .................................................................................................................423
17.5.3　内容注入 .................................................................................................................423
17.5.4　对比转码与静态预生成 .........................................................................................423
17.6　下一步计划 ...........................................................................................................................424
17.7　更多信息 ...............................................................................................................................424
第五部分　内容发布与分发
第18 章　Web 主机托管 ...............................................................................................................429
18.1　主机托管服务 .......................................................................................................................430
18.2　虚拟主机托管 .......................................................................................................................431
18.2.1　虚拟服务器请求缺乏主机信息 .............................................................................432
18.2.2　设法让虚拟主机托管正常工作 .............................................................................433
18.2.3　HTTP/1.1 的Host 首部 ..........................................................................................437
18.3　使网站更可靠 .......................................................................................................................438
18.3.1　镜像的服务器集群 .................................................................................................438
18.3.2　内容分发网络 .........................................................................................................440
18.3.3　CDN 中的反向代理缓存 .......................................................................................440
18.3.4　CDN 中的代理缓存 ...............................................................................................440
18.4　让网站更快 ...........................................................................................................................441
18.5　更多信息 ...............................................................................................................................441
第19 章　发布系统 .........................................................................................................................443
19.1　FrontPage 为支持发布而做的服务器扩展 .........................................................................444
19.1.1　FrontPage 服务器扩展 ...........................................................................................444
19.1.2　FrontPage 术语表 ...................................................................................................445
19.1.3　FrontPage 的RPC 协议 ..........................................................................................445
19.1.4　FrontPage 的安全模型 ...........................................................................................448
19.2　WebDAV 与协作写作 ..........................................................................................................449
19.2.1　WebDAV 的方法.....................................................................................................449
19.2.2　WebDAV 与XML ...................................................................................................450
19.2.3　WebDAV 首部集.....................................................................................................451
19.2.4　WebDAV 的锁定与防止覆写.................................................................................452
19.2.5　LOCK 方法 ...............................................................................................................453
19.2.6　UNLOCK 方法 ..........................................................................................................456
19.2.7　属性和元数据 .........................................................................................................456
19.2.8　PROPFIND 方法 .....................................................................................................457
19.2.9　PROPPATCH 方法 ...................................................................................................459
19.2.10　集合与名字空间管理 ...........................................................................................460
19.2.11　MKCOL 方法...........................................................................................................460
19.2.12　DELETE 方法 ........................................................................................................461
19.2.13　COPY 与MOVE 方法 .............................................................................................462
19.2.14　增强的HTTP/1.1 方法 .........................................................................................465
19.2.15　WebDAV 中的版本管理.......................................................................................466
19.2.16　WebDAV 的未来发展...........................................................................................466
19.3　更多信息 ...............................................................................................................................467
第20 章　重定向与负载均衡 .......................................................................................................469
20.1　为什么要重定向 ...................................................................................................................470
20.2　重定向到何地 .......................................................................................................................471
20.3　重定向协议概览 ...................................................................................................................471
20.4　通用的重定向方法 ...............................................................................................................474
20.4.1　HTTP 重定向 ..........................................................................................................474
20.4.2　DNS 重定向 ............................................................................................................475
20.4.3　任播寻址 .................................................................................................................480
20.4.4　IP MAC 转发 ..........................................................................................................481
20.4.5　IP 地址转发 ............................................................................................................482
20.4.6　网元控制协议 .........................................................................................................484
20.5　代理的重定向方法 ...............................................................................................................485
20.5.1　显式浏览器配置 .....................................................................................................485
20.5.2　代理自动配置 .........................................................................................................485
20.5.3　Web 代理自动发现协议 .........................................................................................487
20.6　缓存重定向方法 ...................................................................................................................492
20.7　因特网缓存协议 ...................................................................................................................496
20.8　缓存阵列路由协议 ...............................................................................................................497
20.9　超文本缓存协议 ...................................................................................................................500
20.9.1　HTCP 认证 ..............................................................................................................502
20.9.2　设置缓存策略 .........................................................................................................503
20.10　更多信息 .............................................................................................................................504
第21 章　日志记录与使用情况跟踪 ..........................................................................................505
21.1　记录的内容 ...........................................................................................................................506
21.2　日志格式 ...............................................................................................................................507
21.2.1　常见日志格式 .........................................................................................................507
21.2.2　组合日志格式 .........................................................................................................508
21.2.3　Netscape 的扩展日志格式 .....................................................................................509
21.2.4　Netscape 扩展2 日志格式 .....................................................................................510
21.2.5　Squid 代理日志格式 ...............................................................................................512
21.3　命中率测量 ...........................................................................................................................515
21.3.1　概述 .........................................................................................................................515
21.3.2　Meter 首部 ..............................................................................................................516
21.4　关于隐私的考虑 ...................................................................................................................517
21.5　更多信息 ...............................................................................................................................518
第六部分　附　录
附录A　URI 方案 ............................................................................................................................521
附录B　HTTP 状态码 ....................................................................................................................529
附录C　HTTP 首部参考 ...............................................................................................................533
附录D　MIME 类型 ........................................................................................................................557
附录E　Base-64 编码 ....................................................................................................................603
附录F　摘要认证 .............................................................................................................................607
附录G　语言标记 ............................................................................................................................615
附录H　MIME 字符集注册表.......................................................................................................641
索引 ......................................................................................................................................................661