REORG: http: create http_msg.c to place there some legacy HTTP parts

Lots of HTTP code still uses struct http_msg. Not only this code is
still huge, but it's part of the legacy interface. Let's move most
of these functions to a separate file http_msg.c to make it more
visible which file relies on what. It's mostly symmetrical with
what is present in http_htx.c.

The function http_transform_header_str() which used to rely on two
function pointers to look up a header was simplified to rely on
two variants http_legacy_replace_{,full_}header(), making both
sides of the function much simpler.

No code was changed beyond these moves.
diff --git a/src/proto_http.c b/src/proto_http.c
index 6c7cfcb..a6492b6 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -86,296 +86,6 @@
 	[STAT_STATUS_UNKN] = "UNKN",
 };
 
-/*
- * Adds a header and its CRLF at the tail of the message's buffer, just before
- * the last CRLF. <len> bytes are copied, not counting the CRLF.
- * The header is also automatically added to the index <hdr_idx>, and the end
- * of headers is automatically adjusted. The number of bytes added is returned
- * on success, otherwise <0 is returned indicating an error.
- */
-int http_header_add_tail2(struct http_msg *msg,
-                          struct hdr_idx *hdr_idx, const char *text, int len)
-{
-	int bytes;
-
-	bytes = ci_insert_line2(msg->chn, msg->eoh, text, len);
-	if (!bytes)
-		return -1;
-	http_msg_move_end(msg, bytes);
-	return hdr_idx_add(len, 1, hdr_idx, hdr_idx->tail);
-}
-
-/* Find the first or next occurrence of header <name> in message buffer <sol>
- * using headers index <idx>, and return it in the <ctx> structure. This
- * structure holds everything necessary to use the header and find next
- * occurrence. If its <idx> member is 0, the header is searched from the
- * beginning. Otherwise, the next occurrence is returned. The function returns
- * 1 when it finds a value, and 0 when there is no more. It is very similar to
- * http_find_header2() except that it is designed to work with full-line headers
- * whose comma is not a delimiter but is part of the syntax. As a special case,
- * if ctx->val is NULL when searching for a new values of a header, the current
- * header is rescanned. This allows rescanning after a header deletion.
- */
-int http_find_full_header2(const char *name, int len,
-                           char *sol, struct hdr_idx *idx,
-                           struct hdr_ctx *ctx)
-{
-	char *eol, *sov;
-	int cur_idx, old_idx;
-
-	cur_idx = ctx->idx;
-	if (cur_idx) {
-		/* We have previously returned a header, let's search another one */
-		sol = ctx->line;
-		eol = sol + idx->v[cur_idx].len;
-		goto next_hdr;
-	}
-
-	/* first request for this header */
-	sol += hdr_idx_first_pos(idx);
-	old_idx = 0;
-	cur_idx = hdr_idx_first_idx(idx);
-	while (cur_idx) {
-		eol = sol + idx->v[cur_idx].len;
-
-		if (len == 0) {
-			/* No argument was passed, we want any header.
-			 * To achieve this, we simply build a fake request. */
-			while (sol + len < eol && sol[len] != ':')
-				len++;
-			name = sol;
-		}
-
-		if ((len < eol - sol) &&
-		    (sol[len] == ':') &&
-		    (strncasecmp(sol, name, len) == 0)) {
-			ctx->del = len;
-			sov = sol + len + 1;
-			while (sov < eol && HTTP_IS_LWS(*sov))
-				sov++;
-
-			ctx->line = sol;
-			ctx->prev = old_idx;
-			ctx->idx  = cur_idx;
-			ctx->val  = sov - sol;
-			ctx->tws = 0;
-			while (eol > sov && HTTP_IS_LWS(*(eol - 1))) {
-				eol--;
-				ctx->tws++;
-			}
-			ctx->vlen = eol - sov;
-			return 1;
-		}
-	next_hdr:
-		sol = eol + idx->v[cur_idx].cr + 1;
-		old_idx = cur_idx;
-		cur_idx = idx->v[cur_idx].next;
-	}
-	return 0;
-}
-
-/* Find the first or next header field in message buffer <sol> using headers
- * index <idx>, and return it in the <ctx> structure. This structure holds
- * everything necessary to use the header and find next occurrence. If its
- * <idx> member is 0, the first header is retrieved. Otherwise, the next
- * occurrence is returned. The function returns 1 when it finds a value, and
- * 0 when there is no more. It is equivalent to http_find_full_header2() with
- * no header name.
