rte_ip.h

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/* SPDX-License-Identifier: BSD-3-Clause
 * Copyright(c) 1982, 1986, 1990, 1993
 *      The Regents of the University of California.
 * Copyright(c) 2010-2014 Intel Corporation.
 * Copyright(c) 2014 6WIND S.A.
 * All rights reserved.
 */

#ifndef _RTE_IP_H_
#define _RTE_IP_H_

#include <stdint.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netinet/ip.h>

#include <rte_byteorder.h>
#include <rte_mbuf.h>

#ifdef __cplusplus
extern "C" {
#endif

struct ipv4_hdr {
    uint8_t  version_ihl;       
    uint8_t  type_of_service;   
    uint16_t total_length;      
    uint16_t packet_id;     
    uint16_t fragment_offset;   
    uint8_t  time_to_live;      
    uint8_t  next_proto_id;     
    uint16_t hdr_checksum;      
    uint32_t src_addr;      
    uint32_t dst_addr;      
} __attribute__((__packed__));

#define IPv4(a,b,c,d) ((uint32_t)(((a) & 0xff) << 24) | \
                       (((b) & 0xff) << 16) | \
                       (((c) & 0xff) << 8)  | \
                       ((d) & 0xff))

#define IPV4_MAX_PKT_LEN        65535

#define IPV4_HDR_IHL_MASK   (0x0f)

#define IPV4_IHL_MULTIPLIER (4)

/* Fragment Offset * Flags. */
#define IPV4_HDR_DF_SHIFT   14
#define IPV4_HDR_MF_SHIFT   13
#define IPV4_HDR_FO_SHIFT   3

#define IPV4_HDR_DF_FLAG    (1 << IPV4_HDR_DF_SHIFT)
#define IPV4_HDR_MF_FLAG    (1 << IPV4_HDR_MF_SHIFT)

#define IPV4_HDR_OFFSET_MASK    ((1 << IPV4_HDR_MF_SHIFT) - 1)

#define IPV4_HDR_OFFSET_UNITS   8

/*
 * IPv4 address types
 */
#define IPV4_ANY              ((uint32_t)0x00000000) 
#define IPV4_LOOPBACK         ((uint32_t)0x7f000001) 
#define IPV4_BROADCAST        ((uint32_t)0xe0000000) 
#define IPV4_ALLHOSTS_GROUP   ((uint32_t)0xe0000001) 
#define IPV4_ALLRTRS_GROUP    ((uint32_t)0xe0000002) 
#define IPV4_MAX_LOCAL_GROUP  ((uint32_t)0xe00000ff) 
/*
 * IPv4 Multicast-related macros
 */
#define IPV4_MIN_MCAST  IPv4(224, 0, 0, 0)          
#define IPV4_MAX_MCAST  IPv4(239, 255, 255, 255)    
#define IS_IPV4_MCAST(x) \
    ((x) >= IPV4_MIN_MCAST && (x) <= IPV4_MAX_MCAST) 
/* IPv4 default fields values */
#define IPV4_MIN_IHL    (0x5)
#define IPV4_VHL_DEF    (IPVERSION | IPV4_MIN_IHL)

static inline uint32_t
__rte_raw_cksum(const void *buf, size_t len, uint32_t sum)
{
    /* workaround gcc strict-aliasing warning */
    uintptr_t ptr = (uintptr_t)buf;
    typedef uint16_t __attribute__((__may_alias__)) u16_p;
    const u16_p *u16_buf = (const u16_p *)ptr;

    while (len >= (sizeof(*u16_buf) * 4)) {
        sum += u16_buf[0];
        sum += u16_buf[1];
        sum += u16_buf[2];
        sum += u16_buf[3];
        len -= sizeof(*u16_buf) * 4;
        u16_buf += 4;
    }
    while (len >= sizeof(*u16_buf)) {
        sum += *u16_buf;
        len -= sizeof(*u16_buf);
        u16_buf += 1;
    }

