Seeking for help with C Gemini client

📧 Messages: 5
🗣️ Authors: 3
📅 First Message: 2020-08-19 11:36
📅 Last Message: 2020-08-19 18:26

1. Paul Warren (pwarren (a) pwarren.id.au)

📅 Sent: 2020-08-19 11:36
📧 Message 1 of 5

G'day!

Gemini, while simple, isn't quite that simple. All protocol commands and
responses are over TLS connections, so doing a send/recv on a raw
network socket will not work!

I'm not 100% sure on the best or simplest way to get a TLS stack going
in C, I've done some bits with OpenSSL, but it was not simple!

Cheers
--
Paul



On 19/8/20 11:57 pm, - wrote:
> Hello,
> 
> I've started writing a client for Gemini protocol, but since I've never 
been writing networking programs, I find myself at the dead end at the 
moment. Please could someone help me? When I send a request and get a 
response, the only thing I have in response is "gemini://" and nothing 
else. The code is given below:
> 
> #include <arpa/inet.h>
> #include <locale.h>
> #include <netdb.h>
> #include <netinet/in.h>
> #include <stdio.h>
> #include <stdlib.h>
> #include <string.h>
> #include <sys/types.h>
> #include <sys/socket.h>
> #include <unistd.h>
> 
> #define STATUS_CODE_INPUT 10
> #define STATUS_CODE_SENSITIVE_INPUT 11
> #define STATUS_CODE_SUCCESS 20
> #define STATUS_CODE_REDIRECT_TEMP 30
> #define STATUS_CODE_REDIRECT_PERM 31
> #define STATUS_CODE_TEMP_FAILURE 40
> #define STATUS_CODE_SERVER_UNAVAILABLE 41
> #define STATUS_CODE_CGI_ERROR 42
> #define STATUS_CODE_PROXY_ERROR 43
> #define STATUS_CODE_SLOW_DOWN 44
> #define STATUS_CODE_PERM_FAILURE 50
> #define STATUS_CODE_NOT_FOUND 51
> #define STATUS_CODE_GONE 52
> #define STATUS_CODE_PROXY_REQUEST_REFUSED 53
> #define STATUS_CODE_BAD_REQUEST 59
> #define STATUS_CODE_CLIENT_CERT_REQUIRED 60
> #define STATUS_CODE_CERT_NO_AUTH 61
> #define STATUS_CODE_CERT_NOT_VALID 62
> 
> #define GEMINI_PORT 1965
> 
> int main() {
> 	char *locale;
> 	locale = setlocale(LC_ALL, "");
> 	
> 	int sockfd = socket(AF_INET, SOCK_STREAM, 0);
> 	if (sockfd < 0) {
> 		perror("socket");
> 		exit(1);
> 	}
> 	char *url = malloc(sizeof(char)*1024);
> 	strcpy(url, "gemini://gemini.circumlunar.space/\r\n");
> 	char rec_buf[1029] = {0};
> 	struct hostent *host_entry;
> 	host_entry = gethostbyname(url);
> 	struct sockaddr_in addr;
> 	addr.sin_family = AF_INET;
> 	addr.sin_port = htons(GEMINI_PORT);
> 	addr.sin_addr.s_addr = htonl(INADDR_ANY);
> 	int opt = 1;
> 	if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) < 0) {
> 		perror("setsockopt");
> 		exit(1);
> 	}
> 	if (bind(sockfd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
> 		perror("bind");
> 		exit(2);
> 	}
> 	if (connect(sockfd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
> 		perror("connect");
> 		exit(3);
> 	}
> 	send(sockfd, url, sizeof(url), 0);
> 	recv(sockfd, rec_buf, sizeof(rec_buf), 0);
> 	printf("%s\n", rec_buf);
> 	close(sockfd);
> 	shutdown(sockfd, SHUT_RDWR);
> 	free(url);
> 	return 0;
> }
> 
> 