- */
-int http_find_next_header(char *sol, struct hdr_idx *idx, struct hdr_ctx *ctx)
-{
-	char *eol, *sov;
-	int cur_idx, old_idx;
-	int len;
-
-	cur_idx = ctx->idx;
-	if (cur_idx) {
-		/* We have previously returned a header, let's search another one */
-		sol = ctx->line;
-		eol = sol + idx->v[cur_idx].len;
-		goto next_hdr;
-	}
-
-	/* first request for this header */
-	sol += hdr_idx_first_pos(idx);
-	old_idx = 0;
-	cur_idx = hdr_idx_first_idx(idx);
-	while (cur_idx) {
-		eol = sol + idx->v[cur_idx].len;
-
-		len = 0;
-		while (1) {
-			if (len >= eol - sol)
-				goto next_hdr;
-			if (sol[len] == ':')
-				break;
-			len++;
-		}
-
-		ctx->del = len;
-		sov = sol + len + 1;
-		while (sov < eol && HTTP_IS_LWS(*sov))
-			sov++;
-
-		ctx->line = sol;
-		ctx->prev = old_idx;
-		ctx->idx  = cur_idx;
-		ctx->val  = sov - sol;
-		ctx->tws = 0;
-
-		while (eol > sov && HTTP_IS_LWS(*(eol - 1))) {
-			eol--;
-			ctx->tws++;
-		}
-		ctx->vlen = eol - sov;
-		return 1;
-
-	next_hdr:
-		sol = eol + idx->v[cur_idx].cr + 1;
-		old_idx = cur_idx;
-		cur_idx = idx->v[cur_idx].next;
-	}
-	return 0;
-}
-
-/* Find the first or next occurrence of header <name> in message buffer <sol>
- * using headers index <idx>, and return it in the <ctx> structure. This
- * structure holds everything necessary to use the header and find next
- * occurrence. If its <idx> member is 0, the header is searched from the
- * beginning. Otherwise, the next occurrence is returned. The function returns
- * 1 when it finds a value, and 0 when there is no more. It is designed to work
- * with headers defined as comma-separated lists. As a special case, if ctx->val
- * is NULL when searching for a new values of a header, the current header is
- * rescanned. This allows rescanning after a header deletion.
- */
-int http_find_header2(const char *name, int len,
-		      char *sol, struct hdr_idx *idx,
-		      struct hdr_ctx *ctx)
-{
-	char *eol, *sov;
-	int cur_idx, old_idx;
-
-	cur_idx = ctx->idx;
-	if (cur_idx) {
-		/* We have previously returned a value, let's search
-		 * another one on the same line.
-		 */
-		sol = ctx->line;
-		ctx->del = ctx->val + ctx->vlen + ctx->tws;
-		sov = sol + ctx->del;
-		eol = sol + idx->v[cur_idx].len;
-
-		if (sov >= eol)
-			/* no more values in this header */
-			goto next_hdr;
-
-		/* values remaining for this header, skip the comma but save it
-		 * for later use (eg: for header deletion).
-		 */
-		sov++;
-		while (sov < eol && HTTP_IS_LWS((*sov)))
-			sov++;
-
-		goto return_hdr;
-	}
-
-	/* first request for this header */
-	sol += hdr_idx_first_pos(idx);
-	old_idx = 0;
-	cur_idx = hdr_idx_first_idx(idx);
-	while (cur_idx) {
-		eol = sol + idx->v[cur_idx].len;
-
-		if (len == 0) {
-			/* No argument was passed, we want any header.
