MEDIUM: counters: factor out smp_fetch_sc*_http_err_cnt

smp_fetch_sc0_http_err_cnt, smp_fetch_sc1_http_err_cnt, smp_fetch_sc2_http_err_cnt,
smp_fetch_src_http_err_cnt and smp_fetch_http_err_cnt were merged into a single
function which relies on the fetch name to decide what to return.
diff --git a/src/session.c b/src/session.c
index a0e1c96..42f182c 100644
--- a/src/session.c
+++ b/src/session.c
@@ -2945,15 +2945,24 @@
 	return 1;
 }
 
-/* set temp integer to the cumulated number of sessions in the stksess entry <ts> */
+/* set <smp> to the cumulated number of HTTP requests errors from the session's
+ * tracked frontend counters. Supports being called as "sc[0-9]_http_err_cnt" or
+ * "src_http_err_cnt" only.
+ */
 static int
-smp_fetch_http_err_cnt(struct stktable *table, struct sample *smp, struct stksess *ts)
+smp_fetch_sc_http_err_cnt(struct proxy *px, struct session *l4, void *l7, unsigned int opt,
+                          const struct arg *args, struct sample *smp, const char *kw)
 {
+	struct stkctr *stkctr = smp_fetch_sc_stkctr(l4, args, kw);
+
+	if (!stkctr)
+		return 0;
+
 	smp->flags = SMP_F_VOL_TEST;
 	smp->type = SMP_T_UINT;
 	smp->data.uint = 0;
-	if (ts != NULL) {
-		void *ptr = stktable_data_ptr(table, ts, STKTABLE_DT_HTTP_ERR_CNT);
+	if (stkctr->entry != NULL) {
+		void *ptr = stktable_data_ptr(stkctr->table, stkctr->entry, STKTABLE_DT_HTTP_ERR_CNT);
 		if (!ptr)
 			return 0; /* parameter not stored */
 		smp->data.uint = stktable_data_cast(ptr, http_err_cnt);
@@ -2961,57 +2970,6 @@
 	return 1;
 }
 