    /* if length is in odd bytes */
    if (len == 1) {
        uint16_t left = 0;
        *(uint8_t *)&left = *(const uint8_t *)u16_buf;
        sum += left;
    }

    return sum;
}

static inline uint16_t
__rte_raw_cksum_reduce(uint32_t sum)
{
    sum = ((sum & 0xffff0000) >> 16) + (sum & 0xffff);
    sum = ((sum & 0xffff0000) >> 16) + (sum & 0xffff);
    return (uint16_t)sum;
}

static inline uint16_t
rte_raw_cksum(const void *buf, size_t len)
{
    uint32_t sum;

    sum = __rte_raw_cksum(buf, len, 0);
    return __rte_raw_cksum_reduce(sum);
}

static inline int
rte_raw_cksum_mbuf(const struct rte_mbuf *m, uint32_t off, uint32_t len,
    uint16_t *cksum)
{
    const struct rte_mbuf *seg;
    const char *buf;
    uint32_t sum, tmp;
    uint32_t seglen, done;

    /* easy case: all data in the first segment */
    if (off + len <= rte_pktmbuf_data_len(m)) {
        *cksum = rte_raw_cksum(rte_pktmbuf_mtod_offset(m,
                const char *, off), len);
        return 0;
    }

    if (unlikely(off + len > rte_pktmbuf_pkt_len(m)))
        return -1; /* invalid params, return a dummy value */

    /* else browse the segment to find offset */
    seglen = 0;
    for (seg = m; seg != NULL; seg = seg->next) {
        seglen = rte_pktmbuf_data_len(seg);
        if (off < seglen)
            break;
        off -= seglen;
    }
    RTE_ASSERT(seg != NULL);
    if (seg == NULL)
        return -1;
    seglen -= off;
    buf = rte_pktmbuf_mtod_offset(seg, const char *, off);
    if (seglen >= len) {
        /* all in one segment */
        *cksum = rte_raw_cksum(buf, len);
        return 0;
    }

    /* hard case: process checksum of several segments */
    sum = 0;
    done = 0;
    for (;;) {
        tmp = __rte_raw_cksum(buf, seglen, 0);
        if (done & 1)
            tmp = rte_bswap16((uint16_t)tmp);
        sum += tmp;
        done += seglen;
        if (done == len)
            break;
        seg = seg->next;
        buf = rte_pktmbuf_mtod(seg, const char *);
        seglen = rte_pktmbuf_data_len(seg);
        if (seglen > len - done)
            seglen = len - done;
    }

    *cksum = __rte_raw_cksum_reduce(sum);
    return 0;
}

static inline uint16_t
rte_ipv4_cksum(const struct ipv4_hdr *ipv4_hdr)
{
    uint16_t cksum;
    cksum = rte_raw_cksum(ipv4_hdr, sizeof(struct ipv4_hdr));
    return (uint16_t)~cksum;
}

static inline uint16_t
rte_ipv4_phdr_cksum(const struct ipv4_hdr *ipv4_hdr, uint64_t ol_flags)
{
    struct ipv4_psd_header {
        uint32_t src_addr; /* IP address of source host. */
        uint32_t dst_addr; /* IP address of destination host. */
        uint8_t  zero;     /* zero. */
        uint8_t  proto;    /* L4 protocol type. */
        uint16_t len;      /* L4 length. */
    } psd_hdr;

    psd_hdr.src_addr = ipv4_hdr->src_addr;
    psd_hdr.dst_addr = ipv4_hdr->dst_addr;
    psd_hdr.zero = 0;
    psd_hdr.proto = ipv4_hdr->next_proto_id;
    if (ol_flags & PKT_TX_TCP_SEG) {
        psd_hdr.len = 0;
    } else {
        psd_hdr.len = rte_cpu_to_be_16(
            (uint16_t)(rte_be_to_cpu_16(ipv4_hdr->total_length)
                - sizeof(struct ipv4_hdr)));
    }
    return rte_raw_cksum(&psd_hdr, sizeof(psd_hdr));
}

