Created
February 19, 2014 14:18
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#include <sys/types.h> | |
#include <sys/socket.h> | |
#include <stdlib.h> | |
#include <stdio.h> | |
#include <string.h> | |
#include <errno.h> | |
#include <netinet/in.h> /* this is needed for struct sockaddr_in (IPv4 address) */ | |
#include <unistd.h> /* close syscall */ | |
#include <arpa/inet.h> /* for inet_ntop */ | |
static int connect_server(const char * caddr, uint16_t port) | |
{ | |
int sockfd; | |
struct sockaddr_in addr; | |
/* AF_INET: IPv4 protocol | |
* SOCK_STREAM: TCP protocol | |
*/ | |
if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) { | |
fprintf(stderr, "Socket creation failed: %s\n", strerror(errno)); | |
exit(1); | |
} | |
memset(&addr, 0, sizeof(addr)); | |
addr.sin_family = AF_INET; | |
addr.sin_port = htons(port); | |
/* NOTE: inet_pton returns 1 on success. This differs from syscall */ | |
if (inet_pton(AF_INET, caddr, &addr.sin_addr) == 0) { | |
fprintf(stderr, "Conversion of IP address %s failed.\n", caddr); | |
exit(1); | |
} | |
/* connect to server @ address:port */ | |
if (connect(sockfd, (struct sockaddr *) &addr, sizeof(addr)) == -1) { | |
fprintf(stderr, "Failed to connect socket to %s:%u : %m\n", | |
caddr, port); | |
exit(1); | |
} | |
return sockfd; | |
} | |
void send_msg(int sockfd, char * msg) | |
{ | |
uint8_t len; | |
if (strlen(msg) > 254) { /* truncate our string because we limit to 255 character msg (including null byte) */ | |
msg[254] = 0; | |
} | |
len = strlen(msg) + 1; | |
/* FIXME: add checking for send return length */ | |
send(sockfd, &len, 1, 0); | |
send(sockfd, msg, strlen(msg) + 1, 0); | |
} | |
int main(int argc, char * argv[]) | |
{ | |
int sock_fd; | |
unsigned long port; | |
char * caddr, * endptr; | |
if (argc != 4) { | |
fprintf(stderr, "Usage: %s address port_number message\n", argv[0]); | |
exit(1); | |
} | |
caddr = argv[1]; | |
port = strtoul(argv[2], &endptr, 10); | |
if (endptr[0] != 0 || port > UINT16_MAX) { | |
fprintf(stderr, "Invalid argument %s for port number\n", argv[2]); | |
exit(1); | |
} | |
sock_fd = connect_server(caddr, port); | |
send_msg(sock_fd, argv[3]); | |
close(sock_fd); | |
return 0; | |
} |
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