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uipc_socket.c
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uipc_socket.c
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/* $OpenBSD: uipc_socket.c,v 1.293 2022/12/12 08:30:22 tb Exp $ */
/* $NetBSD: uipc_socket.c,v 1.21 1996/02/04 02:17:52 christos Exp $ */
/*
* Copyright (c) 1982, 1986, 1988, 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)uipc_socket.c 8.3 (Berkeley) 4/15/94
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/domain.h>
#include <sys/event.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#include <sys/unpcb.h>
#include <sys/socketvar.h>
#include <sys/signalvar.h>
#include <sys/pool.h>
#include <sys/atomic.h>
#include <sys/rwlock.h>
#include <sys/time.h>
#include <sys/refcnt.h>
#ifdef DDB
#include <machine/db_machdep.h>
#endif
void sbsync(struct sockbuf *, struct mbuf *);
int sosplice(struct socket *, int, off_t, struct timeval *);
void sounsplice(struct socket *, struct socket *, int);
void soidle(void *);
void sotask(void *);
void soreaper(void *);
void soput(void *);
int somove(struct socket *, int);
void sorflush(struct socket *);
void filt_sordetach(struct knote *kn);
int filt_soread(struct knote *kn, long hint);
void filt_sowdetach(struct knote *kn);
int filt_sowrite(struct knote *kn, long hint);
int filt_soexcept(struct knote *kn, long hint);
int filt_solisten(struct knote *kn, long hint);
int filt_somodify(struct kevent *kev, struct knote *kn);
int filt_soprocess(struct knote *kn, struct kevent *kev);
const struct filterops solisten_filtops = {
.f_flags = FILTEROP_ISFD | FILTEROP_MPSAFE,
.f_attach = NULL,
.f_detach = filt_sordetach,
.f_event = filt_solisten,
.f_modify = filt_somodify,
.f_process = filt_soprocess,
};
const struct filterops soread_filtops = {
.f_flags = FILTEROP_ISFD | FILTEROP_MPSAFE,
.f_attach = NULL,
.f_detach = filt_sordetach,
.f_event = filt_soread,
.f_modify = filt_somodify,
.f_process = filt_soprocess,
};
const struct filterops sowrite_filtops = {
.f_flags = FILTEROP_ISFD | FILTEROP_MPSAFE,
.f_attach = NULL,
.f_detach = filt_sowdetach,
.f_event = filt_sowrite,
.f_modify = filt_somodify,
.f_process = filt_soprocess,
};
const struct filterops soexcept_filtops = {
.f_flags = FILTEROP_ISFD | FILTEROP_MPSAFE,
.f_attach = NULL,
.f_detach = filt_sordetach,
.f_event = filt_soexcept,
.f_modify = filt_somodify,
.f_process = filt_soprocess,
};
#ifndef SOMINCONN
#define SOMINCONN 80
#endif /* SOMINCONN */
int somaxconn = SOMAXCONN;
int sominconn = SOMINCONN;
struct pool socket_pool;
#ifdef SOCKET_SPLICE
struct pool sosplice_pool;
struct taskq *sosplice_taskq;
struct rwlock sosplice_lock = RWLOCK_INITIALIZER("sosplicelk");
#endif
void
soinit(void)
{
pool_init(&socket_pool, sizeof(struct socket), 0, IPL_SOFTNET, 0,
"sockpl", NULL);
#ifdef SOCKET_SPLICE
pool_init(&sosplice_pool, sizeof(struct sosplice), 0, IPL_SOFTNET, 0,
"sosppl", NULL);
#endif
}
struct socket *
soalloc(int wait)
{
struct socket *so;
so = pool_get(&socket_pool, (wait == M_WAIT ? PR_WAITOK : PR_NOWAIT) |
PR_ZERO);
if (so == NULL)
return (NULL);
rw_init_flags(&so->so_lock, "solock", RWL_DUPOK);
refcnt_init(&so->so_refcnt);
return (so);
}
/*
* Socket operation routines.
* These routines are called by the routines in
* sys_socket.c or from a system process, and
* implement the semantics of socket operations by
* switching out to the protocol specific routines.