-			 * To achieve this, we simply build a fake request. */
-			while (sol + len < eol && sol[len] != ':')
-				len++;
-			name = sol;
-		}
-
-		if ((len < eol - sol) &&
-		    (sol[len] == ':') &&
-		    (strncasecmp(sol, name, len) == 0)) {
-			ctx->del = len;
-			sov = sol + len + 1;
-			while (sov < eol && HTTP_IS_LWS(*sov))
-				sov++;
-
-			ctx->line = sol;
-			ctx->prev = old_idx;
-		return_hdr:
-			ctx->idx  = cur_idx;
-			ctx->val  = sov - sol;
-
-			eol = http_find_hdr_value_end(sov, eol);
-			ctx->tws = 0;
-			while (eol > sov && HTTP_IS_LWS(*(eol - 1))) {
-				eol--;
-				ctx->tws++;
-			}
-			ctx->vlen = eol - sov;
-			return 1;
-		}
-	next_hdr:
-		sol = eol + idx->v[cur_idx].cr + 1;
-		old_idx = cur_idx;
-		cur_idx = idx->v[cur_idx].next;
-	}
-	return 0;
-}
-
-/* Remove one value of a header. This only works on a <ctx> returned by one of
- * the http_find_header functions. The value is removed, as well as surrounding
- * commas if any. If the removed value was alone, the whole header is removed.
- * The ctx is always updated accordingly, as well as the buffer and HTTP
- * message <msg>. The new index is returned. If it is zero, it means there is
- * no more header, so any processing may stop. The ctx is always left in a form
- * that can be handled by http_find_header2() to find next occurrence.
- */
-int http_remove_header2(struct http_msg *msg, struct hdr_idx *idx, struct hdr_ctx *ctx)
-{
-	int cur_idx = ctx->idx;
-	char *sol = ctx->line;
-	struct hdr_idx_elem *hdr;
-	int delta, skip_comma;
-
-	if (!cur_idx)
-		return 0;
-
-	hdr = &idx->v[cur_idx];
-	if (sol[ctx->del] == ':' && ctx->val + ctx->vlen + ctx->tws == hdr->len) {
-		/* This was the only value of the header, we must now remove it entirely. */
-		delta = b_rep_blk(&msg->chn->buf, sol, sol + hdr->len + hdr->cr + 1, NULL, 0);
-		http_msg_move_end(msg, delta);
-		idx->used--;
-		hdr->len = 0;   /* unused entry */
-		idx->v[ctx->prev].next = idx->v[ctx->idx].next;
-		if (idx->tail == ctx->idx)
-			idx->tail = ctx->prev;
-		ctx->idx = ctx->prev;    /* walk back to the end of previous header */
-		ctx->line -= idx->v[ctx->idx].len + idx->v[ctx->idx].cr + 1;
-		ctx->val = idx->v[ctx->idx].len; /* point to end of previous header */
-		ctx->tws = ctx->vlen = 0;
-		return ctx->idx;
-	}
-
-	/* This was not the only value of this header. We have to remove between
-	 * ctx->del+1 and ctx->val+ctx->vlen+ctx->tws+1 included. If it is the
-	 * last entry of the list, we remove the last separator.
-	 */
-
-	skip_comma = (ctx->val + ctx->vlen + ctx->tws == hdr->len) ? 0 : 1;
-	delta = b_rep_blk(&msg->chn->buf, sol + ctx->del + skip_comma,
-				sol + ctx->val + ctx->vlen + ctx->tws + skip_comma,
-				NULL, 0);
-	hdr->len += delta;
-	http_msg_move_end(msg, delta);
-	ctx->val = ctx->del;
-	ctx->tws = ctx->vlen = 0;
-	return ctx->idx;
-}
-
 /* This function handles a server error at the stream interface level. The
  * stream interface is assumed to be already in a closed state. An optional
  * message is copied into the input buffer.
