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- /*
- * dial - connect to a service (parallel version)
- */
- #include <u.h>
- #include <libc.h>
- typedef struct Conn Conn;
- typedef struct Dest Dest;
- typedef struct DS DS;
- enum
- {
- Maxstring = 128,
- Maxpath = 256,
- Maxcsreply = 64*80, /* this is probably overly generous */
- /*
- * this should be a plausible slight overestimate for non-interactive
- * use even if it's ridiculously long for interactive use.
- */
- Maxconnms = 2*60*1000, /* 2 minutes */
- };
- struct DS {
- /* dist string */
- char buf[Maxstring];
- char *netdir;
- char *proto;
- char *rem;
- /* other args */
- char *local;
- char *dir;
- int *cfdp;
- };
- /*
- * malloc these; they need to be writable by this proc & all children.
- * the stack is private to each proc, and static allocation in the data
- * segment would not permit concurrent dials within a multi-process program.
- */
- struct Conn {
- int pid;
- int dead;
- int dfd;
- int cfd;
- char dir[NETPATHLEN+1];
- char err[ERRMAX];
- };
- struct Dest {
- Conn *conn; /* allocated array */
- Conn *connend;
- int nkid;
- long oalarm;
- int naddrs;
- QLock winlck;
- int winner; /* index into conn[] */
- char *nextaddr;
- char addrlist[Maxcsreply];
- };
- static int call(char*, char*, DS*, Dest*, Conn*);
- static int csdial(DS*);
- static void _dial_string_parse(char*, DS*);
- /*
- * the dialstring is of the form '[/net/]proto!dest'
- */
- static int
- dialimpl(char *dest, char *local, char *dir, int *cfdp)
- {
- DS ds;
- int rv;
- char err[ERRMAX], alterr[ERRMAX];
- ds.local = local;
- ds.dir = dir;
- ds.cfdp = cfdp;
- _dial_string_parse(dest, &ds);
- if(ds.netdir)
- return csdial(&ds);
- ds.netdir = "/net";
- rv = csdial(&ds);
- if(rv >= 0)
- return rv;
- err[0] = '\0';
- errstr(err, sizeof err);
- if(strstr(err, "refused") != 0){
- werrstr("%s", err);
- return rv;
- }
- ds.netdir = "/net.alt";
- rv = csdial(&ds);
- if(rv >= 0)
- return rv;
- alterr[0] = 0;
- errstr(alterr, sizeof alterr);
- if(strstr(alterr, "translate") || strstr(alterr, "does not exist"))
- werrstr("%s", err);
- else
- werrstr("%s", alterr);
- return rv;
- }
- /*
- * the thread library can't cope with rfork(RFMEM|RFPROC),
- * so it must override this with a private version of dial.
- */
- int (*_dial)(char *, char *, char *, int *) = dialimpl;
- int
- dial(char *dest, char *local, char *dir, int *cfdp)
- {
- return (*_dial)(dest, local, dir, cfdp);
- }
- static int
- connsalloc(Dest *dp, int addrs)
- {
- Conn *conn;
- free(dp->conn);
- dp->connend = nil;
- assert(addrs > 0);
- dp->conn = mallocz(addrs * sizeof *dp->conn, 1);
- if(dp->conn == nil)
- return -1;
- dp->connend = dp->conn + addrs;
- for(conn = dp->conn; conn < dp->connend; conn++)
- conn->cfd = conn->dfd = -1;
- return 0;
- }
- static void
- freedest(Dest *dp)
- {
- long oalarm;
- if (dp == nil)
- return;
- oalarm = dp->oalarm;
- free(dp->conn);
- free(dp);
- if (oalarm >= 0)
- alarm(oalarm);
- }
- static void
- closeopenfd(int *fdp)
- {
- if (*fdp >= 0) {
- close(*fdp);
- *fdp = -1;
- }
- }
- static void
- notedeath(Dest *dp, char *exitsts)
- {
- int i, n, pid;
- char *fields[5]; /* pid + 3 times + error */
- Conn *conn;
- for (i = 0; i < nelem(fields); i++)
- fields[i] = "";
- n = tokenize(exitsts, fields, nelem(fields));
- if (n < 4)
- return;
- pid = atoi(fields[0]);
- if (pid <= 0)
- return;
- for (conn = dp->conn; conn < dp->connend; conn++)
- if (conn->pid == pid && !conn->dead) { /* it's one we know? */
- if (conn - dp->conn != dp->winner) {
- closeopenfd(&conn->dfd);
- closeopenfd(&conn->cfd);
- }
- strncpy(conn->err, fields[4], sizeof conn->err - 1);
- conn->err[sizeof conn->err - 1] = '\0';
- conn->dead = 1;
- return;
- }
- /* not a proc that we forked */
- }
- static int
- outstandingprocs(Dest *dp)
- {
- Conn *conn;
- for (conn = dp->conn; conn < dp->connend; conn++)
- if (!conn->dead)
- return 1;
- return 0;
- }
- static int
- reap(Dest *dp)
- {
- char exitsts[2*ERRMAX];
