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- #include <stdlib.h> /* exit */
- #include <unistd.h> /* read, write, close */
- #include <string.h> /* memcpy, memset */
- #include <sys/socket.h> /* socket, connect */
- #include <netinet/in.h> /* struct sockaddr_in, struct sockaddr */
- #include <netdb.h> /* struct hostent, gethostbyname */
- #include <stdio.h>
- #include <sys/types.h>
- #include <unistd.h>
- #include <stdint.h>
- #include <stdlib.h>
- static char encoding_table[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
- 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
- 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
- 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
- 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
- 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
- 'w', 'x', 'y', 'z', '0', '1', '2', '3',
- '4', '5', '6', '7', '8', '9', '+', '/'};
- static char *decoding_table = NULL;
- static int mod_table[] = {0, 2, 1};
- void build_decoding_table() {
- decoding_table = malloc(256);
- for (int i = 0; i < 64; i++)
- decoding_table[(unsigned char) encoding_table[i]] = i;
- }
- void base64_cleanup() {
- free(decoding_table);
- }
- unsigned char *base64_decode(const char *data,
- size_t input_length,
- size_t *output_length) {
- if (decoding_table == NULL) build_decoding_table();
- if (input_length % 4 != 0) return NULL;
- *output_length = input_length / 4 * 3;
- if (data[input_length - 1] == '=') (*output_length)--;
- if (data[input_length - 2] == '=') (*output_length)--;
- unsigned char *decoded_data = malloc(*output_length);
- if (decoded_data == NULL) return NULL;
- for (int i = 0, j = 0; i < input_length;) {
- uint32_t sextet_a = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]];
- uint32_t sextet_b = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]];
- uint32_t sextet_c = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]];
- uint32_t sextet_d = data[i] == '=' ? 0 & i++ : decoding_table[data[i++]];
- uint32_t triple = (sextet_a << 3 * 6)
- + (sextet_b << 2 * 6)
- + (sextet_c << 1 * 6)
- + (sextet_d << 0 * 6);
- if (j < *output_length) decoded_data[j++] = (triple >> 2 * 8) & 0xFF;
- if (j < *output_length) decoded_data[j++] = (triple >> 1 * 8) & 0xFF;
- if (j < *output_length) decoded_data[j++] = (triple >> 0 * 8) & 0xFF;
- }
- return decoded_data;
- }
- #define CHUNK 512 /* read 1024 bytes at a time */
- void main(int argc, char *argv[]) {
- char buffer2[1024];
- strcpy(buffer2,argv[1]);
- char buffer[CHUNK];
- size_t ret;
- int len = strlen(argv[2]);
- char *decoded = base64_decode(argv[2],len,&ret);
- printf("%s",decoded);
- printf("Done!\n");
- }
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