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2. - (anridellal (a) yandex.ru)

📅 Sent: 2020-08-19 13:57
📧 Message 2 of 5

Hello,

I've started writing a client for Gemini protocol, but since I've never 
been writing networking programs, I find myself at the dead end at the 
moment. Please could someone help me? When I send a request and get a 
response, the only thing I have in response is "gemini://" and nothing 
else. The code is given below:

#include <arpa/inet.h>
#include <locale.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>

#define STATUS_CODE_INPUT 10
#define STATUS_CODE_SENSITIVE_INPUT 11
#define STATUS_CODE_SUCCESS 20
#define STATUS_CODE_REDIRECT_TEMP 30
#define STATUS_CODE_REDIRECT_PERM 31
#define STATUS_CODE_TEMP_FAILURE 40
#define STATUS_CODE_SERVER_UNAVAILABLE 41
#define STATUS_CODE_CGI_ERROR 42
#define STATUS_CODE_PROXY_ERROR 43
#define STATUS_CODE_SLOW_DOWN 44
#define STATUS_CODE_PERM_FAILURE 50
#define STATUS_CODE_NOT_FOUND 51
#define STATUS_CODE_GONE 52
#define STATUS_CODE_PROXY_REQUEST_REFUSED 53
#define STATUS_CODE_BAD_REQUEST 59
#define STATUS_CODE_CLIENT_CERT_REQUIRED 60
#define STATUS_CODE_CERT_NO_AUTH 61
#define STATUS_CODE_CERT_NOT_VALID 62

#define GEMINI_PORT 1965

int main() {
	char *locale;
	locale = setlocale(LC_ALL, "");
	
	int sockfd = socket(AF_INET, SOCK_STREAM, 0);
	if (sockfd < 0) {
		perror("socket");
		exit(1);
	}
	char *url = malloc(sizeof(char)*1024);
	strcpy(url, "gemini://gemini.circumlunar.space/\r\n");
	char rec_buf[1029] = {0};
	struct hostent *host_entry;
	host_entry = gethostbyname(url);
	struct sockaddr_in addr;
	addr.sin_family = AF_INET;
	addr.sin_port = htons(GEMINI_PORT);
	addr.sin_addr.s_addr = htonl(INADDR_ANY);
	int opt = 1;
	if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) < 0) {
		perror("setsockopt");
		exit(1);
	}
	if (bind(sockfd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
		perror("bind");
		exit(2);
	}
	if (connect(sockfd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
		perror("connect");
		exit(3);
	}
	send(sockfd, url, sizeof(url), 0);
	recv(sockfd, rec_buf, sizeof(rec_buf), 0);
	printf("%s\n", rec_buf);
	close(sockfd);
	shutdown(sockfd, SHUT_RDWR);
	free(url);
	return 0;
}


-- 
- <anridellal at yandex.ru>

Link to individual message.

3. Kevin Sangeelee (kevin (a) susa.net)

📅 Sent: 2020-08-19 14:55
📧 Message 3 of 5

This is something I had been tinkering with, before getting distracted
onto something else(!). I found two examples of simple echo servers,
one for GnuTLS and one OpenSSL. The code is here

    gemini://gemini.susa.net/c/

Both certainly compiled (I have binaries on disk), but I can't recall
any more detail than that, so just sharing this as a pointer to the
original poster.