- if (outstandingprocs(dp) && await(exitsts, sizeof exitsts) >= 0) {
- notedeath(dp, exitsts);
- return 0;
- }
- return -1;
- }
- static int
- fillinds(DS *ds, Dest *dp)
- {
- Conn *conn;
- if (dp->winner < 0)
- return -1;
- conn = &dp->conn[dp->winner];
- if (ds->cfdp)
- *ds->cfdp = conn->cfd;
- if (ds->dir) {
- strncpy(ds->dir, conn->dir, NETPATHLEN);
- ds->dir[NETPATHLEN-1] = '\0';
- }
- return conn->dfd;
- }
- static int
- connectwait(Dest *dp, char *besterr)
- {
- Conn *conn;
- /* wait for a winner or all attempts to time out */
- while (dp->winner < 0 && reap(dp) >= 0)
- ;
- /* kill all of our still-live kids & reap them */
- for (conn = dp->conn; conn < dp->connend; conn++)
- if (!conn->dead)
- postnote(PNPROC, conn->pid, "alarm");
- while (reap(dp) >= 0)
- ;
- /* rummage about and report some error string */
- for (conn = dp->conn; conn < dp->connend; conn++)
- if (conn - dp->conn != dp->winner && conn->dead &&
- conn->err[0]) {
- strncpy(besterr, conn->err, ERRMAX-1);
- besterr[ERRMAX-1] = '\0';
- break;
- }
- return dp->winner;
- }
- static int
- parsecs(Dest *dp, char **clonep, char **destp)
- {
- char *dest, *p;
- dest = strchr(dp->nextaddr, ' ');
- if(dest == nil) {
- p = strchr(dp->nextaddr, '\n');
- if(p)
- *p = '\0';
- werrstr("malformed clone cmd from cs `%s'", dp->nextaddr);
- if(p)
- *p = '\n';
- return -1;
- }
- *dest++ = '\0';
- p = strchr(dest, '\n');
- if(p == nil)
- return -1;
- *p++ = '\0';
- *clonep = dp->nextaddr;
- *destp = dest;
- dp->nextaddr = p; /* advance to next line */
- return 0;
- }
- static void
- pickuperr(char *besterr, char *err)
- {
- err[0] = '\0';
- errstr(err, ERRMAX);
- if(strstr(err, "does not exist") == 0)
- strcpy(besterr, err);
- }
- static int
- catcher(void *, char *s)
- {
- return strstr(s, "alarm") != nil;
- }
- /*
- * try all addresses in parallel and take the first one that answers;
- * this helps when systems have ip v4 and v6 addresses but are
- * only reachable from here on one (or some) of them.
- */
- static int
- dialmulti(DS *ds, Dest *dp)
- {
- int rv, kid, kidme;
- char *clone, *dest;
- char besterr[ERRMAX];
- dp->winner = -1;
- dp->nkid = 0;
- while(dp->winner < 0 && *dp->nextaddr != '\0' &&
- parsecs(dp, &clone, &dest) >= 0) {
- kidme = dp->nkid++; /* make private copy on stack */
- kid = rfork(RFPROC|RFMEM); /* spin off a call attempt */
- if (kid < 0)
- --dp->nkid;
- else if (kid == 0) {
- char err[ERRMAX];
- /* only in kid, to avoid atnotify callbacks in parent */
- atnotify(catcher, 1);
- *besterr = '\0';
- rv = call(clone, dest, ds, dp, &dp->conn[kidme]);
- if(rv < 0)
- pickuperr(besterr, err);
- _exits(besterr); /* avoid atexit callbacks */
- }
- }
- *besterr = '\0';
- rv = connectwait(dp, besterr);
- if(rv < 0)
- werrstr("%s", (*besterr? besterr: "unknown error"));
- return rv;
- }
- static int
- csdial(DS *ds)
- {
- int n, fd, rv, addrs, bleft;
- char c;
- char *addrp, *clone2, *dest;
- char buf[Maxstring], clone[Maxpath], err[ERRMAX], besterr[ERRMAX];
- Dest *dp;
- werrstr("");
- dp = mallocz(sizeof *dp, 1);
- if(dp == nil)
- return -1;
- dp->winner = -1;
- dp->oalarm = alarm(0);
- if (connsalloc(dp, 1) < 0) { /* room for a single conn. */
- freedest(dp);
- return -1;
- }
- /*
- * open connection server
- */
- snprint(buf, sizeof(buf), "%s/cs", ds->netdir);
- fd = open(buf, ORDWR);
- if(fd < 0){
- /* no connection server, don't translate */
- snprint(clone, sizeof(clone), "%s/%s/clone", ds->netdir, ds->proto);
- rv = call(clone, ds->rem, ds, dp, &dp->conn[0]);
- fillinds(ds, dp);
- freedest(dp);
- return rv;
- }
- /*
- * ask connection server to translate
- * e.g., net!cs.bell-labs.com!smtp
- */
- snprint(buf, sizeof(buf), "%s!%s", ds->proto, ds->rem);
- if(write(fd, buf, strlen(buf)) < 0){
- close(fd);
- freedest(dp);
- return -1;
- }
- /*
- * read all addresses from the connection server:
- * /net/tcp/clone 135.104.9.78!25
- * /net/tcp/clone 2620:0:dc0:1805::29!25
- *
- * assumes that we'll get one record per read.
