From ea4b5f90662c63d6ceccc7c9c851dd183e65d0e6 Mon Sep 17 00:00:00 2001
From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Sun, 7 Nov 2010 20:38:35 +0100
Subject: nlmsg: rework mnl_nlmsg_fprintf
This patch reworks mnl_nlmsg_fprintf. It breaks backward compatibility
of this function, there was no way to improve it without doing so
(and we are still in time to break thing, BTW).
Signed-off-bu: Pablo Neira Ayuso <pablo@netfilter.org>
---
src/nlmsg.c | 156 ++++++++++++++++++++++++++++++++++++++++++++++++++----------
1 file changed, 132 insertions(+), 24 deletions(-)
(limited to 'src')
diff --git a/src/nlmsg.c b/src/nlmsg.c
index f89a9ec..a3dc0c1 100644
--- a/src/nlmsg.c
+++ b/src/nlmsg.c
@@ -233,37 +233,145 @@ bool mnl_nlmsg_portid_ok(const struct nlmsghdr *nlh, unsigned int portid)
return nlh->nlmsg_pid && portid ? nlh->nlmsg_pid == portid : true;
}
-/**
- * mnl_nlmsg_fprintf - print netlink message to file
- * \param nlh pointer to netlink message that we want to print
- *
- * This function prints the netlink header to a file handle.
- * It may be useful for debugging purposes.
- */
-void mnl_nlmsg_fprintf(FILE *fd, const struct nlmsghdr *nlh)
+static void mnl_nlmsg_fprintf_header(FILE *fd, const struct nlmsghdr *nlh)
{
- size_t i;
+ fprintf(fd, "----------------\t------------------\n");
+ fprintf(fd, "| %.010u |\t| message length |\n", nlh->nlmsg_len);
+ fprintf(fd, "| %.05u | %c%c%c%c |\t| type | flags |\n",
+ nlh->nlmsg_type,
+ nlh->nlmsg_flags & NLM_F_REQUEST ? 'R' : '-',
+ nlh->nlmsg_flags & NLM_F_MULTI ? 'M' : '-',
+ nlh->nlmsg_flags & NLM_F_ACK ? 'A' : '-',
+ nlh->nlmsg_flags & NLM_F_ECHO ? 'E' : '-');
+ fprintf(fd, "| %.010u |\t| sequence number|\n", nlh->nlmsg_seq);
+ fprintf(fd, "| %.010u |\t| port ID |\n", nlh->nlmsg_pid);
+ fprintf(fd, "----------------\t------------------\n");
+}
- fprintf(fd, "========= netlink header ==========\n");
- fprintf(fd, "length(32 bits)=%.08u\n", nlh->nlmsg_len);
- fprintf(fd, "type(16 bits)=%.04u flags(16 bits)=%.04x\n",
- nlh->nlmsg_type, nlh->nlmsg_flags);
- fprintf(fd, "sequence number(32 bits)=%.08x\n", nlh->nlmsg_seq);
- fprintf(fd, "port ID(32 bits)=%.08u\n", nlh->nlmsg_pid);
- fprintf(fd, "===================================\n");
+static void
+mnl_nlmsg_fprintf_payload(FILE *fd, const struct nlmsghdr *nlh,
+ size_t extra_header_size)
+{
+ int rem = 0;
+ unsigned int i;
for (i=sizeof(struct nlmsghdr); i<nlh->nlmsg_len; i+=4) {
char *b = (char *) nlh;
+ struct nlattr *attr = (struct nlattr *) (b+i);
+
+ /* netlink control message. */
+ if (nlh->nlmsg_type < NLMSG_MIN_TYPE) {
+ fprintf(fd, "| %.2x %.2x %.2x %.2x |\t",
+ 0xff & b[i], 0xff & b[i+1],
+ 0xff & b[i+2], 0xff & b[i+3]);
+ fprintf(fd, "| |\n");
+ /* special handling for the extra header. */
+ } else if (extra_header_size > 0) {
+ extra_header_size -= 4;
+ fprintf(fd, "| %.2x %.2x %.2x %.2x |\t",
+ 0xff & b[i], 0xff & b[i+1],
+ 0xff & b[i+2], 0xff & b[i+3]);
+ fprintf(fd, "| extra header |\n");
+ /* this seems like an attribute header. */
+ } else if (rem == 0 && (attr->nla_type & NLA_TYPE_MASK) != 0) {
+ fprintf(fd, "|%c[%d;%dm"
+ "%.5u"
+ "%c[%dm"
+ "|"
+ "%c[%d;%dm"
+ "%c%c"
+ "%c[%dm"
+ "|"