Kevin

On Wed, 19 Aug 2020 at 12:36, Paul Warren <pwarren at pwarren.id.au> wrote:
>
> G'day!
>
> Gemini, while simple, isn't quite that simple. All protocol commands and
> responses are over TLS connections, so doing a send/recv on a raw
> network socket will not work!
>
> I'm not 100% sure on the best or simplest way to get a TLS stack going
> in C, I've done some bits with OpenSSL, but it was not simple!
>
> Cheers
> --
> Paul
>
>
>
> On 19/8/20 11:57 pm, - wrote:
> > Hello,
> >
> > I've started writing a client for Gemini protocol, but since I've 
never been writing networking programs, I find myself at the dead end at 
the moment. Please could someone help me? When I send a request and get a 
response, the only thing I have in response is "gemini://" and nothing 
else. The code is given below:
> >
> > #include <arpa/inet.h>
> > #include <locale.h>
> > #include <netdb.h>
> > #include <netinet/in.h>
> > #include <stdio.h>
> > #include <stdlib.h>
> > #include <string.h>
> > #include <sys/types.h>
> > #include <sys/socket.h>
> > #include <unistd.h>
> >
> > #define STATUS_CODE_INPUT 10
> > #define STATUS_CODE_SENSITIVE_INPUT 11
> > #define STATUS_CODE_SUCCESS 20
> > #define STATUS_CODE_REDIRECT_TEMP 30
> > #define STATUS_CODE_REDIRECT_PERM 31
> > #define STATUS_CODE_TEMP_FAILURE 40
> > #define STATUS_CODE_SERVER_UNAVAILABLE 41
> > #define STATUS_CODE_CGI_ERROR 42
> > #define STATUS_CODE_PROXY_ERROR 43
> > #define STATUS_CODE_SLOW_DOWN 44
> > #define STATUS_CODE_PERM_FAILURE 50
> > #define STATUS_CODE_NOT_FOUND 51
> > #define STATUS_CODE_GONE 52
> > #define STATUS_CODE_PROXY_REQUEST_REFUSED 53
> > #define STATUS_CODE_BAD_REQUEST 59
> > #define STATUS_CODE_CLIENT_CERT_REQUIRED 60
> > #define STATUS_CODE_CERT_NO_AUTH 61
> > #define STATUS_CODE_CERT_NOT_VALID 62
> >
> > #define GEMINI_PORT 1965
> >
> > int main() {
> >       char *locale;
> >       locale = setlocale(LC_ALL, "");
> >
> >       int sockfd = socket(AF_INET, SOCK_STREAM, 0);
> >       if (sockfd < 0) {
> >               perror("socket");
> >               exit(1);
> >       }
> >       char *url = malloc(sizeof(char)*1024);
> >       strcpy(url, "gemini://gemini.circumlunar.space/\r\n");
> >       char rec_buf[1029] = {0};
> >       struct hostent *host_entry;
> >       host_entry = gethostbyname(url);
> >       struct sockaddr_in addr;
> >       addr.sin_family = AF_INET;
> >       addr.sin_port = htons(GEMINI_PORT);
> >       addr.sin_addr.s_addr = htonl(INADDR_ANY);
> >       int opt = 1;
> >       if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) < 0) {
> >               perror("setsockopt");
> >               exit(1);
> >       }
> >       if (bind(sockfd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
> >               perror("bind");
> >               exit(2);
> >       }
> >       if (connect(sockfd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
> >               perror("connect");
> >               exit(3);
> >       }
> >       send(sockfd, url, sizeof(url), 0);
> >       recv(sockfd, rec_buf, sizeof(rec_buf), 0);
> >       printf("%s\n", rec_buf);
> >       close(sockfd);
> >       shutdown(sockfd, SHUT_RDWR);
> >       free(url);
> >       return 0;
> > }
> >
> >
>

Link to individual message.

4. - (anridellal (a) yandex.ru)

📅 Sent: 2020-08-19 15:03
📧 Message 4 of 5

I think I misread some parts of specification. Thank you very much.

