MINOR: acme: send the request for challenge ready

This patch sends the "{}" message to specify that a challenge is ready.
It iterates on every challenge URL in the authorization list from the
acme_ctx.

This allows the ACME server to procede to the challenge validation.
https://www.rfc-editor.org/rfc/rfc8555#section-7.5.1

include/haproxy/acme-t.h

@@ -36,6 +36,7 @@ enum acme_st {
 	ACME_NEWACCOUNT,
 	ACME_NEWORDER,
 	ACME_AUTH,
+	ACME_CHALLENGE,
 	ACME_END
 };
 

src/acme.c

@@ -578,6 +578,95 @@ error:
 	return ret;
 }
 
+/*
+ * Send the READY request for the challenge
+ */
+int acme_req_challenge(struct task *task, struct acme_ctx *ctx, struct acme_auth *auth, char **errmsg)
+{
+	struct buffer *req_in = NULL;
+	struct buffer *req_out = NULL;
+	const struct http_hdr hdrs[] = {
+		{ IST("Content-Type"), IST("application/jose+json") },
+		{ IST_NULL, IST_NULL }
+	};
+	int ret = 1;
+
+        if ((req_in = alloc_trash_chunk()) == NULL)
+		goto error;
+        if ((req_out = alloc_trash_chunk()) == NULL)
+		goto error;
+
+	chunk_printf(req_in, "{}");
+
+	if (acme_jws_payload(req_in, ctx->nonce, auth->chall, ctx->cfg->account.pkey, ctx->kid, req_out, errmsg) != 0)
+		goto error;
+
+	if (acme_http_req(task, ctx, auth->chall, HTTP_METH_POST, hdrs, ist2(req_out->area, req_out->data)))
+		goto error;
+
+	ret = 0;
+error:
+	memprintf(errmsg, "couldn't generate the Challenge request");
+
+	free_trash_chunk(req_in);
+	free_trash_chunk(req_out);
+
+	return ret;
+
+}
+
+/* parse the challenge URL response */
+int acme_res_challenge(struct task *task, struct acme_ctx *ctx, struct acme_auth *auth, char **errmsg)
+{
+	struct httpclient *hc;
+	struct http_hdr *hdrs, *hdr;
+	struct buffer *t1 = NULL, *t2 = NULL;
+	int ret = 1;
+
+	hc = ctx->hc;
+	if (!hc)
+		goto error;
+
+        if ((t1 = alloc_trash_chunk()) == NULL)
+		goto error;
+        if ((t2 = alloc_trash_chunk()) == NULL)
+		goto error;
+
+	hdrs = hc->res.hdrs;
+
+	for (hdr = hdrs; isttest(hdr->v); hdr++) {
+		if (isteqi(hdr->n, ist("Replay-Nonce"))) {
+			istfree(&ctx->nonce);
+			ctx->nonce = istdup(hdr->v);
+		}
+	}
+
+	if (hc->res.status < 200 || hc->res.status >= 300) {
+		/* XXX: need a generic URN error parser */
+		if ((ret = mjson_get_string(hc->res.buf.area, hc->res.buf.data, "$.detail", t1->area, t1->size)) > -1)
+			t1->data = ret;
+		if ((ret = mjson_get_string(hc->res.buf.area, hc->res.buf.data, "$.type", t2->area, t2->size)) > -1)
+			t2->data = ret;
+		if (t2->data && t1->data)
+			memprintf(errmsg, "invalid HTTP status code %d when getting Challenge URL: \"%.*s\" (%.*s)", hc->res.status, (int)t1->data, t1->area, (int)t2->data, t2->area);
+		else
+			memprintf(errmsg, "invalid HTTP status code %d when getting Challenge URL", hc->res.status);
+		goto error;
+	}
+
+out:
+	ret = 0;
+
+error:
+	free_trash_chunk(t1);
+	free_trash_chunk(t2);
+	httpclient_destroy(hc);
+	ctx->hc = NULL;
+
+	return ret;
+}
+
+
 /*
  * Get an Auth URL
  */
@@ -1170,6 +1259,25 @@ struct task *acme_process(struct task *task, void *context, unsigned int state)
 					http_st = ACME_HTTP_REQ;
 					goto retry;
 				}
+				http_st = ACME_HTTP_REQ;
+				if ((ctx->next_auth = ctx->next_auth->next) == NULL) {
+					st = ACME_CHALLENGE;
+					ctx->next_auth = ctx->auths;
+				}
+				/* call with next auth or do the challenge step */
+				task_wakeup(task, TASK_WOKEN_MSG);
+			}
+		break;
+		case ACME_CHALLENGE:
+			if (http_st == ACME_HTTP_REQ) {
+				if (acme_req_challenge(task, ctx, ctx->next_auth, &errmsg) != 0)
+					goto retry;
+			}
+			if (http_st == ACME_HTTP_RES) {
+				if (acme_res_challenge(task, ctx, ctx->next_auth, &errmsg) != 0) {
+					http_st = ACME_HTTP_REQ;
+					goto retry;
+				}
 				if ((ctx->next_auth = ctx->next_auth->next) == NULL)
 					goto end;