diff options
Diffstat (limited to 'src/extra/ipv4.c')
| -rw-r--r-- | src/extra/ipv4.c | 109 |
1 files changed, 72 insertions, 37 deletions
diff --git a/src/extra/ipv4.c b/src/extra/ipv4.c index 3eb1054..58fb471 100644 --- a/src/extra/ipv4.c +++ b/src/extra/ipv4.c @@ -14,6 +14,7 @@ #include <arpa/inet.h> #include <netinet/ip.h> +#include <linux/netfilter/nfnetlink_queue.h> #include <libnetfilter_queue/libnetfilter_queue.h> #include <libnetfilter_queue/libnetfilter_queue_ipv4.h> #include <libnetfilter_queue/pktbuff.h> @@ -22,21 +23,34 @@ /** * \defgroup ipv4 IPv4 helper functions + * + * \manonly +.SH SYNOPSIS +.nf +\fB +#include <libmnl/libmnl.h> +#include <libnetfilter_queue/libnetfilter_queue_ipv4.h> +\endmanonly + * * @{ */ /** - * nfq_ip_get_hdr - get IPv4 header - * \param pktb: pointer to network packet buffer + * nfq_ip_get_hdr - get the IPv4 header + * \param pktb: Pointer to user-space network packet buffer + * \returns validated pointer to the IPv4 header or NULL if IP is malformed or + * not version 4 * - * This funcion returns NULL if the IPv4 is malformed or the protocol version - * is not 4. On success, it returns a valid pointer to the IPv4 header. + * Many programs will not need to call this function. A possible use is to + * determine the layer 4 protocol. The validation is that the buffer is big + * enough for the declared lengths in the header, i.e. an extra check for packet + * truncation. */ EXPORT_SYMBOL struct iphdr *nfq_ip_get_hdr(struct pkt_buff *pktb) { struct iphdr *iph; - unsigned int pktlen = pktb->tail - pktb->network_header; + unsigned int pktlen = pktb_tail(pktb) - pktb->network_header; /* Not enough room for IPv4 header. */ if (pktlen < sizeof(struct iphdr)) @@ -56,13 +70,14 @@ struct iphdr *nfq_ip_get_hdr(struct pkt_buff *pktb) } /** - * 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. + * nfq_ip_set_transport_header - set the \b transport_header field in \b pktb + * \param pktb: Pointer to user-space network packet buffer + * \param iph: Pointer to the IPv4 header + * \returns 0 on success or -1 if a minimal validation check fails + * \note + * Most programs should call __nfq_ip_set_transport_header__ as soon as + * possible, since most layer 4 helper functions assume the + * \b transport_header field is valid. */ EXPORT_SYMBOL int nfq_ip_set_transport_header(struct pkt_buff *pktb, struct iphdr *iph) @@ -78,11 +93,29 @@ int nfq_ip_set_transport_header(struct pkt_buff *pktb, struct iphdr *iph) } /** - * nfq_ip_set_checksum - set IPv4 checksum - * \param iph: pointer to the IPv4 header + * \defgroup ip_internals Internal IP functions + * + * Most user-space programs will never need these. + * + * + * \manonly +.SH SYNOPSIS +.nf +\fB +#include <libmnl/libmnl.h> +#include <libnetfilter_queue/libnetfilter_queue_ipv4.h> +\endmanonly * - * \note Call to this function if you modified the IPv4 header to update the - * checksum. + * @{ + */ + +/** + * nfq_ip_set_checksum - set IPv4 checksum + * \param iph: Pointer to the IPv4 header + * \note + * nfq_ip_mangle() invokes this function. + * As long as developers always use the appropriate mangler for the layer being + * mangled, there is no need to call __nfq_ip_set_checksum__. */ EXPORT_SYMBOL void nfq_ip_set_checksum(struct iphdr *iph) @@ -94,44 +127,46 @@ void nfq_ip_set_checksum(struct iphdr *iph) } /** + * @} + */ + +/** * nfq_ip_mangle - mangle IPv4 packet buffer - * \param pktb: pointer to network packet buffer - * \param dataoff: offset to layer 4 header - * \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 + * \param pktb: Pointer to user-space network packet buffer + * \param dataoff: Offset to layer 4 header, or zero to mangle IP header + * \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 * \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) + * \note This function updates the IPv4 length if necessary and recalculates the + * IPv4 checksum. */ EXPORT_SYMBOL -int nfq_ip_mangle(struct pkt_buff *pkt, unsigned int dataoff, +int nfq_ip_mangle(struct pkt_buff *pktb, unsigned int dataoff, unsigned int match_offset, unsigned int match_len, const char *rep_buffer, unsigned int rep_len) { - struct iphdr *iph = (struct iphdr *) pkt->network_header; + struct iphdr *iph = (struct iphdr *) pktb->network_header; - if (!pktb_mangle(pkt, dataoff, match_offset, match_len, - rep_buffer, rep_len)) + if (!pktb_mangle(pktb, dataoff, match_offset, match_len, rep_buffer, + rep_len)) return 0; /* fix IP hdr checksum information */ - iph->tot_len = htons(pkt->len); + iph->tot_len = htons(pktb_tail(pktb) - pktb->network_header); nfq_ip_set_checksum(iph); return 1; } /** - * nfq_pkt_snprintf_ip - print IPv4 header into buffer in iptables LOG format - * \param buf: pointer to buffer that will be used to print the header - * \param size: size of the buffer (or remaining room in it) - * \param ip: pointer to a valid IPv4 header - * - * This function returns the number of bytes that would have been written in - * case that there is enough room in the buffer. Read snprintf manpage for more - * information to know more about this strange behaviour. + * nfq_ip_snprintf - print IPv4 header into buffer in iptables LOG format + * \param buf: Pointer to buffer that will be used to print the header + * \param size: Size of the buffer (or remaining room in it) + * \param iph: Pointer to a valid IPv4 header + * \returns same as snprintf + * \sa **snprintf**(3) */ EXPORT_SYMBOL int nfq_ip_snprintf(char *buf, size_t size, const struct iphdr *iph) |