Revert of Removing HTTPS and SOCKS proxy server code. (patchset #2 id:20001 of https://codereview.webrtc.org/2731673002/ )

Also needed to revert these CLs, which removed code used by the
code being un-removed:
https://codereview.webrtc.org/2745523004
https://codereview.webrtc.org/2754033003
https://codereview.webrtc.org/2758943002

Reason for revert:
This code is still being used by native application developers, so we should send a PSA announcing the deprecation and suggest an alternative before removing it.

Original issue's description:
> Removing HTTPS and SOCKS proxy server code.
>
> This isn't used any more so there's no point in maintaining it.
>
> BUG=None
>
> Review-Url: https://codereview.webrtc.org/2731673002
> Cr-Commit-Position: refs/heads/master@{#17016}
> Committed: https://chromium.googlesource.com/external/webrtc/+/a1991c517598fda9c9c0cf8876886e3968436ff9

TBR=pthatcher@webrtc.org
NOPRESUBMIT=true
NOTRY=true
BUG=None

Review-Url: https://codereview.webrtc.org/2766063005
Cr-Commit-Position: refs/heads/master@{#17369}
diff --git a/webrtc/base/httpcommon.h b/webrtc/base/httpcommon.h
new file mode 100644
index 0000000..7182aa2
--- /dev/null
+++ b/webrtc/base/httpcommon.h
@@ -0,0 +1,458 @@
+/*
+ *  Copyright 2004 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_BASE_HTTPCOMMON_H__
+#define WEBRTC_BASE_HTTPCOMMON_H__
+
+#include <map>
+#include <memory>
+#include <string>
+#include <vector>
+#include "webrtc/base/basictypes.h"
+#include "webrtc/base/checks.h"
+#include "webrtc/base/stringutils.h"
+#include "webrtc/base/stream.h"
+
+namespace rtc {
+
+class CryptString;
+class SocketAddress;
+
+//////////////////////////////////////////////////////////////////////
+// Constants
+//////////////////////////////////////////////////////////////////////
+
+enum HttpCode {
+  HC_OK = 200,
+  HC_NON_AUTHORITATIVE = 203,
+  HC_NO_CONTENT = 204,
+  HC_PARTIAL_CONTENT = 206,
+
+  HC_MULTIPLE_CHOICES = 300,
+  HC_MOVED_PERMANENTLY = 301,
+  HC_FOUND = 302,
+  HC_SEE_OTHER = 303,
+  HC_NOT_MODIFIED = 304,
+  HC_MOVED_TEMPORARILY = 307,
+
+  HC_BAD_REQUEST = 400,
+  HC_UNAUTHORIZED = 401,
+  HC_FORBIDDEN = 403,
+  HC_NOT_FOUND = 404,
+  HC_PROXY_AUTHENTICATION_REQUIRED = 407,
+  HC_GONE = 410,
+
+  HC_INTERNAL_SERVER_ERROR = 500,
+  HC_NOT_IMPLEMENTED = 501,
+  HC_SERVICE_UNAVAILABLE = 503,
+};
+
+enum HttpVersion {
+  HVER_1_0, HVER_1_1, HVER_UNKNOWN,
+  HVER_LAST = HVER_UNKNOWN
+};
+
+enum HttpVerb {
+  HV_GET, HV_POST, HV_PUT, HV_DELETE, HV_CONNECT, HV_HEAD,
+  HV_LAST = HV_HEAD
+};
+
+enum HttpError {
+  HE_NONE,
+  HE_PROTOCOL,            // Received non-valid HTTP data
+  HE_DISCONNECTED,        // Connection closed unexpectedly
+  HE_OVERFLOW,            // Received too much data for internal buffers
+  HE_CONNECT_FAILED,      // The socket failed to connect.