*/
int
socreate(int dom, struct socket **aso, int type, int proto)
{
struct proc *p = curproc; /* XXX */
const struct protosw *prp;
struct socket *so;
int error;
if (proto)
prp = pffindproto(dom, proto, type);
else
prp = pffindtype(dom, type);
if (prp == NULL || prp->pr_usrreqs == NULL)
return (EPROTONOSUPPORT);
if (prp->pr_type != type)
return (EPROTOTYPE);
so = soalloc(M_WAIT);
klist_init(&so->so_rcv.sb_sel.si_note, &socket_klistops, so);
klist_init(&so->so_snd.sb_sel.si_note, &socket_klistops, so);
sigio_init(&so->so_sigio);
TAILQ_INIT(&so->so_q0);
TAILQ_INIT(&so->so_q);
so->so_type = type;
if (suser(p) == 0)
so->so_state = SS_PRIV;
so->so_ruid = p->p_ucred->cr_ruid;
so->so_euid = p->p_ucred->cr_uid;
so->so_rgid = p->p_ucred->cr_rgid;
so->so_egid = p->p_ucred->cr_gid;
so->so_cpid = p->p_p->ps_pid;
so->so_proto = prp;
so->so_snd.sb_timeo_nsecs = INFSLP;
so->so_rcv.sb_timeo_nsecs = INFSLP;
solock(so);
error = pru_attach(so, proto, M_WAIT);
if (error) {
so->so_state |= SS_NOFDREF;
/* sofree() calls sounlock(). */
sofree(so, 0);
return (error);
}
sounlock(so);
*aso = so;
return (0);
}
int
sobind(struct socket *so, struct mbuf *nam, struct proc *p)
{
soassertlocked(so);
return pru_bind(so, nam, p);
}
int
solisten(struct socket *so, int backlog)
{
int error;
soassertlocked(so);
if (so->so_state & (SS_ISCONNECTED|SS_ISCONNECTING|SS_ISDISCONNECTING))
return (EINVAL);
#ifdef SOCKET_SPLICE
if (isspliced(so) || issplicedback(so))
return (EOPNOTSUPP);
#endif /* SOCKET_SPLICE */
error = pru_listen(so);
if (error)
return (error);
if (TAILQ_FIRST(&so->so_q) == NULL)
so->so_options |= SO_ACCEPTCONN;
if (backlog < 0 || backlog > somaxconn)
backlog = somaxconn;
if (backlog < sominconn)
backlog = sominconn;
so->so_qlimit = backlog;
return (0);
}
#define SOSP_FREEING_READ 1
#define SOSP_FREEING_WRITE 2
void
sofree(struct socket *so, int keep_lock)
{
int persocket = solock_persocket(so);
soassertlocked(so);
if (so->so_pcb || (so->so_state & SS_NOFDREF) == 0) {
if (!keep_lock)
sounlock(so);
return;
}
if (so->so_head) {
struct socket *head = so->so_head;
/*
* We must not decommission a socket that's on the accept(2)
* queue. If we do, then accept(2) may hang after select(2)
* indicated that the listening socket was ready.
*/
if (so->so_onq == &head->so_q) {
if (!keep_lock)
sounlock(so);
return;
}
if (persocket) {
/*
* Concurrent close of `head' could
* abort `so' due to re-lock.
*/
soref(so);
soref(head);
sounlock(so);
solock(head);
solock(so);
if (so->so_onq != &head->so_q0) {
sounlock(head);
sounlock(so);
sorele(head);
sorele(so);
return;
}
sorele(head);
sorele(so);
}
soqremque(so, 0);
if (persocket)
sounlock(head);
}
if (persocket) {
sounlock(so);
refcnt_finalize(&so->so_refcnt, "sofinal");
solock(so);
}
sigio_free(&so->so_sigio);
klist_free(&so->so_rcv.sb_sel.si_note);
klist_free(&so->so_snd.sb_sel.si_note);
#ifdef SOCKET_SPLICE
if (so->so_sp) {
if (issplicedback(so)) {
int freeing = SOSP_FREEING_WRITE;
if (so->so_sp->ssp_soback == so)
freeing |= SOSP_FREEING_READ;
sounsplice(so->so_sp->ssp_soback, so, freeing);
}
if (isspliced(so)) {
int freeing = SOSP_FREEING_READ;
if (so == so->so_sp->ssp_socket)
freeing |= SOSP_FREEING_WRITE;
sounsplice(so, so->so_sp->ssp_socket, freeing);
}
}
#endif /* SOCKET_SPLICE */
sbrelease(so, &so->so_snd);
sorflush(so);
if (!keep_lock)
sounlock(so);
#ifdef SOCKET_SPLICE
if (so->so_sp) {
/* Reuse splice idle, sounsplice() has been called before. */
timeout_set_proc(&so->so_sp->ssp_idleto, soreaper, so);
timeout_add(&so->so_sp->ssp_idleto, 0);
} else
#endif /* SOCKET_SPLICE */
{
pool_put(&socket_pool, so);
}
}
static inline uint64_t
solinger_nsec(struct socket *so)
{
if (so->so_linger == 0)
return INFSLP;
return SEC_TO_NSEC(so->so_linger);
}
/*
* Close a socket on last file table reference removal.
