diff options
Diffstat (limited to 'src/extra/pktbuff.c')
-rw-r--r-- | src/extra/pktbuff.c | 160 |
1 files changed, 122 insertions, 38 deletions
diff --git a/src/extra/pktbuff.c b/src/extra/pktbuff.c index f013cfe..40d2250 100644 --- a/src/extra/pktbuff.c +++ b/src/extra/pktbuff.c @@ -23,12 +23,58 @@ /** * \defgroup pktbuff User-space network packet buffer * - * This library provides the user-space network packet buffer. This abstraction - * is strongly inspired by Linux kernel network buffer, the so-called sk_buff. + * These functions provide the user-space network packet buffer. + * This abstraction is strongly inspired by Linux kernel network buffer, + * the so-called sk_buff. + * + * \manonly +.SH SYNOPSIS +.nf +\fB +#include <libmnl/libmnl.h> +#include <libnetfilter_queue/pktbuff.h> +\endmanonly * * @{ */ +static int __pktb_setup(int family, struct pkt_buff *pktb) +{ + struct ethhdr *ethhdr; + + switch (family) { + case AF_INET: + case AF_INET6: + pktb->network_header = pktb->data; + break; + case AF_BRIDGE: + ethhdr = (struct ethhdr *)pktb->data; + pktb->mac_header = pktb->data; + + switch(ethhdr->h_proto) { + case ETH_P_IP: + case ETH_P_IPV6: + pktb->network_header = pktb->data + ETH_HLEN; + break; + default: + /* This protocol is unsupported. */ + errno = EPROTONOSUPPORT; + return -1; + } + break; + } + + return 0; +} + +static void pktb_setup_metadata(struct pkt_buff *pktb, void *pkt_data, + size_t len, size_t extra) +{ + pktb->len = len; + pktb->data_len = len + extra; + pktb->data = pkt_data; +} + /** * pktb_alloc - allocate a new packet buffer * \param family Indicate what family. Currently supported families are @@ -38,7 +84,12 @@ * \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 (if requested). + * some extra memory room in the tail (if requested). This function copies + * the memory area provided as a pointer to packet data into the packet buffer + * structure. + * + * The extra length provides extra packet data room at the tail of the packet + * buffer in case you need to mangle it. * * \return Pointer to a new userspace packet buffer or NULL on failure. * \par Errors @@ -52,7 +103,6 @@ EXPORT_SYMBOL struct pkt_buff *pktb_alloc(int family, void *data, size_t len, size_t extra) { struct pkt_buff *pktb; - struct ethhdr *ethhdr; void *pkt_data; pktb = calloc(1, sizeof(struct pkt_buff) + len + extra); @@ -63,35 +113,44 @@ struct pkt_buff *pktb_alloc(int family, void *data, size_t len, size_t extra) pkt_data = (uint8_t *)pktb + sizeof(struct pkt_buff); memcpy(pkt_data, data, len); - pktb->len = len; - pktb->data_len = len + extra; + pktb_setup_metadata(pktb, pkt_data, len, extra); - pktb->head = pkt_data; - pktb->data = pkt_data; - pktb->tail = pktb->head + len; + if (__pktb_setup(family, pktb) < 0) { + free(pktb); + return NULL; + } - switch(family) { - case AF_INET: - case AF_INET6: - pktb->network_header = pktb->data; - break; - case AF_BRIDGE: - ethhdr = (struct ethhdr *)pktb->data; - pktb->mac_header = pktb->data; + return pktb; +} + +/** + * pktb_setup_raw - set up a packet buffer from memory area + * \param pktb Pointer to memory of length pktb_head_size() bytes + * \param family Supported families are AF_BRIDGE, AF_INET & AF_INET6. + * \param data Pointer to packet data + * \param len Packet data length + * \param extra Extra memory available after packet data (for mangling). + * + * Use this function to set up a packet buffer from a memory area, minimum size + * of such