static inline uint16_t
rte_ipv4_udptcp_cksum(const struct ipv4_hdr *ipv4_hdr, const void *l4_hdr)
{
    uint32_t cksum;
    uint32_t l3_len, l4_len;

    l3_len = rte_be_to_cpu_16(ipv4_hdr->total_length);
    if (l3_len < sizeof(struct ipv4_hdr))
        return 0;

    l4_len = l3_len - sizeof(struct ipv4_hdr);

    cksum = rte_raw_cksum(l4_hdr, l4_len);
    cksum += rte_ipv4_phdr_cksum(ipv4_hdr, 0);

    cksum = ((cksum & 0xffff0000) >> 16) + (cksum & 0xffff);
    cksum = (~cksum) & 0xffff;
    /*
     * Per RFC 768:If the computed checksum is zero for UDP,
     * it is transmitted as all ones
     * (the equivalent in one's complement arithmetic).
     */
    if (cksum == 0 && ipv4_hdr->next_proto_id == IPPROTO_UDP)
        cksum = 0xffff;

    return (uint16_t)cksum;
}

struct ipv6_hdr {
    uint32_t vtc_flow;     
    uint16_t payload_len;  
    uint8_t  proto;        
    uint8_t  hop_limits;   
    uint8_t  src_addr[16]; 
    uint8_t  dst_addr[16]; 
} __attribute__((__packed__));

/* IPv6 vtc_flow: IPv / TC / flow_label */
#define IPV6_HDR_FL_SHIFT 0
#define IPV6_HDR_TC_SHIFT 20
#define IPV6_HDR_FL_MASK ((1u << IPV6_HDR_TC_SHIFT) - 1)
#define IPV6_HDR_TC_MASK (0xff << IPV6_HDR_TC_SHIFT)

static inline uint16_t
rte_ipv6_phdr_cksum(const struct ipv6_hdr *ipv6_hdr, uint64_t ol_flags)
{
    uint32_t sum;
    struct {
        uint32_t len;   /* L4 length. */
        uint32_t proto; /* L4 protocol - top 3 bytes must be zero */
    } psd_hdr;

    psd_hdr.proto = (uint32_t)(ipv6_hdr->proto << 24);
    if (ol_flags & PKT_TX_TCP_SEG) {
        psd_hdr.len = 0;
    } else {
        psd_hdr.len = ipv6_hdr->payload_len;
    }

    sum = __rte_raw_cksum(ipv6_hdr->src_addr,
        sizeof(ipv6_hdr->src_addr) + sizeof(ipv6_hdr->dst_addr),
        0);
    sum = __rte_raw_cksum(&psd_hdr, sizeof(psd_hdr), sum);
    return __rte_raw_cksum_reduce(sum);
}

static inline uint16_t
rte_ipv6_udptcp_cksum(const struct ipv6_hdr *ipv6_hdr, const void *l4_hdr)
{
    uint32_t cksum;
    uint32_t l4_len;

    l4_len = rte_be_to_cpu_16(ipv6_hdr->payload_len);

    cksum = rte_raw_cksum(l4_hdr, l4_len);
    cksum += rte_ipv6_phdr_cksum(ipv6_hdr, 0);

    cksum = ((cksum & 0xffff0000) >> 16) + (cksum & 0xffff);
    cksum = (~cksum) & 0xffff;
    /*
     * Per RFC 768: If the computed checksum is zero for UDP,
     * it is transmitted as all ones
     * (the equivalent in one's complement arithmetic).
     */
    if (cksum == 0 && ipv6_hdr->proto == IPPROTO_UDP)
        cksum = 0xffff;

    return (uint16_t)cksum;
}

#ifdef __cplusplus
}
#endif

#endif /* _RTE_IP_H_ */