REORG: h2: extract cookies concat function in http_htx

As specified by RFC 7540, multiple cookie headers are merged in a single
entry before passing it to a HTTP/1.1 connection. This step is
implemented during headers parsing in h2 module.

Extract this code in the generic http_htx module. This will allow to
reuse it quickly for HTTP/3 implementation which has the same
requirement for cookie headers.

include/haproxy/http_htx.h

@@ -25,6 +25,7 @@
 
 #include <import/ist.h>
 #include <haproxy/buf-t.h>
+#include <haproxy/http-hdr-t.h>
 #include <haproxy/http_htx-t.h>
 #include <haproxy/proxy-t.h>
 #include <haproxy/regex-t.h>
@@ -68,6 +69,9 @@ struct http_reply *http_parse_http_reply(const char **args, int *orig_arg, struc
 
 int http_scheme_based_normalize(struct htx *htx);
 
+void http_cookie_register(struct http_hdr *list, int idx, int *first, int *last);
+int http_cookie_merge(struct htx *htx, struct http_hdr *list, int first);
+
 struct buffer *http_load_errorfile(const char *file, char **errmsg);
 struct buffer *http_load_errormsg(const char *key, const struct ist msg, char **errmsg);
 struct buffer *http_parse_errorfile(int status, const char *file, char **errmsg);

src/h2.c

@@ -501,14 +501,7 @@ int h2_make_htx_request(struct http_hdr *list, struct htx *htx, unsigned int *ms
 
 		/* cookie requires special processing at the end */
 		if (isteq(list[idx].n, ist("cookie"))) {
-			list[idx].n.len = -1;
-
-			if (ck < 0)
-				ck = idx;
-			else
-				list[lck].n.len = idx;
-
-			lck = idx;
+			http_cookie_register(list, idx, &ck, &lck);
 			continue;
 		}
 
@@ -561,37 +554,8 @@ int h2_make_htx_request(struct http_hdr *list, struct htx *htx, unsigned int *ms
 	 * visited headers.
 	 */
 	if (ck >= 0) {
-		uint32_t fs; // free space
-		uint32_t bs; // block size
-		uint32_t vl; // value len
-		uint32_t tl; // total length
-		struct htx_blk *blk;
-
-		blk = htx_add_header(htx, ist("cookie"), list[ck].v);
-		if (!blk)
+		if (http_cookie_merge(htx, list, ck))
 			goto fail;
-
-		tl = list[ck].v.len;
-		fs = htx_free_data_space(htx);
-		bs = htx_get_blksz(blk);
-
-		/* for each extra cookie, we'll extend the cookie's value and
-		 * insert "; " before the new value.
-		 */
-		fs += tl; // first one is already counted
-		while ((ck = list[ck].n.len) >= 0) {
-			vl = list[ck].v.len;
-			tl += vl + 2;
-			if (tl > fs)
-				goto fail;
-
-			htx_change_blk_value_len(htx, blk, tl);
-			*(char *)(htx_get_blk_ptr(htx, blk) + bs + 0) = ';';
-			*(char *)(htx_get_blk_ptr(htx, blk) + bs + 1) = ' ';
-			memcpy(htx_get_blk_ptr(htx, blk) + bs + 2, list[ck].v.ptr, vl);
-			bs += vl + 2;
-		}
-
 	}
 
 	/* now send the end of headers marker */

src/http_htx.c

@@ -21,6 +21,7 @@
 #include <haproxy/global.h>
 #include <haproxy/h1.h>
 #include <haproxy/http.h>
+#include <haproxy/http-hdr.h>
 #include <haproxy/http_fetch.h>
 #include <haproxy/http_htx.h>
 #include <haproxy/htx.h>
@@ -1799,6 +1800,83 @@ int http_scheme_based_normalize(struct htx *htx)
 	return 1;
 }
 
+/* First step function to merge multiple cookie headers in a single entry.
+ *
+ * Use it for each cookie header at <idx> index over HTTP headers in <list>.
+ * <first> and <last> are state variables used internally and must be
+ * initialized to -1 before the first invocation.
+ */
+void http_cookie_register(struct http_hdr *list, int idx, int *first, int *last)
+{
+	/* Build a linked list of cookie headers. Use header length to point to
+	 * the next one. The last entry will contains -1.
+	 */
+
+	/* Mark the current end of cookie linked list. */
+	list[idx].n.len = -1;
+	if (*first < 0) {
+		/* Save first found cookie for http_cookie_merge call. */
+		*first = idx;
+	}
+	else {
+		/* Update linked list of cookies. */
+		list[*last].n.len = idx;
+	}
+
+	*last = idx;
+}
+
+/* Second step to merge multiple cookie headers in a single entry.
+ *
+ * Use it when looping over HTTP headers is done and <htx> message is built.
+ * This will concatenate each cookie headers present from <list> directly into
+ * <htx> message. <first> is reused from previous http_cookie_register
+ * invocation.
+ *
+ * Returns 0 on success else non-zero.
+ */
+int http_cookie_merge(struct htx *htx, struct http_hdr *list, int first)
+{
+	uint32_t fs; /* free space */
+	uint32_t bs; /* block size */
+	uint32_t vl; /* value len */
+	uint32_t tl; /* total length */
+	struct htx_blk *blk;
+
+	if (first < 0)
+		return 0;
+
+	blk = htx_add_header(htx, ist("cookie"), list[first].v);
+	if (!blk)
+		return 1;
+
+	tl = list[first].v.len;
+	fs = htx_free_data_space(htx);
+	bs = htx_get_blksz(blk);
+
+	/* for each extra cookie, we'll extend the cookie's value and insert
+	 * ";" before the new value.
+	 */
+	fs += tl; /* first one is already counted */
+
+	/* Loop over cookies linked list built from http_cookie_register. */
+	while ((first = list[first].n.len) >= 0) {
+		vl = list[first].v.len;
+		tl += vl + 2;
+		if (tl > fs)
+			return 1;
+
+		htx_change_blk_value_len(htx, blk, tl);
+		*(char *)(htx_get_blk_ptr(htx, blk) + bs + 0) = ';';
+		*(char *)(htx_get_blk_ptr(htx, blk) + bs + 1) = ' ';
+		memcpy(htx_get_blk_ptr(htx, blk) + bs + 2,
+		       list[first].v.ptr, vl);
+		bs += vl + 2;
+	}
+
+	return 0;
+}
+
 /* Parses the "errorloc[302|303]" proxy keyword */
 static int proxy_parse_errorloc(char **args, int section, struct proxy *curpx,
 				  const struct proxy *defpx, const char *file, int line,