* Initiate disconnect if connected.
* Free socket when disconnect complete.
*/
int
soclose(struct socket *so, int flags)
{
struct socket *so2;
int error = 0;
solock(so);
/* Revoke async IO early. There is a final revocation in sofree(). */
sigio_free(&so->so_sigio);
if (so->so_state & SS_ISCONNECTED) {
if (so->so_pcb == NULL)
goto discard;
if ((so->so_state & SS_ISDISCONNECTING) == 0) {
error = sodisconnect(so);
if (error)
goto drop;
}
if (so->so_options & SO_LINGER) {
if ((so->so_state & SS_ISDISCONNECTING) &&
(flags & MSG_DONTWAIT))
goto drop;
while (so->so_state & SS_ISCONNECTED) {
error = sosleep_nsec(so, &so->so_timeo,
PSOCK | PCATCH, "netcls",
solinger_nsec(so));
if (error)
break;
}
}
}
drop:
if (so->so_pcb) {
int error2;
error2 = pru_detach(so);
if (error == 0)
error = error2;
}
if (so->so_options & SO_ACCEPTCONN) {
int persocket = solock_persocket(so);
if (persocket) {
/* Wait concurrent sonewconn() threads. */
while (so->so_newconn > 0) {
so->so_state |= SS_NEWCONN_WAIT;
sosleep_nsec(so, &so->so_newconn, PSOCK,
"netlck", INFSLP);
}
}
while ((so2 = TAILQ_FIRST(&so->so_q0)) != NULL) {
if (persocket)
solock(so2);
(void) soqremque(so2, 0);
if (persocket)
sounlock(so);
soabort(so2);
if (persocket)
solock(so);
}
while ((so2 = TAILQ_FIRST(&so->so_q)) != NULL) {
if (persocket)
solock(so2);
(void) soqremque(so2, 1);
if (persocket)
sounlock(so);
soabort(so2);
if (persocket)
solock(so);
}
}
discard:
if (so->so_state & SS_NOFDREF)
panic("soclose NOFDREF: so %p, so_type %d", so, so->so_type);
so->so_state |= SS_NOFDREF;
/* sofree() calls sounlock(). */
sofree(so, 0);
return (error);
}
void
soabort(struct socket *so)
{
soassertlocked(so);
pru_abort(so);
}
int
soaccept(struct socket *so, struct mbuf *nam)
{
int error = 0;
soassertlocked(so);
if ((so->so_state & SS_NOFDREF) == 0)
panic("soaccept !NOFDREF: so %p, so_type %d", so, so->so_type);
so->so_state &= ~SS_NOFDREF;
if ((so->so_state & SS_ISDISCONNECTED) == 0 ||
(so->so_proto->pr_flags & PR_ABRTACPTDIS) == 0)
error = pru_accept(so, nam);
else
error = ECONNABORTED;
return (error);
}
int
soconnect(struct socket *so, struct mbuf *nam)
{
int error;
soassertlocked(so);
if (so->so_options & SO_ACCEPTCONN)
return (EOPNOTSUPP);
/*
* If protocol is connection-based, can only connect once.
* Otherwise, if connected, try to disconnect first.
* This allows user to disconnect by connecting to, e.g.,
* a null address.