+  HE_SOCKET_ERROR,        // An error occurred on a connected socket
+  HE_SHUTDOWN,            // Http object is being destroyed
+  HE_OPERATION_CANCELLED, // Connection aborted locally
+  HE_AUTH,                // Proxy Authentication Required
+  HE_CERTIFICATE_EXPIRED, // During SSL negotiation
+  HE_STREAM,              // Problem reading or writing to the document
+  HE_CACHE,               // Problem reading from cache
+  HE_DEFAULT
+};
+
+enum HttpHeader {
+  HH_AGE,
+  HH_CACHE_CONTROL,
+  HH_CONNECTION,
+  HH_CONTENT_DISPOSITION,
+  HH_CONTENT_LENGTH,
+  HH_CONTENT_RANGE,
+  HH_CONTENT_TYPE,
+  HH_COOKIE,
+  HH_DATE,
+  HH_ETAG,
+  HH_EXPIRES,
+  HH_HOST,
+  HH_IF_MODIFIED_SINCE,
+  HH_IF_NONE_MATCH,
+  HH_KEEP_ALIVE,
+  HH_LAST_MODIFIED,
+  HH_LOCATION,
+  HH_PROXY_AUTHENTICATE,
+  HH_PROXY_AUTHORIZATION,
+  HH_PROXY_CONNECTION,
+  HH_RANGE,
+  HH_SET_COOKIE,
+  HH_TE,
+  HH_TRAILERS,
+  HH_TRANSFER_ENCODING,
+  HH_UPGRADE,
+  HH_USER_AGENT,
+  HH_WWW_AUTHENTICATE,
+  HH_LAST = HH_WWW_AUTHENTICATE
+};
+
+const uint16_t HTTP_DEFAULT_PORT = 80;
+const uint16_t HTTP_SECURE_PORT = 443;
+
+//////////////////////////////////////////////////////////////////////
+// Utility Functions
+//////////////////////////////////////////////////////////////////////
+
+inline HttpError mkerr(HttpError err, HttpError def_err = HE_DEFAULT) {
+  return (err != HE_NONE) ? err : def_err;
+}
+
+const char* ToString(HttpVersion version);
+bool FromString(HttpVersion& version, const std::string& str);
+
+const char* ToString(HttpVerb verb);
+bool FromString(HttpVerb& verb, const std::string& str);
+
+const char* ToString(HttpHeader header);
+bool FromString(HttpHeader& header, const std::string& str);
+
+inline bool HttpCodeIsInformational(uint32_t code) {
+  return ((code / 100) == 1);
+}
+inline bool HttpCodeIsSuccessful(uint32_t code) {
+  return ((code / 100) == 2);
+}
+inline bool HttpCodeIsRedirection(uint32_t code) {
+  return ((code / 100) == 3);
+}
+inline bool HttpCodeIsClientError(uint32_t code) {
+  return ((code / 100) == 4);
+}
+inline bool HttpCodeIsServerError(uint32_t code) {
+  return ((code / 100) == 5);
+}
+
+bool HttpCodeHasBody(uint32_t code);
+bool HttpCodeIsCacheable(uint32_t code);
+bool HttpHeaderIsEndToEnd(HttpHeader header);
+bool HttpHeaderIsCollapsible(HttpHeader header);
+
+struct HttpData;
+bool HttpShouldKeepAlive(const HttpData& data);
+
+typedef std::pair<std::string, std::string> HttpAttribute;
+typedef std::vector<HttpAttribute> HttpAttributeList;
+void HttpComposeAttributes(const HttpAttributeList& attributes, char separator,
+                           std::string* composed);
+void HttpParseAttributes(const char * data, size_t len,
+                         HttpAttributeList& attributes);
+bool HttpHasAttribute(const HttpAttributeList& attributes,
+                      const std::string& name,
+                      std::string* value);
+bool HttpHasNthAttribute(HttpAttributeList& attributes,
+                         size_t index,
+                         std::string* name,
+                         std::string* value);
+
+// Convert RFC1123 date (DoW, DD Mon YYYY HH:MM:SS TZ) to unix timestamp
+bool HttpDateToSeconds(const std::string& date, time_t* seconds);
+
+inline uint16_t HttpDefaultPort(bool secure) {
+  return secure ? HTTP_SECURE_PORT : HTTP_DEFAULT_PORT;
+}
+
+// Returns the http server notation for a given address
+std::string HttpAddress(const SocketAddress& address, bool secure);
+
+// functional for insensitive std::string compare
+struct iless {
+  bool operator()(const std::string& lhs, const std::string& rhs) const {
+    return (::_stricmp(lhs.c_str(), rhs.c_str()) < 0);
+  }
+};
+
+// put quotes around a string and escape any quotes inside it
+std::string quote(const std::string& str);
+
+//////////////////////////////////////////////////////////////////////
+// Url
+//////////////////////////////////////////////////////////////////////
+
+template<class CTYPE>
+class Url {
+public:
+  typedef typename Traits<CTYPE>::string string;
+
+  // TODO: Implement Encode/Decode
+  static int Encode(const CTYPE* source, CTYPE* destination, size_t len);
