MINOR: mux-h2/traces: add buffer-related info to h2s and h2c

The traces currently don't contain any info about the amount of data
present in buffers, making it difficult to figure if an empty buffer
is the cause for not demuxing or if a full buffer is the cause for
not reading more data. Let's add them, with the head/tail info as
well.

src/mux_h2.c

@@ -541,6 +541,10 @@ static void h2s_alert(struct h2s *h2s);
 static inline void h2_remove_from_list(struct h2s *h2s);
 static int h2_dump_h2c_info(struct buffer *msg, struct h2c *h2c, const char *pfx);
 static int h2_dump_h2s_info(struct buffer *msg, const struct h2s *h2s, const char *pfx);
+static inline struct buffer *h2s_rxbuf_head(const struct h2s *h2s);
+static inline struct buffer *h2s_rxbuf_tail(const struct h2s *h2s);
+static inline struct buffer *h2s_rxbuf_head(const struct h2s *h2s);
+static inline struct buffer *h2s_rxbuf_tail(const struct h2s *h2s);
 
 /* returns the stconn associated to the H2 stream */
 static forceinline struct stconn *h2s_sc(const struct h2s *h2s)
@@ -557,6 +561,7 @@ static void h2_trace(enum trace_level level, uint64_t mask, const struct trace_s
                      const struct ist where, const struct ist func,
                      const void *a1, const void *a2, const void *a3, const void *a4)
 {
+	const struct buffer *hmbuf, *tmbuf;
 	const struct connection *conn = a1;
 	const struct h2c *h2c    = conn ? conn->ctx : NULL;
 	const struct h2s *h2s    = a2;
@@ -586,16 +591,40 @@ static void h2_trace(enum trace_level level, uint64_t mask, const struct trace_s
 			chunk_appendf(&trace_buf, " dft=%s/%02x dfl=%d", h2_ft_str(h2c->dft), h2c->dff, h2c->dfl);
 		}
 
+		hmbuf = br_head((struct buffer*)h2c->mbuf);
+		tmbuf = br_tail((struct buffer*)h2c->mbuf);
+		chunk_appendf(&trace_buf, " .dbuf=%u@%p+%u/%u .mbuf=[%u..%u|%u],h=[%u@%p+%u/%u],t=[%u@%p+%u/%u]",
+		              (uint)b_data(&h2c->dbuf), b_orig(&h2c->dbuf),
+		              (uint)b_head_ofs(&h2c->dbuf), (uint)b_size(&h2c->dbuf),
+		              br_head_idx(h2c->mbuf), br_tail_idx(h2c->mbuf), br_size(h2c->mbuf),
+		              (uint)b_data(hmbuf), b_orig(hmbuf),
+		              (uint)b_head_ofs(hmbuf), (uint)b_size(hmbuf),
+		              (uint)b_data(tmbuf), b_orig(tmbuf),
+		              (uint)b_head_ofs(tmbuf), (uint)b_size(tmbuf));
+
 		if (h2s) {
 			if (h2s->id <= 0)
 				chunk_appendf(&trace_buf, " dsi=%d", h2c->dsi);
 			if (h2s == h2_idle_stream)
 				chunk_appendf(&trace_buf, " h2s=IDL");
-			else if (h2s != h2_closed_stream && h2s != h2_refused_stream && h2s != h2_error_stream)
-				chunk_appendf(&trace_buf, " h2s=%p(%d,%s,%#x) .rxw=%u .txw=%d",
+			else if (h2s != h2_closed_stream && h2s != h2_refused_stream && h2s != h2_error_stream) {
+				const struct buffer *head, *tail;
+
+				head = h2s_rxbuf_head(h2s);
+				tail = h2s_rxbuf_tail(h2s);
+				chunk_appendf(&trace_buf, " h2s=%p(%d,%s,%#x) .txw=%d .rxw=%u .rxb.c=%u .h=%u@%p+%u/%u .t=%u@%p+%u/%u",
 				              h2s, h2s->id, h2s_st_to_str(h2s->st), h2s->flags,
-				              (uint)(h2s->next_max_ofs - h2s->curr_rx_ofs),
-				              h2s->sws + h2c->miw);
+				              h2s->sws + h2c->miw, (uint)(h2s->next_max_ofs - h2s->curr_rx_ofs),
+				              h2s->rx_count,
+				              head ? (uint)b_data(head) : 0,
+				              head ? b_orig(head) : NULL,
+				              head ? (uint)b_head_ofs(head) : 0,
+				              head ? (uint)b_size(head) : 0,
+				              tail ? (uint)b_data(tail) : 0,
+				              tail ? b_orig(tail) : NULL,
+				              tail ? (uint)b_head_ofs(tail) : 0,
+				              tail ? (uint)b_size(tail) : 0);
+			}
 			else if (h2c->dsi > 0) // don't show that before sid is known
 				chunk_appendf(&trace_buf, " h2s=CLO");
 			if (h2s->id && h2s->errcode)