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src/event/quic/bpf/ngx_quic_reuseport_helper.c - nginx-1.31.9 nginx/ @ 2a3a19c6f

Global variables defined

Data types defined

Functions defined

Macros defined

Source code

  1. #include <errno.h>
  2. #include <linux/string.h>
  3. #include <linux/udp.h>
  4. #include <linux/bpf.h>
  5. /*
  6. * the bpf_helpers.h is not included into linux-headers, only available
  7. * with kernel sources in "tools/lib/bpf/bpf_helpers.h" or in libbpf.
  8. */
  9. #include <bpf/bpf_helpers.h>


  12. #if !defined(SEC)
  13. ‌#define SEC(NAME)  __attribute__((section(NAME), used))
  14. #endif


  17. #if defined(LICENSE_GPL)

  19. /*
  20. * To see debug:
  21. *
  22. *  echo 1 > /sys/kernel/debug/tracing/events/bpf_trace/enable
  23. *  cat /sys/kernel/debug/tracing/trace_pipe
  24. *  echo 0 > /sys/kernel/debug/tracing/events/bpf_trace/enable
  25. */

  27. ‌#define debugmsg(fmt, ...)                                                    \
  28. do {                                                                          \
  29.     char __buf[] = fmt;                                                       \
  30.     bpf_trace_printk(__buf, sizeof(__buf), ##__VA_ARGS__);                    \
  31. } while (0)

  33. #else

  35. ‌#define debugmsg(fmt, ...)

  37. #endif

  39. ‌char _license[] SEC("license") = LICENSE;

  41. /*****************************************************************************/

  43. ‌#define NGX_QUIC_PKT_LONG        0x80  /* header form */
  44. ‌#define NGX_QUIC_SERVER_CID_LEN  20


  47. ‌#define ngx_quic_parse_uint64(p)                                              \
  48.     (((__u64)(p)[0] << 56) |                                                  \
  49.      ((__u64)(p)[1] << 48) |                                                  \
  50.      ((__u64)(p)[2] << 40) |                                                  \
  51.      ((__u64)(p)[3] << 32) |                                                  \
  52.      ((__u64)(p)[4] << 24) |                                                  \
  53.      ((__u64)(p)[5] << 16) |                                                  \
  54.      ((__u64)(p)[6] << 8)  |                                                  \
  55.      ((__u64)(p)[7]))

  57. ‌#define ngx_quic_bpf_listen_key(worker)                                       \
  58.     (((__u64) 0xFF << 56) | ((__u64) (worker) & 0xFFFFFFFFFFFFULL))


  61. /*
  62. * actual map object is created by the "bpf" system call,
  63. * all pointers to this variable are replaced by the bpf loader
  64. */
  65. ‌struct {} ngx_quic_sockmap SEC(".maps");
  66. ‌struct {} ngx_quic_worker_counts SEC(".maps");


  69. ‌SEC(PROGNAME)
  70. int ngx_quic_select_socket_by_dcid(struct sk_reuseport_md *ctx)
  71. {
  72.     int             rc, worker_idx;
  73.     __u32           wc_key, *wc0, *wc1, n, m;
  74.     __u64           key;
  75.     size_t          offset;
  76.     unsigned char  *start, *end, *dcid, byte, buf[NGX_QUIC_SERVER_CID_LEN];

  78.     start = (unsigned char *) ctx->data;
  79.     end = (unsigned char *) ctx->data_end;
  80.     offset = sizeof(struct udphdr);

  82.     if (start + offset >= end) {

  84.         if (bpf_skb_load_bytes(ctx, offset, &byte, 1)) {
  85.             goto failed;
  86.         }

  88.     } else {
  89.         byte = start[offset];
  90.     }

  92.     if (byte & NGX_QUIC_PKT_LONG) {

  94.         offset += 5;

  96.         if (start + offset >= end) {

  98.             if (bpf_skb_load_bytes(ctx, offset, &byte, 1)) {
  99.                 goto failed;
  100.             }

  102.         } else {
  103.             byte = start[offset];
  104.         }

  106.         if (byte != NGX_QUIC_SERVER_CID_LEN) {
  107.             goto new;
  108.         }
  109.     }

  111.     offset++;

  113.     if (start + offset + NGX_QUIC_SERVER_CID_LEN > end) {

  115.         if (bpf_skb_load_bytes(ctx, offset, buf, NGX_QUIC_SERVER_CID_LEN)) {
  116.             goto failed;
  117.         }

  119.         dcid = buf;

  121.     } else {
  122.         dcid = start + offset;
  123.     }

  125.     key = ngx_quic_parse_uint64(dcid);

  127.     if ((key >> 56) == 0xFF) {
  128.         goto new;
  129.     }

  131.     rc = bpf_sk_select_reuseport(ctx, &ngx_quic_sockmap, &key, 0);

  133.     if (rc == 0) {
  134.         debugmsg("nginx quic worker socket selected by dcid");
  135.         return SK_PASS;
  136.     }

  138.     if (rc != -ENOENT) {
  139.         debugmsg("nginx quic bpf_sk_select_reuseport() failed: %d", rc);
  140.         return SK_DROP;
  141.     }

  143. new:

  145.     wc_key = 0;
  146.     wc0 = bpf_map_lookup_elem(&ngx_quic_worker_counts, &wc_key);
  147.     if (wc0 == NULL) {
  148.         debugmsg("nginx quic worker count 0 undefined");
  149.         return SK_DROP;
  150.     }

  152.     wc_key = 1;
  153.     wc1 = bpf_map_lookup_elem(&ngx_quic_worker_counts, &wc_key);
  154.     if (wc1 == NULL) {
  155.         debugmsg("nginx quic worker count 1 undefined");
  156.         return SK_DROP;
  157.     }

  159.     n = *wc0 > *wc1 ? *wc0 : *wc1;

  161.     if (n == 0) {
  162.         debugmsg("nginx quic no active workers");
  163.         return SK_DROP;
  164.     }

  166.     worker_idx = ctx->hash % n;
  167.     key = ngx_quic_bpf_listen_key(worker_idx);

  169.     rc = bpf_sk_select_reuseport(ctx, &ngx_quic_sockmap, &key, 0);

  171.     if (rc == 0) {
  172.         debugmsg("nginx quic listener socket selected worker index:%d",
  173.                  worker_idx);
  174.         return SK_PASS;
  175.     }

  177.     if (rc != -ENOENT) {
  178.         debugmsg("nginx quic bpf_sk_select_reuseport() failed: %d", rc);
  179.         return SK_DROP;
  180.     }

  182.     m = *wc0 < *wc1 ? *wc0 : *wc1;

  184.     if (m && m != n) {
  185.         worker_idx = ctx->hash % m;
  186.         key = ngx_quic_bpf_listen_key(worker_idx);

  188.         rc = bpf_sk_select_reuseport(ctx, &ngx_quic_sockmap, &key, 0);

  190.         if (rc == 0) {
  191.             debugmsg("nginx quic listener socket selected "
  192.                      "worker index:%d (fallback)", worker_idx);
  193.             return SK_PASS;
  194.         }

  196.         debugmsg("nginx quic bpf_sk_select_reuseport() fallback "
  197.                  "failed: %d", rc);
  198.     }

  200.     return SK_DROP;

  202. failed:

  204.     debugmsg("nginx quic bad datagram");

  206.     return SK_DROP;
  207. }

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