Revert of HttpServer: avoid DCHECK'ing on non-HTTP/1.1 requests.

net/http/http_response_headers.cc

Index: net/http/http_response_headers.cc
diff --git a/net/http/http_response_headers.cc b/net/http/http_response_headers.cc
index 408739b3876d3b838adab677f87272bd395b05a3..cc4cec4d8878678a9760449a669cbd5599c44176 100644
--- a/net/http/http_response_headers.cc
+++ b/net/http/http_response_headers.cc
@@ -627,21 +627,62 @@
 
 // Note: this implementation implicitly assumes that line_end points at a valid
 // sentinel character (such as '\0').
+// static
+HttpVersion HttpResponseHeaders::ParseVersion(
+    std::string::const_iterator line_begin,
+    std::string::const_iterator line_end) {
+  std::string::const_iterator p = line_begin;
+
+  // RFC2616 sec 3.1: HTTP-Version   = "HTTP" "/" 1*DIGIT "." 1*DIGIT
+  // TODO: (1*DIGIT apparently means one or more digits, but we only handle 1).
+  // TODO: handle leading zeros, which is allowed by the rfc1616 sec 3.1.
+
+  if ((line_end - p < 4) || !LowerCaseEqualsASCII(p, p + 4, "http")) {
+    DVLOG(1) << "missing status line";
+    return HttpVersion();
+  }
+
+  p += 4;
+
+  if (p >= line_end || *p != '/') {
+    DVLOG(1) << "missing version";
+    return HttpVersion();
+  }
+
+  std::string::const_iterator dot = std::find(p, line_end, '.');
+  if (dot == line_end) {
+    DVLOG(1) << "malformed version";
+    return HttpVersion();
+  }
+
+  ++p;  // from / to first digit.
+  ++dot;  // from . to second digit.
+
+  if (!(*p >= '0' && *p <= '9' && *dot >= '0' && *dot <= '9')) {
+    DVLOG(1) << "malformed version number";
+    return HttpVersion();
+  }
+
+  uint16 major = *p - '0';
+  uint16 minor = *dot - '0';
+
+  return HttpVersion(major, minor);
+}
+
+// Note: this implementation implicitly assumes that line_end points at a valid
+// sentinel character (such as '\0').
 void HttpResponseHeaders::ParseStatusLine(
     std::string::const_iterator line_begin,
     std::string::const_iterator line_end,
     bool has_headers) {
   // Extract the version number
-  std::string::const_iterator first_space =
-      std::find(line_begin, line_end, ' ');
-  std::string version(line_begin, first_space);
-  bool success = HttpUtil::ParseVersion(version, &parsed_http_version_);
+  parsed_http_version_ = ParseVersion(line_begin, line_end);
 
   // Clamp the version number to one of: {0.9, 1.0, 1.1}
-  if (success && parsed_http_version_ == HttpVersion(0, 9) && !has_headers) {
+  if (parsed_http_version_ == HttpVersion(0, 9) && !has_headers) {
     http_version_ = HttpVersion(0, 9);
     raw_headers_ = "HTTP/0.9";
-  } else if (success && parsed_http_version_ >= HttpVersion(1, 1)) {
+  } else if (parsed_http_version_ >= HttpVersion(1, 1)) {
     http_version_ = HttpVersion(1, 1);
     raw_headers_ = "HTTP/1.1";
   } else {
@@ -655,7 +696,7 @@
   }
 
   // TODO(eroman): this doesn't make sense if ParseVersion failed.
-  std::string::const_iterator p = first_space;
+  std::string::const_iterator p = std::find(line_begin, line_end, ' ');
 
   if (p == line_end) {
     DVLOG(1) << "missing response status; assuming 200 OK";