From d4c5d1c650ae0e97a083b0ce7a705c20fc001f07 Mon Sep 17 00:00:00 2001
From: Aram Sargsyan <aram@isc.org>
Date: Wed, 20 Jul 2022 10:18:56 +0000
Subject: [PATCH] Fix statistics channel multiple request processing with
 non-empty bodies

When the HTTP request has a body part after the HTTP headers, it is
not getting processed and is being prepended to the next request's data,
which results in an error when trying to parse it.

Improve the httpd.c:process_request() function with the following
additions:

1. Require that HTTP POST requests must have Content-Length header.
2. When Content-Length header is set, extract its value, and make sure
   that it is valid and that the whole request's body is received before
   processing the request.
3. Discard the request's body by consuming Content-Length worth of data
   in the buffer.

(cherry picked from commit c2bbdc8a648c9630b2c9cea5227ad5c309c2ade5)
---
 lib/isc/httpd.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/lib/isc/httpd.c b/lib/isc/httpd.c
index a2bff7bc17..a701fb2a84 100644
--- a/lib/isc/httpd.c
+++ b/lib/isc/httpd.c
@@ -408,8 +408,10 @@ have_header(isc_httpd_t *httpd, const char *header, const char *value,
 static isc_result_t
 process_request(isc_httpd_t *httpd, isc_region_t *region, size_t *buflen) {
 	char *s = NULL, *p = NULL, *urlend = NULL;
+	const char *content_length = NULL;
 	size_t limit = sizeof(httpd->recvbuf) - httpd->recvlen - 1;
 	size_t len = region->length;
+	size_t clen = 0;
 	int delim;
 	bool truncated = false;
 
@@ -566,6 +568,29 @@ process_request(isc_httpd_t *httpd, isc_region_t *region, size_t *buflen) {
 
 	httpd->headers = s;
 
+	if (!have_header(httpd, "Content-Length:", NULL, NULL, &content_length))
+	{
+		/* Require a Content-Length header for POST requests. */
+		if (httpd->method == METHOD_POST) {
+			return (ISC_R_BADNUMBER);
+		}
+	} else {
+		INSIST(content_length != NULL);
+
+		clen = (size_t)strtoul(content_length, NULL, 10);
+		if (clen == ULONG_MAX) {
+			/* Invalid number in the header value. */
+			return (ISC_R_BADNUMBER);
+		}
+		if (httpd->recvlen < httpd->consume + clen) {
+			/* The request data isn't complete yet. */
+			return (ISC_R_NOTFOUND);
+		}
+
+		/* Consume the request's data, which we do not use. */
+		httpd->consume += clen;
+	}
+
 	if (have_header(httpd, "Connection:", "close", ", \t\r\n", NULL)) {
 		httpd->flags |= HTTPD_CLOSE;
 	}