-/* set temp integer to the cumulated number of sessions from the session's tracked FE counters */
-static int
-smp_fetch_sc0_http_err_cnt(struct proxy *px, struct session *l4, void *l7, unsigned int opt,
-                           const struct arg *args, struct sample *smp, const char *kw)
-{
-	if (!l4->stkctr[0].entry)
-		return 0;
-
-	return smp_fetch_http_err_cnt(l4->stkctr[0].table, smp, l4->stkctr[0].entry);
-}
-
-/* set temp integer to the cumulated number of sessions from the session's tracked BE counters */
-static int
-smp_fetch_sc1_http_err_cnt(struct proxy *px, struct session *l4, void *l7, unsigned int opt,
-                           const struct arg *args, struct sample *smp, const char *kw)
-{
-	if (!l4->stkctr[1].entry)
-		return 0;
-
-	return smp_fetch_http_err_cnt(l4->stkctr[1].table, smp, l4->stkctr[1].entry);
-}
-
-/* set temp integer to the cumulated number of sessions from the session's tracked BE counters */
-static int
-smp_fetch_sc2_http_err_cnt(struct proxy *px, struct session *l4, void *l7, unsigned int opt,
-                           const struct arg *args, struct sample *smp, const char *kw)
-{
-	if (!l4->stkctr[2].entry)
-		return 0;
-
-	return smp_fetch_http_err_cnt(l4->stkctr[2].table, smp, l4->stkctr[2].entry);
-}
-
-/* set temp integer to the cumulated number of session from the session's source
- * address in the table pointed to by expr.
- * Accepts exactly 1 argument of type table.
- */
-static int
-smp_fetch_src_http_err_cnt(struct proxy *px, struct session *l4, void *l7, unsigned int opt,
-                           const struct arg *args, struct sample *smp, const char *kw)
-{
-	struct stktable_key *key;
-
-	key = addr_to_stktable_key(&l4->si[0].conn->addr.from);
-	if (!key)
-		return 0;
-
-	px = args->data.prx;
-	return smp_fetch_http_err_cnt(&px->table, smp, stktable_lookup_key(&px->table, key));
-}
-
 /* set temp integer to the session rate in the stksess entry <ts> over the configured period */
 static int
 smp_fetch_http_err_rate(struct stktable *table, struct sample *smp, struct stksess *ts)
@@ -3465,7 +3423,7 @@
 	{ "sc0_conn_rate",      smp_fetch_sc_conn_rate,       0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
 	{ "sc0_get_gpc0",       smp_fetch_sc_get_gpc0,        0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
 	{ "sc0_gpc0_rate",      smp_fetch_sc_gpc0_rate,       0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
-	{ "sc0_http_err_cnt",   smp_fetch_sc0_http_err_cnt,   0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
+	{ "sc0_http_err_cnt",   smp_fetch_sc_http_err_cnt,    0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
 	{ "sc0_http_err_rate",  smp_fetch_sc0_http_err_rate,  0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
 	{ "sc0_http_req_cnt",   smp_fetch_sc_http_req_cnt,    0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
 	{ "sc0_http_req_rate",  smp_fetch_sc_http_req_rate,   0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
@@ -3484,7 +3442,7 @@
 	{ "sc1_conn_rate",      smp_fetch_sc_conn_rate,       0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
 	{ "sc1_get_gpc0",       smp_fetch_sc_get_gpc0,        0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
 	{ "sc1_gpc0_rate",      smp_fetch_sc_gpc0_rate,       0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
-	{ "sc1_http_err_cnt",   smp_fetch_sc1_http_err_cnt,   0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
+	{ "sc1_http_err_cnt",   smp_fetch_sc_http_err_cnt,    0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
 	{ "sc1_http_err_rate",  smp_fetch_sc1_http_err_rate,  0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
 	{ "sc1_http_req_cnt",   smp_fetch_sc_http_req_cnt,    0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
 	{ "sc1_http_req_rate",  smp_fetch_sc_http_req_rate,   0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
@@ -3503,7 +3461,7 @@
 	{ "sc2_conn_rate",      smp_fetch_sc_conn_rate,       0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
 	{ "sc2_get_gpc0",       smp_fetch_sc_get_gpc0,        0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
 	{ "sc2_gpc0_rate",      smp_fetch_sc_gpc0_rate,       0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
-	{ "sc2_http_err_cnt",   smp_fetch_sc2_http_err_cnt,   0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
+	{ "sc2_http_err_cnt",   smp_fetch_sc_http_err_cnt,    0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
 	{ "sc2_http_err_rate",  smp_fetch_sc2_http_err_rate,  0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
 	{ "sc2_http_req_cnt",   smp_fetch_sc_http_req_cnt,    0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
 	{ "sc2_http_req_rate",  smp_fetch_sc_http_req_rate,   0,           NULL, SMP_T_UINT, SMP_USE_INTRN, },
@@ -3522,7 +3480,7 @@
 	{ "src_conn_rate",      smp_fetch_sc_conn_rate,       ARG1(1,TAB), NULL, SMP_T_UINT, SMP_USE_L4CLI, },
 	{ "src_get_gpc0",       smp_fetch_sc_get_gpc0,        ARG1(1,TAB), NULL, SMP_T_UINT, SMP_USE_L4CLI, },
 	{ "src_gpc0_rate",      smp_fetch_sc_gpc0_rate,       ARG1(1,TAB), NULL, SMP_T_UINT, SMP_USE_L4CLI, },
-	{ "src_http_err_cnt",   smp_fetch_src_http_err_cnt,   ARG1(1,TAB), NULL, SMP_T_UINT, SMP_USE_L4CLI, },
+	{ "src_http_err_cnt",   smp_fetch_sc_http_err_cnt,    ARG1(1,TAB), NULL, SMP_T_UINT, SMP_USE_L4CLI, },
 	{ "src_http_err_rate",  smp_fetch_src_http_err_rate,  ARG1(1,TAB), NULL, SMP_T_UINT, SMP_USE_L4CLI, },
 	{ "src_http_req_cnt",   smp_fetch_sc_http_req_cnt,    ARG1(1,TAB), NULL, SMP_T_UINT, SMP_USE_L4CLI, },
 	{ "src_http_req_rate",  smp_fetch_sc_http_req_rate,   ARG1(1,TAB), NULL, SMP_T_UINT, SMP_USE_L4CLI, },