- */
- seek(fd, 0, 0);
- addrs = 0;
- addrp = dp->nextaddr = dp->addrlist;
- bleft = sizeof dp->addrlist - 2; /* 2 is room for \n\0 */
- while(bleft > 0 && (n = read(fd, addrp, bleft)) > 0) {
- if (addrp[n-1] != '\n')
- addrp[n++] = '\n';
- addrs++;
- addrp += n;
- bleft -= n;
- }
- *addrp = '\0';
- /*
- * if we haven't read all of cs's output, assume the last line might
- * have been truncated and ignore it. we really don't expect this
- * to happen.
- */
- if (addrs > 0 && bleft <= 0 && read(fd, &c, 1) == 1)
- addrs--;
- close(fd);
- *besterr = 0;
- rv = -1; /* pessimistic default */
- dp->naddrs = addrs;
- if (addrs == 0)
- werrstr("no address to dial");
- else if (addrs == 1) {
- /* common case: dial one address without forking */
- if (parsecs(dp, &clone2, &dest) >= 0 &&
- (rv = call(clone2, dest, ds, dp, &dp->conn[0])) < 0) {
- pickuperr(besterr, err);
- werrstr("%s", besterr);
- }
- } else if (connsalloc(dp, addrs) >= 0)
- rv = dialmulti(ds, dp);
- /* fill in results */
- if (rv >= 0 && dp->winner >= 0)
- rv = fillinds(ds, dp);
- freedest(dp);
- return rv;
- }
- static int
- call(char *clone, char *dest, DS *ds, Dest *dp, Conn *conn)
- {
- int fd, cfd, n, calleralarm, oalarm;
- char cname[Maxpath], name[Maxpath], data[Maxpath], *p;
- /* because cs is in a different name space, replace the mount point */
- if(*clone == '/'){
- p = strchr(clone+1, '/');
- if(p == nil)
- p = clone;
- else
- p++;
- } else
- p = clone;
- snprint(cname, sizeof cname, "%s/%s", ds->netdir, p);
- conn->pid = getpid();
- conn->cfd = cfd = open(cname, ORDWR);
- if(cfd < 0)
- return -1;
- /* get directory name */
- n = read(cfd, name, sizeof(name)-1);
- if(n < 0){
- closeopenfd(&conn->cfd);
- return -1;
- }
- name[n] = 0;
- for(p = name; *p == ' '; p++)
- ;
- snprint(name, sizeof(name), "%ld", strtoul(p, 0, 0));
- p = strrchr(cname, '/');
- *p = 0;
- if(ds->dir)
- snprint(conn->dir, NETPATHLEN, "%s/%s", cname, name);
- snprint(data, sizeof(data), "%s/%s/data", cname, name);
- /* should be no alarm pending now; re-instate caller's alarm, if any */
- calleralarm = dp->oalarm > 0;
- if (calleralarm)
- alarm(dp->oalarm);
- else if (dp->naddrs > 1) /* in a sub-process? */
- alarm(Maxconnms);
- /* connect */
- if(ds->local)
- snprint(name, sizeof(name), "connect %s %s", dest, ds->local);
- else
- snprint(name, sizeof(name), "connect %s", dest);
- if(write(cfd, name, strlen(name)) < 0){
- closeopenfd(&conn->cfd);
- return -1;
- }
- oalarm = alarm(0); /* don't let alarm interrupt critical section */
- if (calleralarm)
- dp->oalarm = oalarm; /* time has passed, so update user's */
- /* open data connection */
- conn->dfd = fd = open(data, ORDWR);
- if(fd < 0){
- closeopenfd(&conn->cfd);
- alarm(dp->oalarm);
- return -1;
- }
- if(ds->cfdp == nil)
- closeopenfd(&conn->cfd);
- n = conn - dp->conn;
- if (dp->winner < 0) {
- qlock(&dp->winlck);
- if (dp->winner < 0 && conn < dp->connend)
- dp->winner = n;
- qunlock(&dp->winlck);
- }
- alarm(calleralarm? dp->oalarm: 0);
- return fd;
- }
- /*
- * parse a dial string
- */
- static void
- _dial_string_parse(char *str, DS *ds)
- {
- char *p, *p2;
- strncpy(ds->buf, str, Maxstring);
- ds->buf[Maxstring-1] = 0;
- p = strchr(ds->buf, '!');
- if(p == 0) {
- ds->netdir = 0;
- ds->proto = "net";
- ds->rem = ds->buf;
- } else {
- if(*ds->buf != '/' && *ds->buf != '#'){
- ds->netdir = 0;
- ds->proto = ds->buf;
- } else {
- /* expecting /net.alt/tcp!foo or #I1/tcp!foo */
- for(p2 = p; p2 > ds->buf && *p2 != '/'; p2--)
- ;
- *p2++ = 0;
- ds->netdir = ds->buf;
- ds->proto = p2;
- }
- *p = 0;
- ds->rem = p + 1;
- }
- }
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