+  static int Encode(const string& source, string& destination);
+  static int Decode(const CTYPE* source, CTYPE* destination, size_t len);
+  static int Decode(const string& source, string& destination);
+
+  Url(const string& url) { do_set_url(url.c_str(), url.size()); }
+  Url(const string& path, const string& host, uint16_t port = HTTP_DEFAULT_PORT)
+      : host_(host), port_(port), secure_(HTTP_SECURE_PORT == port) {
+    set_full_path(path);
+  }
+
+  bool valid() const { return !host_.empty(); }
+  void clear() {
+    host_.clear();
+    port_ = HTTP_DEFAULT_PORT;
+    secure_ = false;
+    path_.assign(1, static_cast<CTYPE>('/'));
+    query_.clear();
+  }
+
+  void set_url(const string& val) {
+    do_set_url(val.c_str(), val.size());
+  }
+  string url() const {
+    string val; do_get_url(&val); return val;
+  }
+
+  void set_address(const string& val) {
+    do_set_address(val.c_str(), val.size());
+  }
+  string address() const {
+    string val; do_get_address(&val); return val;
+  }
+
+  void set_full_path(const string& val) {
+    do_set_full_path(val.c_str(), val.size());
+  }
+  string full_path() const {
+    string val; do_get_full_path(&val); return val;
+  }
+
+  void set_host(const string& val) { host_ = val; }
+  const string& host() const { return host_; }
+
+  void set_port(uint16_t val) { port_ = val; }
+  uint16_t port() const { return port_; }
+
+  void set_secure(bool val) { secure_ = val; }
+  bool secure() const { return secure_; }
+
+  void set_path(const string& val) {
+    if (val.empty()) {
+      path_.assign(1, static_cast<CTYPE>('/'));
+    } else {
+      RTC_DCHECK(val[0] == static_cast<CTYPE>('/'));
+      path_ = val;
+    }
+  }
+  const string& path() const { return path_; }
+
+  void set_query(const string& val) {
+    RTC_DCHECK(val.empty() || (val[0] == static_cast<CTYPE>('?')));
+    query_ = val;
+  }
+  const string& query() const { return query_; }
+
+  bool get_attribute(const string& name, string* value) const;
+
+private:
+  void do_set_url(const CTYPE* val, size_t len);
+  void do_set_address(const CTYPE* val, size_t len);
+  void do_set_full_path(const CTYPE* val, size_t len);
+
+  void do_get_url(string* val) const;
+  void do_get_address(string* val) const;
+  void do_get_full_path(string* val) const;
+
+  string host_, path_, query_;
+  uint16_t port_;
+  bool secure_;
+};
+
+//////////////////////////////////////////////////////////////////////
+// HttpData
+//////////////////////////////////////////////////////////////////////
+
+struct HttpData {
+  typedef std::multimap<std::string, std::string, iless> HeaderMap;
+  typedef HeaderMap::const_iterator const_iterator;
+  typedef HeaderMap::iterator iterator;
+
+  HttpVersion version;
+  std::unique_ptr<StreamInterface> document;
+
+  HttpData();
+
+  enum HeaderCombine { HC_YES, HC_NO, HC_AUTO, HC_REPLACE, HC_NEW };
+  void changeHeader(const std::string& name, const std::string& value,
+                    HeaderCombine combine);
+  inline void addHeader(const std::string& name, const std::string& value,
+                        bool append = true) {
+    changeHeader(name, value, append ? HC_AUTO : HC_NO);
+  }
+  inline void setHeader(const std::string& name, const std::string& value,
+                        bool overwrite = true) {
+    changeHeader(name, value, overwrite ? HC_REPLACE : HC_NEW);
+  }
+  // Returns count of erased headers
+  size_t clearHeader(const std::string& name);
+  // Returns iterator to next header
+  iterator clearHeader(iterator header);
+
+  // keep in mind, this may not do what you want in the face of multiple headers
+  bool hasHeader(const std::string& name, std::string* value) const;
+
+  inline const_iterator begin() const {
+    return headers_.begin();
+  }
+  inline const_iterator end() const {
+    return headers_.end();
+  }
+  inline iterator begin() {
+    return headers_.begin();
+  }
+  inline iterator end() {
+    return headers_.end();
+  }
+  inline const_iterator begin(const std::string& name) const {
+    return headers_.lower_bound(name);
+  }
+  inline const_iterator end(const std::string& name) const {
+    return headers_.upper_bound(name);
+  }
