HTTP parser: allowed more characters in header field names.

Previously, all requests that contained in header field names characters other
than alphanumeric, or "-", or "_" were rejected with a 400 "Bad Request" error
response.

Now, the parser allows the same set of characters as specified in RFC 7230,
including: "!", "#", "$", "%", "&", "'", "*", "+", ".", "^", "`", "|", and "~".
Header field names that contain only these characters are considered valid.

Also, there's a new option introduced: "discard_unsafe_fields".  It accepts
boolean value and it is set to "true" by default.

When this option is "true", all header field names that contain characters
in valid range, but other than alphanumeric or "-" are skipped during parsing.
When the option is "false", these header fields aren't skipped.

Requests with non-valid characters in header field names according to
RFC 7230 are rejected regardless of "discard_unsafe_fields" setting.

This closes #422 issue on GitHub.

1 files changed, 43 insertions, 24 deletions

diff --git a/src/nxt_http_parse.c b/src/nxt_http_parse.c
index 22004cc1..338b0a90 100644
--- a/src/nxt_http_parse.c
+++ b/src/nxt_http_parse.c
@@ -288,11 +288,13 @@ continue_target:
         case NXT_HTTP_TARGET_SPACE:
             rp->target_end = p;
             goto space_after_target;
-
+#if 0
         case NXT_HTTP_TARGET_QUOTE_MARK:
             rp->quoted_target = 1;
             goto rest_of_target;
-
+#else
+        case NXT_HTTP_TARGET_QUOTE_MARK:
+#endif
         case NXT_HTTP_TARGET_HASH:
             rp->complex_target = 1;
             goto rest_of_target;
@@ -378,7 +380,7 @@ space_after_target:
             }
         }
 
-        rp->space_in_target = 1;
+        //rp->space_in_target = 1;
 
         if (rest) {
             goto rest_of_target;
@@ -397,7 +399,7 @@ space_after_target:
             goto space_after_target;
         }
 
-        rp->space_in_target = 1;
+        //rp->space_in_target = 1;
 
         if (rest) {
             goto rest_of_target;
@@ -432,7 +434,12 @@ space_after_target:
             *pos = p + 10;
         }
 
-        if (rp->complex_target != 0 || rp->quoted_target != 0) {
+        if (rp->complex_target != 0
+#if 0
+            || rp->quoted_target != 0
+#endif
+           )
+        {
             rc = nxt_http_parse_complex_target(rp);
 
             if (nxt_slow_path(rc != NXT_OK)) {
@@ -518,11 +525,13 @@ nxt_http_parse_field_name(nxt_http_request_parse_t *rp, u_char **pos,
 
     static const u_char  normal[256]  nxt_aligned(64) =
         "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
-        "\0\0\0\0\0\0\0\0\0\0\0\0\0-\0\0" "0123456789\0\0\0\0\0\0"
+    /*   \s ! " # $ % & ' ( ) * + ,        . /                 : ; < = > ?   */
+        "\0\1\0\1\1\1\1\1\0\0\1\1\0" "-" "\1\0" "0123456789" "\0\0\0\0\0\0"
 
-        /* These 64 bytes should reside in one cache line. */
-        "\0abcdefghijklmnopqrstuvwxyz\0\0\0\0_"
-        "\0abcdefghijklmnopqrstuvwxyz\0\0\0\0\0"
+    /*    @                                 [ \ ] ^ _                        */
+        "\0" "abcdefghijklmnopqrstuvwxyz" "\0\0\0\1\1"
+    /*    `                                 { | } ~                          */
+        "\1" "abcdefghijklmnopqrstuvwxyz" "\0\1\0\1\0"
 
         "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
         "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"
@@ -538,9 +547,14 @@ nxt_http_parse_field_name(nxt_http_request_parse_t *rp, u_char **pos,
                                                                               \
         c = normal[ch];                                                       \
                                                                               \
-        if (nxt_slow_path(c == '\0')) {                                       \
-            p = &(ch);                                                        \
-            goto name_end;                                                    \
+        if (nxt_slow_path(c <= '\1')) {                                       \
+            if (c == '\0') {                                                  \
+                p = &(ch);                                                    \
+                goto name_end;                                                \
+            }                                                                 \
+                                                                              \
+            rp->skip_field = rp->discard_unsafe_fields;                       \
+            c = ch;                                                           \
         }                                                                     \
                                                                               \
         hash = nxt_http_field_hash_char(hash, c);
@@ -777,20 +791,25 @@ nxt_http_parse_field_end(nxt_http_request_parse_t *rp, u_char **pos,
         *pos = p + 1;
 
         if (rp->field_name.length != 0) {
-            field = nxt_list_add(rp->fields);
+            if (rp->skip_field) {
+                rp->skip_field = 0;
 
-            if (nxt_slow_path(field == NULL)) {
-                return NXT_ERROR;
-            }
+            } else {
+                field = nxt_list_add(rp->fields);
 
-            field->hash = nxt_http_field_hash_end(rp->field_hash);
-            field->skip = 0;
-            field->hopbyhop = 0;
+                if (nxt_slow_path(field == NULL)) {
+                    return NXT_ERROR;
+                }
 
-            field->name_length = rp->field_name.length;
-            field->value_length = rp->field_value.length;
-            field->name = rp->field_name.start;
-            field->value = rp->field_value.start;
+                field->hash = nxt_http_field_hash_end(rp->field_hash);
+                field->skip = 0;
+                field->hopbyhop = 0;
+
+                field->name_length = rp->field_name.length;
+                field->value_length = rp->field_value.length;
+                field->name = rp->field_name.start;
+                field->value = rp->field_value.start;
+            }
 
             rp->field_hash = NXT_HTTP_FIELD_HASH_INIT;
 
@@ -1023,7 +1042,7 @@ nxt_http_parse_complex_target(nxt_http_request_parse_t *rp)
             break;
 
         case sw_quoted:
-            rp->quoted_target = 1;
+            //rp->quoted_target = 1;
 
             if (ch >= '0' && ch <= '9') {
                 high = (u_char) (ch - '0');