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Annotation of 43BSD/contrib/courier/daemon/courierd.c, revision 1.1

1.1     ! root        1: #ifndef lint
        !             2: static char sccsid[] = "@(#)courierd.c 4.4 (Berkeley) 9/17/85";
        !             3: #endif
        !             4: 
        !             5: /*
        !             6:  * Courier program instantiation server
        !             7:  *
        !             8:  * When a connection is made, it reads the program name as a Courier string.
        !             9:  * The directory /usr/new/lib/courier is used as a database of program names;
        !            10:  * the executable program must either reside there or have a link there.
        !            11:  * The program is spawned with user and group ID equal to that of the
        !            12:  * executable file, and must write a single zero byte back to the caller to 
        !            13:  * indicate successful instantiation.
        !            14:  * If instantiation was unsuccessful, the daemon will write back a null-
        !            15:  * terminated error message.
        !            16:  */
        !            17: #include <sys/types.h>
        !            18: #include <sys/socket.h>
        !            19: #include <sys/stat.h>
        !            20: #include <sys/wait.h>
        !            21: 
        !            22: #include <netinet/in.h>
        !            23: 
        !            24: #include <stdio.h>
        !            25: #include <signal.h>
        !            26: #include <errno.h>
        !            27: #include <netdb.h>
        !            28: #include <setjmp.h>
        !            29: #include <syslog.h>
        !            30: 
        !            31: #include "../lib/courier.h"
        !            32: 
        !            33: #define LIBCOURIER "/usr/new/lib/courier"
        !            34: 
        !            35: jmp_buf        alarmbuf;
        !            36: int    catch();
        !            37: 
        !            38: main(argc, argv)
        !            39:        int argc;
        !            40:        char **argv;
        !            41: {
        !            42:        struct sockaddr_in sin;
        !            43:        Cardinal n, nbytes;
        !            44:        struct stat statbuf;
        !            45:        char name[200];
        !            46:        int len;
        !            47: 
        !            48:        len = sizeof (sin);
        !            49:        if (getpeername(0, &sin, &len) < 0) {
        !            50:                fprintf(stderr, "%s: ", argv[0]), perror("getpeername");
        !            51:                _exit(1);
        !            52:        }
        !            53:        openlog("courier", LOG_ODELAY, LOG_DAEMON);
        !            54:        if (chdir(LIBCOURIER)) {
        !            55:                syslog(LOG_ERR, "chdir: %s: %m", LIBCOURIER);
        !            56:                _exit(2);
        !            57:        }
        !            58:        setpgrp(0, getpid());
        !            59:        signal(SIGHUP, SIG_DFL);
        !            60:        signal(SIGINT, SIG_DFL);
        !            61:        signal(SIGQUIT, SIG_DFL);
        !            62:        signal(SIGALRM, catch);
        !            63: 
        !            64:        dup2(0, 1);
        !            65: 
        !            66:        alarm(60);
        !            67:        if (setjmp(alarmbuf) == 0)
        !            68:                read(0, &n, sizeof(Cardinal));
        !            69:        alarm(0);
        !            70: 
        !            71:        UnpackCardinal(&nbytes, &n);
        !            72:        /*
        !            73:         * Courier strings are always word-aligned, so if the byte count is odd,
        !            74:         * we must also read the padding byte.
        !            75:         */
        !            76:        read(0, name, nbytes + (nbytes % 2));
        !            77:        name[nbytes] = '\0';
        !            78: 
        !            79:        if (name[0] == '/' || name[0] == '.' || stat(name, &statbuf) != 0)
        !            80:                goto bad;
        !            81:        setgroups(0, 0);
        !            82:        setregid(statbuf.st_gid, statbuf.st_gid);
        !            83:        setreuid(statbuf.st_uid, statbuf.st_uid);
        !            84:        execl(name, name, 0);
        !            85: bad:
        !            86:        error("Unknown Courier program.\n");
        !            87:        syslog(LOG_ERR, "Unknown Courier program");
        !            88:        exit(1);
        !            89: }
        !            90: 
        !            91: /*
        !            92:  * Catch alarm clock so read's will timeout.
        !            93:  */
        !            94: catch()
        !            95: {
        !            96: 
        !            97:        longjmp(alarmbuf, 1);
        !            98: }
        !            99: 
        !           100: /*
        !           101:  * Write back a null-terminated error message.
        !           102:  */
        !           103: error(s)
        !           104:        char *s;
        !           105: {
        !           106:        write(1, s, strlen(s)+1);
        !           107: }

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