Better handling of parse errors in HttpTime

strptime can return non-NULL values even if it only parsed part of the
string. This was sometimes making us use the wrong format. Now we try
all formats and checks how much of the string strptime managed to parse.
We stop when it has parsed a big enough part of it.

src/kits/network/libnetapi/HttpTime.cpp

@@ -13,11 +13,12 @@
 #include <cstdio>
 
 
-static const char* 	kRfc1123Format			= "%a, %d %b %Y %H:%M:%S GMT";
-static const char* 	kCookieFormat			= "%a, %d-%b-%Y %H:%M:%S GMT";
-static const char* 	kRfc1036Format			= "%A, %d-%b-%y %H:%M:%S GMT";
-static const char* 	kAscTimeFormat			= "%a %d %b %H:%M:%S %Y";
-static const uint16	kTimetToStringMaxLength	= 128;
+static const char* kDateFormats[] = {
+	"%a, %d %b %Y %H:%M:%S GMT",
+	"%a, %d-%b-%Y %H:%M:%S GMT",
+	"%A, %d-%b-%y %H:%M:%S GMT",
+	"%a %d %b %H:%M:%S %Y"
+};
 
 using namespace BPrivate;
 
@@ -84,22 +85,25 @@ BHttpTime::Parse()
 	expireTime.tm_wday = 0;
 	expireTime.tm_yday = 0;
 	expireTime.tm_isdst = 0;
-		
-	if (fDateString[3] == ',') {
-		if (strptime(fDateString.String(), kRfc1123Format, &expireTime)
-				== NULL) {
-			strptime(fDateString.String(), kCookieFormat, &expireTime);
-			fDateFormat = B_HTTP_TIME_FORMAT_COOKIE;
-		} else
-			fDateFormat = B_HTTP_TIME_FORMAT_RFC1123;
-	} else if (fDateString[3] == ' ') {
-		strptime(fDateString.String(), kRfc1036Format, &expireTime);
-		fDateFormat = B_HTTP_TIME_FORMAT_RFC1036;
-	} else {
-		strptime(fDateString.String(), kAscTimeFormat, &expireTime);
-		fDateFormat = B_HTTP_TIME_FORMAT_ASCTIME;
+
+	fDateFormat = B_HTTP_TIME_FORMAT_PARSED;
+	unsigned int i;
+	for (i = 0; i < sizeof(kDateFormats) / sizeof(const char*);
+		i++) {
+		const char* result = strptime(fDateString.String(), kDateFormats[i],
+			&expireTime);
+
+		// Make sure we parsed enough of the date string, not just a small
+		// part of it.
+		if (result != NULL && result > fDateString.String() + 24) {
+			fDateFormat = i;
+			break;
+		}
 	}
 
+	if (fDateFormat == B_HTTP_TIME_FORMAT_PARSED)
+		return 0;
+
 	BTime time(expireTime.tm_hour, expireTime.tm_min, expireTime.tm_sec);
 	BDate date(expireTime.tm_year + 1900, expireTime.tm_mon + 1,
 		expireTime.tm_mday);
@@ -123,27 +127,18 @@ BHttpTime::ToString(int8 format)
 	expirationTm.tm_yday = 0;
 	expirationTm.tm_isdst = 0;
 
-	char expirationString[kTimetToStringMaxLength + 1];
-	size_t strLength;
+	if (format == B_HTTP_TIME_FORMAT_PARSED)
+		format = fDateFormat;
+
+	if (format != B_HTTP_TIME_FORMAT_PARSED) {
+		static const uint16 kTimetToStringMaxLength = 128;
+		char expirationString[kTimetToStringMaxLength + 1];
+		size_t strLength;
 
-	switch ((format == B_HTTP_TIME_FORMAT_PARSED)?fDateFormat:format) {
-		default:
-		case B_HTTP_TIME_FORMAT_RFC1123:
-			strLength = strftime(expirationString, kTimetToStringMaxLength,
-				kRfc1123Format, &expirationTm);
-			break;
-
-		case B_HTTP_TIME_FORMAT_RFC1036:
-			strLength = strftime(expirationString, kTimetToStringMaxLength,
-				kRfc1036Format, &expirationTm);
-			break;
-
-		case B_HTTP_TIME_FORMAT_ASCTIME:
-			strLength = strftime(expirationString, kTimetToStringMaxLength,
-				kAscTimeFormat, &expirationTm);
-			break;		
-	}
+		strLength = strftime(expirationString, kTimetToStringMaxLength,
+			kDateFormats[format], &expirationTm);
 
-	expirationFinal.SetTo(expirationString, strLength);	
+		expirationFinal.SetTo(expirationString, strLength);
+	}
 	return expirationFinal;
 }