+ "%c[%d;%dm"
+ "%.5u"
+ "%c[%dm|\t",
+ 27, 1, 31,
+ attr->nla_len,
+ 27, 0,
+ 27, 1, 32,
+ attr->nla_type & NLA_F_NESTED ? 'N' : '-',
+ attr->nla_type &
+ NLA_F_NET_BYTEORDER ? 'B' : '-',
+ 27, 0,
+ 27, 1, 34,
+ attr->nla_type & NLA_TYPE_MASK,
+ 27, 0);
+ fprintf(fd, "|len |flags| type|\n");
+
+ if (!(attr->nla_type & NLA_F_NESTED)) {
+ rem = NLA_ALIGN(attr->nla_len) -
+ sizeof(struct nlattr);
+ }
+ /* this is the attribute payload. */
+ } else if (rem > 0) {
+ rem -= 4;
+ fprintf(fd, "| %.2x %.2x %.2x %.2x |\t",
+ 0xff & b[i], 0xff & b[i+1],
+ 0xff & b[i+2], 0xff & b[i+3]);
+ fprintf(fd, "| data |");
+ fprintf(fd, "\t %c %c %c %c\n",
+ isalnum(b[i]) ? b[i] : 0,
+ isalnum(b[i+1]) ? b[i+1] : 0,
+ isalnum(b[i+2]) ? b[i+2] : 0,
+ isalnum(b[i+3]) ? b[i+3] : 0);
+ }
+ }
+ fprintf(fd, "----------------\t------------------\n");
+}
- fprintf(fd, "(%03zu) %.2x %.2x %.2x %.2x | ", i,
- 0xff & b[i], 0xff & b[i+1],
- 0xff & b[i+2], 0xff & b[i+3]);
+/**
+ * mnl_nlmsg_fprintf - print netlink message to file
+ * \param fd pointer to file type
+ * \param data pointer to the buffer that contains messages to be printed
+ * \param datalen length of data stored in the buffer
+ * \param extra_header_size size of the extra header (if any)
+ *
+ * This function prints the netlink header to a file handle.
+ * It may be useful for debugging purposes. One example of the output
+ * is the following:
+ *
+ *\verbatim
+---------------- ------------------
+| 0000000040 | | message length |
+| 00016 | R-A- | | type | flags |
+| 1289148991 | | sequence number|
+| 0000000000 | | port ID |
+---------------- ------------------
+| 00 00 00 00 | | extra header |
+| 00 00 00 00 | | extra header |
+| 01 00 00 00 | | extra header |
+| 01 00 00 00 | | extra header |
+|00008|--|00003| |len |flags| type|
+| 65 74 68 30 | | data | e t h 0
+---------------- ------------------
+\endverbatim
+ *
+ * This example above shows the netlink message that is send to kernel-space
+ * to set up the link interface eth0. The netlink and attribute header data
+ * are displayed in base 10 whereas the extra header and the attribute payload
+ * are expressed in base 16. The possible flags in the netlink header are:
+ *
+ * - R, that indicates that NLM_F_REQUEST is set.
+ * - M, that indicates that NLM_F_MULTI is set.
+ * - A, that indicates that NLM_F_ACK is set.
+ * - E, that indicates that NLM_F_ECHO is set.
+ *
+ * The lack of one flag is displayed with '-'. On the other hand, the possible
+ * attribute flags available are:
+ *
+ * - N, that indicates that NLA_F_NESTED is set.
+ * - B, that indicates that NLA_F_NET_BYTEORDER is set.
+ */
+void mnl_nlmsg_fprintf(FILE *fd, const void *data,
+ size_t datalen, size_t extra_header_size)
+{
+ const struct nlmsghdr *nlh = data;
+ int len = datalen;
- fprintf(fd, "%c %c %c %c\n",
- isalnum(b[i]) ? b[i] : 0,
- isalnum(b[i+1]) ? b[i+1] : 0,
- isalnum(b[i+2]) ? b[i+2] : 0,
- isalnum(b[i+3]) ? b[i+3] : 0);
+ while (mnl_nlmsg_ok(nlh, len)) {
+ mnl_nlmsg_fprintf_header(fd, nlh);
+ mnl_nlmsg_fprintf_payload(fd, nlh, extra_header_size);
+ nlh = mnl_nlmsg_next(nlh, &len);
}
}
--
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