*/
if (so->so_state & (SS_ISCONNECTED|SS_ISCONNECTING) &&
((so->so_proto->pr_flags & PR_CONNREQUIRED) ||
(error = sodisconnect(so))))
error = EISCONN;
else
error = pru_connect(so, nam);
return (error);
}
int
soconnect2(struct socket *so1, struct socket *so2)
{
int persocket, error;
if ((persocket = solock_persocket(so1)))
solock_pair(so1, so2);
else
solock(so1);
error = pru_connect2(so1, so2);
if (persocket)
sounlock(so2);
sounlock(so1);
return (error);
}
int
sodisconnect(struct socket *so)
{
int error;
soassertlocked(so);
if ((so->so_state & SS_ISCONNECTED) == 0)
return (ENOTCONN);
if (so->so_state & SS_ISDISCONNECTING)
return (EALREADY);
error = pru_disconnect(so);
return (error);
}
int m_getuio(struct mbuf **, int, long, struct uio *);
#define SBLOCKWAIT(f) (((f) & MSG_DONTWAIT) ? M_NOWAIT : M_WAITOK)
/*
* Send on a socket.
* If send must go all at once and message is larger than
* send buffering, then hard error.
* Lock against other senders.
* If must go all at once and not enough room now, then
* inform user that this would block and do nothing.
* Otherwise, if nonblocking, send as much as possible.
* The data to be sent is described by "uio" if nonzero,
* otherwise by the mbuf chain "top" (which must be null
* if uio is not). Data provided in mbuf chain must be small
* enough to send all at once.
*
* Returns nonzero on error, timeout or signal; callers
* must check for short counts if EINTR/ERESTART are returned.
* Data and control buffers are freed on return.
*/
int
sosend(struct socket *so, struct mbuf *addr, struct uio *uio, struct mbuf *top,
struct mbuf *control, int flags)
{
long space, clen = 0;
size_t resid;
int error;
int atomic = sosendallatonce(so) || top;
if (uio)
resid = uio->uio_resid;
else
resid = top->m_pkthdr.len;
/* MSG_EOR on a SOCK_STREAM socket is invalid. */
if (so->so_type == SOCK_STREAM && (flags & MSG_EOR)) {
m_freem(top);
m_freem(control);
return (EINVAL);
}
if (uio && uio->uio_procp)
uio->uio_procp->p_ru.ru_msgsnd++;
if (control) {
/*
* In theory clen should be unsigned (since control->m_len is).
* However, space must be signed, as it might be less than 0
* if we over-committed, and we must use a signed comparison
* of space and clen.
*/
clen = control->m_len;
/* reserve extra space for AF_UNIX's internalize */
if (so->so_proto->pr_domain->dom_family == AF_UNIX &&
clen >= CMSG_ALIGN(sizeof(struct cmsghdr)) &&
mtod(control, struct cmsghdr *)->cmsg_type == SCM_RIGHTS)
clen = CMSG_SPACE(
(clen - CMSG_ALIGN(sizeof(struct cmsghdr))) *
(sizeof(struct fdpass) / sizeof(int)));
}
#define snderr(errno) { error = errno; goto release; }
solock(so);
restart:
if ((error = sblock(so, &so->so_snd, SBLOCKWAIT(flags))) != 0)
goto out;
so->so_state |= SS_ISSENDING;
do {
if (so->so_state & SS_CANTSENDMORE)
snderr(EPIPE);
if (so->so_error) {
error = so->so_error;
so->so_error = 0;
snderr(error);
}
if ((so->so_state & SS_ISCONNECTED) == 0) {
if (so->so_proto->pr_flags & PR_CONNREQUIRED) {
if (!(resid == 0 && clen != 0))
snderr(ENOTCONN);
} else if (addr == NULL)
snderr(EDESTADDRREQ);
}
space = sbspace(so, &so->so_snd);
if (flags & MSG_OOB)
space += 1024;
if (so->so_proto->pr_domain->dom_family == AF_UNIX) {
if (atomic && resid > so->so_snd.sb_hiwat)
snderr(EMSGSIZE);
} else {
if (clen > so->so_snd.sb_hiwat ||
(atomic && resid > so->so_snd.sb_hiwat - clen))
snderr(EMSGSIZE);
}
if (space < clen ||
(space - clen < resid &&
(atomic || space < so->so_snd.sb_lowat))) {
if (flags & MSG_DONTWAIT)
snderr(EWOULDBLOCK);
sbunlock(so, &so->so_snd);
error = sbwait(so, &so->so_snd);
so->so_state &= ~SS_ISSENDING;
if (error)
goto out;
goto restart;
}
space -= clen;
do {
if (uio == NULL) {
/*
* Data is prepackaged in "top".
