ref: b8986a889d7e3a445c0265c5cfb3b1db385db756
dir: /sys/src/cmd/ssh/sshserve.c/
#include "ssh.h" char *cipherlist = "blowfish rc4 3des"; char *authlist = "tis"; void fromnet(Conn*); void startcmd(Conn*, char*, int*, int*); int maxmsg = 256*1024; Cipher *allcipher[] = { &cipherrc4, &cipherblowfish, &cipher3des, &cipherdes, &ciphernone, &ciphertwiddle, }; Authsrv *allauthsrv[] = { &authsrvpassword, &authsrvtis, }; Cipher* findcipher(char *name, Cipher **list, int nlist) { int i; for(i=0; i<nlist; i++) if(strcmp(name, list[i]->name) == 0) return list[i]; error("unknown cipher %s", name); return nil; } Authsrv* findauthsrv(char *name, Authsrv **list, int nlist) { int i; for(i=0; i<nlist; i++) if(strcmp(name, list[i]->name) == 0) return list[i]; error("unknown authsrv %s", name); return nil; } void usage(void) { fprint(2, "usage: sshserve [-A authlist] [-c cipherlist] client-ip-address\n"); exits("usage"); } void main(int argc, char **argv) { char *f[16]; int i; Conn c; fmtinstall('B', mpfmt); fmtinstall('H', encodefmt); atexit(atexitkiller); atexitkill(getpid()); memset(&c, 0, sizeof c); ARGBEGIN{ case 'D': debuglevel = atoi(EARGF(usage())); break; case 'A': authlist = EARGF(usage()); break; case 'c': cipherlist = EARGF(usage()); break; default: usage(); }ARGEND if(argc != 1) usage(); c.host = argv[0]; sshlog("connect from %s", c.host); /* limit of 768 bits in remote host key? */ c.serverpriv = rsagen(768, 6, 0); if(c.serverpriv == nil) sysfatal("rsagen failed: %r"); c.serverkey = &c.serverpriv->pub; c.nokcipher = getfields(cipherlist, f, nelem(f), 1, ", "); c.okcipher = emalloc(sizeof(Cipher*)*c.nokcipher); for(i=0; i<c.nokcipher; i++) c.okcipher[i] = findcipher(f[i], allcipher, nelem(allcipher)); c.nokauthsrv = getfields(authlist, f, nelem(f), 1, ", "); c.okauthsrv = emalloc(sizeof(Authsrv*)*c.nokauthsrv); for(i=0; i<c.nokauthsrv; i++) c.okauthsrv[i] = findauthsrv(f[i], allauthsrv, nelem(allauthsrv)); sshserverhandshake(&c); fromnet(&c); } void fromnet(Conn *c) { int infd, kidpid, n; char *cmd; Msg *m; infd = kidpid = -1; for(;;){ m = recvmsg(c, -1); if(m == nil) exits(nil); switch(m->type){ default: //badmsg(m, 0); sendmsg(allocmsg(c, SSH_SMSG_FAILURE, 0)); break; case SSH_MSG_DISCONNECT: sysfatal("client disconnected"); case SSH_CMSG_REQUEST_PTY: sendmsg(allocmsg(c, SSH_SMSG_SUCCESS, 0)); break; case SSH_CMSG_X11_REQUEST_FORWARDING: sendmsg(allocmsg(c, SSH_SMSG_FAILURE, 0)); break; case SSH_CMSG_MAX_PACKET_SIZE: maxmsg = getlong(m); sendmsg(allocmsg(c, SSH_SMSG_SUCCESS, 0)); break; case SSH_CMSG_REQUEST_COMPRESSION: sendmsg(allocmsg(c, SSH_SMSG_FAILURE, 0)); break; case SSH_CMSG_EXEC_SHELL: startcmd(c, nil, &kidpid, &infd); goto InteractiveMode; case SSH_CMSG_EXEC_CMD: cmd = getstring(m); startcmd(c, cmd, &kidpid, &infd); goto InteractiveMode; } free(m); } InteractiveMode: for(;;){ free(m); m = recvmsg(c, -1); if(m == nil) exits(nil); switch(m->type){ default: badmsg(m, 0); case SSH_MSG_DISCONNECT: postnote(PNGROUP, kidpid, "hangup"); sysfatal("client disconnected"); case SSH_CMSG_STDIN_DATA: if(infd != 0){ n = getlong(m); write(infd, getbytes(m, n), n); } break; case SSH_CMSG_EOF: close(infd); infd = -1; break; case SSH_CMSG_EXIT_CONFIRMATION: /* sent by some clients as dying breath */ exits(nil); case SSH_CMSG_WINDOW_SIZE: /* we don't care */ break; } } } void copyout(Conn *c, int fd, int mtype) { char buf[8192]; int n, max, pid; Msg *m; max = sizeof buf; if(max > maxmsg - 32) /* 32 is an overestimate of packet overhead */ max = maxmsg - 32; if(max <= 0) sysfatal("maximum message size too small"); switch(pid = rfork(RFPROC|RFMEM|RFNOWAIT)){ case -1: sysfatal("fork: %r"); case 0: break; default: atexitkill(pid); return; } while((n = read(fd, buf, max)) > 0){ m = allocmsg(c, mtype, 4+n); putlong(m, n); putbytes(m, buf, n); sendmsg(m); } exits(nil); } void startcmd(Conn *c, char *cmd, int *kidpid, int *kidin) { int i, pid, kpid; int pfd[3][2]; char *dir; char *sysname, *tz; Msg *m; Waitmsg *w; for(i=0; i<3; i++) if(pipe(pfd[i]) < 0) sysfatal("pipe: %r"); sysname = getenv("sysname"); tz = getenv("timezone"); switch(pid = rfork(RFPROC|RFMEM|RFNOWAIT)){ case -1: sysfatal("fork: %r"); case 0: switch(kpid = rfork(RFPROC|RFNOTEG|RFENVG|RFFDG)){ case -1: sysfatal("fork: %r"); case 0: for(i=0; i<3; i++){ if(dup(pfd[i][1], i) < 0) sysfatal("dup: %r"); close(pfd[i][0]); close(pfd[i][1]); } putenv("user", c->user); if(sysname) putenv("sysname", sysname); if(tz) putenv("tz", tz); dir = smprint("/usr/%s", c->user); if(dir == nil || chdir(dir) < 0) chdir("/"); if(cmd){ putenv("service", "rx"); execl("/bin/rc", "rc", "-lc", cmd, nil); sysfatal("cannot exec /bin/rc: %r"); }else{ putenv("service", "con"); execl("/bin/ip/telnetd", "telnetd", "-tn", nil); sysfatal("cannot exec /bin/ip/telnetd: %r"); } default: *kidpid = kpid; rendezvous(kidpid, 0); for(;;){ if((w = wait()) == nil) sysfatal("wait: %r"); if(w->pid == kpid) break; free(w); } if(w->msg[0]){ m = allocmsg(c, SSH_MSG_DISCONNECT, 4+strlen(w->msg)); putstring(m, w->msg); sendmsg(m); }else{ m = allocmsg(c, SSH_SMSG_EXITSTATUS, 4); putlong(m, 0); sendmsg(m); } for(i=0; i<3; i++) close(pfd[i][0]); free(w); exits(nil); break; } default: atexitkill(pid); rendezvous(kidpid, 0); break; } for(i=0; i<3; i++) close(pfd[i][1]); copyout(c, pfd[1][0], SSH_SMSG_STDOUT_DATA); copyout(c, pfd[2][0], SSH_SMSG_STDERR_DATA); *kidin = pfd[0][0]; }