MINOR: hpack: provide a function to encode an HTTP path

The new function hpack_encode_path() supports encoding a path into
the ":path" header. It knows about "/" and "/index.html" which use
a single byte, and falls back to literal encoding for other ones,
with a fast path for short paths < 127 bytes.

diff --git a/include/common/hpack-enc.h b/include/common/hpack-enc.h
index 831689b968c4c9d010e12e1ebb791a015acebe27..4ab38bf5f068c9211fe1208a14690f915e020052 100644 (file)
--- a/include/common/hpack-enc.h
+++ b/include/common/hpack-enc.h
@@ -238,4 +238,25 @@ static inline int hpack_encode_scheme(struct buffer *out, struct ist scheme)
        return 1;
 }
 
+/* Tries to encode a :path pseudo-header with the path in <path>, into the
+ * aligned buffer <out>. Returns non-zero on success or 0 on failure (buffer
+ * full). The well-known values "/" and "/index.html" are recognized, and other
+ * ones are handled as literals. The caller is responsible for ensuring that
+ * the buffer is aligned.  Normally the compiler will detect constant strings
+ * in the comparison if the code remains inlined.
+ */
+static inline int hpack_encode_path(struct buffer *out, struct ist path)
+{
+       if (out->data < out->size && isteq(path, ist("/")))
+               out->area[out->data++] = 0x84; // indexed field : idx[04]=(":path", "/")
+       else if (out->data < out->size && isteq(path, ist("/index.html")))
+               out->area[out->data++] = 0x85; // indexed field : idx[05]=(":path", "/index.html")
+       else if (path.len < 127)
+               return hpack_encode_short_idx(out, 4, path); // name=":path" (idx 4)
+       else
+               return hpack_encode_long_idx(out, 4, path); // name=":path" (idx 4)
+       return 1;
+}
+
+
 #endif /* _COMMON_HPACK_ENC_H */