*/
resid = 0;
if (flags & MSG_EOR)
top->m_flags |= M_EOR;
} else {
sounlock(so);
error = m_getuio(&top, atomic, space, uio);
solock(so);
if (error)
goto release;
space -= top->m_pkthdr.len;
resid = uio->uio_resid;
if (flags & MSG_EOR)
top->m_flags |= M_EOR;
}
if (resid == 0)
so->so_state &= ~SS_ISSENDING;
if (top && so->so_options & SO_ZEROIZE)
top->m_flags |= M_ZEROIZE;
if (flags & MSG_OOB)
error = pru_sendoob(so, top, addr, control);
else
error = pru_send(so, top, addr, control);
clen = 0;
control = NULL;
top = NULL;
if (error)
goto release;
} while (resid && space > 0);
} while (resid);
release:
so->so_state &= ~SS_ISSENDING;
sbunlock(so, &so->so_snd);
out:
sounlock(so);
m_freem(top);
m_freem(control);
return (error);
}
int
m_getuio(struct mbuf **mp, int atomic, long space, struct uio *uio)
{
struct mbuf *m, *top = NULL;
struct mbuf **nextp = ⊤
u_long len, mlen;
size_t resid = uio->uio_resid;
int error;
do {
if (top == NULL) {
MGETHDR(m, M_WAIT, MT_DATA);
mlen = MHLEN;
m->m_pkthdr.len = 0;
m->m_pkthdr.ph_ifidx = 0;
} else {
MGET(m, M_WAIT, MT_DATA);
mlen = MLEN;
}
/* chain mbuf together */
*nextp = m;
nextp = &m->m_next;
resid = ulmin(resid, space);
if (resid >= MINCLSIZE) {
MCLGETL(m, M_NOWAIT, ulmin(resid, MAXMCLBYTES));
if ((m->m_flags & M_EXT) == 0)
MCLGETL(m, M_NOWAIT, MCLBYTES);
if ((m->m_flags & M_EXT) == 0)
goto nopages;
mlen = m->m_ext.ext_size;
len = ulmin(mlen, resid);
/*
* For datagram protocols, leave room
* for protocol headers in first mbuf.
*/
if (atomic && m == top && len < mlen - max_hdr)
m->m_data += max_hdr;
} else {
nopages:
len = ulmin(mlen, resid);
/*
* For datagram protocols, leave room
* for protocol headers in first mbuf.
*/
if (atomic && m == top && len < mlen - max_hdr)
m_align(m, len);
}
error = uiomove(mtod(m, caddr_t), len, uio);
if (error) {
m_freem(top);
return (error);
}
/* adjust counters */
resid = uio->uio_resid;
space -= len;
m->m_len = len;
top->m_pkthdr.len += len;
/* Is there more space and more data? */
} while (space > 0 && resid > 0);
*mp = top;
return 0;
}
/*
* Following replacement or removal of the first mbuf on the first
* mbuf chain of a socket buffer, push necessary state changes back
* into the socket buffer so that other consumers see the values
* consistently. 'nextrecord' is the callers locally stored value of
* the original value of sb->sb_mb->m_nextpkt which must be restored
* when the lead mbuf changes. NOTE: 'nextrecord' may be NULL.
*/
void
sbsync(struct sockbuf *sb, struct mbuf *nextrecord)
{
/*
* First, update for the new value of nextrecord. If necessary,
* make it the first record.
*/
if (sb->sb_mb != NULL)
sb->sb_mb->m_nextpkt = nextrecord;
else
sb->sb_mb = nextrecord;
/*
* Now update any dependent socket buffer fields to reflect
* the new state. This is an inline of SB_EMPTY_FIXUP, with
* the addition of a second clause that takes care of the
* case where sb_mb has been updated, but remains the last
* record.
