Parse response header data as returned by curl_fetch, either as a set of strings or into a named list.
parse_headers(txt, multiple = FALSE)
parse_headers_list(txt)The parse_headers_list function parses the headers into a normalized (lowercase field names, trimmed whitespace) named list.
If a request has followed redirects, the data can contain multiple sets of headers. When multiple = TRUE, the function returns a list with the response headers for each request. By default it only returns the headers of the final request.
req <- curl_fetch_memory("https://hb.cran.dev/redirect/3")
parse_headers(req$headers)
#> [1] "HTTP/2 200 "
#> [2] "date: Tue, 08 Jul 2025 20:26:04 GMT"
#> [3] "content-type: application/json"
#> [4] "server: cloudflare"
#> [5] "nel: {\"report_to\":\"cf-nel\",\"success_fraction\":0.0,\"max_age\":604800}"
#> [6] "access-control-allow-origin: *"
#> [7] "access-control-allow-credentials: true"
#> [8] "x-powered-by: Flask"
#> [9] "x-processed-time: 0"
#> [10] "cf-cache-status: DYNAMIC"
#> [11] "report-to: {\"group\":\"cf-nel\",\"max_age\":604800,\"endpoints\":[{\"url\":\"https://a.nel.cloudflare.com/report/v4?s=md7gEGOiwJsWC8XZGxo7J%2FcsJyXclIXBeGOmv1zs%2FmkuYcy6mN2jg5fBtYQEDGO%2F4n0bLiz1zxEwK8FhYNocHbp323uwDHwMsg%3D%3D\"}]}"
#> [12] "content-encoding: zstd"
#> [13] "cf-ray: 95c25083882d7118-YYZ"
#> [14] "alt-svc: h3=\":443\"; ma=86400"
parse_headers(req$headers, multiple = TRUE)
#> [[1]]
#> [1] "HTTP/2 302 "
#> [2] "date: Tue, 08 Jul 2025 20:26:04 GMT"
#> [3] "content-type: text/html; charset=utf-8"
#> [4] "server: cloudflare"
#> [5] "nel: {\"report_to\":\"cf-nel\",\"success_fraction\":0.0,\"max_age\":604800}"
#> [6] "location: /relative-redirect/2"
#> [7] "access-control-allow-origin: *"
#> [8] "access-control-allow-credentials: true"
#> [9] "x-powered-by: Flask"
#> [10] "x-processed-time: 0"
#> [11] "cf-cache-status: DYNAMIC"
#> [12] "report-to: {\"group\":\"cf-nel\",\"max_age\":604800,\"endpoints\":[{\"url\":\"https://a.nel.cloudflare.com/report/v4?s=Cwe0NioDLdSTV1vHsDtwAmPkMJe%2F%2B37TY7%2BLtHrsf%2BiZMeeboiwiAPO2rua%2Bl80GowtlxtMNKkFG%2F8PNGV7cG0PPqxxtm0eemw%3D%3D\"}]}"
#> [13] "cf-ray: 95c25082bf7c7118-YYZ"
#> [14] "alt-svc: h3=\":443\"; ma=86400"
#>
#> [[2]]
#> [1] "HTTP/2 302 "
#> [2] "date: Tue, 08 Jul 2025 20:26:04 GMT"
#> [3] "content-type: text/html; charset=utf-8"
#> [4] "server: cloudflare"
#> [5] "nel: {\"report_to\":\"cf-nel\",\"success_fraction\":0.0,\"max_age\":604800}"
#> [6] "location: /relative-redirect/1"
#> [7] "access-control-allow-origin: *"
#> [8] "access-control-allow-credentials: true"
#> [9] "x-powered-by: Flask"
#> [10] "x-processed-time: 0"
#> [11] "cf-cache-status: DYNAMIC"
