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icmp: Implement ping tracking based on echo identifiers

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Open and bind a socket for each possible ICMP/ICMPv6 echo identifier,
and add a tracking mechanism. Otherwise, multiple pings in parallel
won't work, and a single ping to a different destination would make
an existing ping sequence stop working.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
Stefano Brivio 2021-05-21 11:14:50 +02:00
parent af243857fa
commit d303cfdd55
3 changed files with 33 additions and 31 deletions
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53
icmp.c
View file

@ -33,6 +33,10 @@
#include "util.h" #include "util.h"
#include "icmp.h" #include "icmp.h"
/* Indexed by ICMP echo identifier */
static int icmp_s_v4[USHRT_MAX];
static int icmp_s_v6[USHRT_MAX];
/** /**
* icmp_sock_handler() - Handle new data from socket * icmp_sock_handler() - Handle new data from socket
* @c: Execution context * @c: Execution context
@ -91,48 +95,43 @@ void icmp_sock_handler(struct ctx *c, int s, uint32_t events, char *pkt_buf,
int icmp_tap_handler(struct ctx *c, int af, void *addr, int icmp_tap_handler(struct ctx *c, int af, void *addr,
struct tap_msg *msg, int count, struct timespec *now) struct tap_msg *msg, int count, struct timespec *now)
{ {
int s;
(void)count; (void)count;
(void)now; (void)now;
(void)c;
if (af == AF_INET) { if (af == AF_INET) {
struct icmphdr *ih = (struct icmphdr *)msg[0].l4h; struct icmphdr *ih = (struct icmphdr *)msg[0].l4h;
struct sockaddr_in sa = { struct sockaddr_in sa = {
.sin_family = AF_INET, .sin_family = AF_INET,
.sin_addr.s_addr = htonl(INADDR_ANY), .sin_addr = *(struct in_addr *)addr,
}; };
if (c->icmp.s4 < 0)
return 1;
if (msg[0].l4_len < sizeof(*ih) || ih->type != ICMP_ECHO) if (msg[0].l4_len < sizeof(*ih) || ih->type != ICMP_ECHO)
return 1; return 1;
sa.sin_port = ih->un.echo.id; if ((s = icmp_s_v4[ntohs(ih->un.echo.id)]) < 0)
bind(c->icmp.s4, (struct sockaddr *)&sa, sizeof(sa)); return 1;
sa.sin_addr = *(struct in_addr *)addr; sendto(s, msg[0].l4h, msg[0].l4_len,
sendto(c->icmp.s4, msg[0].l4h, msg[0].l4_len,
MSG_DONTWAIT | MSG_NOSIGNAL, MSG_DONTWAIT | MSG_NOSIGNAL,
(struct sockaddr *)&sa, sizeof(sa)); (struct sockaddr *)&sa, sizeof(sa));
} else if (af == AF_INET6) { } else if (af == AF_INET6) {
struct icmp6hdr *ih = (struct icmp6hdr *)msg[0].l4h;
struct sockaddr_in6 sa = { struct sockaddr_in6 sa = {
.sin6_family = AF_INET6, .sin6_family = AF_INET6,
.sin6_addr = IN6ADDR_ANY_INIT, .sin6_addr = *(struct in6_addr *)addr,
}; };
struct icmp6hdr *ih = (struct icmp6hdr *)msg[0].l4h;
if (c->icmp.s6 < 0)
return 1;
if (msg[0].l4_len < sizeof(*ih) || if (msg[0].l4_len < sizeof(*ih) ||
(ih->icmp6_type != 128 && ih->icmp6_type != 129)) (ih->icmp6_type != 128 && ih->icmp6_type != 129))
return 1; return 1;
sa.sin6_port = ih->icmp6_identifier; if ((s = icmp_s_v6[ntohs(ih->icmp6_identifier)]) < 0)
bind(c->icmp.s6, (struct sockaddr *)&sa, sizeof(sa)); return 1;
sa.sin6_addr = *(struct in6_addr *)addr; sendto(s, msg[0].l4h, msg[0].l4_len,
sendto(c->icmp.s6, msg[0].l4h, msg[0].l4_len,
MSG_DONTWAIT | MSG_NOSIGNAL, MSG_DONTWAIT | MSG_NOSIGNAL,
(struct sockaddr *)&sa, sizeof(sa)); (struct sockaddr *)&sa, sizeof(sa));
} }
@ -148,21 +147,31 @@ int icmp_tap_handler(struct ctx *c, int af, void *addr,
*/ */
int icmp_sock_init(struct ctx *c) int icmp_sock_init(struct ctx *c)
{ {
int fail = 0; int i, fail = 0;
c->icmp.fd_min = INT_MAX; c->icmp.fd_min = INT_MAX;
c->icmp.fd_max = 0; c->icmp.fd_max = 0;
if (c->v4 && (c->icmp.s4 = sock_l4(c, AF_INET, IPPROTO_ICMP, 0)) < 0) if (c->v4) {
for (i = 0; i < USHRT_MAX; i++) {
icmp_s_v4[i] = sock_l4(c, AF_INET, IPPROTO_ICMP, i);
if (icmp_s_v4[i] < 0)
fail = 1; fail = 1;
}
}
if (c->v6 && (c->icmp.s6 = sock_l4(c, AF_INET6, IPPROTO_ICMPV6, 0)) < 0) if (c->v6) {
for (i = 0; i < USHRT_MAX; i++) {
icmp_s_v6[i] = sock_l4(c, AF_INET6, IPPROTO_ICMPV6, i);
if (icmp_s_v6[i] < 0)
fail = 1; fail = 1;
}
}
if (fail) { if (fail) {
warn("Cannot open \"ping\" socket. You might need to:"); warn("Cannot open some \"ping\" sockets. You might need to:");
warn(" sysctl -w net.ipv4.ping_group_range=\"0 2147483647\""); warn(" sysctl -w net.ipv4.ping_group_range=\"0 2147483647\"");
warn("...continuing without echo request/reply support."); warn("...echo requests/replies might fail.");
} }
return 0; return 0;

4
icmp.h
View file

@ -11,14 +11,10 @@ int icmp_sock_init(struct ctx *c);
/** /**
* struct icmp_ctx - Execution context for ICMP routines * struct icmp_ctx - Execution context for ICMP routines
* @s4: ICMP socket number
* @s6: ICMPv6 socket number
* @fd_min: Lowest file descriptor number for ICMP/ICMPv6 ever used * @fd_min: Lowest file descriptor number for ICMP/ICMPv6 ever used
* @fd_max: Highest file descriptor number for ICMP/ICMPv6 ever used * @fd_max: Highest file descriptor number for ICMP/ICMPv6 ever used
*/ */
struct icmp_ctx { struct icmp_ctx {
int s4;
int s6;
int fd_min; int fd_min;
int fd_max; int fd_max;
}; };

3
util.c
View file

@ -189,9 +189,6 @@ int sock_l4(struct ctx *c, int af, uint16_t proto, uint16_t port)
return -1; return -1;
} }
if (proto == IPPROTO_ICMP || proto == IPPROTO_ICMPV6)
goto epoll_add;
if (af == AF_INET) { if (af == AF_INET) {
sa = (const struct sockaddr *)&addr4; sa = (const struct sockaddr *)&addr4;
sl = sizeof(addr4); sl = sizeof(addr4);