rename msg.c to nlmsg.c

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 230 insertions, 0 deletions

diff --git a/src/nlmsg.c b/src/nlmsg.c
new file mode 100644
index 0000000..ad387e7
--- /dev/null
+++ b/src/nlmsg.c
@@ -0,0 +1,230 @@
+/*
+ * (C) 2008-2010 by Pablo Neira Ayuso <pablo@netfilter.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <stdio.h>
+#include <ctype.h>
+#include <errno.h>
+#include <string.h>
+#include <libmnl/libmnl.h>
+
+/**
+ * mnl_nlmsg_size - get size of the netlink messages (without alignment)
+ * @len: length of the netlink message
+ *
+ * This function returns the size of a netlink message (header plus payload)
+ * without alignment.
+ */
+size_t mnl_nlmsg_size(int len)
+{
+	return len + MNL_ALIGN(MNL_NLMSG_HDRLEN);
+}
+
+/**
+ * mnl_nlmsg_aligned_size - get size of the netlink messages (with alignment)
+ * @len: length of the netlink message
+ *
+ * This function returns the size of a netlink message (header plus payload)
+ * with alignment.
+ */
+size_t mnl_nlmsg_aligned_size(int len)
+{
+	return MNL_ALIGN(mnl_nlmsg_size(len));
+}
+
+/**
+ * mnl_nlmsg_payload_size - get the size of the payload
+ * @nlh: pointer to the header of the netlink message
+ *
+ * This function returns the size of the netlink payload
+ */
+size_t mnl_nlmsg_payload_size(const struct nlmsghdr *nlh)
+{
+	return nlh->nlmsg_len - MNL_NLMSG_HDRLEN;
+}
+
+/**
+ * mnl_nlmsg_put_header - prepare room for Netlink header
+ * @buf: memory already allocated to store the Netlink message
+ *
+ * This function sets to zero the room that is required to put a Netlink
+ * header in the memory buffer passed as parameter. This function also
+ * initializes the nlmsg_len field. This function returns a pointer to the
+ * Netlink header structure.
+ */
+struct nlmsghdr *mnl_nlmsg_put_header(void *buf)
+{
+	int len = MNL_ALIGN(sizeof(struct nlmsghdr));
+	struct nlmsghdr *nlh = buf;
+
+	memset(buf, 0, len);
+	nlh->nlmsg_len = len;
+	return nlh;
+}
+
+/**
+ * mnl_nlmsg_put_extra_header - prepare room for an extra header
+ * @nlh: pointer to Netlink header
+ * @size: size of the extra header that we want to put
+ *
+ * This function sets to zero the room that is required to put the extra
+ * header after the initial Netlink header. This function also increases
+ * the nlmsg_len field. This function returns a pointer to the extra
+ * header.
+ */
+void *mnl_nlmsg_put_extra_header(struct nlmsghdr *nlh, int size)
+{
+	char *ptr = (char *)nlh + nlh->nlmsg_len;
+	nlh->nlmsg_len += MNL_ALIGN(size);
+	memset(ptr, 0, size);
+	return ptr;
+}
+
+/**
+ * mnl_nlmsg_get_len - get the length field from the netlink message
+ * @nlh: pointer to a netlink header
+ *
+ * This function returns the length of the netlink message by return the field
+ * nlmsg_len of the message.
+ */
+uint16_t mnl_nlmsg_get_len(const struct nlmsghdr *nlh)
+{
+	return nlh->nlmsg_len;
+}
+
+/**
+ * mnl_nlmsg_get_data - get a pointer to the payload of the netlink message
+ * @nlh: pointer to a netlink header
+ *
+ * This function returns a pointer to the payload of the netlink message.
+ */
+void *mnl_nlmsg_get_data(const struct nlmsghdr *nlh)
+{
+	return (void *)nlh + MNL_NLMSG_HDRLEN;
+}
+
+/**
+ * mnl_nlmsg_get_data_offset - get a pointer to the payload of the message
+ * @nlh: pointer to a netlink header
+ * @offset: offset to the payload of the attributes TLV set
+ *
+ * This function returns a pointer to the payload of the netlink message plus
+ * a given offset.
