From ae497107eb8b44e2ad8429a0ffa971ded1fe801c Mon Sep 17 00:00:00 2001 From: Duncan Roe Date: Tue, 8 Oct 2019 11:49:44 +1100 Subject: src: doc: Miscellaneous updates (These updates only cover functions used in a recent project) src/extra/ipv4.c: - nfq_ip_set_transport_header(): Add explanatory notes - nfq_ip_mangle() - Advise that there is a return code - Note that IPv4 length is updated as well as checksum src/extra/pktbuff.c: - pktb_alloc(): Minor rewording (English usage) - pktb_mangle(): Document src/extra/udp.c: - nfq_udp_get_hdr(): Fix params - nfq_udp_get_payload(): Fix params - nfq_udp_get_payload_len(): Fix params - nfq_udp_mangle_ipv4(): Rewrite documentation src/nlmsg.c: - nfq_nlmsg_verdict_put(): Document - nfq_nlmsg_cfg_put_cmd(): - Change name (was: nfq_nlmsg_cfg_build_request) - Fix params - Delete function return documentation (void fn) - nfq_nlmsg_cfg_put_params(); Document (params only) - nfq_nlmsg_cfg_put_qmaxlen(): Document (params only) - nfq_nlmsg_parse: - Change name (was: nfq_pkt_parse) - Fix params Signed-off-by: Duncan Roe Signed-off-by: Pablo Neira Ayuso --- src/extra/ipv4.c | 9 +++++++-- src/extra/pktbuff.c | 15 ++++++++++++++- src/extra/udp.c | 28 +++++++++++++++------------- src/nlmsg.c | 36 +++++++++++++++++++++++++++--------- 4 files changed, 63 insertions(+), 25 deletions(-) diff --git a/src/extra/ipv4.c b/src/extra/ipv4.c index a93d113..20f3c12 100644 --- a/src/extra/ipv4.c +++ b/src/extra/ipv4.c @@ -59,6 +59,10 @@ EXPORT_SYMBOL(nfq_ip_get_hdr); * nfq_ip_set_transport_header - set transport header * \param pktb: pointer to network packet buffer * \param iph: pointer to the IPv4 header + * + * Sets the \b transport_header field in \b pktb + * + * Level 4 helper functions need this to be set. */ int nfq_ip_set_transport_header(struct pkt_buff *pktb, struct iphdr *iph) { @@ -97,8 +101,9 @@ EXPORT_SYMBOL(nfq_ip_set_checksum); * \param match_len: length of the existing content you want to mangle * \param rep_buffer: pointer to data you want to use to replace current content * \param rep_len: length of data you want to use to replace current content - * - * \note This function recalculates the IPv4 checksum (if needed). + * \returns 1 for success and 0 for failure. See pktb_mangle() for failure case + * \note This function updates the IPv4 length and recalculates the IPv4 + * checksum (if necessary) */ int nfq_ip_mangle(struct pkt_buff *pkt, unsigned int dataoff, unsigned int match_offset, unsigned int match_len, diff --git a/src/extra/pktbuff.c b/src/extra/pktbuff.c index 1c15a00..25b173b 100644 --- a/src/extra/pktbuff.c +++ b/src/extra/pktbuff.c @@ -36,7 +36,7 @@ * \param extra Extra memory in the tail to be allocated (for mangling) * * This function returns a packet buffer that contains the packet data and - * some extra memory room in the tail (in case of requested). + * some extra memory room in the tail (if requested). * * \return a pointer to a new queue handle or NULL on failure. */ @@ -224,6 +224,19 @@ static int enlarge_pkt(struct pkt_buff *pkt, unsigned int extra) return 1; } +/** + * pktb_mangle - adjust contents of a packet + * \param pkt Pointer to packet buffer + * \param dataoff Offset to layer 3 header. Specify zero to access layer 2 (IP) + * header + * \param match_offset Further offset to content that you want to mangle + * \param match_len Length of the existing content you want to mangle + * \param rep_buffer Pointer to data you want to use to replace current content + * \param rep_len Length of data you want to use to replace current content + * \returns 1 for success and 0 for failure. Failure will occur if the \b extra + * argument to the pktb_alloc() call that created \b pkt is less than the excess + * of \b rep_len over \b match_len + */ int pktb_mangle(struct pkt_buff *pkt, unsigned int dataoff, unsigned int match_offset, diff --git a/src/extra/udp.c b/src/extra/udp.c index f89d314..92165b4 100644 --- a/src/extra/udp.c +++ b/src/extra/udp.c @@ -31,8 +31,7 @@ /** * nfq_udp_get_hdr - get the UDP header. - * \param head: pointer to the beginning of the packet - * \param tail: pointer to the tail of the packet + * \param pktb: Pointer to network packet buffer * * This function returns NULL if invalid UDP header is found. On success, * it returns the UDP header. @@ -52,8 +51,8 @@ EXPORT_SYMBOL(nfq_udp_get_hdr); /** * nfq_udp_get_payload - get the UDP packet payload. - * \param udph: the pointer to the UDP header. - * \param tail: pointer to the tail of the packet + * \param udph: Pointer