*/
if (sb->sb_mb == NULL) {
sb->sb_mbtail = NULL;
sb->sb_lastrecord = NULL;
} else if (sb->sb_mb->m_nextpkt == NULL)
sb->sb_lastrecord = sb->sb_mb;
}
/*
* Implement receive operations on a socket.
* We depend on the way that records are added to the sockbuf
* by sbappend*. In particular, each record (mbufs linked through m_next)
* must begin with an address if the protocol so specifies,
* followed by an optional mbuf or mbufs containing ancillary data,
* and then zero or more mbufs of data.
* In order to avoid blocking network for the entire time here, we release
* the solock() while doing the actual copy to user space.
* Although the sockbuf is locked, new data may still be appended,
* and thus we must maintain consistency of the sockbuf during that time.
*
* The caller may receive the data as a single mbuf chain by supplying
* an mbuf **mp0 for use in returning the chain. The uio is then used
* only for the count in uio_resid.
*/
int
soreceive(struct socket *so, struct mbuf **paddr, struct uio *uio,
struct mbuf **mp0, struct mbuf **controlp, int *flagsp,
socklen_t controllen)
{
struct mbuf *m, **mp;
struct mbuf *cm;
u_long len, offset, moff;
int flags, error, type, uio_error = 0;
const struct protosw *pr = so->so_proto;
struct mbuf *nextrecord;
size_t resid, orig_resid = uio->uio_resid;
mp = mp0;
if (paddr)
*paddr = NULL;
if (controlp)
*controlp = NULL;
if (flagsp)
flags = *flagsp &~ MSG_EOR;
else
flags = 0;
if (flags & MSG_OOB) {
m = m_get(M_WAIT, MT_DATA);
solock(so);
error = pru_rcvoob(so, m, flags & MSG_PEEK);
sounlock(so);
if (error)
goto bad;
do {
error = uiomove(mtod(m, caddr_t),
ulmin(uio->uio_resid, m->m_len), uio);
m = m_free(m);
} while (uio->uio_resid && error == 0 && m);
bad:
m_freem(m);
return (error);
}
if (mp)
*mp = NULL;
solock_shared(so);
restart:
if ((error = sblock(so, &so->so_rcv, SBLOCKWAIT(flags))) != 0) {
sounlock_shared(so);
return (error);
}
m = so->so_rcv.sb_mb;
#ifdef SOCKET_SPLICE
if (isspliced(so))
m = NULL;
#endif /* SOCKET_SPLICE */
/*
* If we have less data than requested, block awaiting more
* (subject to any timeout) if:
* 1. the current count is less than the low water mark,
* 2. MSG_WAITALL is set, and it is possible to do the entire
* receive operation at once if we block (resid <= hiwat), or
* 3. MSG_DONTWAIT is not set.
* If MSG_WAITALL is set but resid is larger than the receive buffer,
* we have to do the receive in sections, and thus risk returning
* a short count if a timeout or signal occurs after we start.
*/
if (m == NULL || (((flags & MSG_DONTWAIT) == 0 &&
so->so_rcv.sb_cc < uio->uio_resid) &&
(so->so_rcv.sb_cc < so->so_rcv.sb_lowat ||
((flags & MSG_WAITALL) && uio->uio_resid <= so->so_rcv.sb_hiwat)) &&
m->m_nextpkt == NULL && (pr->pr_flags & PR_ATOMIC) == 0)) {
#ifdef DIAGNOSTIC
if (m == NULL && so->so_rcv.sb_cc)
#ifdef SOCKET_SPLICE
if (!isspliced(so))
#endif /* SOCKET_SPLICE */
panic("receive 1: so %p, so_type %d, sb_cc %lu",
so, so->so_type, so->so_rcv.sb_cc);
#endif
if (so->so_error) {
if (m)
goto dontblock;
error = so->so_error;
if ((flags & MSG_PEEK) == 0)
so->so_error = 0;
goto release;
}
if (so->so_state & SS_CANTRCVMORE) {
if (m)
goto dontblock;
else if (so->so_rcv.sb_cc == 0)
goto release;
}
for (; m; m = m->m_next)
if (m->m_type == MT_OOBDATA || (m->m_flags & M_EOR)) {
m = so->so_rcv.sb_mb;
goto dontblock;
}
if ((so->so_state & (SS_ISCONNECTED|SS_ISCONNECTING)) == 0 &&
(so->so_proto->pr_flags & PR_CONNREQUIRED)) {
error = ENOTCONN;
goto release;
}
if (uio->uio_resid == 0 && controlp == NULL)
goto release;
if (flags & MSG_DONTWAIT) {
error = EWOULDBLOCK;
goto release;
}
SBLASTRECORDCHK(&so->so_rcv, "soreceive sbwait 1");
SBLASTMBUFCHK(&so->so_rcv, "soreceive sbwait 1");
sbunlock(so, &so->so_rcv);
error = sbwait(so, &so->so_rcv);
if (error) {
sounlock_shared(so);
return (error);
}
goto restart;
}
dontblock:
/*
* On entry here, m points to the first record of the socket buffer.
