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Suppression : programme C first-free-port

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Ahurac 2024-03-27 12:12:18 +01:00
parent a2d75a7a99
commit 58473c78ab
1 changed files with 0 additions and 124 deletions
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124
src/first-free-port.c
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@ -1,124 +0,0 @@
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sysexits.h>
#include <string.h>
#include <errno.h>
#define MIN_TCP_PORT 1
#define TCP_TABLE_PATH "/proc/net/tcp"
#define TCP_TABLE_LINE_LENGTH 151
#define LOCALHOSTIP_HEX "0100007F"
#define WILDCARDIP_HEX "00000000"
#define LISTENING_HEX "0A"
#define BLOCKS_TO_ALLOC 4
/**
* Print a nice error message
*/
static void print_error(char *name, const char *message) {
fprintf(stderr, "%s: %s\n", name, message);
}
/**
* Get all the listening TCP ports
*/
static unsigned short *get_listening_ports(FILE *tcp_table_fptr) {
unsigned short *listening_ports = malloc(BLOCKS_TO_ALLOC * sizeof(short));
char line[TCP_TABLE_LINE_LENGTH];
char delimiter[] = " ";
unsigned short len = 0;
char *address;
char *state;
char *field;
size_t blocks_allocated = BLOCKS_TO_ALLOC;
// Skip first line (header)
fgets(line, sizeof(line), tcp_table_fptr);
// Tokenize lines one by one
while (fgets(line, sizeof(line), tcp_table_fptr) != NULL) {
strtok(line, delimiter);
address = strtok(NULL, delimiter);
strtok(NULL, delimiter);
state = strtok(NULL, delimiter);
field = strtok(NULL, delimiter);
while (field != NULL) {
field = strtok(NULL, delimiter);
}
if ((!strncmp(address, LOCALHOSTIP_HEX, 8) || !strncmp(address, WILDCARDIP_HEX, 8)) && !strncmp(state, LISTENING_HEX, 2)) {
if (len == blocks_allocated) {
blocks_allocated = blocks_allocated + BLOCKS_TO_ALLOC;
listening_ports = realloc(listening_ports, blocks_allocated * sizeof(short));
}
listening_ports[len] = strtol(address + strlen(address) - 4, NULL, 16);
len++;
}
}
if (len == blocks_allocated) {
listening_ports = realloc(listening_ports, blocks_allocated + 1);
}
listening_ports[len] = 0;
return listening_ports;
}
static unsigned char is_port_available(const unsigned short port, const unsigned short *listening_ports) {
unsigned short i = 0;
while (listening_ports[i] != 0 && listening_ports[i] != port) {
i++;
}
return listening_ports[i] == 0;
}
static inline unsigned char is_valid_tcp_port(const unsigned short tcp_port) {
return tcp_port >= MIN_TCP_PORT;
}
int main(int argc, char *argv[]) {
unsigned short current_port;
if (argc >= 2) {
current_port = atoi(argv[1]);
} else {
current_port = 0;
}
if (!is_valid_tcp_port(current_port)) {
print_error(argv[0], "provide a valid TCP port number as first argument.");
return EX_USAGE;
}
// Open TCP table
FILE *tcp_table_fptr = fopen(TCP_TABLE_PATH, "r");
if (tcp_table_fptr == NULL) {
print_error(argv[0], "error opening the TCP table.");
return errno;
}
unsigned short *listening_ports = get_listening_ports(tcp_table_fptr);
if (fclose(tcp_table_fptr) != 0) {
print_error(argv[0], "can't close the TCP table.");
return errno;
}
// Check if the current port is available, add
while (!is_port_available(current_port, listening_ports)) {
current_port++;
}
free(listening_ports);
if (is_valid_tcp_port(current_port)) {
printf("%d\n", current_port);
return EXIT_SUCCESS;
} else {
print_error(argv[0], "no more ports available; how did you fuck up that bad ???");
return EX_TEMPFAIL;
}
}