to UDP header + * \param pktb: Pointer to network packet buffer */ void *nfq_udp_get_payload(struct udphdr *udph, struct pkt_buff *pktb) { @@ -73,7 +72,8 @@ EXPORT_SYMBOL(nfq_udp_get_payload); /** * nfq_udp_get_payload_len - get the udp packet payload. - * \param udp: the pointer to the udp header. + * \param udph: Pointer to UDP header + * \param pktb: Pointer to network packet buffer */ unsigned int nfq_udp_get_payload_len(struct udphdr *udph, struct pkt_buff *pktb) { @@ -120,14 +120,16 @@ nfq_udp_compute_checksum_ipv6(struct udphdr *udph, struct ip6_hdr *ip6h) EXPORT_SYMBOL(nfq_udp_compute_checksum_ipv6); /** - * nfq_tcp_mangle_ipv4 - mangle TCP/IPv4 packet buffer - * \param pktb: pointer to network packet buffer - * \param match_offset: offset to content that you want to mangle - * \param match_len: length of the existing content you want to mangle - * \param rep_buffer: pointer to data you want to use to replace current content - * \param rep_len: length of data you want to use to replace current content - * - * \note This function recalculates the IPv4 and TCP checksums for you. + * nfq_udp_mangle_ipv4 - Mangle UDP/IPv4 packet buffer + * \param pktb: Pointer to network packet buffer + * \param match_offset: Offset from start of UDP data of content that you want + * to mangle + * \param match_len: Length of the existing content you want to mangle + * \param rep_buffer: Pointer to data you want to use to replace current content + * \param rep_len: Length of data you want to use to replace current content + * \returns 1 for success and 0 for failure. See pktb_mangle() for failure case + * \note This function updates the IPv4 and UDP lengths and recalculates their + * checksums for you. */ int nfq_udp_mangle_ipv4(struct pkt_buff *pkt, diff --git a/src/nlmsg.c b/src/nlmsg.c index ba28c77..ac0adab 100644 --- a/src/nlmsg.c +++ b/src/nlmsg.c @@ -30,6 +30,16 @@ * @{ */ +/** + * nfq_nlmsg_verdict_put - Put a verdict into a Netlink header + * \param nlh Pointer to netlink message + * \param id ID assigned to packet by netfilter + * \param verdict verdict to return to netfilter (NF_ACCEPT, NF_DROP) + * + * See examples/nf-queue.c, line 46 for an example of how to use this function. + * The calling sequence is \b main --> \b mnl_cb_run --> \b queue_cb --> + * \b nfq_send_verdict --> \b nfq_nlmsg_verdict_put + */ void nfq_nlmsg_verdict_put(struct nlmsghdr *nlh, int id, int verdict) { struct nfqnl_msg_verdict_hdr vh = { @@ -63,13 +73,10 @@ EXPORT_SYMBOL(nfq_nlmsg_verdict_put_pkt); */ /** - * nfq_nlmsg_cfg_build_request- build netlink config message - * \param buf Buffer where netlink message is going to be written. - * \param cfg Structure that contains the config parameters. - * \param command nfqueue nfnetlink command. - * - * This function returns a pointer to the netlink message. If something goes - * wrong it returns NULL. + * nfq_nlmsg_cfg_put_cmd Add netlink config command to netlink message + * \param nlh Pointer to netlink message + * \param pf Packet family (e.g. AF_INET) + * \param cmd nfqueue nfnetlink command. * * Possible commands are: * @@ -95,6 +102,12 @@ void nfq_nlmsg_cfg_put_cmd(struct nlmsghdr *nlh, uint16_t pf, uint8_t cmd) } EXPORT_SYMBOL(nfq_nlmsg_cfg_put_cmd); +/** + * nfq_nlmsg_cfg_put_params Add parameter to netlink message + * \param nlh Pointer to netlink message + * \param mode one of NFQNL_COPY_NONE, NFQNL_COPY_META or NFQNL_COPY_PACKET + * \param range value of parameter + */ void nfq_nlmsg_cfg_put_params(struct nlmsghdr *nlh, uint8_t mode, int range) { struct nfqnl_msg_config_params params = { @@ -105,6 +118,11 @@ void nfq_nlmsg_cfg_put_params(struct nlmsghdr *nlh, uint8_t mode, int range) } EXPORT_SYMBOL(nfq_nlmsg_cfg_put_params); +/** + * nfq_nlmsg_cfg_put_qmaxlen Add queue maximum length to netlink message + * \param nlh Pointer to netlink message + * \param queue_maxlen Maximum queue length + */ void nfq_nlmsg_cfg_put_qmaxlen(struct nlmsghdr *nlh, uint32_t queue_maxlen) { mnl_attr_put_u32(nlh, NFQA_CFG_QUEUE_MAXLEN, htonl(queue_maxlen)); @@ -172,9 +190,9 @@ static int nfq_pkt_parse_attr_cb(const struct nlattr *attr, void *data) } /** - * nfq_pkt_parse - set packet attributes from netlink message + * nfq_nlmsg_parse - set packet attributes from netlink message * \param nlh netlink message that you want to read. - * \param pkt pointer to the packet to set. + * \param attr pointer to array of attributes to set. * * This function returns MNL_CB_ERROR if any error occurs, or MNL_CB_OK on * success. -- cgit v1.2.3