* From this point onward, we maintain 'nextrecord' as a cache of the
* pointer to the next record in the socket buffer. We must keep the
* various socket buffer pointers and local stack versions of the
* pointers in sync, pushing out modifications before operations that
* may sleep, and re-reading them afterwards.
*
* Otherwise, we will race with the network stack appending new data
* or records onto the socket buffer by using inconsistent/stale
* versions of the field, possibly resulting in socket buffer
* corruption.
*/
if (uio->uio_procp)
uio->uio_procp->p_ru.ru_msgrcv++;
KASSERT(m == so->so_rcv.sb_mb);
SBLASTRECORDCHK(&so->so_rcv, "soreceive 1");
SBLASTMBUFCHK(&so->so_rcv, "soreceive 1");
nextrecord = m->m_nextpkt;
if (pr->pr_flags & PR_ADDR) {
#ifdef DIAGNOSTIC
if (m->m_type != MT_SONAME)
panic("receive 1a: so %p, so_type %d, m %p, m_type %d",
so, so->so_type, m, m->m_type);
#endif
orig_resid = 0;
if (flags & MSG_PEEK) {
if (paddr)
*paddr = m_copym(m, 0, m->m_len, M_NOWAIT);
m = m->m_next;
} else {
sbfree(so, &so->so_rcv, m);
if (paddr) {
*paddr = m;
so->so_rcv.sb_mb = m->m_next;
m->m_next = NULL;
m = so->so_rcv.sb_mb;
} else {
so->so_rcv.sb_mb = m_free(m);
m = so->so_rcv.sb_mb;
}
sbsync(&so->so_rcv, nextrecord);
}
}
while (m && m->m_type == MT_CONTROL && error == 0) {
int skip = 0;
if (flags & MSG_PEEK) {
if (mtod(m, struct cmsghdr *)->cmsg_type ==
SCM_RIGHTS) {
/* don't leak internalized SCM_RIGHTS msgs */
skip = 1;
} else if (controlp)
*controlp = m_copym(m, 0, m->m_len, M_NOWAIT);
m = m->m_next;
} else {
sbfree(so, &so->so_rcv, m);
so->so_rcv.sb_mb = m->m_next;
m->m_nextpkt = m->m_next = NULL;
cm = m;
m = so->so_rcv.sb_mb;
sbsync(&so->so_rcv, nextrecord);
if (controlp) {
if (pr->pr_domain->dom_externalize) {
sounlock_shared(so);
error =
(*pr->pr_domain->dom_externalize)
(cm, controllen, flags);
solock_shared(so);
}
*controlp = cm;
} else {
/*
* Dispose of any SCM_RIGHTS message that went
* through the read path rather than recv.
*/
if (pr->pr_domain->dom_dispose)
pr->pr_domain->dom_dispose(cm);
m_free(cm);
}
}
if (m != NULL)
nextrecord = so->so_rcv.sb_mb->m_nextpkt;
else
nextrecord = so->so_rcv.sb_mb;
if (controlp && !skip)
controlp = &(*controlp)->m_next;
orig_resid = 0;
}
/* If m is non-NULL, we have some data to read. */
if (m) {
type = m->m_type;
if (type == MT_OOBDATA)
flags |= MSG_OOB;
if (m->m_flags & M_BCAST)
flags |= MSG_BCAST;
if (m->m_flags & M_MCAST)
flags |= MSG_MCAST;