xsh_udpecho.c File Reference

#include <xinu.h>
#include <stdio.h>
#include <string.h>

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Functions
int	atoi (char *)
	ASCII文字列をint型に変換する。 More...
shellcmd	xsh_udpecho (int nargs, char *args[])

Function Documentation

atoi()

int atoi

(

char *

p

)

ASCII文字列をint型に変換する。

処理の流れは、
Step1. 「不要な文字（空白、TAB）の削除」もしくは「正数／負数の判定」を行う
Step2. 0〜9の範囲の値であれば、一桁ずつ記録する。それ以外の文字は呼び飛ばす
ASCIIコードとして、0=0x30、1=0x31、2=0x32、…、9=0x39であるため、
「0x30〜0x39の範囲のASCIIコード値(0〜9の値) - '0'(=0x30)」と計算すれば、
0〜9の整数値が得られる。
Step3. Step.1で取得した符号情報（±）を反映した整数を返す。

Parameters

[in]

p

ASCII文字列

Returns

ASCII文字列をint型に変換した整数値

Note

ASCIIコード情報は、ターミナル上で"$ man ascii"で確認できる。

Definition at line 19 of file atoi.c.

Referenced by xsh_udpecho().

{
    int n = 0, f = 0;

    for (;; p++)
    {
        switch (*p)
        {
        case ' ':
        case '\t':
            continue;
        case '-':
            f++;
        case '+':
            p++;
        }
        break;
    }

    while (*p >= '0' && *p <= '9')
    {
        n = n * 10 + *p++ - '0';
    }

    return (f ? -n : n);
}

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xsh_udpecho()

shellcmd xsh_udpecho	(	int	nargs,
		char *	args[]
	)

Definition at line 14 of file xsh_udpecho.c.

References atoi(), delay(), dot2ip(), fprintf(), printf(), stderr, strncmp(), strnlen(), SYSERR, TIMEOUT, udp_recv(), udp_register(), udp_release(), and udp_send().

{
    int i;          /* index into buffer        */
    int retval;         /* return value         */
    char    msg[] = "Xinu testing UDP echo"; /* message to send */
    char    inbuf[1500];        /* buffer for incoming reply    */
    int32   slot;           /* UDP slot to use      */
    int32   msglen;         /* length of outgoing message   */
    uint32  remoteip;       /* remote IP address to use */
    uint16  remport= 7;     /* remote port number to use    */
    uint16  locport = 52743;    /* local port to use        */
    int32   retries = 3;        /* number of retries        */
    int32   delay   = 500;      /* reception delay in ms    */

    /* For argument '--help', emit help about the 'udpecho' command */

    if (nargs == 2 && strncmp(args[1], "--help", 7) == 0) {
        printf("Use: %s  REMOTEIP\n\n", args[0]);
        printf("Description:\n");
        printf("\tBounce a message off a remote UDP echo server\n");
        printf("Options:\n");
        printf("\tREMOTEIP:\tIP address in dotted decimal\n");
        printf("\t--help\t display this help and exit\n");
        return 0;
    }

    /* Check for valid IP address argument */

    if (nargs != 2) {
        fprintf(stderr, "%s: invalid number of argument(s)\n", args[0]);
        fprintf(stderr, "Try '%s --help' for more information\n",
                args[0]);
        return 1;
    }

    if (dot2ip(args[1], &remoteip) == SYSERR) {
        fprintf(stderr, "%s: invalid IP address argument\r\n",
            args[0]);
        return 1;
    }
    if (nargs == 3) {
        retval = atoi(args[2]);
        if ( (retval <= 0) || (retval > 64535) ) {
            fprintf(stderr, "%s: invalid port argument\r\n",
                args[0]);
            return 1;
        }
        remport = (uint16) retval;
    }

    fprintf(stderr, "using remote port %d\n", remport);

    /* register local UDP port */

    slot = udp_register(remoteip, remport, locport);
    if (slot == SYSERR) {
        fprintf(stderr, "%s: could not reserve UDP port %d\n",
                args[0], locport);
        return 1;
    }

    /* Retry sending outgoing datagram and getting response */

    msglen = strnlen(msg, 1200);
    for (i=0; i<retries; i++) {
        retval = udp_send(slot, msg, msglen);
        if (retval == SYSERR) {
            fprintf(stderr, "%s: error sending UDP \n",
                args[0]);
            return 1;
        }

        retval = udp_recv(slot, inbuf, sizeof(inbuf), delay);
        if (retval == TIMEOUT) {
            fprintf(stderr, "%s: timeout...\n", args[0]);
            continue;
        } else if (retval == SYSERR) {
            fprintf(stderr, "%s: error from udp_recv \n",
                args[0]);
            udp_release(slot);
            return 1;
        }
        break;
    }

    udp_release(slot);
    if (retval == TIMEOUT) {
        fprintf(stderr, "%s: retry limit exceeded\n",
            args[0]);
        return 1;
    }

    /* Response received - check contents */

    if (retval != msglen) {
        fprintf(stderr, "%s: sent %d bytes and received %d\n",
            args[0], msglen, retval);
        return 1;
    }
    for (i = 0; i < msglen; i++) {
        if (msg[i] != inbuf[i]) {
            fprintf(stderr, "%s: reply differs at byte %d\n",
                args[0], i);
            return 1;
        }
    }

    printf("UDP echo test was successful\n");
    return 0;
}

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