+ */
+void *mnl_nlmsg_get_data_offset(const struct nlmsghdr *nlh, int offset)
+{
+	return (void *)nlh + MNL_NLMSG_HDRLEN + MNL_ALIGN(offset);
+}
+
+/**
+ * mnl_nlmsg_ok - check a there is room for netlink message
+ * @nlh: netlink message that we want to check
+ * @len: remaining bytes in a buffer that contains the netlink message
+ *
+ * This function is used to check that a buffer that contains a netlink
+ * message has enough room for the netlink message that it stores, ie. this
+ * function can be used to verify that a netlink message is not malformed nor
+ * truncated.
+ *
+ * This function does not set errno in case of error since it is intended
+ * for iterations. Thus, it returns 1 on success and 0 on error.
+ *
+ * The @len parameter may become negative in malformed messages during message
+ * iteration, that is why we use a signed integer.
+ */
+int mnl_nlmsg_ok(const struct nlmsghdr *nlh, int len)
+{
+	return len >= (int)sizeof(struct nlmsghdr) &&
+	       nlh->nlmsg_len >= sizeof(struct nlmsghdr) &&
+	       (int)nlh->nlmsg_len <= len;
+}
+
+/**
+ * mnl_nlmsg_next - get the next netlink message in a multipart message
+ * @nlh: current netlink message that we are handling
+ * @len: pointer to the current remaining bytes in the buffer
+ *
+ * This function returns a pointer to the next netlink message that is part
+ * of a multi-part netlink message. Netlink can batches messages into a buffer
+ * so that the receiver has to iterate over the whole set of netlink
+ * messages.
+ */
+struct nlmsghdr *mnl_nlmsg_next(const struct nlmsghdr *nlh, int *len)
+{
+	*len -= MNL_ALIGN(nlh->nlmsg_len);
+	return (struct nlmsghdr *)((void *)nlh + MNL_ALIGN(nlh->nlmsg_len));
+}
+
+/**
+ * mnl_nlmsg_get_tail - get the ending of the netlink message
+ * @nlh: pointer to netlink message
+ *
+ * This function returns a pointer to the netlink message tail. This is useful
+ * to build a message since we continue adding attribute at the end of it.
+ */
+void *mnl_nlmsg_get_tail(const struct nlmsghdr *nlh)
+{
+	return (struct nlmsghdr *)((void *)nlh + MNL_ALIGN(nlh->nlmsg_len));
+}
+
+/**
+ * mnl_nlmsg_seq_ok - perform sequence tracking
+ * @nlh: current netlink message that we are handling
+ * @seq: last sequence number used to send a message
+ *
+ * This functions returns 1 if the sequence tracking is fulfilled, otherwise
+ * 0 is returned. We skip the tracking for netlink messages whose sequence
+ * number is zero since it is usually reserved for event-based kernel
+ * notifications.
+ */
+int mnl_nlmsg_seq_ok(const struct nlmsghdr *nlh, unsigned int seq)
+{
+	return nlh->nlmsg_seq ? nlh->nlmsg_seq == seq : 1;
+}
+
+/**
+ * mnl_nlmsg_portid_ok - perform portID origin check
+ * @nlh: current netlink message that we are handling
+ * @seq: netlink portid that we want to check
+ *
+ * This functions return 1 if the origin is fulfilled, otherwise
+ * 0 is returned.  We skip the tracking for netlink message whose portID 
+ * is zero since it is reserved for event-based kernel notifications.
+ */
+int mnl_nlmsg_portid_ok(const struct nlmsghdr *nlh, unsigned int portid)
+{
+	return nlh->nlmsg_pid ? nlh->nlmsg_pid == portid : 1;
+}
+
+/* XXX: rework this, please */
+void mnl_nlmsg_print(const struct nlmsghdr *nlh)
+{
+	int i;
+
+	printf("========= netlink header ==========\n");
+	printf("length(32 bits)=%.08u\n", nlh->nlmsg_len);
+	printf("type(16 bits)=%.04u flags(16 bits)=%.04x\n",
+		nlh->nlmsg_type, nlh->nlmsg_flags);
+	printf("sequence number(32 bits)=%.08x\n", nlh->nlmsg_seq);
+	printf("port ID(32 bits)=%.08u\n", nlh->nlmsg_pid);
+	printf("===================================\n");
+
+	for (i=sizeof(struct nlmsghdr); i<mnl_nlmsg_get_len(nlh); i+=4) {
+		char *b = (char *) nlh;
+
+		printf("(%.3d) %.2x %.2x %.2x %.2x | ", i,
+			0xff & b[i],	0xff & b[i+1],
+			0xff & b[i+2],	0xff & b[i+3]);
+
+		printf("%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);
+	}
+}