Maintenance: use SBufs for ErrorDetailEntry data fields (#1451)

Also fixed (re)configuration crashes when an error-details.txt entry is
missing a required "detail" or "descr" field.

src/HttpHeader.h

@@ -199,6 +199,26 @@ class HttpHeader
 
 int httpHeaderParseQuotedString(const char *start, const int len, String *val);
 
+namespace Http {
+
+/**
+ * Parses an HTTP quoted-string sequence (RFC 9110, Section 5.6.4).
+ *
+ * \param a brief human-friendly description of the string being parsed
+ * \param start input buffer (an opening double-quote is expected at *start)
+ * \param length is the number of characters in the given buffer
+ *
+ * \returns string contents with open/closing quotes stripped and any quoted-pairs decoded
+ *
+ * Avoid this slow function on performance-sensitive code paths.
+ * TODO: Replace with an efficient, SBuf-friendly implementation.
+ *
+ * \sa httpHeaderParseQuotedString() for a String-friendly function.
+ */
+SBuf SlowlyParseQuotedString(const char *description, const char *start, size_t length);
+
+}
+
 /// quotes string using RFC 7230 quoted-string rules
 SBuf httpHeaderQuoteString(const char *raw);
 

src/HttpHeaderTools.cc

@@ -27,6 +27,8 @@
 #include "HttpHeaderTools.h"
 #include "HttpRequest.h"
 #include "MemBuf.h"
+#include "sbuf/Stream.h"
+#include "sbuf/StringConvert.h"
 #include "SquidConfig.h"
 #include "Store.h"
 #include "StrList.h"
@@ -233,6 +235,15 @@ httpHeaderParseQuotedString(const char *start, const int len, String *val)
     return 1;
 }
 
+SBuf
+Http::SlowlyParseQuotedString(const char * const description, const char * const start, const size_t length)
+{
+    String s;
+    if (!httpHeaderParseQuotedString(start, length, &s))
+        throw TextException(ToSBuf("Cannot parse ", description, " as a quoted string"), Here());
+    return StringToSBuf(s);
+}
+
 SBuf
 httpHeaderQuoteString(const char *raw)
 {