REORG: http: move the HTTP semantics definitions to http.h/http.c

It's a bit painful to have to deal with HTTP semantics for each protocol
version (H1 and H2), and working on the version-agnostic code further
emphasizes the problem.

This patch creates http.h and http.c which are agnostic to the version
in use, and which borrow a few parts from proto_http and from h1. For
example the once thought h1-specific h1_char_classes array is in fact
dictated by RFC7231 and is used to parse HTTP headers. A few changes
were made to a few files which were including proto_http.h while they
only needed http.h.

Certain string definitions pre-dated the introduction of indirect
strings (ist) so some were used to simplify the definition of the known
HTTP methods. The current lookup code saves 2 kB of a heavily used table
and is faster than the previous table based lookup (typ. 14 ns vs 16
before).
diff --git a/include/common/http.h b/include/common/http.h
new file mode 100644
index 0000000..d283e29
--- /dev/null
+++ b/include/common/http.h
@@ -0,0 +1,125 @@
+/*
+ * include/common/http.h
+ *
+ * Version-agnostic and implementation-agnostic HTTP protocol definitions.
+ *
+ * Copyright (C) 2000-2018 Willy Tarreau - w@1wt.eu
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation, version 2.1
+ * exclusively.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifndef _COMMON_HTTP_H
+#define _COMMON_HTTP_H
+
+#include <common/buf.h>
+#include <common/ist.h>
+
+/* these macros are used mainly when parsing header fields */
+#define HTTP_FLG_CTL  0x01
+#define HTTP_FLG_SEP  0x02
+#define HTTP_FLG_LWS  0x04
+#define HTTP_FLG_SPHT 0x08
+#define HTTP_FLG_CRLF 0x10
+#define HTTP_FLG_TOK  0x20
+#define HTTP_FLG_VER  0x40
+#define HTTP_FLG_DIG  0x80
+
+#define HTTP_IS_CTL(x)       (http_char_classes[(uint8_t)(x)] & HTTP_FLG_CTL)
+#define HTTP_IS_SEP(x)       (http_char_classes[(uint8_t)(x)] & HTTP_FLG_SEP)
+#define HTTP_IS_LWS(x)       (http_char_classes[(uint8_t)(x)] & HTTP_FLG_LWS)
+#define HTTP_IS_SPHT(x)      (http_char_classes[(uint8_t)(x)] & HTTP_FLG_SPHT)
+#define HTTP_IS_CRLF(x)      (http_char_classes[(uint8_t)(x)] & HTTP_FLG_CRLF)
+#define HTTP_IS_TOKEN(x)     (http_char_classes[(uint8_t)(x)] & HTTP_FLG_TOK)
+#define HTTP_IS_VER_TOKEN(x) (http_char_classes[(uint8_t)(x)] & HTTP_FLG_VER)
+#define HTTP_IS_DIGIT(x)     (http_char_classes[(uint8_t)(x)] & HTTP_FLG_DIG)
+
+/* Known HTTP methods */
+enum http_meth_t {
+	HTTP_METH_OPTIONS,
+	HTTP_METH_GET,
+	HTTP_METH_HEAD,
+	HTTP_METH_POST,
+	HTTP_METH_PUT,
+	HTTP_METH_DELETE,
+	HTTP_METH_TRACE,
+	HTTP_METH_CONNECT,
+	HTTP_METH_OTHER, /* Must be the last entry */
+} __attribute__((packed));
+
+/* Known HTTP authentication schemes */
+enum ht_auth_m {
+	HTTP_AUTH_WRONG		= -1,		/* missing or unknown */
+	HTTP_AUTH_UNKNOWN	= 0,
+	HTTP_AUTH_BASIC,
+	HTTP_AUTH_DIGEST,
+} __attribute__((packed));
+
+/* All implemented HTTP status codes */
+enum {
+	HTTP_ERR_200 = 0,
+	HTTP_ERR_400,
+	HTTP_ERR_403,
+	HTTP_ERR_405,
+	HTTP_ERR_408,
+	HTTP_ERR_421,
+	HTTP_ERR_425,
+	HTTP_ERR_429,
+	HTTP_ERR_500,
+	HTTP_ERR_502,
+	HTTP_ERR_503,
+	HTTP_ERR_504,
+	HTTP_ERR_SIZE
+};
+
+/* Note: the strings below make use of chunks. Chunks may carry an allocated
+ * size in addition to the length. The size counts from the beginning (str)
+ * to the end. If the size is unknown, it MUST be zero, in which case the
+ * sample will automatically be duplicated when a change larger than <len> has
+ * to be performed. Thus it is safe to always set size to zero.
+ */
+struct http_meth {
+	enum http_meth_t meth;
+	struct buffer str;
+};
+
+struct http_auth_data {
+	enum ht_auth_m method;                /* one of HTTP_AUTH_* */
+	/* 7 bytes unused here */
+	struct buffer method_data;            /* points to the creditial part from 'Authorization:' header */
+	char *user, *pass;                    /* extracted username & password */
+};
+
+struct http_method_desc {
+	enum http_meth_t meth;
+	const struct ist text;
+};
+
+extern const int http_err_codes[HTTP_ERR_SIZE];
+extern struct buffer http_err_chunks[HTTP_ERR_SIZE];
+const struct ist http_known_methods[HTTP_METH_OTHER];
+extern const uint8_t http_char_classes[256];
+extern const char *HTTP_302;
+extern const char *HTTP_303;
+
+enum http_meth_t find_http_meth(const char *str, const int len);
+
+#endif /* _COMMON_HTTP_H */
+
+/*
+ * Local variables:
+ *  c-indent-level: 8
+ *  c-basic-offset: 8
+ * End:
+ */