diff options
Diffstat (limited to 'net/ipv4/netfilter/ip_nat_proto_udp.c')
| -rw-r--r-- | net/ipv4/netfilter/ip_nat_proto_udp.c | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/ip_nat_proto_udp.c b/net/ipv4/netfilter/ip_nat_proto_udp.c new file mode 100644 index 00000000000..c669e3b5f5d --- /dev/null +++ b/net/ipv4/netfilter/ip_nat_proto_udp.c @@ -0,0 +1,165 @@ +/* (C) 1999-2001 Paul `Rusty' Russell + * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/types.h> +#include <linux/init.h> +#include <linux/netfilter.h> +#include <linux/ip.h> +#include <linux/udp.h> +#include <linux/if.h> + +#include <linux/netfilter_ipv4/ip_nat.h> +#include <linux/netfilter_ipv4/ip_nat_core.h> +#include <linux/netfilter_ipv4/ip_nat_rule.h> +#include <linux/netfilter_ipv4/ip_nat_protocol.h> + +static int +udp_in_range(const struct ip_conntrack_tuple *tuple, + enum ip_nat_manip_type maniptype, + const union ip_conntrack_manip_proto *min, + const union ip_conntrack_manip_proto *max) +{ + u_int16_t port; + + if (maniptype == IP_NAT_MANIP_SRC) + port = tuple->src.u.udp.port; + else + port = tuple->dst.u.udp.port; + + return ntohs(port) >= ntohs(min->udp.port) + && ntohs(port) <= ntohs(max->udp.port); +} + +static int +udp_unique_tuple(struct ip_conntrack_tuple *tuple, + const struct ip_nat_range *range, + enum ip_nat_manip_type maniptype, + const struct ip_conntrack *conntrack) +{ + static u_int16_t port, *portptr; + unsigned int range_size, min, i; + + if (maniptype == IP_NAT_MANIP_SRC) + portptr = &tuple->src.u.udp.port; + else + portptr = &tuple->dst.u.udp.port; + + /* If no range specified... */ + if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)) { + /* If it's dst rewrite, can't change port */ + if (maniptype == IP_NAT_MANIP_DST) + return 0; + + if (ntohs(*portptr) < 1024) { + /* Loose convention: >> 512 is credential passing */ + if (ntohs(*portptr)<512) { + min = 1; + range_size = 511 - min + 1; + } else { + min = 600; + range_size = 1023 - min + 1; + } + } else { + min = 1024; + range_size = 65535 - 1024 + 1; + } + } else { + min = ntohs(range->min.udp.port); + range_size = ntohs(range->max.udp.port) - min + 1; + } + + for (i = 0; i < range_size; i++, port++) { + *portptr = htons(min + port % range_size); + if (!ip_nat_used_tuple(tuple, conntrack)) + return 1; + } + return 0; +} + +static int +udp_manip_pkt(struct sk_buff **pskb, + unsigned int iphdroff, + const struct ip_conntrack_tuple *tuple, + enum ip_nat_manip_type maniptype) +{ + struct iphdr *iph = (struct iphdr *)((*pskb)->data + iphdroff); + struct udphdr *hdr; + unsigned int hdroff = iphdroff + iph->ihl*4; + u32 oldip, newip; + u16 *portptr, newport; + + if (!skb_ip_make_writable(pskb, hdroff + sizeof(*hdr))) + return 0; + + iph = (struct iphdr *)((*pskb)->data + iphdroff); + hdr = (struct udphdr *)((*pskb)->data + hdroff); + + if (maniptype == IP_NAT_MANIP_SRC) { + /* Get rid of src ip and src pt */ + oldip = iph->saddr; + newip = tuple->src.ip; + newport = tuple->src.u.udp.port; + portptr = &hdr->source; + } else { + /* Get rid of dst ip and dst pt */ + oldip = iph->daddr; + newip = tuple->dst.ip; + newport = tuple->dst.u.udp.port; + portptr = &hdr->dest; + } + if (hdr->check) /* 0 is a special case meaning no checksum */ + hdr->check = ip_nat_cheat_check(~oldip, newip, + ip_nat_cheat_check(*portptr ^ 0xFFFF, + newport, + hdr->check)); + *portptr = newport; + return 1; +} + +static unsigned int +udp_print(char *buffer, + const struct ip_conntrack_tuple *match, + const struct ip_conntrack_tuple *mask) +{ + unsigned int len = 0; + + if (mask->src.u.udp.port) + len += sprintf(buffer + len, "srcpt=%u ", + ntohs(match->src.u.udp.port)); + + + if (mask->dst.u.udp.port) + len += sprintf(buffer + len, "dstpt=%u ", + ntohs(match->dst.u.udp.port)); + + return len; +} + +static unsigned int +udp_print_range(char *buffer, const struct ip_nat_range *range) +{ + if (range->min.udp.port != 0 || range->max.udp.port != 0xFFFF) { + if (range->min.udp.port == range->max.udp.port) + return sprintf(buffer, "port %u ", + ntohs(range->min.udp.port)); + else + return sprintf(buffer, "ports %u-%u ", + ntohs(range->min.udp.port), + ntohs(range->max.udp.port)); + } + else return 0; +} + +struct ip_nat_protocol ip_nat_protocol_udp += { "UDP", IPPROTO_UDP, + udp_manip_pkt, + udp_in_range, + udp_unique_tuple, + udp_print, + udp_print_range +}; |