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samples: net: big_http_download: Add minimal support for redirect

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It's often the case with TLS file servers, that the download link does
not lead to downloaded file, but rather redirects to another server.
Therefore it makes sense to have a minimal support in the sample for
HTTP redirection, so that the file can still be downloaded.

Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>
This commit is contained in:
Robert Lubos 2022-12-07 13:28:59 +01:00 • committed by Carles Cufí
commit 1c911904d5
2 changed files with 140 additions and 13 deletions
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4
samples/net/sockets/big_http_download/Kconfig
View file

@ -11,6 +11,10 @@ config SAMPLE_BIG_HTTP_DL_URL
help
URL to download.
config SAMPLE_BIG_HTTP_DL_MAX_URL_LENGTH
int "Maximum length of the download URL"
default 256
config SAMPLE_BIG_HTTP_DL_NUM_ITER
int "Limit number of iterations"
default 0

149
samples/net/sockets/big_http_download/src/big_http_download.c
View file

@ -8,6 +8,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include "mbedtls/md.h"
@ -36,8 +37,14 @@
#define bytes2KiB(Bytes) (Bytes / (1024u))
#define bytes2MiB(Bytes) (Bytes / (1024u * 1024u))
#if defined(CONFIG_SAMPLE_BIG_HTTP_DL_MAX_URL_LENGTH)
#define MAX_URL_LENGTH CONFIG_SAMPLE_BIG_HTTP_DL_MAX_URL_LENGTH
#else
#define MAX_URL_LENGTH 256
#endif
/* This URL is parsed in-place, so buffer must be non-const. */
static char download_url[] =
static char download_url[MAX_URL_LENGTH] =
#if defined(CONFIG_SAMPLE_BIG_HTTP_DL_URL)
CONFIG_SAMPLE_BIG_HTTP_DL_URL;
#else
@ -99,30 +106,132 @@ ssize_t sendall(int sock, const void *buf, size_t len)
return 0;
}
int skip_headers(int sock)
static int parse_status(bool *redirect)
{
char *ptr;
int code;
ptr = strstr(response, "HTTP");
if (ptr == NULL) {
return -1;
}
ptr = strstr(response, " ");
if (ptr == NULL) {
return -1;
}
ptr++;
code = atoi(ptr);
if (code >= 300 && code < 400) {
*redirect = true;
}
return 0;
}
static int parse_header(bool *location_found)
{
char *ptr;
ptr = strstr(response, ":");
if (ptr == NULL) {
return 0;
}
*ptr = '\0';
ptr = response;
while (*ptr != '\0') {
*ptr = tolower(*ptr);
ptr++;
}
if (strcmp(response, "location") != 0) {
return 0;
}
/* Skip whitespace */
while (*(++ptr) == ' ') {
;
}
strncpy(download_url, ptr, sizeof(download_url));
download_url[sizeof(download_url) - 1] = '\0';
/* Trim LF. */
ptr = strstr(download_url, "\n");
if (ptr == NULL) {
printf("Redirect URL too long or malformed\n");
return -1;
}
*ptr = '\0';
/* Trim CR if present. */
ptr = strstr(download_url, "\r");
if (ptr != NULL) {
*ptr = '\0';
}
*location_found = true;
return 0;
}
int skip_headers(int sock, bool *redirect)
{
int state = 0;
int i = 0;
bool status_line = true;
bool redirect_code = false;
bool location_found = false;
while (1) {
char c;
int st;
st = recv(sock, &c, 1, 0);
st = recv(sock, response + i, 1, 0);
if (st <= 0) {
return st;
}
if (state == 0 && c == '\r') {
if (state == 0 && response[i] == '\r') {
state++;
} else if (state == 1 && c == '\n') {
} else if ((state == 0 || state == 1) && response[i] == '\n') {
state = 2;
response[i + 1] = '\0';
i = 0;
if (status_line) {
if (parse_status(&redirect_code) < 0) {
return -1;
}
status_line = false;
} else {
if (parse_header(&location_found) < 0) {
return -1;
}
}
continue;
} else if (state == 2 && response[i] == '\r') {
state++;
} else if (state == 2 && c == '\r') {
state++;
} else if (state == 3 && c == '\n') {
} else if ((state == 2 || state == 3) && response[i] == '\n') {
break;
} else {
state = 0;
}
i++;
if (i >= sizeof(response) - 1) {
i = 0;
}
}
if (redirect_code && location_found) {
*redirect = true;
}
return 1;
@ -135,7 +244,7 @@ void print_hex(const unsigned char *p, int len)
}
}
void download(struct addrinfo *ai, bool is_tls)
bool download(struct addrinfo *ai, bool is_tls, bool *redirect)
{
int sock;
struct timeval timeout = {
@ -143,13 +252,14 @@ void download(struct addrinfo *ai, bool is_tls)
};
cur_bytes = 0U;
*redirect = false;
if (is_tls) {
#if defined(CONFIG_NET_SOCKETS_SOCKOPT_TLS)
sock = socket(ai->ai_family, ai->ai_socktype, IPPROTO_TLS_1_2);
# else
printf("TLS not supported\n");
return;
return false;
#endif
} else {
sock = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
@ -184,11 +294,16 @@ void download(struct addrinfo *ai, bool is_tls)
sendall(sock, host, strlen(host));
sendall(sock, "\r\n\r\n", SSTRLEN("\r\n\r\n"));
if (skip_headers(sock) <= 0) {
if (skip_headers(sock, redirect) <= 0) {
printf("EOF or error in response headers\n");
goto error;
}
if (*redirect) {
printf("Server requested redirection to %s\n", download_url);
goto error;
}
mbedtls_md_starts(&hash_ctx);
while (1) {
@ -233,6 +348,8 @@ void download(struct addrinfo *ai, bool is_tls)
error:
(void)close(sock);
return redirect;
}
void main(void)
@ -245,6 +362,7 @@ void main(void)
int resolve_attempts = 10;
bool is_tls = false;
unsigned int num_iterations = CONFIG_SAMPLE_BIG_HTTP_DL_NUM_ITER;
bool redirect = false;
#if defined(CONFIG_NET_SOCKETS_SOCKOPT_TLS)
tls_credential_add(CA_CERTIFICATE_TAG, TLS_CREDENTIAL_CA_CERTIFICATE,
@ -253,6 +371,7 @@ void main(void)
setbuf(stdout, NULL);
redirect:
if (strncmp(download_url, "http://", SSTRLEN("http://")) == 0) {
port = "80";
p = download_url + SSTRLEN("http://");
@ -335,7 +454,11 @@ void main(void)
printf("\nIteration %u of %u:\n",
current_iteration, total_iterations);
}
download(res, is_tls);
download(res, is_tls, &redirect);
if (redirect) {
goto redirect;
}
total_bytes += cur_bytes;
printf("Total downloaded so far: %u MiB\n",