@@ -1639,50 +1349,18 @@
                               const char *str, struct my_regex *re,
                               int action)
 {
-	struct hdr_ctx ctx;
-	char *buf = ci_head(msg->chn);
 	struct hdr_idx *idx = &s->txn->hdr_idx;
-	int (*http_find_hdr_func)(const char *name, int len, char *sol,
-	                          struct hdr_idx *idx, struct hdr_ctx *ctx);
 	struct buffer *output = get_trash_chunk();
 
-	ctx.idx = 0;
-
 	/* Choose the header browsing function. */
 	switch (action) {
 	case ACT_HTTP_REPLACE_VAL:
-		http_find_hdr_func = http_find_header2;
-		break;
+		return http_legacy_replace_header(idx, msg, name, name_len, str, re, output);
 	case ACT_HTTP_REPLACE_HDR:
-		http_find_hdr_func = http_find_full_header2;
-		break;
+		return http_legacy_replace_full_header(idx, msg, name, name_len, str, re, output);
 	default: /* impossible */
 		return -1;
 	}
-
-	while (http_find_hdr_func(name, name_len, buf, idx, &ctx)) {
-		struct hdr_idx_elem *hdr = idx->v + ctx.idx;
-		int delta, len;
-		char *val = ctx.line + ctx.val;
-		char* val_end = val + ctx.vlen;
-
-		if (!regex_exec_match2(re, val, val_end-val, MAX_MATCH, pmatch, 0))
-			continue;
-
-		len = exp_replace(output->area, output->size, val, str, pmatch);
-		if (len == -1)
-			return -1;
-
-		delta = b_rep_blk(&msg->chn->buf, val, val_end, output->area, len);
-
-		hdr->len += delta;
-		http_msg_move_end(msg, delta);
-
-		/* Adjust the length of the current value of the index. */
-		ctx.vlen += delta;
-	}
-
-	return 0;
 }
 
 static int http_transform_header(struct stream* s, struct http_msg *msg,
@@ -6164,7 +5842,7 @@
  *   - there are non-space chars before <from> ;
  *   - there is a CR/LF at or after <next>.
  */
-int del_hdr_value(struct buffer *buf, char **from, char *next)
+static int del_hdr_value(struct buffer *buf, char **from, char *next)
 {
 	char *prev = *from;
 
@@ -7435,139 +7113,6 @@
 	                    &ctx, http_show_error_snapshot);
 }
 
-/* Return in <vptr> and <vlen> the pointer and length of occurrence <occ> of
- * header whose name is <hname> of length <hlen>. If <ctx> is null, lookup is
- * performed over the whole headers. Otherwise it must contain a valid header
- * context, initialised with ctx->idx=0 for the first lookup in a series. If
- * <occ> is positive or null, occurrence #occ from the beginning (or last ctx)
- * is returned. Occ #0 and #1 are equivalent. If <occ> is negative (and no less
- * than -MAX_HDR_HISTORY), the occurrence is counted from the last one which is
- * -1. The value fetch stops at commas, so this function is suited for use with
- * list headers.
- * The return value is 0 if nothing was found, or non-zero otherwise.
- */
-unsigned int http_get_hdr(const struct http_msg *msg, const char *hname, int hlen,
-			  struct hdr_idx *idx, int occ,
-			  struct hdr_ctx *ctx, char **vptr, size_t *vlen)
-{
-	struct hdr_ctx local_ctx;
-	char *ptr_hist[MAX_HDR_HISTORY];
-	unsigned int len_hist[MAX_HDR_HISTORY];
-	unsigned int hist_ptr;
-	int found;
-
-	if (!ctx) {
-		local_ctx.idx = 0;
-		ctx = &local_ctx;
-	}
-
-	if (occ >= 0) {
-		/* search from the beginning */
-		while (http_find_header2(hname, hlen, ci_head(msg->chn), idx, ctx)) {
-			occ--;
-			if (occ <= 0) {
-				*vptr = ctx->line + ctx->val;
-				*vlen = ctx->vlen;
-				return 1;
-			}
-		}
-		return 0;
-	}
-
-	/* negative occurrence, we scan all the list then walk back */
-	if (-occ > MAX_HDR_HISTORY)
-		return 0;
-
-	found = hist_ptr = 0;
-	while (http_find_header2(hname, hlen, ci_head(msg->chn), idx, ctx)) {
-		ptr_hist[hist_ptr] = ctx->line + ctx->val;
-		len_hist[hist_ptr] = ctx->vlen;
-		if (++hist_ptr >= MAX_HDR_HISTORY)
-			hist_ptr = 0;
-		found++;
-	}
-	if (-occ > found)
-		return 0;
-	/* OK now we have the last occurrence in [hist_ptr-1], and we need to
-	 * find occurrence -occ. 0 <= hist_ptr < MAX_HDR_HISTORY, and we have
-	 * -10 <= occ <= -1. So we have to check [hist_ptr%MAX_HDR_HISTORY+occ]
-	 * to remain in the 0..9 range.