On Wed, 19 Aug 2020 21:36:18 +1000
Paul Warren <pwarren at pwarren.id.au> wrote:

> G'day!
> 
> Gemini, while simple, isn't quite that simple. All protocol commands and
> responses are over TLS connections, so doing a send/recv on a raw
> network socket will not work!
> 
> I'm not 100% sure on the best or simplest way to get a TLS stack going
> in C, I've done some bits with OpenSSL, but it was not simple!
> 
> Cheers
> --
> Paul
> 
> 
> 
> On 19/8/20 11:57 pm, - wrote:
> > Hello,
> > 
> > I've started writing a client for Gemini protocol, but since I've 
never been writing networking programs, I find myself at the dead end at 
the moment. Please could someone help me? When I send a request and get a 
response, the only thing I have in response is "gemini://" and nothing 
else. The code is given below:
> > 
> > #include <arpa/inet.h>
> > #include <locale.h>
> > #include <netdb.h>
> > #include <netinet/in.h>
> > #include <stdio.h>
> > #include <stdlib.h>
> > #include <string.h>
> > #include <sys/types.h>
> > #include <sys/socket.h>
> > #include <unistd.h>
> > 
> > #define STATUS_CODE_INPUT 10
> > #define STATUS_CODE_SENSITIVE_INPUT 11
> > #define STATUS_CODE_SUCCESS 20
> > #define STATUS_CODE_REDIRECT_TEMP 30
> > #define STATUS_CODE_REDIRECT_PERM 31
> > #define STATUS_CODE_TEMP_FAILURE 40
> > #define STATUS_CODE_SERVER_UNAVAILABLE 41
> > #define STATUS_CODE_CGI_ERROR 42
> > #define STATUS_CODE_PROXY_ERROR 43
> > #define STATUS_CODE_SLOW_DOWN 44
> > #define STATUS_CODE_PERM_FAILURE 50
> > #define STATUS_CODE_NOT_FOUND 51
> > #define STATUS_CODE_GONE 52
> > #define STATUS_CODE_PROXY_REQUEST_REFUSED 53
> > #define STATUS_CODE_BAD_REQUEST 59
> > #define STATUS_CODE_CLIENT_CERT_REQUIRED 60
> > #define STATUS_CODE_CERT_NO_AUTH 61
> > #define STATUS_CODE_CERT_NOT_VALID 62
> > 
> > #define GEMINI_PORT 1965
> > 
> > int main() {
> > 	char *locale;
> > 	locale = setlocale(LC_ALL, "");
> > 	
> > 	int sockfd = socket(AF_INET, SOCK_STREAM, 0);
> > 	if (sockfd < 0) {
> > 		perror("socket");
> > 		exit(1);
> > 	}
> > 	char *url = malloc(sizeof(char)*1024);
> > 	strcpy(url, "gemini://gemini.circumlunar.space/\r\n");
> > 	char rec_buf[1029] = {0};
> > 	struct hostent *host_entry;
> > 	host_entry = gethostbyname(url);
> > 	struct sockaddr_in addr;
> > 	addr.sin_family = AF_INET;
> > 	addr.sin_port = htons(GEMINI_PORT);
> > 	addr.sin_addr.s_addr = htonl(INADDR_ANY);
> > 	int opt = 1;
> > 	if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) < 0) {
> > 		perror("setsockopt");
> > 		exit(1);
> > 	}
> > 	if (bind(sockfd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
> > 		perror("bind");
> > 		exit(2);
> > 	}
> > 	if (connect(sockfd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
> > 		perror("connect");
> > 		exit(3);
> > 	}
> > 	send(sockfd, url, sizeof(url), 0);
> > 	recv(sockfd, rec_buf, sizeof(rec_buf), 0);
> > 	printf("%s\n", rec_buf);
> > 	close(sockfd);
> > 	shutdown(sockfd, SHUT_RDWR);
> > 	free(url);
> > 	return 0;
> > }
> > 
> > 
> 


-- 
- <anridellal at yandex.ru>

Link to individual message.