memory area must be pktb_head_size(). This function attaches the + * packet data that is provided to the packet buffer (data is not copied). Use + * this function as an alternative to the pktb_alloc() interface for more + * control on memory management. + * + * \return Pointer to a new userspace packet buffer or NULL on failure. + * \par Errors + * __EPROTONOSUPPORT__ _family_ was __AF_BRIDGE__ and this is not an IP packet + * (v4 or v6) + */ +EXPORT_SYMBOL +struct pkt_buff *pktb_setup_raw(void *pktb, int family, void *data, + size_t len, size_t extra) +{ + memset(pktb, 0, sizeof (struct pkt_buff)); + pktb_setup_metadata(pktb, data, len, extra); + if (__pktb_setup(family, pktb) < 0) + pktb = NULL; - switch(ethhdr->h_proto) { - case ETH_P_IP: - case ETH_P_IPV6: - pktb->network_header = pktb->data + ETH_HLEN; - break; - default: - /* This protocol is unsupported. */ - errno = EPROTONOSUPPORT; - free(pktb); - return NULL; - } - break; - } return pktb; } @@ -141,21 +200,37 @@ void pktb_free(struct pkt_buff *pktb) * \n * 1. Functions to get values of members of opaque __struct pktbuff__, described * below - * \n + * * 2. Internal functions, described in Module __Internal functions__ * + * \manonly +.SH SYNOPSIS +.nf +\fB +#include <libmnl/libmnl.h> +#include <libnetfilter_queue/pktbuff.h> +\endmanonly + * * @{ */ /** - * \defgroup uselessfns Internal functions + * \defgroup do_not_use Internal functions * - * \warning Do not use these functions. Instead, always use the mangle + * Do not use these functions. Instead, always use the mangle * function appropriate to the level at which you are working. * \n * pktb_mangle() uses all the below functions except _pktb_pull_, which is not * used by anything. * + * \manonly +.SH SYNOPSIS +.nf +\fB +#include <libmnl/libmnl.h> +#include <libnetfilter_queue/pktbuff.h> +\endmanonly + * * @{ */ @@ -191,7 +266,6 @@ void pktb_pull(struct pkt_buff *pktb, unsigned int len) EXPORT_SYMBOL void pktb_put(struct pkt_buff *pktb, unsigned int len) { - pktb->tail += len; pktb->len += len; } @@ -204,7 +278,6 @@ EXPORT_SYMBOL void pktb_trim(struct pkt_buff *pktb, unsigned int len) { pktb->len = len; - pktb->tail = pktb->head + len; } /** @@ -280,7 +353,6 @@ static int pktb_expand_tail(struct pkt_buff *pktb, int extra) return 0; pktb->len += extra; - pktb->tail = pktb->tail + extra; return 1; } @@ -311,7 +383,7 @@ static int enlarge_pkt(struct pkt_buff *pktb, unsigned int extra) * excess of \b rep_len over \b match_len \warning pktb_mangle does not update any checksums. Developers should use the appropriate mangler for the protocol level: nfq_ip_mangle(), - nfq_tcp_mangle_ipv4() or nfq_udp_mangle_ipv4(). IPv6 versions are planned. + nfq_tcp_mangle_ipv4(), nfq_udp_mangle_ipv4() or IPv6 variants. \n It is appropriate to use pktb_mangle to change the MAC header. */ @@ -335,7 +407,7 @@ int pktb_mangle(struct pkt_buff *pktb, /* move post-replacement */ memmove(data + match_offset + rep_len, data + match_offset + match_len, - pktb->tail - (pktb->network_header + dataoff + + pktb_tail(pktb) - (pktb->network_header + dataoff + match_offset + match_len)); /* insert data from buffer */ @@ -367,5 +439,17 @@ bool pktb_mangled(const struct pkt_buff *pktb) } /** + * pktb_head_size - get number of bytes needed for a packet buffer + * (control part only) + * \return size of struct pkt_buff + */ + +EXPORT_SYMBOL +size_t pktb_head_size(void) +{ + return sizeof(struct pkt_buff); +} + +/** * @} */ |