-	 */
-	hist_ptr += occ + MAX_HDR_HISTORY;
-	if (hist_ptr >= MAX_HDR_HISTORY)
-		hist_ptr -= MAX_HDR_HISTORY;
-	*vptr = ptr_hist[hist_ptr];
-	*vlen = len_hist[hist_ptr];
-	return 1;
-}
-
-/* Return in <vptr> and <vlen> the pointer and length of occurrence <occ> of
- * header whose name is <hname> of length <hlen>. If <ctx> is null, lookup is
- * performed over the whole headers. Otherwise it must contain a valid header
- * context, initialised with ctx->idx=0 for the first lookup in a series. If
- * <occ> is positive or null, occurrence #occ from the beginning (or last ctx)
- * is returned. Occ #0 and #1 are equivalent. If <occ> is negative (and no less
- * than -MAX_HDR_HISTORY), the occurrence is counted from the last one which is
- * -1. This function differs from http_get_hdr() in that it only returns full
- * line header values and does not stop at commas.
- * The return value is 0 if nothing was found, or non-zero otherwise.
- */
-unsigned int http_get_fhdr(const struct http_msg *msg, const char *hname, int hlen,
-			   struct hdr_idx *idx, int occ,
-			   struct hdr_ctx *ctx, char **vptr, size_t *vlen)
-{
-	struct hdr_ctx local_ctx;
-	char *ptr_hist[MAX_HDR_HISTORY];
-	unsigned int len_hist[MAX_HDR_HISTORY];
-	unsigned int hist_ptr;
-	int found;
-
-	if (!ctx) {
-		local_ctx.idx = 0;
-		ctx = &local_ctx;
-	}
-
-	if (occ >= 0) {
-		/* search from the beginning */
-		while (http_find_full_header2(hname, hlen, ci_head(msg->chn), idx, ctx)) {
-			occ--;
-			if (occ <= 0) {
-				*vptr = ctx->line + ctx->val;
-				*vlen = ctx->vlen;
-				return 1;
-			}
-		}
-		return 0;
-	}
-
-	/* negative occurrence, we scan all the list then walk back */
-	if (-occ > MAX_HDR_HISTORY)
-		return 0;
-
-	found = hist_ptr = 0;
-	while (http_find_full_header2(hname, hlen, ci_head(msg->chn), idx, ctx)) {
-		ptr_hist[hist_ptr] = ctx->line + ctx->val;
-		len_hist[hist_ptr] = ctx->vlen;
-		if (++hist_ptr >= MAX_HDR_HISTORY)
-			hist_ptr = 0;
-		found++;
-	}
-	if (-occ > found)
-		return 0;
-
-	/* OK now we have the last occurrence in [hist_ptr-1], and we need to
-	 * find occurrence -occ. 0 <= hist_ptr < MAX_HDR_HISTORY, and we have
-	 * -10 <= occ <= -1. So we have to check [hist_ptr%MAX_HDR_HISTORY+occ]
-	 * to remain in the 0..9 range.
-	 */
-	hist_ptr += occ + MAX_HDR_HISTORY;
-	if (hist_ptr >= MAX_HDR_HISTORY)
-		hist_ptr -= MAX_HDR_HISTORY;
-	*vptr = ptr_hist[hist_ptr];
-	*vlen = len_hist[hist_ptr];
-	return 1;
-}
-
 /*
  * Print a debug line with a header. Always stop at the first CR or LF char,
  * so it is safe to pass it a full buffer if needed. If <err> is not NULL, an