5. - (anridellal (a) yandex.ru)

📅 Sent: 2020-08-19 18:26
📧 Message 5 of 5

Thank you.
I managed to make it work with LibreSSL's libtls:

https://man.openbsd.org/tls_init.3

Sharing the code in case someone wants to take a look at an implementation 
(the code is far from perfection, but I'll fix it later):

#include <arpa/inet.h>
#include <locale.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <tls.h>
#include <unistd.h>

#define STATUS_CODE_INPUT "10"
#define STATUS_CODE_SENSITIVE_INPUT "11"
#define STATUS_CODE_SUCCESS "20"
#define STATUS_CODE_REDIRECT_TEMP "30"
#define STATUS_CODE_REDIRECT_PERM "31"
#define STATUS_CODE_TEMP_FAILURE "40"
#define STATUS_CODE_SERVER_UNAVAILABLE "41"
#define STATUS_CODE_CGI_ERROR "42"
#define STATUS_CODE_PROXY_ERROR "43"
#define STATUS_CODE_SLOW_DOWN "44"
#define STATUS_CODE_PERM_FAILURE "50"
#define STATUS_CODE_NOT_FOUND "51"
#define STATUS_CODE_GONE "52"
#define STATUS_CODE_PROXY_REQUEST_REFUSED "53"
#define STATUS_CODE_BAD_REQUEST "59"
#define STATUS_CODE_CLIENT_CERT_REQUIRED "60"
#define STATUS_CODE_CERT_NO_AUTH "61"
#define STATUS_CODE_CERT_NOT_VALID "62"

#define GEMINI_PORT "1965"

int main() {
	char *locale;
	locale = setlocale(LC_ALL, "");
	
	tls_init();
	struct tls_config *tlsconf = tls_config_new();

	struct tls *client = tls_client();
	tls_config_set_protocols(tlsconf, TLS_PROTOCOL_TLSv1_3);
	tls_configure(client, tlsconf);

	const char *hostname = "gemini.circumlunar.space";

	char *url = malloc(sizeof(char)*1024);
	strcpy(url, "gemini://gemini.circumlunar.space/");
	char rec_buf[1029];
	int writebytes = sprintf(url, "%s\r\n", url);
	tls_connect(client, hostname, GEMINI_PORT);
	while (writebytes > 0) {
		ssize_t outbytes;

		outbytes = tls_write(client, url, (size_t)writebytes);
		if (outbytes == TLS_WANT_POLLIN || outbytes == TLS_WANT_POLLOUT)
			continue;
		if (outbytes == -1) {
			perror("tls_write");
		}
		url += outbytes;
		writebytes -= outbytes;
	}
	// read header
	tls_read(client, rec_buf, sizeof(rec_buf));
	printf("%s\n", rec_buf);
	char status_code[3];
	strncpy(status_code, rec_buf, 2);
	if (strcmp(status_code, STATUS_CODE_SUCCESS) == 0) {
		writebytes = tls_read(client, rec_buf, (size_t)sizeof(rec_buf));
		printf("%d\n", writebytes);
		while (writebytes > 0) {
			printf(rec_buf);
			writebytes = tls_read(client, rec_buf, (size_t)writebytes);
			printf("\n%d\n", writebytes);
		}
		printf("\r\n");
	}

	tls_close(client);
	tls_free(client);
	return 0;
}

On Wed, 19 Aug 2020 15:55:00 +0100
Kevin Sangeelee <kevin at susa.net> wrote:

> This is something I had been tinkering with, before getting distracted
> onto something else(!). I found two examples of simple echo servers,
> one for GnuTLS and one OpenSSL. The code is here
> 
>     gemini://gemini.susa.net/c/
> 
> Both certainly compiled (I have binaries on disk), but I can't recall
> any more detail than that, so just sharing this as a pointer to the
> original poster.
> 
> Kevin
> 
> On Wed, 19 Aug 2020 at 12:36, Paul Warren <pwarren at pwarren.id.au> wrote:
> >
> > G'day!
> >
> > Gemini, while simple, isn't quite that simple. All protocol commands and
> > responses are over TLS connections, so doing a send/recv on a raw
> > network socket will not work!
> >
> > I'm not 100% sure on the best or simplest way to get a TLS stack going
> > in C, I've done some bits with OpenSSL, but it was not simple!
> >
> > Cheers
> > --
> > Paul
> >
> >
> >
> > On 19/8/20 11:57 pm, - wrote:
> > > Hello,
> > >
> > > I've started writing a client for Gemini protocol, but since I've 
never been writing networking programs, I find myself at the dead end at 
the moment. Please could someone help me? When I send a request and get a 
response, the only thing I have in response is "gemini://" and nothing 
else. The code is given below:
> > >
> > > #include <arpa/inet.h>
> > > #include <locale.h>
> > > #include <netdb.h>
> > > #include <netinet/in.h>
> > > #include <stdio.h>
> > > #include <stdlib.h>
> > > #include <string.h>
> > > #include <sys/types.h>
> > > #include <sys/socket.h>
> > > #include <unistd.h>
> > >
> > > #define STATUS_CODE_INPUT 10
> > > #define STATUS_CODE_SENSITIVE_INPUT 11
> > > #define STATUS_CODE_SUCCESS 20
> > > #define STATUS_CODE_REDIRECT_TEMP 30
> > > #define STATUS_CODE_REDIRECT_PERM 31
> > > #define STATUS_CODE_TEMP_FAILURE 40
> > > #define STATUS_CODE_SERVER_UNAVAILABLE 41
> > > #define STATUS_CODE_CGI_ERROR 42
> > > #define STATUS_CODE_PROXY_ERROR 43
> > > #define STATUS_CODE_SLOW_DOWN 44
> > > #define STATUS_CODE_PERM_FAILURE 50
> > > #define STATUS_CODE_NOT_FOUND 51
> > > #define STATUS_CODE_GONE 52
> > > #define STATUS_CODE_PROXY_REQUEST_REFUSED 53
> > > #define STATUS_CODE_BAD_REQUEST 59
> > > #define STATUS_CODE_CLIENT_CERT_REQUIRED 60
> > > #define STATUS_CODE_CERT_NO_AUTH 61
> > > #define STATUS_CODE_CERT_NOT_VALID 62
> > >
> > > #define GEMINI_PORT 1965
> > >
> > > int main() {
> > >       char *locale;
> > >       locale = setlocale(LC_ALL, "");
> > >
> > >       int sockfd = socket(AF_INET, SOCK_STREAM, 0);
> > >       if (sockfd < 0) {
> > >               perror("socket");
> > >               exit(1);
> > >       }
> > >       char *url = malloc(sizeof(char)*1024);
> > >       strcpy(url, "gemini://gemini.circumlunar.space/\r\n");
> > >       char rec_buf[1029] = {0};
> > >       struct hostent *host_entry;
> > >       host_entry = gethostbyname(url);
> > >       struct sockaddr_in addr;
> > >       addr.sin_family = AF_INET;
> > >       addr.sin_port = htons(GEMINI_PORT);
> > >       addr.sin_addr.s_addr = htonl(INADDR_ANY);
> > >       int opt = 1;
> > >       if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt)) < 0) {
> > >               perror("setsockopt");
> > >               exit(1);
> > >       }
> > >       if (bind(sockfd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
> > >               perror("bind");
> > >               exit(2);
> > >       }
> > >       if (connect(sockfd, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
> > >               perror("connect");
> > >               exit(3);
> > >       }
> > >       send(sockfd, url, sizeof(url), 0);
> > >       recv(sockfd, rec_buf, sizeof(rec_buf), 0);
> > >       printf("%s\n", rec_buf);
> > >       close(sockfd);
> > >       shutdown(sockfd, SHUT_RDWR);
> > >       free(url);
> > >       return 0;
> > > }
> > >
> > >
> >


-- 
- <anridellal at yandex.ru>

Link to individual message.

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