#> [12] "report-to: {\"group\":\"cf-nel\",\"max_age\":604800,\"endpoints\":[{\"url\":\"https://a.nel.cloudflare.com/report/v4?s=Wg7SC2vp5abJQezi2AoA3BamNFrehZwaHKFTdQrz4fcthPhgNvYVqnb3ZsiCpHAq4xkQUC5EfvsorXRbg2ll76TN0AvFD0lBkA%3D%3D\"}]}"
#> [13] "cf-ray: 95c250830fbf7118-YYZ"
#> [14] "alt-svc: h3=\":443\"; ma=86400"
#>
#> [[3]]
#> [1] "HTTP/2 302 "
#> [2] "date: Tue, 08 Jul 2025 20:26:04 GMT"
#> [3] "content-type: text/html; charset=utf-8"
#> [4] "server: cloudflare"
#> [5] "nel: {\"report_to\":\"cf-nel\",\"success_fraction\":0.0,\"max_age\":604800}"
#> [6] "location: /get"
#> [7] "access-control-allow-origin: *"
#> [8] "access-control-allow-credentials: true"
#> [9] "x-powered-by: Flask"
#> [10] "x-processed-time: 0"
#> [11] "cf-cache-status: DYNAMIC"
#> [12] "report-to: {\"group\":\"cf-nel\",\"max_age\":604800,\"endpoints\":[{\"url\":\"https://a.nel.cloudflare.com/report/v4?s=jg9P2JCJ%2FxZ87OvrzKLDhPvHA4%2BeMg5UEtPoTH1MKK96lytgH61%2B3zUjTdh70yHzt0jcTXPYKNh1wETYZZb7yQCF73PYdGx2hg%3D%3D\"}]}"
#> [13] "cf-ray: 95c250834ff97118-YYZ"
#> [14] "alt-svc: h3=\":443\"; ma=86400"
#>
#> [[4]]
#> [1] "HTTP/2 200 "
#> [2] "date: Tue, 08 Jul 2025 20:26:04 GMT"
#> [3] "content-type: application/json"
#> [4] "server: cloudflare"
#> [5] "nel: {\"report_to\":\"cf-nel\",\"success_fraction\":0.0,\"max_age\":604800}"
#> [6] "access-control-allow-origin: *"
#> [7] "access-control-allow-credentials: true"
#> [8] "x-powered-by: Flask"
#> [9] "x-processed-time: 0"
#> [10] "cf-cache-status: DYNAMIC"
#> [11] "report-to: {\"group\":\"cf-nel\",\"max_age\":604800,\"endpoints\":[{\"url\":\"https://a.nel.cloudflare.com/report/v4?s=md7gEGOiwJsWC8XZGxo7J%2FcsJyXclIXBeGOmv1zs%2FmkuYcy6mN2jg5fBtYQEDGO%2F4n0bLiz1zxEwK8FhYNocHbp323uwDHwMsg%3D%3D\"}]}"
#> [12] "content-encoding: zstd"
#> [13] "cf-ray: 95c25083882d7118-YYZ"
#> [14] "alt-svc: h3=\":443\"; ma=86400"
#>
# Parse into named list
parse_headers_list(req$headers)
#> $date
#> [1] "Tue, 08 Jul 2025 20:26:04 GMT"
#>
#> $`content-type`
#> [1] "application/json"
#>
#> $server
#> [1] "cloudflare"
#>
#> $nel
#> [1] "{\"report_to\":\"cf-nel\",\"success_fraction\":0.0,\"max_age\":604800}"
#>
#> $`access-control-allow-origin`
#> [1] "*"
#>
#> $`access-control-allow-credentials`
#> [1] "true"
#>
#> $`x-powered-by`
#> [1] "Flask"
#>
#> $`x-processed-time`
#> [1] "0"
#>
#> $`cf-cache-status`
#> [1] "DYNAMIC"
#>
#> $`report-to`
#> [1] "{\"group\":\"cf-nel\",\"max_age\":604800,\"endpoints\":[{\"url\":\"https://a.nel.cloudflare.com/report/v4?s=md7gEGOiwJsWC8XZGxo7J%2FcsJyXclIXBeGOmv1zs%2FmkuYcy6mN2jg5fBtYQEDGO%2F4n0bLiz1zxEwK8FhYNocHbp323uwDHwMsg%3D%3D\"}]}"
#>
#> $`content-encoding`
#> [1] "zstd"
#>
#> $`cf-ray`
#> [1] "95c25083882d7118-YYZ"
#>
#> $`alt-svc`
#> [1] "h3=\":443\"; ma=86400"
#>