+/*
+ * Check header memory for the token "trailers".
+ * Parse the tokens as separated by comma and surrounded by whitespace.
+ * Returns TRUE if found or FALSE if not.
+ */
+static bool contains_trailers(const char *p, size_t len)
+{
+ const char *end = p + len;
+ for(;;) {
+ for(; p != end && (*p == ' ' || *p == '\t'); ++p)
+ ;
+ if(p == end || (size_t)(end - p) < sizeof("trailers") - 1)
+ return FALSE;
+ if(strncasecompare("trailers", p, sizeof("trailers") - 1)) {
+ p += sizeof("trailers") - 1;
+ for(; p != end && (*p == ' ' || *p == '\t'); ++p)
+ ;
+ if(p == end || *p == ',')
+ return TRUE;
+ }
+ /* skip to next token */
+ for(; p != end && *p != ','; ++p)
+ ;
+ if(p == end)
+ return FALSE;
+ ++p;
+ }
+}
+
+typedef enum {
+ /* Send header to server */
+ HEADERINST_FORWARD,
+ /* Don't send header to server */
+ HEADERINST_IGNORE,
+ /* Discard header, and replace it with "te: trailers" */
+ HEADERINST_TE_TRAILERS
+} header_instruction;
+
+/* Decides how to treat given header field. */
+static header_instruction inspect_header(const char *name, size_t namelen,
+ const char *value, size_t valuelen) {
+ switch(namelen) {
+ case 2:
+ if(!strncasecompare("te", name, namelen))
+ return HEADERINST_FORWARD;
+
+ return contains_trailers(value, valuelen) ?
+ HEADERINST_TE_TRAILERS : HEADERINST_IGNORE;
+ case 7:
+ return strncasecompare("upgrade", name, namelen) ?
+ HEADERINST_IGNORE : HEADERINST_FORWARD;
+ case 10:
+ return (strncasecompare("connection", name, namelen) ||
+ strncasecompare("keep-alive", name, namelen)) ?
+ HEADERINST_IGNORE : HEADERINST_FORWARD;
+ case 16:
+ return strncasecompare("proxy-connection", name, namelen) ?
+ HEADERINST_IGNORE : HEADERINST_FORWARD;
+ case 17:
+ return strncasecompare("transfer-encoding", name, namelen) ?
+ HEADERINST_IGNORE : HEADERINST_FORWARD;
+ default:
+ return HEADERINST_FORWARD;
+ }
+}
+