From 727eea070834dfd93d1aeec9d4d8cab0ab9e9d87 Mon Sep 17 00:00:00 2001
From: Yann Ylavic <ylavic@apache.org>
Date: Tue, 10 Jan 2017 08:15:38 +0000
Subject: Merge r1777460, r1777672 from trunk:

http: allow folding in check_headers(), still compliant with RFC 7230 (3.2.4).


http: follow up to r1777460.
We MUST unfold outgoing HTTP headers in any case, "message/http" is for
inner content.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x-merge-http-strict@1778095 13f79535-47bb-0310-9956-ffa450edef68
---
 modules/http/http_filters.c | 69 +++++++++++++++++++++++++++++++++++----------
 1 file changed, 54 insertions(+), 15 deletions(-)

diff --git a/modules/http/http_filters.c b/modules/http/http_filters.c
index 11b02f2f8b..388f899361 100644
--- a/modules/http/http_filters.c
+++ b/modules/http/http_filters.c
@@ -690,10 +690,11 @@ struct check_header_ctx {
 };
 
 /* check a single header, to be used with apr_table_do() */
-static int check_header(void *arg, const char *name, const char *val)
+static int check_header(struct check_header_ctx *ctx,
+                        const char *name, const char **val)
 {
-    struct check_header_ctx *ctx = arg;
-    const char *test;
+    const char *pos, *end;
+    char *dst = NULL;
 
     if (name[0] == '\0') {
         ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, ctx->r, APLOGNO(02428)
@@ -702,12 +703,12 @@ static int check_header(void *arg, const char *name, const char *val)
     }
 
     if (ctx->strict) { 
-        test = ap_scan_http_token(name);
+        end = ap_scan_http_token(name);
     }
     else {
-        test = ap_scan_vchar_obstext(name);
+        end = ap_scan_vchar_obstext(name);
     }
-    if (*test) {
+    if (*end) {
         ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, ctx->r, APLOGNO(02429)
                       "Response header name '%s' contains invalid "
                       "characters, aborting request",
@@ -715,13 +716,51 @@ static int check_header(void *arg, const char *name, const char *val)
         return 0;
     }
 
-    test = ap_scan_http_field_content(val);
-    if (*test) {
-        ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, ctx->r, APLOGNO(02430)
-                      "Response header '%s' value of '%s' contains invalid "
-                      "characters, aborting request",
-                      name, val);
-        return 0;
+    for (pos = *val; *pos; pos = end) {
+        end = ap_scan_http_field_content(pos);
+        if (*end) {
+            if (end[0] != CR || end[1] != LF || (end[2] != ' ' &&
+                                                 end[2] != '\t')) {
+                ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, ctx->r, APLOGNO(02430)
+                              "Response header '%s' value of '%s' contains "
+                              "invalid characters, aborting request",
+                              name, pos);
+                return 0;
+            }
+            if (!dst) {
+                *val = dst = apr_palloc(ctx->r->pool, strlen(*val) + 1);
+            }
+        }
+        if (dst) {
+            memcpy(dst, pos, end - pos);
+            dst += end - pos;
+            if (*end) {
+                /* skip folding and replace with a single space */
+                end += 3 + strspn(end + 3, "\t ");
+                *dst++ = ' ';
+            }
+        }
+    }
+    if (dst) {
+        *dst = '\0';
+    }
+    return 1;
+}
+
+static int check_headers_table(apr_table_t *t, struct check_header_ctx *ctx)
+{
+    const apr_array_header_t *headers = apr_table_elts(t);
+    apr_table_entry_t *header;
+    int i;
+
+    for (i = 0; i < headers->nelts; ++i) {
+        header = &APR_ARRAY_IDX(headers, i, apr_table_entry_t);
+        if (!header->key) {
+            continue;
+        }
+        if (!check_header(ctx, header->key, (const char **)&header->val)) {
+            return 0;
+        }
     }
     return 1;
 }
@@ -738,8 +777,8 @@ static APR_INLINE int check_headers(request_rec *r)
 
     ctx.r = r;
     ctx.strict = (conf->http_conformance != AP_HTTP_CONFORMANCE_UNSAFE);
-    return apr_table_do(check_header, &ctx, r->headers_out, NULL) &&
-           apr_table_do(check_header, &ctx, r->err_headers_out, NULL);
+    return check_headers_table(r->headers_out, &ctx) &&
+           check_headers_table(r->err_headers_out, &ctx);
 }
 
 static int check_headers_recursion(request_rec *r)
-- 
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