+  inline iterator begin(const std::string& name) {
+    return headers_.lower_bound(name);
+  }
+  inline iterator end(const std::string& name) {
+    return headers_.upper_bound(name);
+  }
+
+  // Convenience methods using HttpHeader
+  inline void changeHeader(HttpHeader header, const std::string& value,
+                           HeaderCombine combine) {
+    changeHeader(ToString(header), value, combine);
+  }
+  inline void addHeader(HttpHeader header, const std::string& value,
+                        bool append = true) {
+    addHeader(ToString(header), value, append);
+  }
+  inline void setHeader(HttpHeader header, const std::string& value,
+                        bool overwrite = true) {
+    setHeader(ToString(header), value, overwrite);
+  }
+  inline void clearHeader(HttpHeader header) {
+    clearHeader(ToString(header));
+  }
+  inline bool hasHeader(HttpHeader header, std::string* value) const {
+    return hasHeader(ToString(header), value);
+  }
+  inline const_iterator begin(HttpHeader header) const {
+    return headers_.lower_bound(ToString(header));
+  }
+  inline const_iterator end(HttpHeader header) const {
+    return headers_.upper_bound(ToString(header));
+  }
+  inline iterator begin(HttpHeader header) {
+    return headers_.lower_bound(ToString(header));
+  }
+  inline iterator end(HttpHeader header) {
+    return headers_.upper_bound(ToString(header));
+  }
+
+  void setContent(const std::string& content_type, StreamInterface* document);
+  void setDocumentAndLength(StreamInterface* document);
+
+  virtual size_t formatLeader(char* buffer, size_t size) const = 0;
+  virtual HttpError parseLeader(const char* line, size_t len) = 0;
+
+protected:
+ virtual ~HttpData();
+  void clear(bool release_document);
+  void copy(const HttpData& src);
+
+private:
+  HeaderMap headers_;
+};
+
+struct HttpRequestData : public HttpData {
+  HttpVerb verb;
+  std::string path;
+
+  HttpRequestData() : verb(HV_GET) { }
+
+  void clear(bool release_document);
+  void copy(const HttpRequestData& src);
+
+  size_t formatLeader(char* buffer, size_t size) const override;
+  HttpError parseLeader(const char* line, size_t len) override;
+
+  bool getAbsoluteUri(std::string* uri) const;
+  bool getRelativeUri(std::string* host, std::string* path) const;
+};
+
+struct HttpResponseData : public HttpData {
+  uint32_t scode;
+  std::string message;
+
+  HttpResponseData() : scode(HC_INTERNAL_SERVER_ERROR) { }
+  void clear(bool release_document);
+  void copy(const HttpResponseData& src);
+
+  // Convenience methods
+  void set_success(uint32_t scode = HC_OK);
+  void set_success(const std::string& content_type,
+                   StreamInterface* document,
+                   uint32_t scode = HC_OK);
+  void set_redirect(const std::string& location,
+                    uint32_t scode = HC_MOVED_TEMPORARILY);
+  void set_error(uint32_t scode);
+
+  size_t formatLeader(char* buffer, size_t size) const override;
+  HttpError parseLeader(const char* line, size_t len) override;
+};
+
+struct HttpTransaction {
+  HttpRequestData request;
+  HttpResponseData response;
+};
+
+//////////////////////////////////////////////////////////////////////
+// Http Authentication
+//////////////////////////////////////////////////////////////////////
+
+struct HttpAuthContext {
+  std::string auth_method;
+  HttpAuthContext(const std::string& auth) : auth_method(auth) { }
+  virtual ~HttpAuthContext() { }
+};
+
+enum HttpAuthResult { HAR_RESPONSE, HAR_IGNORE, HAR_CREDENTIALS, HAR_ERROR };
+
+// 'context' is used by this function to record information between calls.
+// Start by passing a null pointer, then pass the same pointer each additional
+// call.  When the authentication attempt is finished, delete the context.
+HttpAuthResult HttpAuthenticate(
+  const char * challenge, size_t len,
+  const SocketAddress& server,
+  const std::string& method, const std::string& uri,
+  const std::string& username, const CryptString& password,
+  HttpAuthContext *& context, std::string& response, std::string& auth_method);
+
+//////////////////////////////////////////////////////////////////////
+
+} // namespace rtc
+
+#endif // WEBRTC_BASE_HTTPCOMMON_H__