hexdump

hexdump.c

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

extern void hexdump(FILE * stream, void const * data, unsigned int len)
{
    unsigned int i;
    unsigned int r,c;
    
    if (!stream)
        return;
    if (!data)
        return;
    
    for (r=0,i=0; r<(len/16+(len%16!=0)); r++,i+=16)
    {
        fprintf(stream,"%04X:   ",i); /* location of first byte in line */

        for (c=i; c<i+8; c++) /* left half of hex dump */
            if (c<len)
                fprintf(stream,"%02X ",((unsigned char const *)data)[c]);
            else
                fprintf(stream,"   "); /* pad if short line */

        fprintf(stream,"  ");

        for (c=i+8; c<i+16; c++) /* right half of hex dump */
            if (c<len)
                fprintf(stream,"%02X ",((unsigned char const *)data)[c]);
            else
                fprintf(stream,"   "); /* pad if short line */

        fprintf(stream,"   ");

        for (c=i; c<i+16; c++) /* ASCII dump */
            if (c<len)
                if (((unsigned char const *)data)[c]>=32 &&
                    ((unsigned char const *)data)[c]<127)
                    fprintf(stream,"%c",((char const *)data)[c]);
                else
                    fprintf(stream,"."); /* put this for non-printables */
            else
                fprintf(stream," "); /* pad if short line */

        fprintf(stream,"\n");
    }
    
    fflush(stream);
}

struct packet
{
    unsigned char smac[6];
    unsigned char dmac[6];
    unsigned char sip[4];
    unsigned char dip[4];
    unsigned char data[128];
};

int main(int argc, char *argv[])
{
    struct packet p = {
        .smac = {0x00, 0x00, 0x00, 0x11, 0x22, 0x33},
        .dmac = {0x00, 0x00, 0x00, 0x44, 0x55, 0x66},
        .sip = {192, 168, 1, 10},
        .dip = {192, 168, 1, 20},
    };
    char *str = "Hello, My name is huzhifeng!";
    unsigned int len = 0;

    if (argc > 1)
    {
        str = argv[1];
    }
    len = strlen(str);

    hexdump(stdout, str, len);
    strcpy((char *)p.data, "This is the test data: hello world");
    hexdump(stdout, &p, sizeof(p));

    return 0;
}

/*
[root@huzhifeng tmp]# gcc -o hexdump hexdump.c 
[root@huzhifeng tmp]# ./hexdump                
0000:   48 65 6C 6C 6F 2C 20 4D   79 20 6E 61 6D 65 20 69    Hello, My name i
0010:   73 20 68 75 7A 68 69 66   65 6E 67 21                s huzhifeng!    
0000:   00 00 00 11 22 33 00 00   00 44 55 66 C0 A8 01 0A    ...."3...DUf....
0010:   C0 A8 01 14 54 68 69 73   20 69 73 20 74 68 65 20    ....This is the 
0020:   74 65 73 74 20 64 61 74   61 3A 20 68 65 6C 6C 6F    test data: hello
0030:   20 77 6F 72 6C 64 00 00   00 00 00 00 00 00 00 00     world..........
0040:   00 00 00 00 00 00 00 00   00 00 00 00 00 00 00 00    ................
0050:   00 00 00 00 00 00 00 00   00 00 00 00 00 00 00 00    ................
0060:   00 00 00 00 00 00 00 00   00 00 00 00 00 00 00 00    ................
0070:   00 00 00 00 00 00 00 00   00 00 00 00 00 00 00 00    ................
0080:   00 00 00 00 00 00 00 00   00 00 00 00 00 00 00 00    ................
0090:   00 00 00 00                                          ....            
[root@huzhifeng tmp]# ./hexdump abcdefghijklmnopqrstuvwxyz1234567890
0000:   61 62 63 64 65 66 67 68   69 6A 6B 6C 6D 6E 6F 70    abcdefghijklmnop
0010:   71 72 73 74 75 76 77 78   79 7A 31 32 33 34 35 36    qrstuvwxyz123456
0020:   37 38 39 30                                          7890            
0000:   00 00 00 11 22 33 00 00   00 44 55 66 C0 A8 01 0A    ...."3...DUf....
0010:   C0 A8 01 14 54 68 69 73   20 69 73 20 74 68 65 20    ....This is the 
0020:   74 65 73 74 20 64 61 74   61 3A 20 68 65 6C 6C 6F    test data: hello
0030:   20 77 6F 72 6C 64 00 00   00 00 00 00 00 00 00 00     world..........
0040:   00 00 00 00 00 00 00 00   00 00 00 00 00 00 00 00    ................
0050:   00 00 00 00 00 00 00 00   00 00 00 00 00 00 00 00    ................
0060:   00 00 00 00 00 00 00 00   00 00 00 00 00 00 00 00    ................
0070:   00 00 00 00 00 00 00 00   00 00 00 00 00 00 00 00    ................
0080:   00 00 00 00 00 00 00 00   00 00 00 00 00 00 00 00    ................
0090:   00 00 00 00                                          ....            
[root@huzhifeng tmp]# 
*/