[PATCH net-next 12/12] tools: ynl: allow fixed-header to be specified per op

[Jakub Kicinski <kuba@kernel.org>]

rtnetlink has variety of ops with different fixed headers.
Detect that op fixed header is not the same as family one,
and use sizeof() directly. For reverse parsing we need to
pass the fixed header len along the policy (in the socket
state).

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
---
 tools/net/ynl/lib/ynl.h          |  1 +
 tools/net/ynl/lib/ynl.c          |  8 ++++----
 tools/net/ynl/pyynl/ynl_gen_c.py | 17 ++++++++++++++++-
 3 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/tools/net/ynl/lib/ynl.h b/tools/net/ynl/lib/ynl.h
index 0b4acc0d288a..5a27b8648120 100644
--- a/tools/net/ynl/lib/ynl.h
+++ b/tools/net/ynl/lib/ynl.h
@@ -80,6 +80,7 @@ struct ynl_sock {
 
 	struct nlmsghdr *nlh;
 	const struct ynl_policy_nest *req_policy;
+	size_t req_hdr_len;
 	unsigned char *tx_buf;
 	unsigned char *rx_buf;
 	unsigned char raw_buf[];
diff --git a/tools/net/ynl/lib/ynl.c b/tools/net/ynl/lib/ynl.c
index c16f01372ca3..d263f6f40ad5 100644
--- a/tools/net/ynl/lib/ynl.c
+++ b/tools/net/ynl/lib/ynl.c
@@ -191,12 +191,12 @@ ynl_ext_ack_check(struct ynl_sock *ys, const struct nlmsghdr *nlh,
 		n = snprintf(bad_attr, sizeof(bad_attr), "%sbad attribute: ",
 			     str ? " (" : "");
 
-		start = ynl_nlmsg_data_offset(ys->nlh, ys->family->hdr_len);
+		start = ynl_nlmsg_data_offset(ys->nlh, ys->req_hdr_len);
 		end = ynl_nlmsg_end_addr(ys->nlh);
 
 		off = ys->err.attr_offs;
 		off -= sizeof(struct nlmsghdr);
-		off -= ys->family->hdr_len;
+		off -= ys->req_hdr_len;
 
 		n += ynl_err_walk(ys, start, end, off, ys->req_policy,
 				  &bad_attr[n], sizeof(bad_attr) - n, NULL);
@@ -216,14 +216,14 @@ ynl_ext_ack_check(struct ynl_sock *ys, const struct nlmsghdr *nlh,
 		n = snprintf(miss_attr, sizeof(miss_attr), "%smissing attribute: ",
 			     bad_attr[0] ? ", " : (str ? " (" : ""));
 
-		start = ynl_nlmsg_data_offset(ys->nlh, ys->family->hdr_len);
+		start = ynl_nlmsg_data_offset(ys->nlh, ys->req_hdr_len);
 		end = ynl_nlmsg_end_addr(ys->nlh);
 
 		nest_pol = ys->req_policy;
 		if (tb[NLMSGERR_ATTR_MISS_NEST]) {
 			off = ynl_attr_get_u32(tb[NLMSGERR_ATTR_MISS_NEST]);
 			off -= sizeof(struct nlmsghdr);
-			off -= ys->family->hdr_len;
+			off -= ys->req_hdr_len;
 
 			n += ynl_err_walk(ys, start, end, off, ys->req_policy,
 					  &miss_attr[n], sizeof(miss_attr) - n,
diff --git a/tools/net/ynl/pyynl/ynl_gen_c.py b/tools/net/ynl/pyynl/ynl_gen_c.py
index fbcd3da72b3d..be7aaa3eef41 100755
--- a/tools/net/ynl/pyynl/ynl_gen_c.py
+++ b/tools/net/ynl/pyynl/ynl_gen_c.py
@@ -1313,8 +1313,15 @@ from lib import SpecFamily, SpecAttrSet, SpecAttr, SpecOperation, SpecEnumSet, S
         self.op = op
 
         self.fixed_hdr = None
+        self.fixed_hdr_len = 'ys->family->hdr_len'
         if op and op.fixed_header:
             self.fixed_hdr = 'struct ' + c_lower(op.fixed_header)
+            if op.fixed_header != family.fixed_header:
+                if family.is_classic():
+                    self.fixed_hdr_len = f"sizeof({self.fixed_hdr})"
+                else:
+                    raise Exception(f"Per-op fixed header not supported, yet")
+
 
         # 'do' and 'dump' response parsing is identical
         self.type_consistent = True
@@ -1801,6 +1808,11 @@ _C_KW = {
         if ri.fixed_hdr:
             local_vars += ['void *hdr;']
         iter_line = "ynl_attr_for_each(attr, nlh, yarg->ys->family->hdr_len)"
+        if ri.op.fixed_header != ri.family.fixed_header:
+            if ri.family.is_classic():
+                iter_line = f"ynl_attr_for_each(attr, nlh, sizeof({ri.fixed_hdr}))"
+            else:
+                raise Exception(f"Per-op fixed header not supported, yet")
 
     array_nests = set()
     multi_attrs = set()
@@ -2018,6 +2030,7 @@ _C_KW = {
         ri.cw.p(f"nlh = ynl_gemsg_start_req(ys, {ri.nl.get_family_id()}, {ri.op.enum_name}, 1);")
 
     ri.cw.p(f"ys->req_policy = &{ri.struct['request'].render_name}_nest;")
+    ri.cw.p(f"ys->req_hdr_len = {ri.fixed_hdr_len};")
     if 'reply' in ri.op[ri.op_mode]:
         ri.cw.p(f"yrs.yarg.rsp_policy = &{ri.struct['reply'].render_name}_nest;")
     ri.cw.nl()
@@ -2097,6 +2110,7 @@ _C_KW = {
 
     if "request" in ri.op[ri.op_mode]:
         ri.cw.p(f"ys->req_policy = &{ri.struct['request'].render_name}_nest;")
+        ri.cw.p(f"ys->req_hdr_len = {ri.fixed_hdr_len};")
         ri.cw.nl()
         for _, attr in ri.struct["request"].member_list():
             attr.attr_put(ri, "req")
@@ -2916,7 +2930,8 @@ _C_KW = {
         cw.p(f'.is_classic\t= true,')
         cw.p(f'.classic_id\t= {family.get("protonum")},')
     if family.is_classic():
-        cw.p(f'.hdr_len\t= sizeof(struct {c_lower(family.fixed_header)}),')
+        if family.fixed_header:
+            cw.p(f'.hdr_len\t= sizeof(struct {c_lower(family.fixed_header)}),')
     elif family.fixed_header:
         cw.p(f'.hdr_len\t= sizeof(struct genlmsghdr) + sizeof(struct {c_lower(family.fixed_header)}),')
     else:
-- 
2.49.0